1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Performance counter callchain support - powerpc architecture code
5 * Copyright © 2009 Paul Mackerras, IBM Corporation.
7 #include <linux/kernel.h>
8 #include <linux/sched.h>
9 #include <linux/perf_event.h>
10 #include <linux/percpu.h>
11 #include <linux/uaccess.h>
13 #include <asm/ptrace.h>
14 #include <asm/pgtable.h>
15 #include <asm/sigcontext.h>
16 #include <asm/ucontext.h>
19 #include "../kernel/ppc32.h"
21 #include <asm/pte-walk.h>
25 * Is sp valid as the address of the next kernel stack frame after prev_sp?
26 * The next frame may be in a different stack area but should not go
27 * back down in the same stack area.
29 static int valid_next_sp(unsigned long sp, unsigned long prev_sp)
32 return 0; /* must be 16-byte aligned */
33 if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
35 if (sp >= prev_sp + STACK_FRAME_MIN_SIZE)
38 * sp could decrease when we jump off an interrupt stack
39 * back to the regular process stack.
41 if ((sp & ~(THREAD_SIZE - 1)) != (prev_sp & ~(THREAD_SIZE - 1)))
47 perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
49 unsigned long sp, next_sp;
50 unsigned long next_ip;
57 perf_callchain_store(entry, perf_instruction_pointer(regs));
59 if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
63 fp = (unsigned long *) sp;
66 if (next_sp == sp + STACK_INT_FRAME_SIZE &&
67 fp[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
69 * This looks like an interrupt frame for an
70 * interrupt that occurred in the kernel
72 regs = (struct pt_regs *)(sp + STACK_FRAME_OVERHEAD);
76 perf_callchain_store_context(entry, PERF_CONTEXT_KERNEL);
82 next_ip = fp[STACK_FRAME_LR_SAVE];
85 * We can't tell which of the first two addresses
86 * we get are valid, but we can filter out the
87 * obviously bogus ones here. We replace them
88 * with 0 rather than removing them entirely so
89 * that userspace can tell which is which.
91 if ((level == 1 && next_ip == lr) ||
92 (level <= 1 && !kernel_text_address(next_ip)))
98 perf_callchain_store(entry, next_ip);
99 if (!valid_next_sp(next_sp, sp))
107 * On 64-bit we don't want to invoke hash_page on user addresses from
108 * interrupt context, so if the access faults, we read the page tables
109 * to find which page (if any) is mapped and access it directly.
111 static int read_user_stack_slow(void __user *ptr, void *buf, int nb)
117 unsigned long addr = (unsigned long) ptr;
118 unsigned long offset;
119 unsigned long pfn, flags;
122 pgdir = current->mm->pgd;
126 local_irq_save(flags);
127 ptep = find_current_mm_pte(pgdir, addr, NULL, &shift);
133 /* align address to page boundary */
134 offset = addr & ((1UL << shift) - 1);
136 pte = READ_ONCE(*ptep);
137 if (!pte_present(pte) || !pte_user(pte))
140 if (!page_is_ram(pfn))
143 /* no highmem to worry about here */
144 kaddr = pfn_to_kaddr(pfn);
145 memcpy(buf, kaddr + offset, nb);
148 local_irq_restore(flags);
152 static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret)
154 if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned long) ||
155 ((unsigned long)ptr & 7))
159 if (!__get_user_inatomic(*ret, ptr)) {
165 return read_user_stack_slow(ptr, ret, 8);
168 static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
170 if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
171 ((unsigned long)ptr & 3))
175 if (!__get_user_inatomic(*ret, ptr)) {
181 return read_user_stack_slow(ptr, ret, 4);
184 static inline int valid_user_sp(unsigned long sp, int is_64)
186 if (!sp || (sp & 7) || sp > (is_64 ? TASK_SIZE : 0x100000000UL) - 32)
192 * 64-bit user processes use the same stack frame for RT and non-RT signals.
