1 /* SPDX-License-Identifier: GPL-2.0-only */
3 * Low-level exception handling code
5 * Copyright (C) 2012 ARM Ltd.
6 * Authors: Catalin Marinas <catalin.marinas@arm.com>
7 * Will Deacon <will.deacon@arm.com>
10 #include <linux/arm-smccc.h>
11 #include <linux/init.h>
12 #include <linux/linkage.h>
14 #include <asm/alternative.h>
15 #include <asm/assembler.h>
16 #include <asm/asm-offsets.h>
17 #include <asm/asm_pointer_auth.h>
19 #include <asm/cpufeature.h>
20 #include <asm/errno.h>
23 #include <asm/memory.h>
25 #include <asm/processor.h>
26 #include <asm/ptrace.h>
28 #include <asm/thread_info.h>
29 #include <asm/asm-uaccess.h>
30 #include <asm/unistd.h>
33 .irp n,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29
38 .macro kernel_ventry, el:req, ht:req, regsize:req, label:req
43 * This must be the first instruction of the EL0 vector entries. It is
44 * skipped by the trampoline vectors, to trigger the cleanup.
46 b .Lskip_tramp_vectors_cleanup\@
53 .Lskip_tramp_vectors_cleanup\@:
56 sub sp, sp, #PT_REGS_SIZE
57 #ifdef CONFIG_VMAP_STACK
59 * Test whether the SP has overflowed, without corrupting a GPR.
60 * Task and IRQ stacks are aligned so that SP & (1 << THREAD_SHIFT)
61 * should always be zero.
63 add sp, sp, x0 // sp' = sp + x0
64 sub x0, sp, x0 // x0' = sp' - x0 = (sp + x0) - x0 = sp
65 tbnz x0, #THREAD_SHIFT, 0f
66 sub x0, sp, x0 // x0'' = sp' - x0' = (sp + x0) - sp = x0
67 sub sp, sp, x0 // sp'' = sp' - x0 = (sp + x0) - x0 = sp
68 b el\el\ht\()_\regsize\()_\label
72 * Either we've just detected an overflow, or we've taken an exception
73 * while on the overflow stack. Either way, we won't return to
74 * userspace, and can clobber EL0 registers to free up GPRs.
77 /* Stash the original SP (minus PT_REGS_SIZE) in tpidr_el0. */
80 /* Recover the original x0 value and stash it in tpidrro_el0 */
84 /* Switch to the overflow stack */
85 adr_this_cpu sp, overflow_stack + OVERFLOW_STACK_SIZE, x0
88 * Check whether we were already on the overflow stack. This may happen
89 * after panic() re-enables interrupts.
91 mrs x0, tpidr_el0 // sp of interrupted context
92 sub x0, sp, x0 // delta with top of overflow stack
93 tst x0, #~(OVERFLOW_STACK_SIZE - 1) // within range?
94 b.ne __bad_stack // no? -> bad stack pointer
96 /* We were already on the overflow stack. Restore sp/x0 and carry on. */
100 b el\el\ht\()_\regsize\()_\label
101 .org .Lventry_start\@ + 128 // Did we overflow the ventry slot?
104 .macro tramp_alias, dst, sym
105 .set .Lalias\@, TRAMP_VALIAS + \sym - .entry.tramp.text
106 movz \dst, :abs_g2_s:.Lalias\@
107 movk \dst, :abs_g1_nc:.Lalias\@
108 movk \dst, :abs_g0_nc:.Lalias\@
112 * This macro corrupts x0-x3. It is the caller's duty to save/restore
115 .macro apply_ssbd, state, tmp1, tmp2
116 alternative_cb ARM64_ALWAYS_SYSTEM, spectre_v4_patch_fw_mitigation_enable
117 b .L__asm_ssbd_skip\@ // Patched to NOP
119 ldr_this_cpu \tmp2, arm64_ssbd_callback_required, \tmp1
120 cbz \tmp2, .L__asm_ssbd_skip\@
121 ldr \tmp2, [tsk, #TSK_TI_FLAGS]
122 tbnz \tmp2, #TIF_SSBD, .L__asm_ssbd_skip\@
123 mov w0, #ARM_SMCCC_ARCH_WORKAROUND_2
125 alternative_cb ARM64_ALWAYS_SYSTEM, smccc_patch_fw_mitigation_conduit
126 nop // Patched to SMC/HVC #0
131 /* Check for MTE asynchronous tag check faults */
132 .macro check_mte_async_tcf, tmp, ti_flags, thread_sctlr
133 #ifdef CONFIG_ARM64_MTE
135 alternative_if_not ARM64_MTE
137 alternative_else_nop_endif
139 * Asynchronous tag check faults are only possible in ASYNC (2) or
140 * ASYM (3) modes. In each of these modes bit 1 of SCTLR_EL1.TCF0 is
141 * set, so skip the check if it is unset.
