Commit | Line | Data |
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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
1da177e4 LT |
2 | /* |
3 | * linux/arch/x86_64/entry.S | |
4 | * | |
5 | * Copyright (C) 1991, 1992 Linus Torvalds | |
6 | * Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs | |
7 | * Copyright (C) 2000 Pavel Machek <pavel@suse.cz> | |
4d732138 | 8 | * |
1da177e4 LT |
9 | * entry.S contains the system-call and fault low-level handling routines. |
10 | * | |
8b4777a4 AL |
11 | * Some of this is documented in Documentation/x86/entry_64.txt |
12 | * | |
0bd7b798 | 13 | * A note on terminology: |
4d732138 IM |
14 | * - iret frame: Architecture defined interrupt frame from SS to RIP |
15 | * at the top of the kernel process stack. | |
2e91a17b AK |
16 | * |
17 | * Some macro usage: | |
4d732138 IM |
18 | * - ENTRY/END: Define functions in the symbol table. |
19 | * - TRACE_IRQ_*: Trace hardirq state for lock debugging. | |
20 | * - idtentry: Define exception entry points. | |
1da177e4 | 21 | */ |
1da177e4 LT |
22 | #include <linux/linkage.h> |
23 | #include <asm/segment.h> | |
1da177e4 LT |
24 | #include <asm/cache.h> |
25 | #include <asm/errno.h> | |
e2d5df93 | 26 | #include <asm/asm-offsets.h> |
1da177e4 LT |
27 | #include <asm/msr.h> |
28 | #include <asm/unistd.h> | |
29 | #include <asm/thread_info.h> | |
30 | #include <asm/hw_irq.h> | |
0341c14d | 31 | #include <asm/page_types.h> |
2601e64d | 32 | #include <asm/irqflags.h> |
72fe4858 | 33 | #include <asm/paravirt.h> |
9939ddaf | 34 | #include <asm/percpu.h> |
d7abc0fa | 35 | #include <asm/asm.h> |
63bcff2a | 36 | #include <asm/smap.h> |
3891a04a | 37 | #include <asm/pgtable_types.h> |
784d5699 | 38 | #include <asm/export.h> |
8c1f7558 | 39 | #include <asm/frame.h> |
2641f08b | 40 | #include <asm/nospec-branch.h> |
d7e7528b | 41 | #include <linux/err.h> |
1da177e4 | 42 | |
6fd166aa PZ |
43 | #include "calling.h" |
44 | ||
4d732138 IM |
45 | .code64 |
46 | .section .entry.text, "ax" | |
16444a8a | 47 | |
72fe4858 | 48 | #ifdef CONFIG_PARAVIRT |
2be29982 | 49 | ENTRY(native_usergs_sysret64) |
8c1f7558 | 50 | UNWIND_HINT_EMPTY |
72fe4858 GOC |
51 | swapgs |
52 | sysretq | |
8c1f7558 | 53 | END(native_usergs_sysret64) |
72fe4858 GOC |
54 | #endif /* CONFIG_PARAVIRT */ |
55 | ||
ca37e57b | 56 | .macro TRACE_IRQS_FLAGS flags:req |
2601e64d | 57 | #ifdef CONFIG_TRACE_IRQFLAGS |
ca37e57b | 58 | bt $9, \flags /* interrupts off? */ |
4d732138 | 59 | jnc 1f |
2601e64d IM |
60 | TRACE_IRQS_ON |
61 | 1: | |
62 | #endif | |
63 | .endm | |
64 | ||
ca37e57b AL |
65 | .macro TRACE_IRQS_IRETQ |
66 | TRACE_IRQS_FLAGS EFLAGS(%rsp) | |
67 | .endm | |
68 | ||
5963e317 SR |
69 | /* |
70 | * When dynamic function tracer is enabled it will add a breakpoint | |
71 | * to all locations that it is about to modify, sync CPUs, update | |
72 | * all the code, sync CPUs, then remove the breakpoints. In this time | |
73 | * if lockdep is enabled, it might jump back into the debug handler | |
74 | * outside the updating of the IST protection. (TRACE_IRQS_ON/OFF). | |
75 | * | |
76 | * We need to change the IDT table before calling TRACE_IRQS_ON/OFF to | |
77 | * make sure the stack pointer does not get reset back to the top | |
78 | * of the debug stack, and instead just reuses the current stack. | |
79 | */ | |
80 | #if defined(CONFIG_DYNAMIC_FTRACE) && defined(CONFIG_TRACE_IRQFLAGS) | |
81 | ||
82 | .macro TRACE_IRQS_OFF_DEBUG | |
4d732138 | 83 | call debug_stack_set_zero |
5963e317 | 84 | TRACE_IRQS_OFF |
4d732138 | 85 | call debug_stack_reset |
5963e317 SR |
86 | .endm |
87 | ||
88 | .macro TRACE_IRQS_ON_DEBUG | |
4d732138 | 89 | call debug_stack_set_zero |
5963e317 | 90 | TRACE_IRQS_ON |
4d732138 | 91 | call debug_stack_reset |
5963e317 SR |
92 | .endm |
93 | ||
f2db9382 | 94 | .macro TRACE_IRQS_IRETQ_DEBUG |
4d732138 IM |
95 | bt $9, EFLAGS(%rsp) /* interrupts off? */ |
96 | jnc 1f | |
5963e317 SR |
97 | TRACE_IRQS_ON_DEBUG |
98 | 1: | |
99 | .endm | |
100 | ||
101 | #else | |
4d732138 IM |
102 | # define TRACE_IRQS_OFF_DEBUG TRACE_IRQS_OFF |
103 | # define TRACE_IRQS_ON_DEBUG TRACE_IRQS_ON | |
104 | # define TRACE_IRQS_IRETQ_DEBUG TRACE_IRQS_IRETQ | |
5963e317 SR |
105 | #endif |
106 | ||
1da177e4 | 107 | /* |
4d732138 | 108 | * 64-bit SYSCALL instruction entry. Up to 6 arguments in registers. |
1da177e4 | 109 | * |
fda57b22 AL |
110 | * This is the only entry point used for 64-bit system calls. The |
111 | * hardware interface is reasonably well designed and the register to | |
112 | * argument mapping Linux uses fits well with the registers that are | |
113 | * available when SYSCALL is used. | |
114 | * | |
115 | * SYSCALL instructions can be found inlined in libc implementations as | |
116 | * well as some other programs and libraries. There are also a handful | |
117 | * of SYSCALL instructions in the vDSO used, for example, as a | |
118 | * clock_gettimeofday fallback. | |
119 | * | |
4d732138 | 120 | * 64-bit SYSCALL saves rip to rcx, clears rflags.RF, then saves rflags to r11, |
b87cf63e DV |
121 | * then loads new ss, cs, and rip from previously programmed MSRs. |
122 | * rflags gets masked by a value from another MSR (so CLD and CLAC | |
123 | * are not needed). SYSCALL does not save anything on the stack | |
124 | * and does not change rsp. | |
125 | * | |
126 | * Registers on entry: | |
1da177e4 | 127 | * rax system call number |
b87cf63e DV |
128 | * rcx return address |
129 | * r11 saved rflags (note: r11 is callee-clobbered register in C ABI) | |
1da177e4 | 130 | * rdi arg0 |
1da177e4 | 131 | * rsi arg1 |
0bd7b798 | 132 | * rdx arg2 |
b87cf63e | 133 | * r10 arg3 (needs to be moved to rcx to conform to C ABI) |
1da177e4 LT |
134 | * r8 arg4 |
135 | * r9 arg5 | |
4d732138 | 136 | * (note: r12-r15, rbp, rbx are callee-preserved in C ABI) |
0bd7b798 | 137 | * |
1da177e4 LT |
138 | * Only called from user space. |
139 | * | |
7fcb3bc3 | 140 | * When user can change pt_regs->foo always force IRET. That is because |
7bf36bbc AK |
141 | * it deals with uncanonical addresses better. SYSRET has trouble |
142 | * with them due to bugs in both AMD and Intel CPUs. | |
0bd7b798 | 143 | */ |
1da177e4 | 144 | |
3386bc8a AL |
145 | .pushsection .entry_trampoline, "ax" |
146 | ||
147 | /* | |
148 | * The code in here gets remapped into cpu_entry_area's trampoline. This means | |
149 | * that the assembler and linker have the wrong idea as to where this code | |
150 | * lives (and, in fact, it's mapped more than once, so it's not even at a | |
151 | * fixed address). So we can't reference any symbols outside the entry | |
152 | * trampoline and expect it to work. | |
153 | * | |
154 | * Instead, we carefully abuse %rip-relative addressing. | |
155 | * _entry_trampoline(%rip) refers to the start of the remapped) entry | |
156 | * trampoline. We can thus find cpu_entry_area with this macro: | |
157 | */ | |
158 | ||
159 | #define CPU_ENTRY_AREA \ | |
160 | _entry_trampoline - CPU_ENTRY_AREA_entry_trampoline(%rip) | |
161 | ||
162 | /* The top word of the SYSENTER stack is hot and is usable as scratch space. */ | |
4fe2d8b1 DH |
163 | #define RSP_SCRATCH CPU_ENTRY_AREA_entry_stack + \ |
164 | SIZEOF_entry_stack - 8 + CPU_ENTRY_AREA | |
3386bc8a AL |
165 | |
166 | ENTRY(entry_SYSCALL_64_trampoline) | |
167 | UNWIND_HINT_EMPTY | |
168 | swapgs | |
169 | ||
170 | /* Stash the user RSP. */ | |
171 | movq %rsp, RSP_SCRATCH | |
172 | ||
8a09317b DH |
173 | /* Note: using %rsp as a scratch reg. */ |
174 | SWITCH_TO_KERNEL_CR3 scratch_reg=%rsp | |
175 | ||
3386bc8a AL |
176 | /* Load the top of the task stack into RSP */ |
177 | movq CPU_ENTRY_AREA_tss + TSS_sp1 + CPU_ENTRY_AREA, %rsp | |
178 | ||
179 | /* Start building the simulated IRET frame. */ | |
180 | pushq $__USER_DS /* pt_regs->ss */ | |
181 | pushq RSP_SCRATCH /* pt_regs->sp */ | |
182 | pushq %r11 /* pt_regs->flags */ | |
183 | pushq $__USER_CS /* pt_regs->cs */ | |
184 | pushq %rcx /* pt_regs->ip */ | |
185 | ||
186 | /* | |
187 | * x86 lacks a near absolute jump, and we can't jump to the real | |
188 | * entry text with a relative jump. We could push the target | |
189 | * address and then use retq, but this destroys the pipeline on | |
190 | * many CPUs (wasting over 20 cycles on Sandy Bridge). Instead, | |
191 | * spill RDI and restore it in a second-stage trampoline. | |
192 | */ | |
193 | pushq %rdi | |
194 | movq $entry_SYSCALL_64_stage2, %rdi | |
2641f08b | 195 | JMP_NOSPEC %rdi |
3386bc8a AL |
196 | END(entry_SYSCALL_64_trampoline) |
197 | ||
198 | .popsection | |
199 | ||
200 | ENTRY(entry_SYSCALL_64_stage2) | |
201 | UNWIND_HINT_EMPTY | |
202 | popq %rdi | |
203 | jmp entry_SYSCALL_64_after_hwframe | |
204 | END(entry_SYSCALL_64_stage2) | |
205 | ||
b2502b41 | 206 | ENTRY(entry_SYSCALL_64) |
8c1f7558 | 207 | UNWIND_HINT_EMPTY |
9ed8e7d8 DV |
208 | /* |
209 | * Interrupts are off on entry. | |
