Commit f9188e02 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

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: default avatarPeter 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: default avatarIngo Molnar <mingo@elte.hu>
parent b8e6d829

arch/x86/kernel/cpu/perf_counter.c

+6 −23
Original line number Diff line number Diff line
@@ -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);

include/linux/perf_counter.h

+17 −11
Original line number Diff line number Diff line
@@ -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;



/**

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