143 tbz \thread_sctlr, #(SCTLR_EL1_TCF0_SHIFT + 1), 1f
144 mrs_s \tmp, SYS_TFSRE0_EL1
145 tbz \tmp, #SYS_TFSR_EL1_TF0_SHIFT, 1f
146 /* Asynchronous TCF occurred for TTBR0 access, set the TI flag */
147 mov \tmp, #_TIF_MTE_ASYNC_FAULT
148 add \ti_flags, tsk, #TSK_TI_FLAGS
149 stset \tmp, [\ti_flags]
154 /* Clear the MTE asynchronous tag check faults */
155 .macro clear_mte_async_tcf thread_sctlr
156 #ifdef CONFIG_ARM64_MTE
157 alternative_if ARM64_MTE
158 /* See comment in check_mte_async_tcf above. */
159 tbz \thread_sctlr, #(SCTLR_EL1_TCF0_SHIFT + 1), 1f
161 msr_s SYS_TFSRE0_EL1, xzr
163 alternative_else_nop_endif
167 .macro mte_set_gcr, mte_ctrl, tmp
168 #ifdef CONFIG_ARM64_MTE
169 ubfx \tmp, \mte_ctrl, #MTE_CTRL_GCR_USER_EXCL_SHIFT, #16
170 orr \tmp, \tmp, #SYS_GCR_EL1_RRND
171 msr_s SYS_GCR_EL1, \tmp
175 .macro mte_set_kernel_gcr, tmp, tmp2
176 #ifdef CONFIG_KASAN_HW_TAGS
177 alternative_cb ARM64_ALWAYS_SYSTEM, kasan_hw_tags_enable
180 mov \tmp, KERNEL_GCR_EL1
181 msr_s SYS_GCR_EL1, \tmp
186 .macro mte_set_user_gcr, tsk, tmp, tmp2
187 #ifdef CONFIG_KASAN_HW_TAGS
188 alternative_cb ARM64_ALWAYS_SYSTEM, kasan_hw_tags_enable
191 ldr \tmp, [\tsk, #THREAD_MTE_CTRL]
193 mte_set_gcr \tmp, \tmp2
198 .macro kernel_entry, el, regsize = 64
200 alternative_insn nop, SET_PSTATE_DIT(1), ARM64_HAS_DIT
203 mov w0, w0 // zero upper 32 bits of x0
205 stp x0, x1, [sp, #16 * 0]
206 stp x2, x3, [sp, #16 * 1]
207 stp x4, x5, [sp, #16 * 2]
208 stp x6, x7, [sp, #16 * 3]
209 stp x8, x9, [sp, #16 * 4]
210 stp x10, x11, [sp, #16 * 5]
211 stp x12, x13, [sp, #16 * 6]
212 stp x14, x15, [sp, #16 * 7]
213 stp x16, x17, [sp, #16 * 8]
214 stp x18, x19, [sp, #16 * 9]
215 stp x20, x21, [sp, #16 * 10]
216 stp x22, x23, [sp, #16 * 11]
217 stp x24, x25, [sp, #16 * 12]
218 stp x26, x27, [sp, #16 * 13]
219 stp x28, x29, [sp, #16 * 14]
224 ldr_this_cpu tsk, __entry_task, x20
228 * Ensure MDSCR_EL1.SS is clear, since we can unmask debug exceptions
231 ldr x19, [tsk, #TSK_TI_FLAGS]
232 disable_step_tsk x19, x20
234 /* Check for asynchronous tag check faults in user space */
235 ldr x0, [tsk, THREAD_SCTLR_USER]
236 check_mte_async_tcf x22, x23, x0
238 #ifdef CONFIG_ARM64_PTR_AUTH
239 alternative_if ARM64_HAS_ADDRESS_AUTH
241 * Enable IA for in-kernel PAC if the task had it disabled. Although
242 * this could be implemented with an unconditional MRS which would avoid
243 * a load, this was measured to be slower on Cortex-A75 and Cortex-A76.
245 * Install the kernel IA key only if IA was enabled in the task. If IA
246 * was disabled on kernel exit then we would have left the kernel IA
247 * installed so there is no need to install it again.
249 tbz x0, SCTLR_ELx_ENIA_SHIFT, 1f
250 __ptrauth_keys_install_kernel_nosync tsk, x20, x22, x23
254 orr x0, x0, SCTLR_ELx_ENIA
257 alternative_else_nop_endif
260 apply_ssbd 1, x22, x23
262 mte_set_kernel_gcr x22, x23
265 * Any non-self-synchronizing system register updates required for
266 * kernel entry should be placed before this point.
