[tip:perfcounters/core] perf_counter: Make callchain samples extensible

tip-bot for Peter Zijlstra
2009-06-19T11:53:24Z

Commit-ID: f9188e023c248d73f5b4a589b480e065c1864068
Gitweb: http://git.kernel.org/tip/f9188e023c248d73f5b4a589b480e065c1864068
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Thu, 18 Jun 2009 22:20:52 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 19 Jun 2009 13:42:34 +0200

perf_counter: Make callchain samples extensible

Before exposing upstream tools to a callchain-samples ABI, tidy it
up to make it more extensible in the future:

Use markers in the IP chain to denote context, use (u64)-1..-4095 range
for these context markers because we use them for ERR_PTR(), so these
addresses are unlikely to be mapped.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

---
arch/x86/kernel/cpu/perf_counter.c | 29 ++++++-----------------------
include/linux/perf_counter.h | 28 +++++++++++++++++-----------
2 files changed, 23 insertions(+), 34 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index ce1ae3f..76dfef2 100644
--- a/arch/x86/kernel/cpu/perf_counter.c
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -1555,9 +1555,9 @@ const struct pmu *hw_perf_counter_init(struct perf_counter *counter)
*/

static inline
-void callchain_store(struct perf_callchain_entry *entry, unsigned long ip)
+void callchain_store(struct perf_callchain_entry *entry, u64 ip)
{
- if (entry->nr < MAX_STACK_DEPTH)
+ if (entry->nr < PERF_MAX_STACK_DEPTH)
entry->ip[entry->nr++] = ip;
}

@@ -1602,22 +1602,10 @@ static const struct stacktrace_ops backtrace_ops = {
static void
perf_callchain_kernel(struct pt_regs *regs, struct perf_callchain_entry *entry)
{
- unsigned long bp;
- char *stack;
- int nr = entry->nr;
-
+ callchain_store(entry, PERF_CONTEXT_KERNEL);
callchain_store(entry, regs->ip);

- stack = ((char *)regs + sizeof(struct pt_regs));
-#ifdef CONFIG_FRAME_POINTER
- get_bp(bp);
-#else
- bp = 0;
-#endif
-
- dump_trace(NULL, regs, (void *)&stack, bp, &backtrace_ops, entry);
-
- entry->kernel = entry->nr - nr;
+ dump_trace(NULL, regs, NULL, 0, &backtrace_ops, entry);
}

/*
@@ -1669,16 +1657,16 @@ perf_callchain_user(struct pt_regs *regs, struct perf_callchain_entry *entry)
{
struct stack_frame frame;
const void __user *fp;
- int nr = entry->nr;

if (!user_mode(regs))
regs = task_pt_regs(current);

fp = (void __user *)regs->bp;

+ callchain_store(entry, PERF_CONTEXT_USER);
callchain_store(entry, regs->ip);

- while (entry->nr < MAX_STACK_DEPTH) {
+ while (entry->nr < PERF_MAX_STACK_DEPTH) {
frame.next_frame = NULL;
frame.return_address = 0;

@@ -1691,8 +1679,6 @@ perf_callchain_user(struct pt_regs *regs, struct perf_callchain_entry *entry)
callchain_store(entry, frame.return_address);
fp = frame.next_frame;
}
-
- entry->user = entry->nr - nr;
}

static void
@@ -1728,9 +1714,6 @@ struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
entry = &__get_cpu_var(irq_entry);

entry->nr = 0;
- entry->hv = 0;
- entry->kernel = 0;
- entry->user = 0;

perf_do_callchain(regs, entry);

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 0765e8e..e7e7e02 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -343,23 +343,22 @@ enum perf_event_type {
* { u64 nr;
* { u64 id, val; } cnt[nr]; } && PERF_SAMPLE_GROUP
*
- * { u16 nr,
- * hv,
- * kernel,
- * user;
+ * { u64 nr,
* u64 ips[nr]; } && PERF_SAMPLE_CALLCHAIN
* };
*/
};

-#define MAX_STACK_DEPTH 255
+enum perf_callchain_context {
+ PERF_CONTEXT_HV = (__u64)-32,
+ PERF_CONTEXT_KERNEL = (__u64)-128,
+ PERF_CONTEXT_USER = (__u64)-512,

-struct perf_callchain_entry {
- __u16 nr;
- __u16 hv;
- __u16 kernel;
- __u16 user;
- __u64 ip[MAX_STACK_DEPTH];
+ PERF_CONTEXT_GUEST = (__u64)-2048,
+ PERF_CONTEXT_GUEST_KERNEL = (__u64)-2176,
+ PERF_CONTEXT_GUEST_USER = (__u64)-2560,
+
+ PERF_CONTEXT_MAX = (__u64)-4095,
};

#ifdef __KERNEL__
@@ -381,6 +380,13 @@ struct perf_callchain_entry {
#include <linux/pid_namespace.h>
#include <asm/atomic.h>

+#define PERF_MAX_STACK_DEPTH 255
+
+struct perf_callchain_entry {
+ __u64 nr;
+ __u64 ip[PERF_MAX_STACK_DEPTH];
+};
+
struct task_struct;

/**