LXR linux/arch/arm/kernel/perf

   1/*
   2 * ARM callchain support
   3 *
   4 * Copyright (C) 2009 picoChip Designs, Ltd., Jamie Iles
   5 * Copyright (C) 2010 ARM Ltd., Will Deacon <will.deacon@arm.com>
   6 *
   7 * This code is based on the ARM OProfile backtrace code.
   8 */
   9#include <linux/perf_event.h>
  10#include <linux/uaccess.h>
  11
  12#include <asm/stacktrace.h>
  13
  14/*
  15 * The registers we're interested in are at the end of the variable
  16 * length saved register structure. The fp points at the end of this
  17 * structure so the address of this struct is:
  18 * (struct frame_tail *)(xxx->fp)-1
  19 *
  20 * This code has been adapted from the ARM OProfile support.
  21 */
  22struct frame_tail {
  23        struct frame_tail __user *fp;
  24        unsigned long sp;
  25        unsigned long lr;
  26} __attribute__((packed));
  27
  28/*
  29 * Get the return address for a single stackframe and return a pointer to the
  30 * next frame tail.
  31 */
  32static struct frame_tail __user *
  33user_backtrace(struct frame_tail __user *tail,
  34               struct perf_callchain_entry_ctx *entry)
  35{
  36        struct frame_tail buftail;
  37        unsigned long err;
  38
  39        if (!access_ok(VERIFY_READ, tail, sizeof(buftail)))
  40                return NULL;
  41
  42        pagefault_disable();
  43        err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));
  44        pagefault_enable();
  45
  46        if (err)
  47                return NULL;
  48
  49        perf_callchain_store(entry, buftail.lr);
  50
  51        /*
  52         * Frame pointers should strictly progress back up the stack
  53         * (towards higher addresses).
  54         */
  55        if (tail + 1 >= buftail.fp)
  56                return NULL;
  57
  58        return buftail.fp - 1;
  59}
  60
  61void
  62perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
  63{
  64        struct frame_tail __user *tail;
  65
  66        if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
  67                /* We don't support guest os callchain now */
  68                return;
  69        }
  70
  71        perf_callchain_store(entry, regs->ARM_pc);
  72
  73        if (!current->mm)
  74                return;
  75
  76        tail = (struct frame_tail __user *)regs->ARM_fp - 1;
  77
  78        while ((entry->nr < entry->max_stack) &&
  79               tail && !((unsigned long)tail & 0x3))
  80                tail = user_backtrace(tail, entry);
  81}
  82
  83/*
  84 * Gets called by walk_stackframe() for every stackframe. This will be called
  85 * whist unwinding the stackframe and is like a subroutine return so we use
  86 * the PC.
  87 */
  88static int
  89callchain_trace(struct stackframe *fr,
  90                void *data)
  91{
  92        struct perf_callchain_entry_ctx *entry = data;
  93        perf_callchain_store(entry, fr->pc);
  94        return 0;
  95}
  96
  97void
  98perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
  99{
 100        struct stackframe fr;
 101
 102        if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
 103                /* We don't support guest os callchain now */
 104                return;
 105        }
 106
 107        arm_get_current_stackframe(regs, &fr);
 108        walk_stackframe(&fr, callchain_trace, entry);
 109}
 110
 111unsigned long perf_instruction_pointer(struct pt_regs *regs)
 112{
 113        if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
 114                return perf_guest_cbs->get_guest_ip();
 115
 116        return instruction_pointer(regs);
 117}
 118
 119unsigned long perf_misc_flags(struct pt_regs *regs)
 120{
 121        int misc = 0;
 122
 123        if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
 124                if (perf_guest_cbs->is_user_mode())
 125                        misc |= PERF_RECORD_MISC_GUEST_USER;
 126                else
 127                        misc |= PERF_RECORD_MISC_GUEST_KERNEL;
 128        } else {
 129                if (user_mode(regs))
 130                        misc |= PERF_RECORD_MISC_USER;
 131                else
 132                        misc |= PERF_RECORD_MISC_KERNEL;
 133        }
 134
 135        return misc;
 136}
 137