268 alternative_if ARM64_MTE
271 alternative_else_nop_endif
272 alternative_if ARM64_HAS_ADDRESS_AUTH
274 alternative_else_nop_endif
279 add x21, sp, #PT_REGS_SIZE
281 .endif /* \el == 0 */
284 stp lr, x21, [sp, #S_LR]
287 * For exceptions from EL0, create a final frame record.
288 * For exceptions from EL1, create a synthetic frame record so the
289 * interrupted code shows up in the backtrace.
292 stp xzr, xzr, [sp, #S_STACKFRAME]
294 stp x29, x22, [sp, #S_STACKFRAME]
296 add x29, sp, #S_STACKFRAME
298 #ifdef CONFIG_ARM64_SW_TTBR0_PAN
299 alternative_if_not ARM64_HAS_PAN
300 bl __swpan_entry_el\el
301 alternative_else_nop_endif
304 stp x22, x23, [sp, #S_PC]
306 /* Not in a syscall by default (el0_svc overwrites for real syscall) */
309 str w21, [sp, #S_SYSCALLNO]
312 #ifdef CONFIG_ARM64_PSEUDO_NMI
313 alternative_if_not ARM64_HAS_GIC_PRIO_MASKING
315 alternative_else_nop_endif
317 mrs_s x20, SYS_ICC_PMR_EL1
318 str x20, [sp, #S_PMR_SAVE]
319 mov x20, #GIC_PRIO_IRQON | GIC_PRIO_PSR_I_SET
320 msr_s SYS_ICC_PMR_EL1, x20
326 * Registers that may be useful after this macro is invoked:
331 * x23 - aborted PSTATE
335 .macro kernel_exit, el
340 #ifdef CONFIG_ARM64_PSEUDO_NMI
341 alternative_if_not ARM64_HAS_GIC_PRIO_MASKING
342 b .Lskip_pmr_restore\@
343 alternative_else_nop_endif
345 ldr x20, [sp, #S_PMR_SAVE]
346 msr_s SYS_ICC_PMR_EL1, x20
348 /* Ensure priority change is seen by redistributor */
349 alternative_if_not ARM64_HAS_GIC_PRIO_RELAXED_SYNC
351 alternative_else_nop_endif
353 .Lskip_pmr_restore\@:
356 ldp x21, x22, [sp, #S_PC] // load ELR, SPSR
358 #ifdef CONFIG_ARM64_SW_TTBR0_PAN
359 alternative_if_not ARM64_HAS_PAN
360 bl __swpan_exit_el\el
361 alternative_else_nop_endif
365 ldr x23, [sp, #S_SP] // load return stack pointer
367 tst x22, #PSR_MODE32_BIT // native task?
370 #ifdef CONFIG_ARM64_ERRATUM_845719
371 alternative_if ARM64_WORKAROUND_845719
372 #ifdef CONFIG_PID_IN_CONTEXTIDR
373 mrs x29, contextidr_el1
374 msr contextidr_el1, x29
376 msr contextidr_el1, xzr
378 alternative_else_nop_endif
383 /* Ignore asynchronous tag check faults in the uaccess routines */
384 ldr x0, [tsk, THREAD_SCTLR_USER]
385 clear_mte_async_tcf x0
387 #ifdef CONFIG_ARM64_PTR_AUTH
388 alternative_if ARM64_HAS_ADDRESS_AUTH
390 * IA was enabled for in-kernel PAC. Disable it now if needed, or
391 * alternatively install the user's IA. All other per-task keys and
392 * SCTLR bits were updated on task switch.
394 * No kernel C function calls after this.