194 struct signal_frame_64 {
195 char dummy[__SIGNAL_FRAMESIZE];
197 unsigned long unused[2];
198 unsigned int tramp[6];
199 struct siginfo *pinfo;
205 static int is_sigreturn_64_address(unsigned long nip, unsigned long fp)
207 if (nip == fp + offsetof(struct signal_frame_64, tramp))
209 if (vdso64_rt_sigtramp && current->mm->context.vdso_base &&
210 nip == current->mm->context.vdso_base + vdso64_rt_sigtramp)
216 * Do some sanity checking on the signal frame pointed to by sp.
217 * We check the pinfo and puc pointers in the frame.
219 static int sane_signal_64_frame(unsigned long sp)
221 struct signal_frame_64 __user *sf;
222 unsigned long pinfo, puc;
224 sf = (struct signal_frame_64 __user *) sp;
225 if (read_user_stack_64((unsigned long __user *) &sf->pinfo, &pinfo) ||
226 read_user_stack_64((unsigned long __user *) &sf->puc, &puc))
228 return pinfo == (unsigned long) &sf->info &&
229 puc == (unsigned long) &sf->uc;
232 static void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry,
233 struct pt_regs *regs)
235 unsigned long sp, next_sp;
236 unsigned long next_ip;
239 struct signal_frame_64 __user *sigframe;
240 unsigned long __user *fp, *uregs;
242 next_ip = perf_instruction_pointer(regs);
245 perf_callchain_store(entry, next_ip);
247 while (entry->nr < entry->max_stack) {
248 fp = (unsigned long __user *) sp;
249 if (!valid_user_sp(sp, 1) || read_user_stack_64(fp, &next_sp))
251 if (level > 0 && read_user_stack_64(&fp[2], &next_ip))
255 * Note: the next_sp - sp >= signal frame size check
256 * is true when next_sp < sp, which can happen when
257 * transitioning from an alternate signal stack to the
260 if (next_sp - sp >= sizeof(struct signal_frame_64) &&
261 (is_sigreturn_64_address(next_ip, sp) ||
262 (level <= 1 && is_sigreturn_64_address(lr, sp))) &&
263 sane_signal_64_frame(sp)) {
265 * This looks like an signal frame
267 sigframe = (struct signal_frame_64 __user *) sp;
268 uregs = sigframe->uc.uc_mcontext.gp_regs;
269 if (read_user_stack_64(&uregs[PT_NIP], &next_ip) ||
270 read_user_stack_64(&uregs[PT_LNK], &lr) ||
271 read_user_stack_64(&uregs[PT_R1], &sp))
274 perf_callchain_store_context(entry, PERF_CONTEXT_USER);
275 perf_callchain_store(entry, next_ip);
281 perf_callchain_store(entry, next_ip);
287 static inline int current_is_64bit(void)
290 * We can't use test_thread_flag() here because we may be on an
291 * interrupt stack, and the thread flags don't get copied over
292 * from the thread_info on the main stack to the interrupt stack.
294 return !test_ti_thread_flag(task_thread_info(current), TIF_32BIT);
297 #else /* CONFIG_PPC64 */
299 * On 32-bit we just access the address and let hash_page create a
300 * HPTE if necessary, so there is no need to fall back to reading
301 * the page tables. Since this is called at interrupt level,
302 * do_page_fault() won't treat a DSI as a page fault.