210 | * We do not frame this tiny irq-off block with TRACE_IRQS_OFF/ON, | |
211 | * it is too small to ever cause noticeable irq latency. | |
212 | */ | |
72fe4858 | 213 | |
8a9949bc | 214 | swapgs |
8a09317b | 215 | /* |
14b1fcc6 | 216 | * This path is only taken when PAGE_TABLE_ISOLATION is disabled so it |
8a09317b DH |
217 | * is not required to switch CR3. |
218 | */ | |
4d732138 IM |
219 | movq %rsp, PER_CPU_VAR(rsp_scratch) |
220 | movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp | |
9ed8e7d8 DV |
221 | |
222 | /* Construct struct pt_regs on stack */ | |
4d732138 IM |
223 | pushq $__USER_DS /* pt_regs->ss */ |
224 | pushq PER_CPU_VAR(rsp_scratch) /* pt_regs->sp */ | |
4d732138 IM |
225 | pushq %r11 /* pt_regs->flags */ |
226 | pushq $__USER_CS /* pt_regs->cs */ | |
227 | pushq %rcx /* pt_regs->ip */ | |
8a9949bc | 228 | GLOBAL(entry_SYSCALL_64_after_hwframe) |
4d732138 IM |
229 | pushq %rax /* pt_regs->orig_ax */ |
230 | pushq %rdi /* pt_regs->di */ | |
231 | pushq %rsi /* pt_regs->si */ | |
232 | pushq %rdx /* pt_regs->dx */ | |
233 | pushq %rcx /* pt_regs->cx */ | |
234 | pushq $-ENOSYS /* pt_regs->ax */ | |
235 | pushq %r8 /* pt_regs->r8 */ | |
236 | pushq %r9 /* pt_regs->r9 */ | |
237 | pushq %r10 /* pt_regs->r10 */ | |
8e1eb3fa DW |
238 | /* |
239 | * Clear extra registers that a speculation attack might | |
240 | * otherwise want to exploit. Interleave XOR with PUSH | |
241 | * for better uop scheduling: | |
242 | */ | |
243 | xorq %r10, %r10 /* nospec r10 */ | |
4d732138 | 244 | pushq %r11 /* pt_regs->r11 */ |
8e1eb3fa | 245 | xorq %r11, %r11 /* nospec r11 */ |
d1f77320 | 246 | pushq %rbx /* pt_regs->rbx */ |
8e1eb3fa | 247 | xorl %ebx, %ebx /* nospec rbx */ |
d1f77320 | 248 | pushq %rbp /* pt_regs->rbp */ |
8e1eb3fa | 249 | xorl %ebp, %ebp /* nospec rbp */ |
d1f77320 | 250 | pushq %r12 /* pt_regs->r12 */ |
8e1eb3fa | 251 | xorq %r12, %r12 /* nospec r12 */ |
d1f77320 | 252 | pushq %r13 /* pt_regs->r13 */ |
8e1eb3fa | 253 | xorq %r13, %r13 /* nospec r13 */ |
d1f77320 | 254 | pushq %r14 /* pt_regs->r14 */ |
8e1eb3fa | 255 | xorq %r14, %r14 /* nospec r14 */ |
d1f77320 | 256 | pushq %r15 /* pt_regs->r15 */ |
8e1eb3fa | 257 | xorq %r15, %r15 /* nospec r15 */ |
d1f77320 | 258 | UNWIND_HINT_REGS |
4d732138 | 259 | |
548c3050 AL |
260 | TRACE_IRQS_OFF |
261 | ||
1e423bff | 262 | /* IRQs are off. */ |
29ea1b25 | 263 | movq %rsp, %rdi |
1e423bff AL |
264 | call do_syscall_64 /* returns with IRQs disabled */ |
265 | ||
29ea1b25 | 266 | TRACE_IRQS_IRETQ /* we're about to change IF */ |
fffbb5dc DV |
267 | |
268 | /* | |
269 | * Try to use SYSRET instead of IRET if we're returning to | |
8a055d7f AL |
270 | * a completely clean 64-bit userspace context. If we're not, |
271 | * go to the slow exit path. | |
fffbb5dc | 272 | */ |
4d732138 IM |
273 | movq RCX(%rsp), %rcx |
274 | movq RIP(%rsp), %r11 | |
8a055d7f AL |
275 | |
276 | cmpq %rcx, %r11 /* SYSRET requires RCX == RIP */ | |
277 | jne swapgs_restore_regs_and_return_to_usermode | |
fffbb5dc DV |
278 | |
279 | /* | |
280 | * On Intel CPUs, SYSRET with non-canonical RCX/RIP will #GP | |
281 | * in kernel space. This essentially lets the user take over | |
17be0aec | 282 | * the kernel, since userspace controls RSP. |
fffbb5dc | 283 | * |
17be0aec | 284 | * If width of "canonical tail" ever becomes variable, this will need |
fffbb5dc | 285 | * to be updated to remain correct on both old and new CPUs. |
361b4b58 | 286 | * |
cbe0317b KS |
287 | * Change top bits to match most significant bit (47th or 56th bit |
288 | * depending on paging mode) in the address. | |
fffbb5dc | 289 | */ |
17be0aec DV |
290 | shl $(64 - (__VIRTUAL_MASK_SHIFT+1)), %rcx |
291 | sar $(64 - (__VIRTUAL_MASK_SHIFT+1)), %rcx | |
4d732138 | 292 | |
17be0aec DV |
293 | /* If this changed %rcx, it was not canonical */ |
294 | cmpq %rcx, %r11 | |
8a055d7f | 295 | jne swapgs_restore_regs_and_return_to_usermode |
fffbb5dc | 296 | |
4d732138 | 297 | cmpq $__USER_CS, CS(%rsp) /* CS must match SYSRET */ |
8a055d7f | 298 | jne swapgs_restore_regs_and_return_to_usermode |
fffbb5dc | 299 | |
4d732138 IM |
300 | movq R11(%rsp), %r11 |
301 | cmpq %r11, EFLAGS(%rsp) /* R11 == RFLAGS */ | |
8a055d7f | 302 | jne swapgs_restore_regs_and_return_to_usermode |
fffbb5dc DV |
303 | |
304 | /* | |
3e035305 BP |
305 | * SYSCALL clears RF when it saves RFLAGS in R11 and SYSRET cannot |
306 | * restore RF properly. If the slowpath sets it for whatever reason, we | |
307 | * need to restore it correctly. | |
308 | * | |
309 | * SYSRET can restore TF, but unlike IRET, restoring TF results in a | |
310 | * trap from userspace immediately after SYSRET. This would cause an | |
311 | * infinite loop whenever #DB happens with register state that satisfies | |
312 | * the opportunistic SYSRET conditions. For example, single-stepping | |
313 | * this user code: | |
fffbb5dc | 314 | * |
4d732138 | 315 | * movq $stuck_here, %rcx |
fffbb5dc DV |
316 | * pushfq |
317 | * popq %r11 | |
318 | * stuck_here: | |
319 | * | |
320 | * would never get past 'stuck_here'. | |
321 | */ | |
4d732138 | 322 | testq $(X86_EFLAGS_RF|X86_EFLAGS_TF), %r11 |
8a055d7f | 323 | jnz swapgs_restore_regs_and_return_to_usermode |
fffbb5dc DV |
324 | |
325 | /* nothing to check for RSP */ | |
326 | ||
4d732138 | 327 | cmpq $__USER_DS, SS(%rsp) /* SS must match SYSRET */ |
8a055d7f | 328 | jne swapgs_restore_regs_and_return_to_usermode |
fffbb5dc DV |
329 | |
330 | /* | |
4d732138 IM |
331 | * We win! This label is here just for ease of understanding |
332 | * perf profiles. Nothing jumps here. | |
fffbb5dc DV |
333 | */ |
334 | syscall_return_via_sysret: | |
17be0aec | 335 | /* rcx and r11 are already restored (see code above) */ |
8c1f7558 | 336 | UNWIND_HINT_EMPTY |
502af0d7 | 337 | POP_REGS pop_rdi=0 skip_r11rcx=1 |
3e3b9293 AL |
338 | |
339 | /* | |
340 | * Now all regs are restored except RSP and RDI. | |
341 | * Save old stack pointer and switch to trampoline stack. | |
342 | */ | |
343 | movq %rsp, %rdi | |
c482feef | 344 | movq PER_CPU_VAR(cpu_tss_rw + TSS_sp0), %rsp |
3e3b9293 AL |
345 | |
346 | pushq RSP-RDI(%rdi) /* RSP */ | |
347 | pushq (%rdi) /* RDI */ | |
348 | ||
349 | /* | |
350 | * We are on the trampoline stack. All regs except RDI are live. | |
351 | * We can do future final exit work right here. | |
352 | */ | |
6fd166aa | 353 | SWITCH_TO_USER_CR3_STACK scratch_reg=%rdi |
3e3b9293 | 354 | |
4fbb3910 | 355 | popq %rdi |
3e3b9293 | 356 | popq %rsp |
fffbb5dc | 357 | USERGS_SYSRET64 |
b2502b41 | 358 | END(entry_SYSCALL_64) |
0bd7b798 | 359 | |
0100301b BG |
360 | /* |
361 | * %rdi: prev task | |
362 | * %rsi: next task | |
363 | */ | |
364 | ENTRY(__switch_to_asm) | |
8c1f7558 | 365 | UNWIND_HINT_FUNC |
0100301b BG |
366 | /* |
367 | * Save callee-saved registers | |
368 | * This must match the order in inactive_task_frame | |
369 | */ | |
370 | pushq %rbp | |
371 | pushq %rbx | |
372 | pushq %r12 | |
373 | pushq %r13 | |
374 | pushq %r14 | |
375 | pushq %r15 | |
376 | ||
377 | /* switch stack */ | |
378 | movq %rsp, TASK_threadsp(%rdi) | |
379 | movq TASK_threadsp(%rsi), %rsp | |
380 | ||
381 | #ifdef CONFIG_CC_STACKPROTECTOR | |
382 | movq TASK_stack_canary(%rsi), %rbx | |
383 | movq %rbx, PER_CPU_VAR(irq_stack_union)+stack_canary_offset | |
384 | #endif | |
385 | ||
c995efd5 DW |
386 | #ifdef CONFIG_RETPOLINE |
387 | /* | |
388 | * When switching from a shallower to a deeper call stack | |
389 | * the RSB may either underflow or use entries populated | |
390 | * with userspace addresses. On CPUs where those concerns | |
391 | * exist, overwrite the RSB with entries which capture | |
392 | * speculative execution to prevent attack. | |
393 | */ | |
1dde7415 BP |
394 | /* Clobbers %rbx */ |
395 | FILL_RETURN_BUFFER RSB_CLEAR_LOOPS, X86_FEATURE_RSB_CTXSW | |
c995efd5 DW |
396 | #endif |
397 | ||
0100301b BG |
398 | /* restore callee-saved registers */ |
399 | popq %r15 | |
400 | popq %r14 | |
401 | popq %r13 | |
402 | popq %r12 | |
403 | popq %rbx | |
404 | popq %rbp | |
405 | ||
406 | jmp __switch_to | |
407 | END(__switch_to_asm) | |
408 | ||
1eeb207f DV |
409 | /* |
410 | * A newly forked process directly context switches into this address. | |
411 | * | |
0100301b | 412 | * rax: prev task we switched from |
616d2483 BG |
413 | * rbx: kernel thread func (NULL for user thread) |
414 | * r12: kernel thread arg | |
1eeb207f DV |
415 | */ |
416 | ENTRY(ret_from_fork) | |
8c1f7558 | 417 | UNWIND_HINT_EMPTY |
0100301b | 418 | movq %rax, %rdi |
ebd57499 | 419 | call schedule_tail /* rdi: 'prev' task parameter */ |
1eeb207f | 420 | |
ebd57499 JP |
421 | testq %rbx, %rbx /* from kernel_thread? */ |
422 | jnz 1f /* kernel threads are uncommon */ | |
24d978b7 | 423 | |
616d2483 | 424 | 2: |
8c1f7558 | 425 | UNWIND_HINT_REGS |
ebd57499 | 426 | movq %rsp, %rdi |
24d978b7 AL |
427 | call syscall_return_slowpath /* returns with IRQs disabled */ |
428 | TRACE_IRQS_ON /* user mode is traced as IRQS on */ | |