396 tbz x0, SCTLR_ELx_ENIA_SHIFT, 1f
397 __ptrauth_keys_install_user tsk, x0, x1, x2
401 bic x0, x0, SCTLR_ELx_ENIA
404 alternative_else_nop_endif
407 mte_set_user_gcr tsk, x0, x1
412 msr elr_el1, x21 // set up the return data
414 ldp x0, x1, [sp, #16 * 0]
415 ldp x2, x3, [sp, #16 * 1]
416 ldp x4, x5, [sp, #16 * 2]
417 ldp x6, x7, [sp, #16 * 3]
418 ldp x8, x9, [sp, #16 * 4]
419 ldp x10, x11, [sp, #16 * 5]
420 ldp x12, x13, [sp, #16 * 6]
421 ldp x14, x15, [sp, #16 * 7]
422 ldp x16, x17, [sp, #16 * 8]
423 ldp x18, x19, [sp, #16 * 9]
424 ldp x20, x21, [sp, #16 * 10]
425 ldp x22, x23, [sp, #16 * 11]
426 ldp x24, x25, [sp, #16 * 12]
427 ldp x26, x27, [sp, #16 * 13]
428 ldp x28, x29, [sp, #16 * 14]
431 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0
432 alternative_insn "b .L_skip_tramp_exit_\@", nop, ARM64_UNMAP_KERNEL_AT_EL0
436 ldr_this_cpu x30, this_cpu_vector, x29
437 tramp_alias x29, tramp_exit
438 msr vbar_el1, x30 // install vector table
439 ldr lr, [sp, #S_LR] // restore x30
440 add sp, sp, #PT_REGS_SIZE // restore sp
443 .L_skip_tramp_exit_\@:
448 add sp, sp, #PT_REGS_SIZE // restore sp
451 /* This must be after the last explicit memory access */
452 alternative_if ARM64_WORKAROUND_SPECULATIVE_UNPRIV_LOAD
455 alternative_else_nop_endif
457 /* Ensure any device/NC reads complete */
458 alternative_insn nop, "dmb sy", ARM64_WORKAROUND_1508412
465 #ifdef CONFIG_ARM64_SW_TTBR0_PAN
467 * Set the TTBR0 PAN bit in SPSR. When the exception is taken from
468 * EL0, there is no need to check the state of TTBR0_EL1 since
469 * accesses are always enabled.
470 * Note that the meaning of this bit differs from the ARMv8.1 PAN
471 * feature as all TTBR0_EL1 accesses are disabled, not just those to
474 SYM_CODE_START_LOCAL(__swpan_entry_el1)
476 tst x21, #TTBR_ASID_MASK // Check for the reserved ASID
477 orr x23, x23, #PSR_PAN_BIT // Set the emulated PAN in the saved SPSR
478 b.eq 1f // TTBR0 access already disabled
479 and x23, x23, #~PSR_PAN_BIT // Clear the emulated PAN in the saved SPSR
480 SYM_INNER_LABEL(__swpan_entry_el0, SYM_L_LOCAL)
481 __uaccess_ttbr0_disable x21
483 SYM_CODE_END(__swpan_entry_el1)
486 * Restore access to TTBR0_EL1. If returning to EL0, no need for SPSR
489 SYM_CODE_START_LOCAL(__swpan_exit_el1)
490 tbnz x22, #22, 1f // Skip re-enabling TTBR0 access if the PSR_PAN_BIT is set
491 __uaccess_ttbr0_enable x0, x1
492 1: and x22, x22, #~PSR_PAN_BIT // ARMv8.0 CPUs do not understand this bit
494 SYM_CODE_END(__swpan_exit_el1)
496 SYM_CODE_START_LOCAL(__swpan_exit_el0)
497 __uaccess_ttbr0_enable x0, x1
499 * Enable errata workarounds only if returning to user. The only
500 * workaround currently required for TTBR0_EL1 changes are for the
501 * Cavium erratum 27456 (broadcast TLBI instructions may cause I-cache
504 b post_ttbr_update_workaround
505 SYM_CODE_END(__swpan_exit_el0)
508 /* GPRs used by entry code */
509 tsk .req x28 // current thread_info
516 .pushsection ".entry.text", "ax"
519 SYM_CODE_START(vectors)
520 kernel_ventry 1, t, 64, sync // Synchronous EL1t
521 kernel_ventry 1, t, 64, irq // IRQ EL1t
522 kernel_ventry 1, t, 64, fiq // FIQ EL1t
523 kernel_ventry 1, t, 64, error // Error EL1t
525 kernel_ventry 1, h, 64, sync // Synchronous EL1h
526 kernel_ventry 1, h, 64, irq // IRQ EL1h
527 kernel_ventry 1, h, 64, fiq // FIQ EL1h
528 kernel_ventry 1, h, 64, error // Error EL1h
530 kernel_ventry 0, t, 64, sync // Synchronous 64-bit EL0
531 kernel_ventry 0, t, 64, irq // IRQ 64-bit EL0
532 kernel_ventry 0, t, 64, fiq // FIQ 64-bit EL0
533 kernel_ventry 0, t, 64, error // Error 64-bit EL0
535 kernel_ventry 0, t, 32, sync // Synchronous 32-bit EL0
536 kernel_ventry 0, t, 32, irq // IRQ 32-bit EL0
537 kernel_ventry 0, t, 32, fiq // FIQ 32-bit EL0
538 kernel_ventry 0, t, 32, error // Error 32-bit EL0
539 SYM_CODE_END(vectors)
541 #ifdef CONFIG_VMAP_STACK
542 SYM_CODE_START_LOCAL(__bad_stack)
544 * We detected an overflow in kernel_ventry, which switched to the
545 * overflow stack. Stash the exception regs, and head to our overflow
549 /* Restore the original x0 value */
553 * Store the original GPRs to the new stack. The orginal SP (minus
554 * PT_REGS_SIZE) was stashed in tpidr_el0 by kernel_ventry.
