common.c

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#include <linux/cpumask.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

/*
 * OProfile has a curious naming scheme for the ARM PMUs, but they are
 * part of the user ABI so we need to map from the perf PMU name for
 * supported PMUs.
 */
static struct op_perf_name {
    char *perf_name;
    char *op_name;
} op_perf_name_map[] = {
    { "xscale1",        "arm/xscale1"   },
    { "xscale1",        "arm/xscale2"   },
    { "v6",         "arm/armv6" },
    { "v6mpcore",       "arm/mpcore"    },
    { "ARMv7 Cortex-A8",    "arm/armv7" },
    { "ARMv7 Cortex-A9",    "arm/armv7-ca9" },
};

char *op_name_from_perf_id(void)
{
    int i;
    struct op_perf_name names;
    const char *perf_name = perf_pmu_name();

    for (i = 0; i < ARRAY_SIZE(op_perf_name_map); ++i) {
        names = op_perf_name_map[i];
        if (!strcmp(names.perf_name, perf_name))
            return names.op_name;
    }

    return NULL;
}
#endif

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 + 1 >= 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)
{
    /* provide backtrace support also in timer mode: */
    ops->backtrace      = arm_backtrace;

    return oprofile_perf_init(ops);
}

void oprofile_arch_exit(void)
{
    oprofile_perf_exit();
}