8a055d7f | 429 | jmp swapgs_restore_regs_and_return_to_usermode |
616d2483 BG |
430 | |
431 | 1: | |
432 | /* kernel thread */ | |
433 | movq %r12, %rdi | |
2641f08b | 434 | CALL_NOSPEC %rbx |
616d2483 BG |
435 | /* |
436 | * A kernel thread is allowed to return here after successfully | |
437 | * calling do_execve(). Exit to userspace to complete the execve() | |
438 | * syscall. | |
439 | */ | |
440 | movq $0, RAX(%rsp) | |
441 | jmp 2b | |
1eeb207f DV |
442 | END(ret_from_fork) |
443 | ||
939b7871 | 444 | /* |
3304c9c3 DV |
445 | * Build the entry stubs with some assembler magic. |
446 | * We pack 1 stub into every 8-byte block. | |
939b7871 | 447 | */ |
3304c9c3 | 448 | .align 8 |
939b7871 | 449 | ENTRY(irq_entries_start) |
3304c9c3 DV |
450 | vector=FIRST_EXTERNAL_VECTOR |
451 | .rept (FIRST_SYSTEM_VECTOR - FIRST_EXTERNAL_VECTOR) | |
8c1f7558 | 452 | UNWIND_HINT_IRET_REGS |
4d732138 | 453 | pushq $(~vector+0x80) /* Note: always in signed byte range */ |
3304c9c3 | 454 | jmp common_interrupt |
3304c9c3 | 455 | .align 8 |
8c1f7558 | 456 | vector=vector+1 |
3304c9c3 | 457 | .endr |
939b7871 PA |
458 | END(irq_entries_start) |
459 | ||
1d3e53e8 AL |
460 | .macro DEBUG_ENTRY_ASSERT_IRQS_OFF |
461 | #ifdef CONFIG_DEBUG_ENTRY | |
e17f8234 BO |
462 | pushq %rax |
463 | SAVE_FLAGS(CLBR_RAX) | |
464 | testl $X86_EFLAGS_IF, %eax | |
1d3e53e8 AL |
465 | jz .Lokay_\@ |
466 | ud2 | |
467 | .Lokay_\@: | |
e17f8234 | 468 | popq %rax |
1d3e53e8 AL |
469 | #endif |
470 | .endm | |
471 | ||
472 | /* | |
473 | * Enters the IRQ stack if we're not already using it. NMI-safe. Clobbers | |
474 | * flags and puts old RSP into old_rsp, and leaves all other GPRs alone. | |
475 | * Requires kernel GSBASE. | |
476 | * | |
477 | * The invariant is that, if irq_count != -1, then the IRQ stack is in use. | |
478 | */ | |
8c1f7558 | 479 | .macro ENTER_IRQ_STACK regs=1 old_rsp |
1d3e53e8 AL |
480 | DEBUG_ENTRY_ASSERT_IRQS_OFF |
481 | movq %rsp, \old_rsp | |
8c1f7558 JP |
482 | |
483 | .if \regs | |
484 | UNWIND_HINT_REGS base=\old_rsp | |
485 | .endif | |
486 | ||
1d3e53e8 | 487 | incl PER_CPU_VAR(irq_count) |
29955909 | 488 | jnz .Lirq_stack_push_old_rsp_\@ |
1d3e53e8 AL |
489 | |
490 | /* | |
491 | * Right now, if we just incremented irq_count to zero, we've | |
492 | * claimed the IRQ stack but we haven't switched to it yet. | |
493 | * | |
494 | * If anything is added that can interrupt us here without using IST, | |
495 | * it must be *extremely* careful to limit its stack usage. This | |
496 | * could include kprobes and a hypothetical future IST-less #DB | |
497 | * handler. | |
29955909 AL |
498 | * |
499 | * The OOPS unwinder relies on the word at the top of the IRQ | |
500 | * stack linking back to the previous RSP for the entire time we're | |
501 | * on the IRQ stack. For this to work reliably, we need to write | |
502 | * it before we actually move ourselves to the IRQ stack. | |
503 | */ | |
504 | ||
505 | movq \old_rsp, PER_CPU_VAR(irq_stack_union + IRQ_STACK_SIZE - 8) | |
506 | movq PER_CPU_VAR(irq_stack_ptr), %rsp | |
507 | ||
508 | #ifdef CONFIG_DEBUG_ENTRY | |
509 | /* | |
510 | * If the first movq above becomes wrong due to IRQ stack layout | |
511 | * changes, the only way we'll notice is if we try to unwind right | |
512 | * here. Assert that we set up the stack right to catch this type | |
513 | * of bug quickly. | |
1d3e53e8 | 514 | */ |
29955909 AL |
515 | cmpq -8(%rsp), \old_rsp |
516 | je .Lirq_stack_okay\@ | |
517 | ud2 | |
518 | .Lirq_stack_okay\@: | |
519 | #endif | |
1d3e53e8 | 520 | |
29955909 | 521 | .Lirq_stack_push_old_rsp_\@: |
1d3e53e8 | 522 | pushq \old_rsp |
8c1f7558 JP |
523 | |
524 | .if \regs | |
525 | UNWIND_HINT_REGS indirect=1 | |
526 | .endif | |
1d3e53e8 AL |
527 | .endm |
528 | ||
529 | /* | |
530 | * Undoes ENTER_IRQ_STACK. | |
531 | */ | |
8c1f7558 | 532 | .macro LEAVE_IRQ_STACK regs=1 |
1d3e53e8 AL |
533 | DEBUG_ENTRY_ASSERT_IRQS_OFF |
534 | /* We need to be off the IRQ stack before decrementing irq_count. */ | |
535 | popq %rsp | |
536 | ||
8c1f7558 JP |
537 | .if \regs |
538 | UNWIND_HINT_REGS | |
539 | .endif | |
540 | ||
1d3e53e8 AL |
541 | /* |
542 | * As in ENTER_IRQ_STACK, irq_count == 0, we are still claiming | |
543 | * the irq stack but we're not on it. | |
544 | */ | |
545 | ||
546 | decl PER_CPU_VAR(irq_count) | |
547 | .endm | |
548 | ||
d99015b1 | 549 | /* |
1da177e4 LT |
550 | * Interrupt entry/exit. |
551 | * | |
552 | * Interrupt entry points save only callee clobbered registers in fast path. | |
d99015b1 AH |
553 | * |
554 | * Entry runs with interrupts off. | |
555 | */ | |
1da177e4 | 556 | |
722024db | 557 | /* 0(%rsp): ~(interrupt number) */ |
1da177e4 | 558 | .macro interrupt func |
f6f64681 | 559 | cld |
7f2590a1 AL |
560 | |
561 | testb $3, CS-ORIG_RAX(%rsp) | |
562 | jz 1f | |
563 | SWAPGS | |
564 | call switch_to_thread_stack | |
565 | 1: | |
566 | ||
3f01daec | 567 | PUSH_AND_CLEAR_REGS |
946c1911 | 568 | ENCODE_FRAME_POINTER |
76f5df43 | 569 | |
ff467594 | 570 | testb $3, CS(%rsp) |
dde74f2e | 571 | jz 1f |
02bc7768 AL |
572 | |
573 | /* | |
7f2590a1 AL |
574 | * IRQ from user mode. |
575 | * | |
f1075053 AL |
576 | * We need to tell lockdep that IRQs are off. We can't do this until |
577 | * we fix gsbase, and we should do it before enter_from_user_mode | |
578 | * (which can take locks). Since TRACE_IRQS_OFF idempotent, | |
579 | * the simplest way to handle it is to just call it twice if | |
580 | * we enter from user mode. There's no reason to optimize this since | |
581 | * TRACE_IRQS_OFF is a no-op if lockdep is off. | |
582 | */ | |
583 | TRACE_IRQS_OFF | |
584 | ||
478dc89c | 585 | CALL_enter_from_user_mode |
02bc7768 | 586 | |
76f5df43 | 587 | 1: |
1d3e53e8 | 588 | ENTER_IRQ_STACK old_rsp=%rdi |
f6f64681 DV |
589 | /* We entered an interrupt context - irqs are off: */ |
590 | TRACE_IRQS_OFF | |
591 | ||
a586f98e | 592 | call \func /* rdi points to pt_regs */ |
1da177e4 LT |
593 | .endm |
594 | ||
722024db AH |
595 | /* |
596 | * The interrupt stubs push (~vector+0x80) onto the stack and | |
597 | * then jump to common_interrupt. | |
598 | */ | |
939b7871 PA |
599 | .p2align CONFIG_X86_L1_CACHE_SHIFT |
600 | common_interrupt: | |
ee4eb87b | 601 | ASM_CLAC |
4d732138 | 602 | addq $-0x80, (%rsp) /* Adjust vector to [-256, -1] range */ |
1da177e4 | 603 | interrupt do_IRQ |
34061f13 | 604 | /* 0(%rsp): old RSP */ |
7effaa88 | 605 | ret_from_intr: |
2140a994 | 606 | DISABLE_INTERRUPTS(CLBR_ANY) |
2601e64d | 607 | TRACE_IRQS_OFF |
625dbc3b | 608 | |
1d3e53e8 | 609 | LEAVE_IRQ_STACK |
625dbc3b | 610 | |
03335e95 | 611 | testb $3, CS(%rsp) |
dde74f2e | 612 | jz retint_kernel |
4d732138 | 613 | |
02bc7768 | 614 | /* Interrupt came from user space */ |
02bc7768 AL |
615 | GLOBAL(retint_user) |
616 | mov %rsp,%rdi | |
617 | call prepare_exit_to_usermode | |
2601e64d | 618 | TRACE_IRQS_IRETQ |
26c4ef9c | 619 | |
8a055d7f | 620 | GLOBAL(swapgs_restore_regs_and_return_to_usermode) |
26c4ef9c AL |
621 | #ifdef CONFIG_DEBUG_ENTRY |
622 | /* Assert that pt_regs indicates user mode. */ | |
1e4c4f61 | 623 | testb $3, CS(%rsp) |
26c4ef9c AL |
624 | jnz 1f |
625 | ud2 | |
626 | 1: | |
627 | #endif | |
502af0d7 | 628 | POP_REGS pop_rdi=0 |
3e3b9293 AL |
629 | |
630 | /* | |
631 | * The stack is now user RDI, orig_ax, RIP, CS, EFLAGS, RSP, SS. | |
632 | * Save old stack pointer and switch to trampoline stack. | |
633 | */ | |
634 | movq %rsp, %rdi | |
c482feef | 635 | movq PER_CPU_VAR(cpu_tss_rw + TSS_sp0), %rsp |
3e3b9293 AL |
636 | |
637 | /* Copy the IRET frame to the trampoline stack. */ | |
638 | pushq 6*8(%rdi) /* SS */ | |
639 | pushq 5*8(%rdi) /* RSP */ | |
640 | pushq 4*8(%rdi) /* EFLAGS */ | |
641 | pushq 3*8(%rdi) /* CS */ | |
642 | pushq 2*8(%rdi) /* RIP */ | |
643 | ||
644 | /* Push user RDI on the trampoline stack. */ | |
645 | pushq (%rdi) | |
646 | ||
647 | /* | |
648 | * We are on the trampoline stack. All regs except RDI are live. | |
649 | * We can do future final exit work right here. | |
650 | */ | |
651 | ||
6fd166aa | 652 | SWITCH_TO_USER_CR3_STACK scratch_reg=%rdi |
8a09317b | 653 | |
3e3b9293 AL |
654 | /* Restore RDI. */ |
655 | popq %rdi | |
656 | SWAPGS | |
26c4ef9c AL |
657 | INTERRUPT_RETURN |
658 | ||
2601e64d | 659 | |
627276cb | 660 | /* Returning to kernel space */ |
6ba71b76 | 661 | retint_kernel: |
627276cb DV |
662 | #ifdef CONFIG_PREEMPT |
663 | /* Interrupts are off */ | |
664 | /* Check if we need preemption */ | |
4d732138 | 665 | bt $9, EFLAGS(%rsp) /* were interrupts off? */ |
6ba71b76 | 666 | jnc 1f |
4d732138 | 667 | 0: cmpl $0, PER_CPU_VAR(__preempt_count) |
36acef25 | 668 | jnz 1f |
627276cb | 669 | call preempt_schedule_irq |
36acef25 | 670 | jmp 0b |
6ba71b76 | 671 | 1: |
627276cb | 672 | #endif |
2601e64d IM |
673 | /* |
674 | * The iretq could re-enable interrupts: | |
675 | */ | |
676 | TRACE_IRQS_IRETQ | |
fffbb5dc | 677 | |