556 sub sp, sp, #PT_REGS_SIZE
559 add x0, x0, #PT_REGS_SIZE
562 /* Stash the regs for handle_bad_stack */
568 SYM_CODE_END(__bad_stack)
569 #endif /* CONFIG_VMAP_STACK */
572 .macro entry_handler el:req, ht:req, regsize:req, label:req
573 SYM_CODE_START_LOCAL(el\el\ht\()_\regsize\()_\label)
574 kernel_entry \el, \regsize
576 bl el\el\ht\()_\regsize\()_\label\()_handler
582 SYM_CODE_END(el\el\ht\()_\regsize\()_\label)
586 * Early exception handlers
588 entry_handler 1, t, 64, sync
589 entry_handler 1, t, 64, irq
590 entry_handler 1, t, 64, fiq
591 entry_handler 1, t, 64, error
593 entry_handler 1, h, 64, sync
594 entry_handler 1, h, 64, irq
595 entry_handler 1, h, 64, fiq
596 entry_handler 1, h, 64, error
598 entry_handler 0, t, 64, sync
599 entry_handler 0, t, 64, irq
600 entry_handler 0, t, 64, fiq
601 entry_handler 0, t, 64, error
603 entry_handler 0, t, 32, sync
604 entry_handler 0, t, 32, irq
605 entry_handler 0, t, 32, fiq
606 entry_handler 0, t, 32, error
608 SYM_CODE_START_LOCAL(ret_to_kernel)
610 SYM_CODE_END(ret_to_kernel)
612 SYM_CODE_START_LOCAL(ret_to_user)
613 ldr x19, [tsk, #TSK_TI_FLAGS] // re-check for single-step
614 enable_step_tsk x19, x2
615 #ifdef CONFIG_GCC_PLUGIN_STACKLEAK
616 bl stackleak_erase_on_task_stack
619 SYM_CODE_END(ret_to_user)
621 .popsection // .entry.text
623 // Move from tramp_pg_dir to swapper_pg_dir
624 .macro tramp_map_kernel, tmp
626 add \tmp, \tmp, #TRAMP_SWAPPER_OFFSET
627 bic \tmp, \tmp, #USER_ASID_FLAG
629 #ifdef CONFIG_QCOM_FALKOR_ERRATUM_1003
630 alternative_if ARM64_WORKAROUND_QCOM_FALKOR_E1003
631 /* ASID already in \tmp[63:48] */
632 movk \tmp, #:abs_g2_nc:(TRAMP_VALIAS >> 12)
633 movk \tmp, #:abs_g1_nc:(TRAMP_VALIAS >> 12)
634 /* 2MB boundary containing the vectors, so we nobble the walk cache */
635 movk \tmp, #:abs_g0_nc:((TRAMP_VALIAS & ~(SZ_2M - 1)) >> 12)
639 alternative_else_nop_endif
640 #endif /* CONFIG_QCOM_FALKOR_ERRATUM_1003 */
643 // Move from swapper_pg_dir to tramp_pg_dir
644 .macro tramp_unmap_kernel, tmp
646 sub \tmp, \tmp, #TRAMP_SWAPPER_OFFSET
647 orr \tmp, \tmp, #USER_ASID_FLAG
650 * We avoid running the post_ttbr_update_workaround here because
651 * it's only needed by Cavium ThunderX, which requires KPTI to be
656 .macro tramp_data_read_var dst, var
657 #ifdef CONFIG_RELOCATABLE
658 ldr \dst, .L__tramp_data_\var
659 .ifndef .L__tramp_data_\var
660 .pushsection ".entry.tramp.rodata", "a", %progbits
668 * As !RELOCATABLE implies !RANDOMIZE_BASE the address is always a
669 * compile time constant (and hence not secret and not worth hiding).
671 * As statically allocated kernel code and data always live in the top
672 * 47 bits of the address space we can sign-extend bit 47 and avoid an
673 * instruction to load the upper 16 bits (which must be 0xFFFF).
