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common.c

/**
 * @file common.c
 *
 * @remark Copyright 2004 Oprofile Authors
 * @remark Copyright 2010 ARM Ltd.
 * @remark Read the file COPYING
 *
 * @author Zwane Mwaikambo
 * @author Will Deacon [move to perf]
 */

#include <linux/cpumask.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/mutex.h>
#include <linux/oprofile.h>
#include <linux/perf_event.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <asm/stacktrace.h>
#include <linux/uaccess.h>

#include <asm/perf_event.h>
#include <asm/ptrace.h>

#ifdef CONFIG_HW_PERF_EVENTS
char *op_name_from_perf_id(void)
{
      enum arm_perf_pmu_ids id = armpmu_get_pmu_id();

      switch (id) {
      case ARM_PERF_PMU_ID_XSCALE1:
            return "arm/xscale1";
      case ARM_PERF_PMU_ID_XSCALE2:
            return "arm/xscale2";
      case ARM_PERF_PMU_ID_V6:
            return "arm/armv6";
      case ARM_PERF_PMU_ID_V6MP:
            return "arm/mpcore";
      case ARM_PERF_PMU_ID_CA8:
            return "arm/armv7";
      case ARM_PERF_PMU_ID_CA9:
            return "arm/armv7-ca9";
      default:
            return NULL;
      }
}

static int report_trace(struct stackframe *frame, void *d)
{
      unsigned int *depth = d;

      if (*depth) {
            oprofile_add_trace(frame->pc);
            (*depth)--;
      }

      return *depth == 0;
}

/*
 * The registers we're interested in are at the end of the variable
 * length saved register structure. The fp points at the end of this
 * structure so the address of this struct is:
 * (struct frame_tail *)(xxx->fp)-1
 */
struct frame_tail {
      struct frame_tail *fp;
      unsigned long sp;
      unsigned long lr;
} __attribute__((packed));

static struct frame_tail* user_backtrace(struct frame_tail *tail)
{
      struct frame_tail buftail[2];

      /* Also check accessibility of one struct frame_tail beyond */
      if (!access_ok(VERIFY_READ, tail, sizeof(buftail)))
            return NULL;
      if (__copy_from_user_inatomic(buftail, tail, sizeof(buftail)))
            return NULL;

      oprofile_add_trace(buftail[0].lr);

      /* frame pointers should strictly progress back up the stack
       * (towards higher addresses) */
      if (tail >= buftail[0].fp)
            return NULL;

      return buftail[0].fp-1;
}

static void arm_backtrace(struct pt_regs * const regs, unsigned int depth)
{
      struct frame_tail *tail = ((struct frame_tail *) regs->ARM_fp) - 1;

      if (!user_mode(regs)) {
            struct stackframe frame;
            frame.fp = regs->ARM_fp;
            frame.sp = regs->ARM_sp;
            frame.lr = regs->ARM_lr;
            frame.pc = regs->ARM_pc;
            walk_stackframe(&frame, report_trace, &depth);
            return;
      }

      while (depth-- && tail && !((unsigned long) tail & 3))
            tail = user_backtrace(tail);
}

int __init oprofile_arch_init(struct oprofile_operations *ops)
{
      ops->backtrace          = arm_backtrace;

      return oprofile_perf_init(ops);
}

void __exit oprofile_arch_exit(void)
{
      oprofile_perf_exit();
}
#else
int __init oprofile_arch_init(struct oprofile_operations *ops)
{
      pr_info("oprofile: hardware counters not available\n");
      return -ENODEV;
}
void __exit oprofile_arch_exit(void) {}
#endif /* CONFIG_HW_PERF_EVENTS */

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