26c4ef9c AL |
678 | GLOBAL(restore_regs_and_return_to_kernel) |
679 | #ifdef CONFIG_DEBUG_ENTRY | |
680 | /* Assert that pt_regs indicates kernel mode. */ | |
1e4c4f61 | 681 | testb $3, CS(%rsp) |
26c4ef9c AL |
682 | jz 1f |
683 | ud2 | |
684 | 1: | |
685 | #endif | |
502af0d7 | 686 | POP_REGS |
e872045b | 687 | addq $8, %rsp /* skip regs->orig_ax */ |
7209a75d AL |
688 | INTERRUPT_RETURN |
689 | ||
690 | ENTRY(native_iret) | |
8c1f7558 | 691 | UNWIND_HINT_IRET_REGS |
3891a04a PA |
692 | /* |
693 | * Are we returning to a stack segment from the LDT? Note: in | |
694 | * 64-bit mode SS:RSP on the exception stack is always valid. | |
695 | */ | |
34273f41 | 696 | #ifdef CONFIG_X86_ESPFIX64 |
4d732138 IM |
697 | testb $4, (SS-RIP)(%rsp) |
698 | jnz native_irq_return_ldt | |
34273f41 | 699 | #endif |
3891a04a | 700 | |
af726f21 | 701 | .global native_irq_return_iret |
7209a75d | 702 | native_irq_return_iret: |
b645af2d AL |
703 | /* |
704 | * This may fault. Non-paranoid faults on return to userspace are | |
705 | * handled by fixup_bad_iret. These include #SS, #GP, and #NP. | |
706 | * Double-faults due to espfix64 are handled in do_double_fault. | |
707 | * Other faults here are fatal. | |
708 | */ | |
1da177e4 | 709 | iretq |
3701d863 | 710 | |
34273f41 | 711 | #ifdef CONFIG_X86_ESPFIX64 |
7209a75d | 712 | native_irq_return_ldt: |
85063fac AL |
713 | /* |
714 | * We are running with user GSBASE. All GPRs contain their user | |
715 | * values. We have a percpu ESPFIX stack that is eight slots | |
716 | * long (see ESPFIX_STACK_SIZE). espfix_waddr points to the bottom | |
717 | * of the ESPFIX stack. | |
718 | * | |
719 | * We clobber RAX and RDI in this code. We stash RDI on the | |
720 | * normal stack and RAX on the ESPFIX stack. | |
721 | * | |
722 | * The ESPFIX stack layout we set up looks like this: | |
723 | * | |
724 | * --- top of ESPFIX stack --- | |
725 | * SS | |
726 | * RSP | |
727 | * RFLAGS | |
728 | * CS | |
729 | * RIP <-- RSP points here when we're done | |
730 | * RAX <-- espfix_waddr points here | |
731 | * --- bottom of ESPFIX stack --- | |
732 | */ | |
733 | ||
734 | pushq %rdi /* Stash user RDI */ | |
8a09317b DH |
735 | SWAPGS /* to kernel GS */ |
736 | SWITCH_TO_KERNEL_CR3 scratch_reg=%rdi /* to kernel CR3 */ | |
737 | ||
4d732138 | 738 | movq PER_CPU_VAR(espfix_waddr), %rdi |
85063fac AL |
739 | movq %rax, (0*8)(%rdi) /* user RAX */ |
740 | movq (1*8)(%rsp), %rax /* user RIP */ | |
4d732138 | 741 | movq %rax, (1*8)(%rdi) |
85063fac | 742 | movq (2*8)(%rsp), %rax /* user CS */ |
4d732138 | 743 | movq %rax, (2*8)(%rdi) |
85063fac | 744 | movq (3*8)(%rsp), %rax /* user RFLAGS */ |
4d732138 | 745 | movq %rax, (3*8)(%rdi) |
85063fac | 746 | movq (5*8)(%rsp), %rax /* user SS */ |
4d732138 | 747 | movq %rax, (5*8)(%rdi) |
85063fac | 748 | movq (4*8)(%rsp), %rax /* user RSP */ |
4d732138 | 749 | movq %rax, (4*8)(%rdi) |
85063fac AL |
750 | /* Now RAX == RSP. */ |
751 | ||
752 | andl $0xffff0000, %eax /* RAX = (RSP & 0xffff0000) */ | |
85063fac AL |
753 | |
754 | /* | |
755 | * espfix_stack[31:16] == 0. The page tables are set up such that | |
756 | * (espfix_stack | (X & 0xffff0000)) points to a read-only alias of | |
757 | * espfix_waddr for any X. That is, there are 65536 RO aliases of | |
758 | * the same page. Set up RSP so that RSP[31:16] contains the | |
759 | * respective 16 bits of the /userspace/ RSP and RSP nonetheless | |
760 | * still points to an RO alias of the ESPFIX stack. | |
761 | */ | |
4d732138 | 762 | orq PER_CPU_VAR(espfix_stack), %rax |
8a09317b | 763 | |
6fd166aa | 764 | SWITCH_TO_USER_CR3_STACK scratch_reg=%rdi |
8a09317b DH |
765 | SWAPGS /* to user GS */ |
766 | popq %rdi /* Restore user RDI */ | |
767 | ||
4d732138 | 768 | movq %rax, %rsp |
8c1f7558 | 769 | UNWIND_HINT_IRET_REGS offset=8 |
85063fac AL |
770 | |
771 | /* | |
772 | * At this point, we cannot write to the stack any more, but we can | |
773 | * still read. | |
774 | */ | |
775 | popq %rax /* Restore user RAX */ | |
776 | ||
777 | /* | |
778 | * RSP now points to an ordinary IRET frame, except that the page | |
779 | * is read-only and RSP[31:16] are preloaded with the userspace | |
780 | * values. We can now IRET back to userspace. | |
781 | */ | |
4d732138 | 782 | jmp native_irq_return_iret |
34273f41 | 783 | #endif |
4b787e0b | 784 | END(common_interrupt) |
3891a04a | 785 | |
1da177e4 LT |
786 | /* |
787 | * APIC interrupts. | |
0bd7b798 | 788 | */ |
cf910e83 | 789 | .macro apicinterrupt3 num sym do_sym |
322648d1 | 790 | ENTRY(\sym) |
8c1f7558 | 791 | UNWIND_HINT_IRET_REGS |
ee4eb87b | 792 | ASM_CLAC |
4d732138 | 793 | pushq $~(\num) |
39e95433 | 794 | .Lcommon_\sym: |
322648d1 | 795 | interrupt \do_sym |
4d732138 | 796 | jmp ret_from_intr |
322648d1 AH |
797 | END(\sym) |
798 | .endm | |
1da177e4 | 799 | |
469f0023 | 800 | /* Make sure APIC interrupt handlers end up in the irqentry section: */ |
229a7186 MH |
801 | #define PUSH_SECTION_IRQENTRY .pushsection .irqentry.text, "ax" |
802 | #define POP_SECTION_IRQENTRY .popsection | |
469f0023 | 803 | |
cf910e83 | 804 | .macro apicinterrupt num sym do_sym |
469f0023 | 805 | PUSH_SECTION_IRQENTRY |
cf910e83 | 806 | apicinterrupt3 \num \sym \do_sym |
469f0023 | 807 | POP_SECTION_IRQENTRY |
cf910e83 SA |
808 | .endm |
809 | ||
322648d1 | 810 | #ifdef CONFIG_SMP |
4d732138 IM |
811 | apicinterrupt3 IRQ_MOVE_CLEANUP_VECTOR irq_move_cleanup_interrupt smp_irq_move_cleanup_interrupt |
812 | apicinterrupt3 REBOOT_VECTOR reboot_interrupt smp_reboot_interrupt | |
322648d1 | 813 | #endif |
1da177e4 | 814 | |
03b48632 | 815 | #ifdef CONFIG_X86_UV |
4d732138 | 816 | apicinterrupt3 UV_BAU_MESSAGE uv_bau_message_intr1 uv_bau_message_interrupt |
03b48632 | 817 | #endif |
4d732138 IM |
818 | |
819 | apicinterrupt LOCAL_TIMER_VECTOR apic_timer_interrupt smp_apic_timer_interrupt | |
820 | apicinterrupt X86_PLATFORM_IPI_VECTOR x86_platform_ipi smp_x86_platform_ipi | |
89b831ef | 821 | |
d78f2664 | 822 | #ifdef CONFIG_HAVE_KVM |
4d732138 IM |
823 | apicinterrupt3 POSTED_INTR_VECTOR kvm_posted_intr_ipi smp_kvm_posted_intr_ipi |
824 | apicinterrupt3 POSTED_INTR_WAKEUP_VECTOR kvm_posted_intr_wakeup_ipi smp_kvm_posted_intr_wakeup_ipi | |
210f84b0 | 825 | apicinterrupt3 POSTED_INTR_NESTED_VECTOR kvm_posted_intr_nested_ipi smp_kvm_posted_intr_nested_ipi |
d78f2664 YZ |
826 | #endif |
827 | ||
33e5ff63 | 828 | #ifdef CONFIG_X86_MCE_THRESHOLD |
4d732138 | 829 | apicinterrupt THRESHOLD_APIC_VECTOR threshold_interrupt smp_threshold_interrupt |
33e5ff63 SA |
830 | #endif |
831 | ||
24fd78a8 | 832 | #ifdef CONFIG_X86_MCE_AMD |
4d732138 | 833 | apicinterrupt DEFERRED_ERROR_VECTOR deferred_error_interrupt smp_deferred_error_interrupt |
24fd78a8 AG |
834 | #endif |
835 | ||
33e5ff63 | 836 | #ifdef CONFIG_X86_THERMAL_VECTOR |
4d732138 | 837 | apicinterrupt THERMAL_APIC_VECTOR thermal_interrupt smp_thermal_interrupt |
33e5ff63 | 838 | #endif |
1812924b | 839 | |
322648d1 | 840 | #ifdef CONFIG_SMP |
4d732138 IM |
841 | apicinterrupt CALL_FUNCTION_SINGLE_VECTOR call_function_single_interrupt smp_call_function_single_interrupt |
842 | apicinterrupt CALL_FUNCTION_VECTOR call_function_interrupt smp_call_function_interrupt | |
843 | apicinterrupt RESCHEDULE_VECTOR reschedule_interrupt smp_reschedule_interrupt | |
322648d1 | 844 | #endif |
1da177e4 | 845 | |
4d732138 IM |
846 | apicinterrupt ERROR_APIC_VECTOR error_interrupt smp_error_interrupt |
847 | apicinterrupt SPURIOUS_APIC_VECTOR spurious_interrupt smp_spurious_interrupt | |
0bd7b798 | 848 | |
e360adbe | 849 | #ifdef CONFIG_IRQ_WORK |
4d732138 | 850 | apicinterrupt IRQ_WORK_VECTOR irq_work_interrupt smp_irq_work_interrupt |
241771ef IM |
851 | #endif |
852 | ||
1da177e4 LT |
853 | /* |
854 | * Exception entry points. | |
0bd7b798 | 855 | */ |
c482feef | 856 | #define CPU_TSS_IST(x) PER_CPU_VAR(cpu_tss_rw) + (TSS_ist + ((x) - 1) * 8) |
577ed45e | 857 | |
7f2590a1 AL |
858 | /* |
859 | * Switch to the thread stack. This is called with the IRET frame and | |
860 | * orig_ax on the stack. (That is, RDI..R12 are not on the stack and | |
861 | * space has not been allocated for them.) | |
862 | */ | |
863 | ENTRY(switch_to_thread_stack) | |
864 | UNWIND_HINT_FUNC | |
865 | ||
866 | pushq %rdi | |
8a09317b DH |
867 | /* Need to switch before accessing the thread stack. */ |
868 | SWITCH_TO_KERNEL_CR3 scratch_reg=%rdi | |
7f2590a1 AL |
869 | movq %rsp, %rdi |
870 | movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp | |
871 | UNWIND_HINT sp_offset=16 sp_reg=ORC_REG_DI | |
872 | ||
873 | pushq 7*8(%rdi) /* regs->ss */ | |
874 | pushq 6*8(%rdi) /* regs->rsp */ | |
875 | pushq 5*8(%rdi) /* regs->eflags */ | |
876 | pushq 4*8(%rdi) /* regs->cs */ | |
877 | pushq 3*8(%rdi) /* regs->ip */ | |
878 | pushq 2*8(%rdi) /* regs->orig_ax */ | |
879 | pushq 8(%rdi) /* return address */ | |
880 | UNWIND_HINT_FUNC | |
881 | ||
882 | movq (%rdi), %rdi | |
883 | ret | |