675 movz \dst, :abs_g2_s:\var
676 movk \dst, :abs_g1_nc:\var
677 movk \dst, :abs_g0_nc:\var
681 #define BHB_MITIGATION_NONE 0
682 #define BHB_MITIGATION_LOOP 1
683 #define BHB_MITIGATION_FW 2
684 #define BHB_MITIGATION_INSN 3
686 .macro tramp_ventry, vector_start, regsize, kpti, bhb
690 msr tpidrro_el0, x30 // Restored in kernel_ventry
693 .if \bhb == BHB_MITIGATION_LOOP
695 * This sequence must appear before the first indirect branch. i.e. the
696 * ret out of tramp_ventry. It appears here because x30 is free.
698 __mitigate_spectre_bhb_loop x30
699 .endif // \bhb == BHB_MITIGATION_LOOP
701 .if \bhb == BHB_MITIGATION_INSN
704 .endif // \bhb == BHB_MITIGATION_INSN
708 * Defend against branch aliasing attacks by pushing a dummy
709 * entry onto the return stack and using a RET instruction to
710 * enter the full-fat kernel vectors.
716 alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003
717 tramp_data_read_var x30, vectors
718 alternative_if_not ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM
719 prfm plil1strm, [x30, #(1b - \vector_start)]
720 alternative_else_nop_endif
728 .if \bhb == BHB_MITIGATION_FW
730 * The firmware sequence must appear before the first indirect branch.
731 * i.e. the ret out of tramp_ventry. But it also needs the stack to be
732 * mapped to save/restore the registers the SMC clobbers.
734 __mitigate_spectre_bhb_fw
735 .endif // \bhb == BHB_MITIGATION_FW
737 add x30, x30, #(1b - \vector_start + 4)
739 .org 1b + 128 // Did we overflow the ventry slot?
742 .macro generate_tramp_vector, kpti, bhb
747 tramp_ventry .Lvector_start\@, 64, \kpti, \bhb
750 tramp_ventry .Lvector_start\@, 32, \kpti, \bhb
754 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0
756 * Exception vectors trampoline.
757 * The order must match __bp_harden_el1_vectors and the
758 * arm64_bp_harden_el1_vectors enum.
760 .pushsection ".entry.tramp.text", "ax"
762 SYM_CODE_START_LOCAL_NOALIGN(tramp_vectors)
763 #ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY
764 generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_LOOP
765 generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_FW
766 generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_INSN
767 #endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */
768 generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_NONE
769 SYM_CODE_END(tramp_vectors)
771 SYM_CODE_START_LOCAL(tramp_exit)
772 tramp_unmap_kernel x29
773 mrs x29, far_el1 // restore x29
776 SYM_CODE_END(tramp_exit)
777 .popsection // .entry.tramp.text
778 #endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */
781 * Exception vectors for spectre mitigations on entry from EL1 when
782 * kpti is not in use.
784 .macro generate_el1_vector, bhb
786 kernel_ventry 1, t, 64, sync // Synchronous EL1t
787 kernel_ventry 1, t, 64, irq // IRQ EL1t
788 kernel_ventry 1, t, 64, fiq // FIQ EL1h
789 kernel_ventry 1, t, 64, error // Error EL1t
791 kernel_ventry 1, h, 64, sync // Synchronous EL1h
792 kernel_ventry 1, h, 64, irq // IRQ EL1h
793 kernel_ventry 1, h, 64, fiq // FIQ EL1h
794 kernel_ventry 1, h, 64, error // Error EL1h
797 tramp_ventry .Lvector_start\@, 64, 0, \bhb
800 tramp_ventry .Lvector_start\@, 32, 0, \bhb
804 /* The order must match tramp_vecs and the arm64_bp_harden_el1_vectors enum. */
805 .pushsection ".entry.text", "ax"
807 SYM_CODE_START(__bp_harden_el1_vectors)
808 #ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY
809 generate_el1_vector bhb=BHB_MITIGATION_LOOP
810 generate_el1_vector bhb=BHB_MITIGATION_FW
811 generate_el1_vector bhb=BHB_MITIGATION_INSN
812 #endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */
813 SYM_CODE_END(__bp_harden_el1_vectors)
818 * Register switch for AArch64. The callee-saved registers need to be saved
819 * and restored. On entry:
820 * x0 = previous task_struct (must be preserved across the switch)
821 * x1 = next task_struct
822 * Previous and next are guaranteed not to be the same.
825 SYM_FUNC_START(cpu_switch_to)
826 mov x10, #THREAD_CPU_CONTEXT
829 stp x19, x20, [x8], #16 // store callee-saved registers
830 stp x21, x22, [x8], #16
831 stp x23, x24, [x8], #16
832 stp x25, x26, [x8], #16
833 stp x27, x28, [x8], #16
834 stp x29, x9, [x8], #16
837 ldp x19, x20, [x8], #16 // restore callee-saved registers
838 ldp x21, x22, [x8], #16
839 ldp x23, x24, [x8], #16
840 ldp x25, x26, [x8], #16
841 ldp x27, x28, [x8], #16
842 ldp x29, x9, [x8], #16
846 ptrauth_keys_install_kernel x1, x8, x9, x10
850 SYM_FUNC_END(cpu_switch_to)
851 NOKPROBE(cpu_switch_to)
854 * This is how we return from a fork.
