perf_callchain.c 4.6 KB

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  1. // SPDX-License-Identifier: GPL-2.0-only
  2. /*
  3. * arm64 callchain support
  4. *
  5. * Copyright (C) 2015 ARM Limited
  6. */
  7. #include <linux/perf_event.h>
  8. #include <linux/uaccess.h>
  9. #include <asm/pointer_auth.h>
  10. #include <asm/stacktrace.h>
  11. struct frame_tail {
  12. struct frame_tail __user *fp;
  13. unsigned long lr;
  14. } __attribute__((packed));
  15. /*
  16. * Get the return address for a single stackframe and return a pointer to the
  17. * next frame tail.
  18. */
  19. static struct frame_tail __user *
  20. user_backtrace(struct frame_tail __user *tail,
  21. struct perf_callchain_entry_ctx *entry)
  22. {
  23. struct frame_tail buftail;
  24. unsigned long err;
  25. unsigned long lr;
  26. /* Also check accessibility of one struct frame_tail beyond */
  27. if (!access_ok(tail, sizeof(buftail)))
  28. return NULL;
  29. pagefault_disable();
  30. err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));
  31. pagefault_enable();
  32. if (err)
  33. return NULL;
  34. lr = ptrauth_strip_insn_pac(buftail.lr);
  35. perf_callchain_store(entry, lr);
  36. /*
  37. * Frame pointers should strictly progress back up the stack
  38. * (towards higher addresses).
  39. */
  40. if (tail >= buftail.fp)
  41. return NULL;
  42. return buftail.fp;
  43. }
  44. #ifdef CONFIG_COMPAT
  45. /*
  46. * The registers we're interested in are at the end of the variable
  47. * length saved register structure. The fp points at the end of this
  48. * structure so the address of this struct is:
  49. * (struct compat_frame_tail *)(xxx->fp)-1
  50. *
  51. * This code has been adapted from the ARM OProfile support.
  52. */
  53. struct compat_frame_tail {
  54. compat_uptr_t fp; /* a (struct compat_frame_tail *) in compat mode */
  55. u32 sp;
  56. u32 lr;
  57. } __attribute__((packed));
  58. static struct compat_frame_tail __user *
  59. compat_user_backtrace(struct compat_frame_tail __user *tail,
  60. struct perf_callchain_entry_ctx *entry)
  61. {
  62. struct compat_frame_tail buftail;
  63. unsigned long err;
  64. /* Also check accessibility of one struct frame_tail beyond */
  65. if (!access_ok(tail, sizeof(buftail)))
  66. return NULL;
  67. pagefault_disable();
  68. err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));
  69. pagefault_enable();
  70. if (err)
  71. return NULL;
  72. perf_callchain_store(entry, buftail.lr);
  73. /*
  74. * Frame pointers should strictly progress back up the stack
  75. * (towards higher addresses).
  76. */
  77. if (tail + 1 >= (struct compat_frame_tail __user *)
  78. compat_ptr(buftail.fp))
  79. return NULL;
  80. return (struct compat_frame_tail __user *)compat_ptr(buftail.fp) - 1;
  81. }
  82. #endif /* CONFIG_COMPAT */
  83. void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
  84. struct pt_regs *regs)
  85. {
  86. struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
  87. if (guest_cbs && guest_cbs->is_in_guest()) {
  88. /* We don't support guest os callchain now */
  89. return;
  90. }
  91. perf_callchain_store(entry, regs->pc);
  92. if (!compat_user_mode(regs)) {
  93. /* AARCH64 mode */
  94. struct frame_tail __user *tail;
  95. tail = (struct frame_tail __user *)regs->regs[29];
  96. while (entry->nr < entry->max_stack &&
  97. tail && !((unsigned long)tail & 0xf))
  98. tail = user_backtrace(tail, entry);
  99. } else {
  100. #ifdef CONFIG_COMPAT
  101. /* AARCH32 compat mode */
  102. struct compat_frame_tail __user *tail;
  103. tail = (struct compat_frame_tail __user *)regs->compat_fp - 1;
  104. while ((entry->nr < entry->max_stack) &&
  105. tail && !((unsigned long)tail & 0x3))
  106. tail = compat_user_backtrace(tail, entry);
  107. #endif
  108. }
  109. }
  110. /*
  111. * Gets called by walk_stackframe() for every stackframe. This will be called
  112. * whist unwinding the stackframe and is like a subroutine return so we use
  113. * the PC.
  114. */
  115. static bool callchain_trace(void *data, unsigned long pc)
  116. {
  117. struct perf_callchain_entry_ctx *entry = data;
  118. perf_callchain_store(entry, pc);
  119. return true;
  120. }
  121. void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
  122. struct pt_regs *regs)
  123. {
  124. struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
  125. struct stackframe frame;
  126. if (guest_cbs && guest_cbs->is_in_guest()) {
  127. /* We don't support guest os callchain now */
  128. return;
  129. }
  130. start_backtrace(&frame, regs->regs[29], regs->pc);
  131. walk_stackframe(current, &frame, callchain_trace, entry);
  132. }
  133. unsigned long perf_instruction_pointer(struct pt_regs *regs)
  134. {
  135. struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
  136. if (guest_cbs && guest_cbs->is_in_guest())
  137. return guest_cbs->get_guest_ip();
  138. return instruction_pointer(regs);
  139. }
  140. unsigned long perf_misc_flags(struct pt_regs *regs)
  141. {
  142. struct perf_guest_info_callbacks *guest_cbs = perf_get_guest_cbs();
  143. int misc = 0;
  144. if (guest_cbs && guest_cbs->is_in_guest()) {
  145. if (guest_cbs->is_user_mode())
  146. misc |= PERF_RECORD_MISC_GUEST_USER;
  147. else
  148. misc |= PERF_RECORD_MISC_GUEST_KERNEL;
  149. } else {
  150. if (user_mode(regs))
  151. misc |= PERF_RECORD_MISC_USER;
  152. else
  153. misc |= PERF_RECORD_MISC_KERNEL;
  154. }
  155. return misc;
  156. }