884 | END(switch_to_thread_stack) | |
885 | ||
577ed45e | 886 | .macro idtentry sym do_sym has_error_code:req paranoid=0 shift_ist=-1 |
322648d1 | 887 | ENTRY(\sym) |
98990a33 | 888 | UNWIND_HINT_IRET_REGS offset=\has_error_code*8 |
8c1f7558 | 889 | |
577ed45e AL |
890 | /* Sanity check */ |
891 | .if \shift_ist != -1 && \paranoid == 0 | |
892 | .error "using shift_ist requires paranoid=1" | |
893 | .endif | |
894 | ||
ee4eb87b | 895 | ASM_CLAC |
cb5dd2c5 | 896 | |
82c62fa0 | 897 | .if \has_error_code == 0 |
4d732138 | 898 | pushq $-1 /* ORIG_RAX: no syscall to restart */ |
cb5dd2c5 AL |
899 | .endif |
900 | ||
76f5df43 | 901 | ALLOC_PT_GPREGS_ON_STACK |
cb5dd2c5 | 902 | |
7f2590a1 | 903 | .if \paranoid < 2 |
4d732138 | 904 | testb $3, CS(%rsp) /* If coming from userspace, switch stacks */ |
7f2590a1 | 905 | jnz .Lfrom_usermode_switch_stack_\@ |
48e08d0f | 906 | .endif |
7f2590a1 AL |
907 | |
908 | .if \paranoid | |
4d732138 | 909 | call paranoid_entry |
cb5dd2c5 | 910 | .else |
4d732138 | 911 | call error_entry |
cb5dd2c5 | 912 | .endif |
8c1f7558 | 913 | UNWIND_HINT_REGS |
ebfc453e | 914 | /* returned flag: ebx=0: need swapgs on exit, ebx=1: don't need it */ |
cb5dd2c5 | 915 | |
cb5dd2c5 | 916 | .if \paranoid |
577ed45e | 917 | .if \shift_ist != -1 |
4d732138 | 918 | TRACE_IRQS_OFF_DEBUG /* reload IDT in case of recursion */ |
577ed45e | 919 | .else |
b8b1d08b | 920 | TRACE_IRQS_OFF |
cb5dd2c5 | 921 | .endif |
577ed45e | 922 | .endif |
cb5dd2c5 | 923 | |
4d732138 | 924 | movq %rsp, %rdi /* pt_regs pointer */ |
cb5dd2c5 AL |
925 | |
926 | .if \has_error_code | |
4d732138 IM |
927 | movq ORIG_RAX(%rsp), %rsi /* get error code */ |
928 | movq $-1, ORIG_RAX(%rsp) /* no syscall to restart */ | |
cb5dd2c5 | 929 | .else |
4d732138 | 930 | xorl %esi, %esi /* no error code */ |
cb5dd2c5 AL |
931 | .endif |
932 | ||
577ed45e | 933 | .if \shift_ist != -1 |
4d732138 | 934 | subq $EXCEPTION_STKSZ, CPU_TSS_IST(\shift_ist) |
577ed45e AL |
935 | .endif |
936 | ||
4d732138 | 937 | call \do_sym |
cb5dd2c5 | 938 | |
577ed45e | 939 | .if \shift_ist != -1 |
4d732138 | 940 | addq $EXCEPTION_STKSZ, CPU_TSS_IST(\shift_ist) |
577ed45e AL |
941 | .endif |
942 | ||
ebfc453e | 943 | /* these procedures expect "no swapgs" flag in ebx */ |
cb5dd2c5 | 944 | .if \paranoid |
4d732138 | 945 | jmp paranoid_exit |
cb5dd2c5 | 946 | .else |
4d732138 | 947 | jmp error_exit |
cb5dd2c5 AL |
948 | .endif |
949 | ||
7f2590a1 | 950 | .if \paranoid < 2 |
48e08d0f | 951 | /* |
7f2590a1 | 952 | * Entry from userspace. Switch stacks and treat it |
48e08d0f AL |
953 | * as a normal entry. This means that paranoid handlers |
954 | * run in real process context if user_mode(regs). | |
955 | */ | |
7f2590a1 | 956 | .Lfrom_usermode_switch_stack_\@: |
4d732138 | 957 | call error_entry |
48e08d0f | 958 | |
4d732138 | 959 | movq %rsp, %rdi /* pt_regs pointer */ |
48e08d0f AL |
960 | |
961 | .if \has_error_code | |
4d732138 IM |
962 | movq ORIG_RAX(%rsp), %rsi /* get error code */ |
963 | movq $-1, ORIG_RAX(%rsp) /* no syscall to restart */ | |
48e08d0f | 964 | .else |
4d732138 | 965 | xorl %esi, %esi /* no error code */ |
48e08d0f AL |
966 | .endif |
967 | ||
4d732138 | 968 | call \do_sym |
48e08d0f | 969 | |
4d732138 | 970 | jmp error_exit /* %ebx: no swapgs flag */ |
48e08d0f | 971 | .endif |
ddeb8f21 | 972 | END(\sym) |
322648d1 | 973 | .endm |
b8b1d08b | 974 | |
4d732138 IM |
975 | idtentry divide_error do_divide_error has_error_code=0 |
976 | idtentry overflow do_overflow has_error_code=0 | |
977 | idtentry bounds do_bounds has_error_code=0 | |
978 | idtentry invalid_op do_invalid_op has_error_code=0 | |
979 | idtentry device_not_available do_device_not_available has_error_code=0 | |
980 | idtentry double_fault do_double_fault has_error_code=1 paranoid=2 | |
981 | idtentry coprocessor_segment_overrun do_coprocessor_segment_overrun has_error_code=0 | |
982 | idtentry invalid_TSS do_invalid_TSS has_error_code=1 | |
983 | idtentry segment_not_present do_segment_not_present has_error_code=1 | |
984 | idtentry spurious_interrupt_bug do_spurious_interrupt_bug has_error_code=0 | |
985 | idtentry coprocessor_error do_coprocessor_error has_error_code=0 | |
986 | idtentry alignment_check do_alignment_check has_error_code=1 | |
987 | idtentry simd_coprocessor_error do_simd_coprocessor_error has_error_code=0 | |
988 | ||
989 | ||
990 | /* | |
991 | * Reload gs selector with exception handling | |
992 | * edi: new selector | |
993 | */ | |
9f9d489a | 994 | ENTRY(native_load_gs_index) |
8c1f7558 | 995 | FRAME_BEGIN |
131484c8 | 996 | pushfq |
b8aa287f | 997 | DISABLE_INTERRUPTS(CLBR_ANY & ~CLBR_RDI) |
ca37e57b | 998 | TRACE_IRQS_OFF |
9f1e87ea | 999 | SWAPGS |
42c748bb | 1000 | .Lgs_change: |
4d732138 | 1001 | movl %edi, %gs |
96e5d28a | 1002 | 2: ALTERNATIVE "", "mfence", X86_BUG_SWAPGS_FENCE |
72fe4858 | 1003 | SWAPGS |
ca37e57b | 1004 | TRACE_IRQS_FLAGS (%rsp) |
131484c8 | 1005 | popfq |
8c1f7558 | 1006 | FRAME_END |
9f1e87ea | 1007 | ret |
8c1f7558 | 1008 | ENDPROC(native_load_gs_index) |
784d5699 | 1009 | EXPORT_SYMBOL(native_load_gs_index) |
0bd7b798 | 1010 | |
42c748bb | 1011 | _ASM_EXTABLE(.Lgs_change, bad_gs) |
4d732138 | 1012 | .section .fixup, "ax" |
1da177e4 | 1013 | /* running with kernelgs */ |
0bd7b798 | 1014 | bad_gs: |
4d732138 | 1015 | SWAPGS /* switch back to user gs */ |
b038c842 AL |
1016 | .macro ZAP_GS |
1017 | /* This can't be a string because the preprocessor needs to see it. */ | |
1018 | movl $__USER_DS, %eax | |
1019 | movl %eax, %gs | |
1020 | .endm | |
1021 | ALTERNATIVE "", "ZAP_GS", X86_BUG_NULL_SEG | |
4d732138 IM |
1022 | xorl %eax, %eax |
1023 | movl %eax, %gs | |
1024 | jmp 2b | |
9f1e87ea | 1025 | .previous |
0bd7b798 | 1026 | |
2699500b | 1027 | /* Call softirq on interrupt stack. Interrupts are off. */ |
7d65f4a6 | 1028 | ENTRY(do_softirq_own_stack) |
4d732138 IM |
1029 | pushq %rbp |
1030 | mov %rsp, %rbp | |
8c1f7558 | 1031 | ENTER_IRQ_STACK regs=0 old_rsp=%r11 |
4d732138 | 1032 | call __do_softirq |
8c1f7558 | 1033 | LEAVE_IRQ_STACK regs=0 |
2699500b | 1034 | leaveq |
ed6b676c | 1035 | ret |
8c1f7558 | 1036 | ENDPROC(do_softirq_own_stack) |
75154f40 | 1037 | |
3d75e1b8 | 1038 | #ifdef CONFIG_XEN |
5878d5d6 | 1039 | idtentry hypervisor_callback xen_do_hypervisor_callback has_error_code=0 |
3d75e1b8 JF |
1040 | |
1041 | /* | |
9f1e87ea CG |
1042 | * A note on the "critical region" in our callback handler. |
1043 | * We want to avoid stacking callback handlers due to events occurring | |
1044 | * during handling of the last event. To do this, we keep events disabled | |
1045 | * until we've done all processing. HOWEVER, we must enable events before | |
1046 | * popping the stack frame (can't be done atomically) and so it would still | |
1047 | * be possible to get enough handler activations to overflow the stack. | |
1048 | * Although unlikely, bugs of that kind are hard to track down, so we'd | |
1049 | * like to avoid the possibility. | |
1050 | * So, on entry to the handler we detect whether we interrupted an | |
1051 | * existing activation in its critical region -- if so, we pop the current | |
1052 | * activation and restart the handler using the previous one. | |
1053 | */ | |
4d732138 IM |
1054 | ENTRY(xen_do_hypervisor_callback) /* do_hypervisor_callback(struct *pt_regs) */ |
1055 | ||
9f1e87ea CG |
1056 | /* |
1057 | * Since we don't modify %rdi, evtchn_do_upall(struct *pt_regs) will | |
1058 | * see the correct pointer to the pt_regs | |
1059 | */ | |
8c1f7558 | 1060 | UNWIND_HINT_FUNC |
4d732138 | 1061 | movq %rdi, %rsp /* we don't return, adjust the stack frame */ |
8c1f7558 | 1062 | UNWIND_HINT_REGS |
1d3e53e8 AL |
1063 | |
1064 | ENTER_IRQ_STACK old_rsp=%r10 | |
4d732138 | 1065 | call xen_evtchn_do_upcall |
1d3e53e8 AL |
1066 | LEAVE_IRQ_STACK |
1067 | ||
fdfd811d | 1068 | #ifndef CONFIG_PREEMPT |
4d732138 | 1069 | call xen_maybe_preempt_hcall |
fdfd811d | 1070 | #endif |
4d732138 | 1071 | jmp error_exit |
371c394a | 1072 | END(xen_do_hypervisor_callback) |
3d75e1b8 JF |
1073 | |
1074 | /* | |
9f1e87ea CG |
1075 | * Hypervisor uses this for application faults while it executes. |
1076 | * We get here for two reasons: | |
1077 | * 1. Fault while reloading DS, ES, FS or GS | |
1078 | * 2. Fault while executing IRET | |
1079 | * Category 1 we do not need to fix up as Xen has already reloaded all segment | |
1080 | * registers that could be reloaded and zeroed the others. | |
1081 | * Category 2 we fix up by killing the current process. We cannot use the | |
1082 | * normal Linux return path in this case because if we use the IRET hypercall | |
1083 | * to pop the stack frame we end up in an infinite loop of failsafe callbacks. | |
1084 | * We distinguish between categories by comparing each saved segment register | |
1085 | * with its current contents: any discrepancy means we in category 1. | |
1086 | */ | |
3d75e1b8 | 1087 | ENTRY(xen_failsafe_callback) |
