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perf: Add ability to attach user stack dump to sample

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Introducing PERF_SAMPLE_STACK_USER sample type bit to trigger the dump
of the user level stack on sample. The size of the dump is specified by
sample_stack_user value.

Being able to dump parts of the user stack, starting from the stack
pointer, will be useful to make a post mortem dwarf CFI based stack
unwinding.

Added HAVE_PERF_USER_STACK_DUMP config option to determine if the
architecture provides user stack dump on perf event samples.  This needs
access to the user stack pointer which is not unified across
architectures. Enabling this for x86 architecture.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Original-patch-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Arun Sharma <asharma@fb.com>
Cc: Benjamin Redelings <benjamin.redelings@nescent.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Ulrich Drepper <drepper@gmail.com>
Link: http://lkml.kernel.org/r/1344345647-11536-6-git-send-email-jolsa@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Jiri Olsa 2012-08-07 15:20:40 +02:00 committed by Arnaldo Carvalho de Melo
parent 5685e0ff45
commit c5ebcedb56
5 changed files with 190 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
arch/Kconfig
View File

@ -228,6 +228,13 @@ config HAVE_PERF_REGS
Support selective register dumps for perf events. This includes
bit-mapping of each registers and a unique architecture id.
config HAVE_PERF_USER_STACK_DUMP
bool
help
Support user stack dumps for perf event samples. This needs
access to the user stack pointer which is not unified across
architectures.
config HAVE_ARCH_JUMP_LABEL
bool

1
arch/x86/Kconfig
View File

@ -61,6 +61,7 @@ config X86
select PERF_EVENTS
select HAVE_PERF_EVENTS_NMI
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
select ANON_INODES
select HAVE_ALIGNED_STRUCT_PAGE if SLUB && !M386
select HAVE_CMPXCHG_LOCAL if !M386

18
include/linux/perf_event.h
View File

@ -131,8 +131,9 @@ enum perf_event_sample_format {
PERF_SAMPLE_RAW = 1U << 10,
PERF_SAMPLE_BRANCH_STACK = 1U << 11,
PERF_SAMPLE_REGS_USER = 1U << 12,
PERF_SAMPLE_STACK_USER = 1U << 13,
PERF_SAMPLE_MAX = 1U << 13, /* non-ABI */
PERF_SAMPLE_MAX = 1U << 14, /* non-ABI */
};
/*
@ -205,6 +206,7 @@ enum perf_event_read_format {
#define PERF_ATTR_SIZE_VER1 72 /* add: config2 */
#define PERF_ATTR_SIZE_VER2 80 /* add: branch_sample_type */
#define PERF_ATTR_SIZE_VER3 88 /* add: sample_regs_user */
#define PERF_ATTR_SIZE_VER4 96 /* add: sample_stack_user */
/*
* Hardware event_id to monitor via a performance monitoring event:
@ -289,6 +291,14 @@ struct perf_event_attr {
* See asm/perf_regs.h for details.
*/
__u64 sample_regs_user;
/*
* Defines size of the user stack to dump on samples.
*/
__u32 sample_stack_user;
/* Align to u64. */
__u32 __reserved_2;
};
/*
@ -568,6 +578,10 @@ enum perf_event_type {
*
* { u64 abi; # enum perf_sample_regs_abi
* u64 regs[weight(mask)]; } && PERF_SAMPLE_REGS_USER
*
* { u64 size;
* char data[size];
* u64 dyn_size; } && PERF_SAMPLE_STACK_USER
* };
*/
PERF_RECORD_SAMPLE = 9,
@ -1160,6 +1174,7 @@ struct perf_sample_data {
struct perf_raw_record *raw;
struct perf_branch_stack *br_stack;
struct perf_regs_user regs_user;
u64 stack_user_size;
};
static inline void perf_sample_data_init(struct perf_sample_data *data,
@ -1172,6 +1187,7 @@ static inline void perf_sample_data_init(struct perf_sample_data *data,
data->period = period;
data->regs_user.abi = PERF_SAMPLE_REGS_ABI_NONE;
data->regs_user.regs = NULL;
data->stack_user_size = 0;
}
extern void perf_output_sample(struct perf_output_handle *handle,