304 static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
308 if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
309 ((unsigned long)ptr & 3))
313 rc = __get_user_inatomic(*ret, ptr);
319 static inline void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry,
320 struct pt_regs *regs)
324 static inline int current_is_64bit(void)
329 static inline int valid_user_sp(unsigned long sp, int is_64)
331 if (!sp || (sp & 7) || sp > TASK_SIZE - 32)
336 #define __SIGNAL_FRAMESIZE32 __SIGNAL_FRAMESIZE
337 #define sigcontext32 sigcontext
338 #define mcontext32 mcontext
339 #define ucontext32 ucontext
340 #define compat_siginfo_t struct siginfo
342 #endif /* CONFIG_PPC64 */
345 * Layout for non-RT signal frames
347 struct signal_frame_32 {
348 char dummy[__SIGNAL_FRAMESIZE32];
349 struct sigcontext32 sctx;
350 struct mcontext32 mctx;
355 * Layout for RT signal frames
357 struct rt_signal_frame_32 {
358 char dummy[__SIGNAL_FRAMESIZE32 + 16];
359 compat_siginfo_t info;
360 struct ucontext32 uc;
364 static int is_sigreturn_32_address(unsigned int nip, unsigned int fp)
366 if (nip == fp + offsetof(struct signal_frame_32, mctx.mc_pad))
368 if (vdso32_sigtramp && current->mm->context.vdso_base &&
369 nip == current->mm->context.vdso_base + vdso32_sigtramp)
374 static int is_rt_sigreturn_32_address(unsigned int nip, unsigned int fp)
376 if (nip == fp + offsetof(struct rt_signal_frame_32,
377 uc.uc_mcontext.mc_pad))
379 if (vdso32_rt_sigtramp && current->mm->context.vdso_base &&
380 nip == current->mm->context.vdso_base + vdso32_rt_sigtramp)
385 static int sane_signal_32_frame(unsigned int sp)
387 struct signal_frame_32 __user *sf;
390 sf = (struct signal_frame_32 __user *) (unsigned long) sp;
391 if (read_user_stack_32((unsigned int __user *) &sf->sctx.regs, ®s))
393 return regs == (unsigned long) &sf->mctx;
396 static int sane_rt_signal_32_frame(unsigned int sp)
398 struct rt_signal_frame_32 __user *sf;
401 sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp;
402 if (read_user_stack_32((unsigned int __user *) &sf->uc.uc_regs, ®s))
404 return regs == (unsigned long) &sf->uc.uc_mcontext;
407 static unsigned int __user *signal_frame_32_regs(unsigned int sp,
408 unsigned int next_sp, unsigned int next_ip)
410 struct mcontext32 __user *mctx = NULL;
411 struct signal_frame_32 __user *sf;
412 struct rt_signal_frame_32 __user *rt_sf;
415 * Note: the next_sp - sp >= signal frame size check
416 * is true when next_sp < sp, for example, when
417 * transitioning from an alternate signal stack to the
420 if (next_sp - sp >= sizeof(struct signal_frame_32) &&
421 is_sigreturn_32_address(next_ip, sp) &&
422 sane_signal_32_frame(sp)) {
423 sf = (struct signal_frame_32 __user *) (unsigned long) sp;
427 if (!mctx && next_sp - sp >= sizeof(struct rt_signal_frame_32) &&
428 is_rt_sigreturn_32_address(next_ip, sp) &&
429 sane_rt_signal_32_frame(sp)) {
430 rt_sf = (struct rt_signal_frame_32 __user *) (unsigned long) sp;
431 mctx = &rt_sf->uc.uc_mcontext;
436 return mctx->mc_gregs;
439 static void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry,
440 struct pt_regs *regs)
442 unsigned int sp, next_sp;
443 unsigned int next_ip;
446 unsigned int __user *fp, *uregs;
448 next_ip = perf_instruction_pointer(regs);
451 perf_callchain_store(entry, next_ip);
453 while (entry->nr < entry->max_stack) {
454 fp = (unsigned int __user *) (unsigned long) sp;
455 if (!valid_user_sp(sp, 0) || read_user_stack_32(fp, &next_sp))
457 if (level > 0 && read_user_stack_32(&fp[1], &next_ip))
460 uregs = signal_frame_32_regs(sp, next_sp, next_ip);
461 if (!uregs && level <= 1)
462 uregs = signal_frame_32_regs(sp, next_sp, lr);
465 * This looks like an signal frame, so restart
466 * the stack trace with the values in it.
468 if (read_user_stack_32(&uregs[PT_NIP], &next_ip) ||
469 read_user_stack_32(&uregs[PT_LNK], &lr) ||
470 read_user_stack_32(&uregs[PT_R1], &sp))
473 perf_callchain_store_context(entry, PERF_CONTEXT_USER);
474 perf_callchain_store(entry, next_ip);
480 perf_callchain_store(entry, next_ip);
487 perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
489 if (current_is_64bit())
490 perf_callchain_user_64(entry, regs);
492 perf_callchain_user_32(entry, regs);