LXR linux/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 */
  26static 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
  43void __no_sanitize_address
  44perf_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
 102void
 103perf_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}
 110