856 SYM_CODE_START(ret_from_fork)
858 cbz x19, 1f // not a kernel thread
861 1: get_current_task tsk
863 bl asm_exit_to_user_mode
865 SYM_CODE_END(ret_from_fork)
866 NOKPROBE(ret_from_fork)
869 * void call_on_irq_stack(struct pt_regs *regs,
870 * void (*func)(struct pt_regs *));
872 * Calls func(regs) using this CPU's irq stack and shadow irq stack.
874 SYM_FUNC_START(call_on_irq_stack)
875 #ifdef CONFIG_SHADOW_CALL_STACK
878 ldr_this_cpu scs_sp, irq_shadow_call_stack_ptr, x17
881 /* Create a frame record to save our LR and SP (implicit in FP) */
882 stp x29, x30, [sp, #-16]!
885 ldr_this_cpu x16, irq_stack_ptr, x17
887 /* Move to the new stack and call the function there */
888 add sp, x16, #IRQ_STACK_SIZE
892 * Restore the SP from the FP, and restore the FP and LR from the frame
896 ldp x29, x30, [sp], #16
899 SYM_FUNC_END(call_on_irq_stack)
900 NOKPROBE(call_on_irq_stack)
902 #ifdef CONFIG_ARM_SDE_INTERFACE
904 #include <asm/sdei.h>
905 #include <uapi/linux/arm_sdei.h>
907 .macro sdei_handler_exit exit_mode
908 /* On success, this call never returns... */
909 cmp \exit_mode, #SDEI_EXIT_SMC
917 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0
919 * The regular SDEI entry point may have been unmapped along with the rest of
920 * the kernel. This trampoline restores the kernel mapping to make the x1 memory
921 * argument accessible.
923 * This clobbers x4, __sdei_handler() will restore this from firmware's
926 .pushsection ".entry.tramp.text", "ax"
927 SYM_CODE_START(__sdei_asm_entry_trampoline)
929 tbz x4, #USER_ASID_BIT, 1f
931 tramp_map_kernel tmp=x4
936 * Remember whether to unmap the kernel on exit.
938 1: str x4, [x1, #(SDEI_EVENT_INTREGS + S_SDEI_TTBR1)]
939 tramp_data_read_var x4, __sdei_asm_handler
941 SYM_CODE_END(__sdei_asm_entry_trampoline)
942 NOKPROBE(__sdei_asm_entry_trampoline)
945 * Make the exit call and restore the original ttbr1_el1
947 * x0 & x1: setup for the exit API call
949 * x4: struct sdei_registered_event argument from registration time.
951 SYM_CODE_START(__sdei_asm_exit_trampoline)
952 ldr x4, [x4, #(SDEI_EVENT_INTREGS + S_SDEI_TTBR1)]
955 tramp_unmap_kernel tmp=x4
957 1: sdei_handler_exit exit_mode=x2
958 SYM_CODE_END(__sdei_asm_exit_trampoline)
959 NOKPROBE(__sdei_asm_exit_trampoline)
960 .popsection // .entry.tramp.text
961 #endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */
964 * Software Delegated Exception entry point.
967 * x1: struct sdei_registered_event argument from registration time.