8c1f7558 | 1088 | UNWIND_HINT_EMPTY |
4d732138 IM |
1089 | movl %ds, %ecx |
1090 | cmpw %cx, 0x10(%rsp) | |
1091 | jne 1f | |
1092 | movl %es, %ecx | |
1093 | cmpw %cx, 0x18(%rsp) | |
1094 | jne 1f | |
1095 | movl %fs, %ecx | |
1096 | cmpw %cx, 0x20(%rsp) | |
1097 | jne 1f | |
1098 | movl %gs, %ecx | |
1099 | cmpw %cx, 0x28(%rsp) | |
1100 | jne 1f | |
3d75e1b8 | 1101 | /* All segments match their saved values => Category 2 (Bad IRET). */ |
4d732138 IM |
1102 | movq (%rsp), %rcx |
1103 | movq 8(%rsp), %r11 | |
1104 | addq $0x30, %rsp | |
1105 | pushq $0 /* RIP */ | |
8c1f7558 | 1106 | UNWIND_HINT_IRET_REGS offset=8 |
4d732138 | 1107 | jmp general_protection |
3d75e1b8 | 1108 | 1: /* Segment mismatch => Category 1 (Bad segment). Retry the IRET. */ |
4d732138 IM |
1109 | movq (%rsp), %rcx |
1110 | movq 8(%rsp), %r11 | |
1111 | addq $0x30, %rsp | |
8c1f7558 | 1112 | UNWIND_HINT_IRET_REGS |
4d732138 | 1113 | pushq $-1 /* orig_ax = -1 => not a system call */ |
3f01daec | 1114 | PUSH_AND_CLEAR_REGS |
946c1911 | 1115 | ENCODE_FRAME_POINTER |
4d732138 | 1116 | jmp error_exit |
3d75e1b8 JF |
1117 | END(xen_failsafe_callback) |
1118 | ||
cf910e83 | 1119 | apicinterrupt3 HYPERVISOR_CALLBACK_VECTOR \ |
38e20b07 SY |
1120 | xen_hvm_callback_vector xen_evtchn_do_upcall |
1121 | ||
3d75e1b8 | 1122 | #endif /* CONFIG_XEN */ |
ddeb8f21 | 1123 | |
bc2b0331 | 1124 | #if IS_ENABLED(CONFIG_HYPERV) |
cf910e83 | 1125 | apicinterrupt3 HYPERVISOR_CALLBACK_VECTOR \ |
bc2b0331 S |
1126 | hyperv_callback_vector hyperv_vector_handler |
1127 | #endif /* CONFIG_HYPERV */ | |
1128 | ||
4d732138 IM |
1129 | idtentry debug do_debug has_error_code=0 paranoid=1 shift_ist=DEBUG_STACK |
1130 | idtentry int3 do_int3 has_error_code=0 paranoid=1 shift_ist=DEBUG_STACK | |
1131 | idtentry stack_segment do_stack_segment has_error_code=1 | |
1132 | ||
6cac5a92 | 1133 | #ifdef CONFIG_XEN |
43e41110 | 1134 | idtentry xennmi do_nmi has_error_code=0 |
5878d5d6 JG |
1135 | idtentry xendebug do_debug has_error_code=0 |
1136 | idtentry xenint3 do_int3 has_error_code=0 | |
6cac5a92 | 1137 | #endif |
4d732138 IM |
1138 | |
1139 | idtentry general_protection do_general_protection has_error_code=1 | |
11a7ffb0 | 1140 | idtentry page_fault do_page_fault has_error_code=1 |
4d732138 | 1141 | |
631bc487 | 1142 | #ifdef CONFIG_KVM_GUEST |
4d732138 | 1143 | idtentry async_page_fault do_async_page_fault has_error_code=1 |
631bc487 | 1144 | #endif |
4d732138 | 1145 | |
ddeb8f21 | 1146 | #ifdef CONFIG_X86_MCE |
6f41c34d | 1147 | idtentry machine_check do_mce has_error_code=0 paranoid=1 |
ddeb8f21 AH |
1148 | #endif |
1149 | ||
ebfc453e DV |
1150 | /* |
1151 | * Save all registers in pt_regs, and switch gs if needed. | |
1152 | * Use slow, but surefire "are we in kernel?" check. | |
1153 | * Return: ebx=0: need swapgs on exit, ebx=1: otherwise | |
1154 | */ | |
1155 | ENTRY(paranoid_entry) | |
8c1f7558 | 1156 | UNWIND_HINT_FUNC |
1eeb207f | 1157 | cld |
f7bafa2b | 1158 | SAVE_AND_CLEAR_REGS 8 |
946c1911 | 1159 | ENCODE_FRAME_POINTER 8 |
4d732138 IM |
1160 | movl $1, %ebx |
1161 | movl $MSR_GS_BASE, %ecx | |
1eeb207f | 1162 | rdmsr |
4d732138 IM |
1163 | testl %edx, %edx |
1164 | js 1f /* negative -> in kernel */ | |
1eeb207f | 1165 | SWAPGS |
4d732138 | 1166 | xorl %ebx, %ebx |
8a09317b DH |
1167 | |
1168 | 1: | |
1169 | SAVE_AND_SWITCH_TO_KERNEL_CR3 scratch_reg=%rax save_reg=%r14 | |
1170 | ||
1171 | ret | |
ebfc453e | 1172 | END(paranoid_entry) |
ddeb8f21 | 1173 | |
ebfc453e DV |
1174 | /* |
1175 | * "Paranoid" exit path from exception stack. This is invoked | |
1176 | * only on return from non-NMI IST interrupts that came | |
1177 | * from kernel space. | |
1178 | * | |
1179 | * We may be returning to very strange contexts (e.g. very early | |
1180 | * in syscall entry), so checking for preemption here would | |
1181 | * be complicated. Fortunately, we there's no good reason | |
1182 | * to try to handle preemption here. | |
4d732138 IM |
1183 | * |
1184 | * On entry, ebx is "no swapgs" flag (1: don't need swapgs, 0: need it) | |
ebfc453e | 1185 | */ |
ddeb8f21 | 1186 | ENTRY(paranoid_exit) |
8c1f7558 | 1187 | UNWIND_HINT_REGS |
2140a994 | 1188 | DISABLE_INTERRUPTS(CLBR_ANY) |
5963e317 | 1189 | TRACE_IRQS_OFF_DEBUG |
4d732138 | 1190 | testl %ebx, %ebx /* swapgs needed? */ |
e5317832 | 1191 | jnz .Lparanoid_exit_no_swapgs |
f2db9382 | 1192 | TRACE_IRQS_IRETQ |
21e94459 | 1193 | RESTORE_CR3 scratch_reg=%rbx save_reg=%r14 |
ddeb8f21 | 1194 | SWAPGS_UNSAFE_STACK |
e5317832 AL |
1195 | jmp .Lparanoid_exit_restore |
1196 | .Lparanoid_exit_no_swapgs: | |
f2db9382 | 1197 | TRACE_IRQS_IRETQ_DEBUG |
e5317832 AL |
1198 | .Lparanoid_exit_restore: |
1199 | jmp restore_regs_and_return_to_kernel | |
ddeb8f21 AH |
1200 | END(paranoid_exit) |
1201 | ||
1202 | /* | |
ebfc453e | 1203 | * Save all registers in pt_regs, and switch gs if needed. |
539f5113 | 1204 | * Return: EBX=0: came from user mode; EBX=1: otherwise |
ddeb8f21 AH |
1205 | */ |
1206 | ENTRY(error_entry) | |
8c1f7558 | 1207 | UNWIND_HINT_FUNC |
ddeb8f21 | 1208 | cld |
f7bafa2b | 1209 | SAVE_AND_CLEAR_REGS 8 |
946c1911 | 1210 | ENCODE_FRAME_POINTER 8 |
03335e95 | 1211 | testb $3, CS+8(%rsp) |
cb6f64ed | 1212 | jz .Lerror_kernelspace |
539f5113 | 1213 | |
cb6f64ed AL |
1214 | /* |
1215 | * We entered from user mode or we're pretending to have entered | |
1216 | * from user mode due to an IRET fault. | |
1217 | */ | |
ddeb8f21 | 1218 | SWAPGS |
8a09317b DH |
1219 | /* We have user CR3. Change to kernel CR3. */ |
1220 | SWITCH_TO_KERNEL_CR3 scratch_reg=%rax | |
539f5113 | 1221 | |
cb6f64ed | 1222 | .Lerror_entry_from_usermode_after_swapgs: |
7f2590a1 AL |
1223 | /* Put us onto the real thread stack. */ |
1224 | popq %r12 /* save return addr in %12 */ | |
1225 | movq %rsp, %rdi /* arg0 = pt_regs pointer */ | |
1226 | call sync_regs | |
1227 | movq %rax, %rsp /* switch stack */ | |
1228 | ENCODE_FRAME_POINTER | |
1229 | pushq %r12 | |
1230 | ||
f1075053 AL |
1231 | /* |
1232 | * We need to tell lockdep that IRQs are off. We can't do this until | |
1233 | * we fix gsbase, and we should do it before enter_from_user_mode | |
1234 | * (which can take locks). | |
1235 | */ | |
1236 | TRACE_IRQS_OFF | |
478dc89c | 1237 | CALL_enter_from_user_mode |
f1075053 | 1238 | ret |
02bc7768 | 1239 | |
cb6f64ed | 1240 | .Lerror_entry_done: |
ddeb8f21 AH |
1241 | TRACE_IRQS_OFF |
1242 | ret | |
ddeb8f21 | 1243 | |
ebfc453e DV |
1244 | /* |
1245 | * There are two places in the kernel that can potentially fault with | |
1246 | * usergs. Handle them here. B stepping K8s sometimes report a | |
1247 | * truncated RIP for IRET exceptions returning to compat mode. Check | |
1248 | * for these here too. | |
1249 | */ | |
cb6f64ed | 1250 | .Lerror_kernelspace: |
4d732138 IM |
1251 | incl %ebx |
1252 | leaq native_irq_return_iret(%rip), %rcx | |
1253 | cmpq %rcx, RIP+8(%rsp) | |
cb6f64ed | 1254 | je .Lerror_bad_iret |
4d732138 IM |
1255 | movl %ecx, %eax /* zero extend */ |
1256 | cmpq %rax, RIP+8(%rsp) | |
cb6f64ed | 1257 | je .Lbstep_iret |
42c748bb | 1258 | cmpq $.Lgs_change, RIP+8(%rsp) |
cb6f64ed | 1259 | jne .Lerror_entry_done |
539f5113 AL |
1260 | |
1261 | /* | |
42c748bb | 1262 | * hack: .Lgs_change can fail with user gsbase. If this happens, fix up |
539f5113 | 1263 | * gsbase and proceed. We'll fix up the exception and land in |
42c748bb | 1264 | * .Lgs_change's error handler with kernel gsbase. |
539f5113 | 1265 | */ |
2fa5f04f | 1266 | SWAPGS |
8a09317b | 1267 | SWITCH_TO_KERNEL_CR3 scratch_reg=%rax |
2fa5f04f | 1268 | jmp .Lerror_entry_done |
ae24ffe5 | 1269 | |
cb6f64ed | 1270 | .Lbstep_iret: |
ae24ffe5 | 1271 | /* Fix truncated RIP */ |
4d732138 | 1272 | movq %rcx, RIP+8(%rsp) |
b645af2d AL |
1273 | /* fall through */ |
1274 | ||
cb6f64ed | 1275 | .Lerror_bad_iret: |
539f5113 | 1276 | /* |
8a09317b DH |
1277 | * We came from an IRET to user mode, so we have user |
1278 | * gsbase and CR3. Switch to kernel gsbase and CR3: | |
539f5113 | 1279 | */ |
b645af2d | 1280 | SWAPGS |
8a09317b | 1281 | SWITCH_TO_KERNEL_CR3 scratch_reg=%rax |
539f5113 AL |
1282 | |
1283 | /* | |
1284 | * Pretend that the exception came from user mode: set up pt_regs | |
1285 | * as if we faulted immediately after IRET and clear EBX so that | |
1286 | * error_exit knows that we will be returning to user mode. | |
1287 | */ | |
4d732138 IM |
1288 | mov %rsp, %rdi |
1289 | call fixup_bad_iret | |
1290 | mov %rax, %rsp | |
539f5113 | 1291 | decl %ebx |
cb6f64ed | 1292 | jmp .Lerror_entry_from_usermode_after_swapgs |
ddeb8f21 AH |
1293 | END(error_entry) |
1294 | ||
1295 | ||
539f5113 | 1296 | /* |
75ca5b22 | 1297 | * On entry, EBX is a "return to kernel mode" flag: |
539f5113 AL |
1298 | * 1: already in kernel mode, don't need SWAPGS |
1299 | * 0: user gsbase is loaded, we need SWAPGS and standard preparation for return to usermode | |
1300 | */ | |
ddeb8f21 | 1301 | ENTRY(error_exit) |