150
kernel/events/core.c
View File

@ -36,6 +36,7 @@
#include <linux/perf_event.h>
#include <linux/ftrace_event.h>
#include <linux/hw_breakpoint.h>
#include <linux/mm_types.h>
#include "internal.h"
@ -3787,6 +3788,101 @@ static void perf_sample_regs_user(struct perf_regs_user *regs_user,
}
}
/*
* Get remaining task size from user stack pointer.
*
* It'd be better to take stack vma map and limit this more
* precisly, but there's no way to get it safely under interrupt,
* so using TASK_SIZE as limit.
*/
static u64 perf_ustack_task_size(struct pt_regs *regs)
{
unsigned long addr = perf_user_stack_pointer(regs);
if (!addr || addr >= TASK_SIZE)
return 0;
return TASK_SIZE - addr;
}
static u16
perf_sample_ustack_size(u16 stack_size, u16 header_size,
struct pt_regs *regs)
{
u64 task_size;
/* No regs, no stack pointer, no dump. */
if (!regs)
return 0;
/*
* Check if we fit in with the requested stack size into the:
* - TASK_SIZE
* If we don't, we limit the size to the TASK_SIZE.
*
* - remaining sample size
* If we don't, we customize the stack size to
* fit in to the remaining sample size.
*/
task_size = min((u64) USHRT_MAX, perf_ustack_task_size(regs));
stack_size = min(stack_size, (u16) task_size);
/* Current header size plus static size and dynamic size. */
header_size += 2 * sizeof(u64);
/* Do we fit in with the current stack dump size? */
if ((u16) (header_size + stack_size) < header_size) {
/*
* If we overflow the maximum size for the sample,
* we customize the stack dump size to fit in.
*/
stack_size = USHRT_MAX - header_size - sizeof(u64);
stack_size = round_up(stack_size, sizeof(u64));
}
return stack_size;
}
static void
perf_output_sample_ustack(struct perf_output_handle *handle, u64 dump_size,
struct pt_regs *regs)
{
/* Case of a kernel thread, nothing to dump */
if (!regs) {
u64 size = 0;
perf_output_put(handle, size);
} else {
unsigned long sp;
unsigned int rem;
u64 dyn_size;
/*
* We dump:
* static size
* - the size requested by user or the best one we can fit
* in to the sample max size
* data
* - user stack dump data
* dynamic size
* - the actual dumped size
*/
/* Static size. */
perf_output_put(handle, dump_size);
/* Data. */
sp = perf_user_stack_pointer(regs);
rem = __output_copy_user(handle, (void *) sp, dump_size);
dyn_size = dump_size - rem;
perf_output_skip(handle, rem);
/* Dynamic size. */
perf_output_put(handle, dyn_size);
}
}
static void __perf_event_header__init_id(struct perf_event_header *header,
struct perf_sample_data *data,
struct perf_event *event)
@ -4064,6 +4160,11 @@ void perf_output_sample(struct perf_output_handle *handle,
mask);
}
}
if (sample_type & PERF_SAMPLE_STACK_USER)
perf_output_sample_ustack(handle,
data->stack_user_size,
data->regs_user.regs);
}
void perf_prepare_sample(struct perf_event_header *header,
@ -4129,6 +4230,35 @@ void perf_prepare_sample(struct perf_event_header *header,
header->size += size;
}
if (sample_type & PERF_SAMPLE_STACK_USER) {
/*
* Either we need PERF_SAMPLE_STACK_USER bit to be allways
* processed as the last one or have additional check added
* in case new sample type is added, because we could eat
* up the rest of the sample size.
*/
struct perf_regs_user *uregs = &data->regs_user;
u16 stack_size = event->attr.sample_stack_user;
u16 size = sizeof(u64);
if (!uregs->abi)
perf_sample_regs_user(uregs, regs);
stack_size = perf_sample_ustack_size(stack_size, header->size,
uregs->regs);
/*
* If there is something to dump, add space for the dump
* itself and for the field that tells the dynamic size,
* which is how many have been actually dumped.
*/
if (stack_size)
size += sizeof(u64) + stack_size;
data->stack_user_size = stack_size;
header->size += size;
}
}
static void perf_event_output(struct perf_event *event,
@ -6205,8 +6335,26 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr,
}
}
if (attr->sample_type & PERF_SAMPLE_REGS_USER)
if (attr->sample_type & PERF_SAMPLE_REGS_USER) {
ret = perf_reg_validate(attr->sample_regs_user);
if (ret)
return ret;
}
if (attr->sample_type & PERF_SAMPLE_STACK_USER) {
if (!arch_perf_have_user_stack_dump())
return -ENOSYS;
/*
* We have __u32 type for the size, but so far
* we can only use __u16 as maximum due to the
* __u16 sample size limit.
*/
if (attr->sample_stack_user >= USHRT_MAX)
ret = -EINVAL;
else if (!IS_ALIGNED(attr->sample_stack_user, sizeof(u64)))
ret = -EINVAL;
}
out:
return ret;

16
kernel/events/internal.h
View File

@ -158,4 +158,20 @@ static inline void put_recursion_context(int *recursion, int rctx)
recursion[rctx]--;
}
#ifdef CONFIG_HAVE_PERF_USER_STACK_DUMP
static inline bool arch_perf_have_user_stack_dump(void)
{
return true;
}
#define perf_user_stack_pointer(regs) user_stack_pointer(regs)
#else
static inline bool arch_perf_have_user_stack_dump(void)
{
return false;
}
#define perf_user_stack_pointer(regs) 0
#endif /* CONFIG_HAVE_PERF_USER_STACK_DUMP */
#endif /* _KERNEL_EVENTS_INTERNAL_H */