arch/powerpc/perf/callchain.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Performance counter callchain support - powerpc architecture code
   4  *
   5  * Copyright © 2009 Paul Mackerras, IBM Corporation.
   6  */
   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>
  12 #include <linux/mm.h>
  13 #include <asm/ptrace.h>
  14 #include <asm/sigcontext.h>
  15 #include <asm/ucontext.h>
  16 #include <asm/vdso.h>
  17 #include <asm/pte-walk.h>
  18
  19 #include "callchain.h"
  20
  21 /*
  22  * Is sp valid as the address of the next kernel stack frame after prev_sp?
  23  * The next frame may be in a different stack area but should not go
  24  * back down in the same stack area.
  25  */
  26 static int valid_next_sp(unsigned long sp, unsigned long prev_sp)
  27 {
  28         if (sp & 0xf)
  29                 return 0;               /* must be 16-byte aligned */
  30         if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
  31                 return 0;
  32         if (sp >= prev_sp + STACK_FRAME_MIN_SIZE)
  33                 return 1;
  34         /*
  35          * sp could decrease when we jump off an interrupt stack
  36          * back to the regular process stack.
  37          */
  38         if ((sp & ~(THREAD_SIZE - 1)) != (prev_sp & ~(THREAD_SIZE - 1)))
  39                 return 1;
  40         return 0;
  41 }
  42
  43 void
  44 perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
  45 {
  46         unsigned long sp, next_sp;
  47         unsigned long next_ip;
  48         unsigned long lr;
  49         long level = 0;
  50         unsigned long *fp;
  51
  52         lr = regs->link;
  53         sp = regs->gpr[1];
  54         perf_callchain_store(entry, perf_instruction_pointer(regs));
  55
  56         if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
  57                 return;
  58
  59         for (;;) {
  60                 fp = (unsigned long *) sp;
  61                 next_sp = fp[0];
  62
  63                 if (next_sp == sp + STACK_INT_FRAME_SIZE &&
  64                     fp[STACK_FRAME_MARKER] == STACK_FRAME_REGS_MARKER) {
  65                         /*
  66                          * This looks like an interrupt frame for an
  67                          * interrupt that occurred in the kernel
  68                          */
  69                         regs = (struct pt_regs *)(sp + STACK_FRAME_OVERHEAD);
  70                         next_ip = regs->nip;
  71                         lr = regs->link;
  72                         level = 0;
  73                         perf_callchain_store_context(entry, PERF_CONTEXT_KERNEL);
  74
  75                 } else {
  76                         if (level == 0)
  77                                 next_ip = lr;
  78                         else
  79                                 next_ip = fp[STACK_FRAME_LR_SAVE];
  80
  81                         /*
  82                          * We can't tell which of the first two addresses
  83                          * we get are valid, but we can filter out the
  84                          * obviously bogus ones here.  We replace them
  85                          * with 0 rather than removing them entirely so
  86                          * that userspace can tell which is which.
  87                          */
  88                         if ((level == 1 && next_ip == lr) ||
  89                             (level <= 1 && !kernel_text_address(next_ip)))
  90                                 next_ip = 0;
  91
  92                         ++level;
  93                 }
  94
  95                 perf_callchain_store(entry, next_ip);
  96                 if (!valid_next_sp(next_sp, sp))
  97                         return;
  98                 sp = next_sp;
  99         }
 100 }
 101
 102 void
 103 perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
 104 {
 105         if (!is_32bit_task())
 106                 perf_callchain_user_64(entry, regs);
 107         else
 108                 perf_callchain_user_32(entry, regs);
 109 }