8c1f7558 | 1302 | UNWIND_HINT_REGS |
2140a994 | 1303 | DISABLE_INTERRUPTS(CLBR_ANY) |
ddeb8f21 | 1304 | TRACE_IRQS_OFF |
2140a994 | 1305 | testl %ebx, %ebx |
4d732138 IM |
1306 | jnz retint_kernel |
1307 | jmp retint_user | |
ddeb8f21 AH |
1308 | END(error_exit) |
1309 | ||
929bacec AL |
1310 | /* |
1311 | * Runs on exception stack. Xen PV does not go through this path at all, | |
1312 | * so we can use real assembly here. | |
8a09317b DH |
1313 | * |
1314 | * Registers: | |
1315 | * %r14: Used to save/restore the CR3 of the interrupted context | |
1316 | * when PAGE_TABLE_ISOLATION is in use. Do not clobber. | |
929bacec | 1317 | */ |
ddeb8f21 | 1318 | ENTRY(nmi) |
8c1f7558 | 1319 | UNWIND_HINT_IRET_REGS |
929bacec | 1320 | |
3f3c8b8c SR |
1321 | /* |
1322 | * We allow breakpoints in NMIs. If a breakpoint occurs, then | |
1323 | * the iretq it performs will take us out of NMI context. | |
1324 | * This means that we can have nested NMIs where the next | |
1325 | * NMI is using the top of the stack of the previous NMI. We | |
1326 | * can't let it execute because the nested NMI will corrupt the | |
1327 | * stack of the previous NMI. NMI handlers are not re-entrant | |
1328 | * anyway. | |
1329 | * | |
1330 | * To handle this case we do the following: | |
1331 | * Check the a special location on the stack that contains | |
1332 | * a variable that is set when NMIs are executing. | |
1333 | * The interrupted task's stack is also checked to see if it | |
1334 | * is an NMI stack. | |
1335 | * If the variable is not set and the stack is not the NMI | |
1336 | * stack then: | |
1337 | * o Set the special variable on the stack | |
0b22930e AL |
1338 | * o Copy the interrupt frame into an "outermost" location on the |
1339 | * stack | |
1340 | * o Copy the interrupt frame into an "iret" location on the stack | |
3f3c8b8c SR |
1341 | * o Continue processing the NMI |
1342 | * If the variable is set or the previous stack is the NMI stack: | |
0b22930e | 1343 | * o Modify the "iret" location to jump to the repeat_nmi |
3f3c8b8c SR |
1344 | * o return back to the first NMI |
1345 | * | |
1346 | * Now on exit of the first NMI, we first clear the stack variable | |
1347 | * The NMI stack will tell any nested NMIs at that point that it is | |
1348 | * nested. Then we pop the stack normally with iret, and if there was | |
1349 | * a nested NMI that updated the copy interrupt stack frame, a | |
1350 | * jump will be made to the repeat_nmi code that will handle the second | |
1351 | * NMI. | |
9b6e6a83 AL |
1352 | * |
1353 | * However, espfix prevents us from directly returning to userspace | |
1354 | * with a single IRET instruction. Similarly, IRET to user mode | |
1355 | * can fault. We therefore handle NMIs from user space like | |
1356 | * other IST entries. | |
3f3c8b8c SR |
1357 | */ |
1358 | ||
e93c1730 AL |
1359 | ASM_CLAC |
1360 | ||
146b2b09 | 1361 | /* Use %rdx as our temp variable throughout */ |
4d732138 | 1362 | pushq %rdx |
3f3c8b8c | 1363 | |
9b6e6a83 AL |
1364 | testb $3, CS-RIP+8(%rsp) |
1365 | jz .Lnmi_from_kernel | |
1366 | ||
1367 | /* | |
1368 | * NMI from user mode. We need to run on the thread stack, but we | |
1369 | * can't go through the normal entry paths: NMIs are masked, and | |
1370 | * we don't want to enable interrupts, because then we'll end | |
1371 | * up in an awkward situation in which IRQs are on but NMIs | |
1372 | * are off. | |
83c133cf AL |
1373 | * |
1374 | * We also must not push anything to the stack before switching | |
1375 | * stacks lest we corrupt the "NMI executing" variable. | |
9b6e6a83 AL |
1376 | */ |
1377 | ||
929bacec | 1378 | swapgs |
9b6e6a83 | 1379 | cld |
8a09317b | 1380 | SWITCH_TO_KERNEL_CR3 scratch_reg=%rdx |
9b6e6a83 AL |
1381 | movq %rsp, %rdx |
1382 | movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp | |
8c1f7558 | 1383 | UNWIND_HINT_IRET_REGS base=%rdx offset=8 |
9b6e6a83 AL |
1384 | pushq 5*8(%rdx) /* pt_regs->ss */ |
1385 | pushq 4*8(%rdx) /* pt_regs->rsp */ | |
1386 | pushq 3*8(%rdx) /* pt_regs->flags */ | |
1387 | pushq 2*8(%rdx) /* pt_regs->cs */ | |
1388 | pushq 1*8(%rdx) /* pt_regs->rip */ | |
8c1f7558 | 1389 | UNWIND_HINT_IRET_REGS |
9b6e6a83 AL |
1390 | pushq $-1 /* pt_regs->orig_ax */ |
1391 | pushq %rdi /* pt_regs->di */ | |
1392 | pushq %rsi /* pt_regs->si */ | |
1393 | pushq (%rdx) /* pt_regs->dx */ | |
1394 | pushq %rcx /* pt_regs->cx */ | |
1395 | pushq %rax /* pt_regs->ax */ | |
f7bafa2b DB |
1396 | /* |
1397 | * Sanitize registers of values that a speculation attack | |
1398 | * might otherwise want to exploit. The lower registers are | |
1399 | * likely clobbered well before they could be put to use in | |
1400 | * a speculative execution gadget. Interleave XOR with PUSH | |
1401 | * for better uop scheduling: | |
1402 | */ | |
9b6e6a83 | 1403 | pushq %r8 /* pt_regs->r8 */ |
f7bafa2b | 1404 | xorq %r8, %r8 /* nospec r8 */ |
9b6e6a83 | 1405 | pushq %r9 /* pt_regs->r9 */ |
f7bafa2b | 1406 | xorq %r9, %r9 /* nospec r9 */ |
9b6e6a83 | 1407 | pushq %r10 /* pt_regs->r10 */ |
f7bafa2b | 1408 | xorq %r10, %r10 /* nospec r10 */ |
9b6e6a83 | 1409 | pushq %r11 /* pt_regs->r11 */ |
f7bafa2b | 1410 | xorq %r11, %r11 /* nospec r11*/ |
9b6e6a83 | 1411 | pushq %rbx /* pt_regs->rbx */ |
f7bafa2b | 1412 | xorl %ebx, %ebx /* nospec rbx*/ |
9b6e6a83 | 1413 | pushq %rbp /* pt_regs->rbp */ |
f7bafa2b | 1414 | xorl %ebp, %ebp /* nospec rbp*/ |
9b6e6a83 | 1415 | pushq %r12 /* pt_regs->r12 */ |
f7bafa2b | 1416 | xorq %r12, %r12 /* nospec r12*/ |
9b6e6a83 | 1417 | pushq %r13 /* pt_regs->r13 */ |
f7bafa2b | 1418 | xorq %r13, %r13 /* nospec r13*/ |
9b6e6a83 | 1419 | pushq %r14 /* pt_regs->r14 */ |
f7bafa2b | 1420 | xorq %r14, %r14 /* nospec r14*/ |
9b6e6a83 | 1421 | pushq %r15 /* pt_regs->r15 */ |
f7bafa2b | 1422 | xorq %r15, %r15 /* nospec r15*/ |
8c1f7558 | 1423 | UNWIND_HINT_REGS |
946c1911 | 1424 | ENCODE_FRAME_POINTER |
9b6e6a83 AL |
1425 | |
1426 | /* | |
1427 | * At this point we no longer need to worry about stack damage | |
1428 | * due to nesting -- we're on the normal thread stack and we're | |
1429 | * done with the NMI stack. | |
1430 | */ | |
1431 | ||
1432 | movq %rsp, %rdi | |
1433 | movq $-1, %rsi | |
1434 | call do_nmi | |
1435 | ||
45d5a168 | 1436 | /* |
9b6e6a83 | 1437 | * Return back to user mode. We must *not* do the normal exit |
946c1911 | 1438 | * work, because we don't want to enable interrupts. |
45d5a168 | 1439 | */ |
8a055d7f | 1440 | jmp swapgs_restore_regs_and_return_to_usermode |
45d5a168 | 1441 | |
9b6e6a83 | 1442 | .Lnmi_from_kernel: |
3f3c8b8c | 1443 | /* |
0b22930e AL |
1444 | * Here's what our stack frame will look like: |
1445 | * +---------------------------------------------------------+ | |
1446 | * | original SS | | |
1447 | * | original Return RSP | | |
1448 | * | original RFLAGS | | |
1449 | * | original CS | | |
1450 | * | original RIP | | |
1451 | * +---------------------------------------------------------+ | |
1452 | * | temp storage for rdx | | |
1453 | * +---------------------------------------------------------+ | |
1454 | * | "NMI executing" variable | | |
1455 | * +---------------------------------------------------------+ | |
1456 | * | iret SS } Copied from "outermost" frame | | |
1457 | * | iret Return RSP } on each loop iteration; overwritten | | |
1458 | * | iret RFLAGS } by a nested NMI to force another | | |
1459 | * | iret CS } iteration if needed. | | |
1460 | * | iret RIP } | | |
1461 | * +---------------------------------------------------------+ | |
1462 | * | outermost SS } initialized in first_nmi; | | |
1463 | * | outermost Return RSP } will not be changed before | | |
1464 | * | outermost RFLAGS } NMI processing is done. | | |
1465 | * | outermost CS } Copied to "iret" frame on each | | |
1466 | * | outermost RIP } iteration. | | |
1467 | * +---------------------------------------------------------+ | |
1468 | * | pt_regs | | |
1469 | * +---------------------------------------------------------+ | |
1470 | * | |
1471 | * The "original" frame is used by hardware. Before re-enabling | |
1472 | * NMIs, we need to be done with it, and we need to leave enough | |
1473 | * space for the asm code here. | |
1474 | * | |
1475 | * We return by executing IRET while RSP points to the "iret" frame. | |
1476 | * That will either return for real or it will loop back into NMI | |
1477 | * processing. | |
1478 | * | |
1479 | * The "outermost" frame is copied to the "iret" frame on each | |
1480 | * iteration of the loop, so each iteration starts with the "iret" | |
1481 | * frame pointing to the final return target. | |
1482 | */ | |
1483 | ||
45d5a168 | 1484 | /* |
0b22930e AL |
1485 | * Determine whether we're a nested NMI. |
1486 | * | |
a27507ca AL |
1487 | * If we interrupted kernel code between repeat_nmi and |
1488 | * end_repeat_nmi, then we are a nested NMI. We must not | |
1489 | * modify the "iret" frame because it's being written by | |
