Commit d7d59fb3 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar

perf_counter: x86: callchain support

Provide the x86 perf_callchain() implementation.

Code based on the ftrace/sysprof code from Soeren Sandmann Pedersen.
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: default avatarPaul Mackerras <paulus@samba.org>
Cc: Soeren Sandmann Pedersen <sandmann@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Orig-LKML-Reference: <20090330171024.341993293@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 394ee076
......@@ -16,8 +16,10 @@
#include <linux/module.h>
#include <linux/kdebug.h>
#include <linux/sched.h>
#include <linux/uaccess.h>
#include <asm/apic.h>
#include <asm/stacktrace.h>
static bool perf_counters_initialized __read_mostly;
......@@ -958,3 +960,155 @@ hw_perf_counter_init(struct perf_counter *counter)
return &x86_perf_counter_ops;
}
/*
* callchain support
*/
static inline
void callchain_store(struct perf_callchain_entry *entry, unsigned long ip)
{
if (entry->nr < MAX_STACK_DEPTH)
entry->ip[entry->nr++] = ip;
}
static DEFINE_PER_CPU(struct perf_callchain_entry, irq_entry);
static DEFINE_PER_CPU(struct perf_callchain_entry, nmi_entry);
static void
backtrace_warning_symbol(void *data, char *msg, unsigned long symbol)
{
/* Ignore warnings */
}
static void backtrace_warning(void *data, char *msg)
{
/* Ignore warnings */
}
static int backtrace_stack(void *data, char *name)
{
/* Don't bother with IRQ stacks for now */
return -1;
}
static void backtrace_address(void *data, unsigned long addr, int reliable)
{
struct perf_callchain_entry *entry = data;
if (reliable)
callchain_store(entry, addr);
}
static const struct stacktrace_ops backtrace_ops = {
.warning = backtrace_warning,
.warning_symbol = backtrace_warning_symbol,
.stack = backtrace_stack,
.address = backtrace_address,
};
static void
perf_callchain_kernel(struct pt_regs *regs, struct perf_callchain_entry *entry)
{
unsigned long bp;
char *stack;
callchain_store(entry, instruction_pointer(regs));
stack = ((char *)regs + sizeof(struct pt_regs));
#ifdef CONFIG_FRAME_POINTER
bp = frame_pointer(regs);
#else
bp = 0;
#endif
dump_trace(NULL, regs, (void *)stack, bp, &backtrace_ops, entry);
}
struct stack_frame {
const void __user *next_fp;
unsigned long return_address;
};
static int copy_stack_frame(const void __user *fp, struct stack_frame *frame)
{
int ret;
if (!access_ok(VERIFY_READ, fp, sizeof(*frame)))
return 0;
ret = 1;
pagefault_disable();
if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
ret = 0;
pagefault_enable();
return ret;
}
static void
perf_callchain_user(struct pt_regs *regs, struct perf_callchain_entry *entry)
{
struct stack_frame frame;
const void __user *fp;
regs = (struct pt_regs *)current->thread.sp0 - 1;
fp = (void __user *)regs->bp;
callchain_store(entry, regs->ip);
while (entry->nr < MAX_STACK_DEPTH) {
frame.next_fp = NULL;
frame.return_address = 0;
if (!copy_stack_frame(fp, &frame))
break;
if ((unsigned long)fp < user_stack_pointer(regs))
break;
callchain_store(entry, frame.return_address);
fp = frame.next_fp;
}
}
static void
perf_do_callchain(struct pt_regs *regs, struct perf_callchain_entry *entry)
{
int is_user;
if (!regs)
return;
is_user = user_mode(regs);
if (!current || current->pid == 0)
return;
if (is_user && current->state != TASK_RUNNING)
return;
if (!is_user)
perf_callchain_kernel(regs, entry);
if (current->mm)
perf_callchain_user(regs, entry);
}
struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
{
struct perf_callchain_entry *entry;
if (in_nmi())
entry = &__get_cpu_var(nmi_entry);
else
entry = &__get_cpu_var(irq_entry);
entry->nr = 0;
perf_do_callchain(regs, entry);
return entry;
}
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