969 * x3: interrupted PSTATE
970 * x4: maybe clobbered by the trampoline
972 * Firmware has preserved x0->x17 for us, we must save/restore the rest to
973 * follow SMC-CC. We save (or retrieve) all the registers as the handler may
976 SYM_CODE_START(__sdei_asm_handler)
977 stp x2, x3, [x1, #SDEI_EVENT_INTREGS + S_PC]
978 stp x4, x5, [x1, #SDEI_EVENT_INTREGS + 16 * 2]
979 stp x6, x7, [x1, #SDEI_EVENT_INTREGS + 16 * 3]
980 stp x8, x9, [x1, #SDEI_EVENT_INTREGS + 16 * 4]
981 stp x10, x11, [x1, #SDEI_EVENT_INTREGS + 16 * 5]
982 stp x12, x13, [x1, #SDEI_EVENT_INTREGS + 16 * 6]
983 stp x14, x15, [x1, #SDEI_EVENT_INTREGS + 16 * 7]
984 stp x16, x17, [x1, #SDEI_EVENT_INTREGS + 16 * 8]
985 stp x18, x19, [x1, #SDEI_EVENT_INTREGS + 16 * 9]
986 stp x20, x21, [x1, #SDEI_EVENT_INTREGS + 16 * 10]
987 stp x22, x23, [x1, #SDEI_EVENT_INTREGS + 16 * 11]
988 stp x24, x25, [x1, #SDEI_EVENT_INTREGS + 16 * 12]
989 stp x26, x27, [x1, #SDEI_EVENT_INTREGS + 16 * 13]
990 stp x28, x29, [x1, #SDEI_EVENT_INTREGS + 16 * 14]
992 stp lr, x4, [x1, #SDEI_EVENT_INTREGS + S_LR]
996 /* Store the registered-event for crash_smp_send_stop() */
997 ldrb w4, [x19, #SDEI_EVENT_PRIORITY]
999 adr_this_cpu dst=x5, sym=sdei_active_normal_event, tmp=x6
1001 1: adr_this_cpu dst=x5, sym=sdei_active_critical_event, tmp=x6
1004 #ifdef CONFIG_VMAP_STACK
1006 * entry.S may have been using sp as a scratch register, find whether
1007 * this is a normal or critical event and switch to the appropriate
1008 * stack for this CPU.
1011 ldr_this_cpu dst=x5, sym=sdei_stack_normal_ptr, tmp=x6
1013 1: ldr_this_cpu dst=x5, sym=sdei_stack_critical_ptr, tmp=x6
1014 2: mov x6, #SDEI_STACK_SIZE
1019 #ifdef CONFIG_SHADOW_CALL_STACK
1020 /* Use a separate shadow call stack for normal and critical events */
1022 ldr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_normal_ptr, tmp=x6
1024 3: ldr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_critical_ptr, tmp=x6
1029 * We may have interrupted userspace, or a guest, or exit-from or
1030 * return-to either of these. We can't trust sp_el0, restore it.
1033 ldr_this_cpu dst=x0, sym=__entry_task, tmp=x1
1036 /* If we interrupted the kernel point to the previous stack/frame. */
1040 csel x29, x29, xzr, eq // fp, or zero
1041 csel x4, x2, xzr, eq // elr, or zero
1043 stp x29, x4, [sp, #-16]!
1046 add x0, x19, #SDEI_EVENT_INTREGS
1051 /* restore regs >x17 that we clobbered */
1052 mov x4, x19 // keep x4 for __sdei_asm_exit_trampoline
1053 ldp x28, x29, [x4, #SDEI_EVENT_INTREGS + 16 * 14]
1054 ldp x18, x19, [x4, #SDEI_EVENT_INTREGS + 16 * 9]
1055 ldp lr, x1, [x4, #SDEI_EVENT_INTREGS + S_LR]
1058 mov x1, x0 // address to complete_and_resume
1059 /* x0 = (x0 <= SDEI_EV_FAILED) ?
1060 * EVENT_COMPLETE:EVENT_COMPLETE_AND_RESUME
1062 cmp x0, #SDEI_EV_FAILED
1063 mov_q x2, SDEI_1_0_FN_SDEI_EVENT_COMPLETE
1064 mov_q x3, SDEI_1_0_FN_SDEI_EVENT_COMPLETE_AND_RESUME
1067 ldr_l x2, sdei_exit_mode
1069 /* Clear the registered-event seen by crash_smp_send_stop() */
1070 ldrb w3, [x4, #SDEI_EVENT_PRIORITY]
1072 adr_this_cpu dst=x5, sym=sdei_active_normal_event, tmp=x6
1074 1: adr_this_cpu dst=x5, sym=sdei_active_critical_event, tmp=x6
1077 alternative_if_not ARM64_UNMAP_KERNEL_AT_EL0
1078 sdei_handler_exit exit_mode=x2
1079 alternative_else_nop_endif
1081 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0
1082 tramp_alias dst=x5, sym=__sdei_asm_exit_trampoline
1085 SYM_CODE_END(__sdei_asm_handler)
1086 NOKPROBE(__sdei_asm_handler)
1088 SYM_CODE_START(__sdei_handler_abort)
1089 mov_q x0, SDEI_1_0_FN_SDEI_EVENT_COMPLETE_AND_RESUME
1091 ldr_l x2, sdei_exit_mode
1092 sdei_handler_exit exit_mode=x2
1093 // exit the handler and jump to the next instruction.
1094 // Exit will stomp x0-x17, PSTATE, ELR_ELx, and SPSR_ELx.
1096 SYM_CODE_END(__sdei_handler_abort)
1097 NOKPROBE(__sdei_handler_abort)
1098 #endif /* CONFIG_ARM_SDE_INTERFACE */