1490 | * the outer NMI. That's okay; the outer NMI handler is | |
1491 | * about to about to call do_nmi anyway, so we can just | |
1492 | * resume the outer NMI. | |
45d5a168 | 1493 | */ |
a27507ca AL |
1494 | |
1495 | movq $repeat_nmi, %rdx | |
1496 | cmpq 8(%rsp), %rdx | |
1497 | ja 1f | |
1498 | movq $end_repeat_nmi, %rdx | |
1499 | cmpq 8(%rsp), %rdx | |
1500 | ja nested_nmi_out | |
1501 | 1: | |
45d5a168 | 1502 | |
3f3c8b8c | 1503 | /* |
a27507ca | 1504 | * Now check "NMI executing". If it's set, then we're nested. |
0b22930e AL |
1505 | * This will not detect if we interrupted an outer NMI just |
1506 | * before IRET. | |
3f3c8b8c | 1507 | */ |
4d732138 IM |
1508 | cmpl $1, -8(%rsp) |
1509 | je nested_nmi | |
3f3c8b8c SR |
1510 | |
1511 | /* | |
0b22930e AL |
1512 | * Now test if the previous stack was an NMI stack. This covers |
1513 | * the case where we interrupt an outer NMI after it clears | |
810bc075 AL |
1514 | * "NMI executing" but before IRET. We need to be careful, though: |
1515 | * there is one case in which RSP could point to the NMI stack | |
1516 | * despite there being no NMI active: naughty userspace controls | |
1517 | * RSP at the very beginning of the SYSCALL targets. We can | |
1518 | * pull a fast one on naughty userspace, though: we program | |
1519 | * SYSCALL to mask DF, so userspace cannot cause DF to be set | |
1520 | * if it controls the kernel's RSP. We set DF before we clear | |
1521 | * "NMI executing". | |
3f3c8b8c | 1522 | */ |
0784b364 DV |
1523 | lea 6*8(%rsp), %rdx |
1524 | /* Compare the NMI stack (rdx) with the stack we came from (4*8(%rsp)) */ | |
1525 | cmpq %rdx, 4*8(%rsp) | |
1526 | /* If the stack pointer is above the NMI stack, this is a normal NMI */ | |
1527 | ja first_nmi | |
4d732138 | 1528 | |
0784b364 DV |
1529 | subq $EXCEPTION_STKSZ, %rdx |
1530 | cmpq %rdx, 4*8(%rsp) | |
1531 | /* If it is below the NMI stack, it is a normal NMI */ | |
1532 | jb first_nmi | |
810bc075 AL |
1533 | |
1534 | /* Ah, it is within the NMI stack. */ | |
1535 | ||
1536 | testb $(X86_EFLAGS_DF >> 8), (3*8 + 1)(%rsp) | |
1537 | jz first_nmi /* RSP was user controlled. */ | |
1538 | ||
1539 | /* This is a nested NMI. */ | |
0784b364 | 1540 | |
3f3c8b8c SR |
1541 | nested_nmi: |
1542 | /* | |
0b22930e AL |
1543 | * Modify the "iret" frame to point to repeat_nmi, forcing another |
1544 | * iteration of NMI handling. | |
3f3c8b8c | 1545 | */ |
23a781e9 | 1546 | subq $8, %rsp |
4d732138 IM |
1547 | leaq -10*8(%rsp), %rdx |
1548 | pushq $__KERNEL_DS | |
1549 | pushq %rdx | |
131484c8 | 1550 | pushfq |
4d732138 IM |
1551 | pushq $__KERNEL_CS |
1552 | pushq $repeat_nmi | |
3f3c8b8c SR |
1553 | |
1554 | /* Put stack back */ | |
4d732138 | 1555 | addq $(6*8), %rsp |
3f3c8b8c SR |
1556 | |
1557 | nested_nmi_out: | |
4d732138 | 1558 | popq %rdx |
3f3c8b8c | 1559 | |
0b22930e | 1560 | /* We are returning to kernel mode, so this cannot result in a fault. */ |
929bacec | 1561 | iretq |
3f3c8b8c SR |
1562 | |
1563 | first_nmi: | |
0b22930e | 1564 | /* Restore rdx. */ |
4d732138 | 1565 | movq (%rsp), %rdx |
62610913 | 1566 | |
36f1a77b AL |
1567 | /* Make room for "NMI executing". */ |
1568 | pushq $0 | |
3f3c8b8c | 1569 | |
0b22930e | 1570 | /* Leave room for the "iret" frame */ |
4d732138 | 1571 | subq $(5*8), %rsp |
28696f43 | 1572 | |
0b22930e | 1573 | /* Copy the "original" frame to the "outermost" frame */ |
3f3c8b8c | 1574 | .rept 5 |
4d732138 | 1575 | pushq 11*8(%rsp) |
3f3c8b8c | 1576 | .endr |
8c1f7558 | 1577 | UNWIND_HINT_IRET_REGS |
62610913 | 1578 | |
79fb4ad6 SR |
1579 | /* Everything up to here is safe from nested NMIs */ |
1580 | ||
a97439aa AL |
1581 | #ifdef CONFIG_DEBUG_ENTRY |
1582 | /* | |
1583 | * For ease of testing, unmask NMIs right away. Disabled by | |
1584 | * default because IRET is very expensive. | |
1585 | */ | |
1586 | pushq $0 /* SS */ | |
1587 | pushq %rsp /* RSP (minus 8 because of the previous push) */ | |
1588 | addq $8, (%rsp) /* Fix up RSP */ | |
1589 | pushfq /* RFLAGS */ | |
1590 | pushq $__KERNEL_CS /* CS */ | |
1591 | pushq $1f /* RIP */ | |
929bacec | 1592 | iretq /* continues at repeat_nmi below */ |
8c1f7558 | 1593 | UNWIND_HINT_IRET_REGS |
a97439aa AL |
1594 | 1: |
1595 | #endif | |
1596 | ||
0b22930e | 1597 | repeat_nmi: |
62610913 JB |
1598 | /* |
1599 | * If there was a nested NMI, the first NMI's iret will return | |
1600 | * here. But NMIs are still enabled and we can take another | |
1601 | * nested NMI. The nested NMI checks the interrupted RIP to see | |
1602 | * if it is between repeat_nmi and end_repeat_nmi, and if so | |
1603 | * it will just return, as we are about to repeat an NMI anyway. | |
1604 | * This makes it safe to copy to the stack frame that a nested | |
1605 | * NMI will update. | |
0b22930e AL |
1606 | * |
1607 | * RSP is pointing to "outermost RIP". gsbase is unknown, but, if | |
1608 | * we're repeating an NMI, gsbase has the same value that it had on | |
1609 | * the first iteration. paranoid_entry will load the kernel | |
36f1a77b AL |
1610 | * gsbase if needed before we call do_nmi. "NMI executing" |
1611 | * is zero. | |
62610913 | 1612 | */ |
36f1a77b | 1613 | movq $1, 10*8(%rsp) /* Set "NMI executing". */ |
3f3c8b8c | 1614 | |
62610913 | 1615 | /* |
0b22930e AL |
1616 | * Copy the "outermost" frame to the "iret" frame. NMIs that nest |
1617 | * here must not modify the "iret" frame while we're writing to | |
1618 | * it or it will end up containing garbage. | |
62610913 | 1619 | */ |
4d732138 | 1620 | addq $(10*8), %rsp |
3f3c8b8c | 1621 | .rept 5 |
4d732138 | 1622 | pushq -6*8(%rsp) |
3f3c8b8c | 1623 | .endr |
4d732138 | 1624 | subq $(5*8), %rsp |
62610913 | 1625 | end_repeat_nmi: |
3f3c8b8c SR |
1626 | |
1627 | /* | |
0b22930e AL |
1628 | * Everything below this point can be preempted by a nested NMI. |
1629 | * If this happens, then the inner NMI will change the "iret" | |
1630 | * frame to point back to repeat_nmi. | |
3f3c8b8c | 1631 | */ |
4d732138 | 1632 | pushq $-1 /* ORIG_RAX: no syscall to restart */ |
76f5df43 DV |
1633 | ALLOC_PT_GPREGS_ON_STACK |
1634 | ||
1fd466ef | 1635 | /* |
ebfc453e | 1636 | * Use paranoid_entry to handle SWAPGS, but no need to use paranoid_exit |
1fd466ef SR |
1637 | * as we should not be calling schedule in NMI context. |
1638 | * Even with normal interrupts enabled. An NMI should not be | |
1639 | * setting NEED_RESCHED or anything that normal interrupts and | |
1640 | * exceptions might do. | |
1641 | */ | |
4d732138 | 1642 | call paranoid_entry |
8c1f7558 | 1643 | UNWIND_HINT_REGS |
7fbb98c5 | 1644 | |
ddeb8f21 | 1645 | /* paranoidentry do_nmi, 0; without TRACE_IRQS_OFF */ |
4d732138 IM |
1646 | movq %rsp, %rdi |
1647 | movq $-1, %rsi | |
1648 | call do_nmi | |
7fbb98c5 | 1649 | |
21e94459 | 1650 | RESTORE_CR3 scratch_reg=%r15 save_reg=%r14 |
8a09317b | 1651 | |
4d732138 IM |
1652 | testl %ebx, %ebx /* swapgs needed? */ |
1653 | jnz nmi_restore | |
ddeb8f21 AH |
1654 | nmi_swapgs: |
1655 | SWAPGS_UNSAFE_STACK | |
1656 | nmi_restore: | |
502af0d7 | 1657 | POP_REGS |
0b22930e | 1658 | |
471ee483 AL |
1659 | /* |
1660 | * Skip orig_ax and the "outermost" frame to point RSP at the "iret" | |
1661 | * at the "iret" frame. | |
1662 | */ | |
1663 | addq $6*8, %rsp | |
28696f43 | 1664 | |
810bc075 AL |
1665 | /* |
1666 | * Clear "NMI executing". Set DF first so that we can easily | |
1667 | * distinguish the remaining code between here and IRET from | |
929bacec AL |
1668 | * the SYSCALL entry and exit paths. |
1669 | * | |
1670 | * We arguably should just inspect RIP instead, but I (Andy) wrote | |
1671 | * this code when I had the misapprehension that Xen PV supported | |
1672 | * NMIs, and Xen PV would break that approach. | |
810bc075 AL |
1673 | */ |
1674 | std | |
1675 | movq $0, 5*8(%rsp) /* clear "NMI executing" */ | |
0b22930e AL |
1676 | |
1677 | /* | |
929bacec AL |
1678 | * iretq reads the "iret" frame and exits the NMI stack in a |
1679 | * single instruction. We are returning to kernel mode, so this | |
1680 | * cannot result in a fault. Similarly, we don't need to worry | |
1681 | * about espfix64 on the way back to kernel mode. | |
0b22930e | 1682 | */ |
929bacec | 1683 | iretq |
ddeb8f21 AH |
1684 | END(nmi) |
1685 | ||
1686 | ENTRY(ignore_sysret) | |
8c1f7558 | 1687 | UNWIND_HINT_EMPTY |
4d732138 | 1688 | mov $-ENOSYS, %eax |
ddeb8f21 | 1689 | sysret |
ddeb8f21 | 1690 | END(ignore_sysret) |
2deb4be2 AL |
1691 | |
1692 | ENTRY(rewind_stack_do_exit) | |
8c1f7558 | 1693 | UNWIND_HINT_FUNC |
2deb4be2 AL |
1694 | /* Prevent any naive code from trying to unwind to our caller. */ |
1695 | xorl %ebp, %ebp | |
1696 | ||
1697 | movq PER_CPU_VAR(cpu_current_top_of_stack), %rax | |
8c1f7558 JP |
1698 | leaq -PTREGS_SIZE(%rax), %rsp |
1699 | UNWIND_HINT_FUNC sp_offset=PTREGS_SIZE | |
2deb4be2 AL |
1700 | |
1701 | call do_exit | |
2deb4be2 | 1702 | END(rewind_stack_do_exit) |