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perf: Add ability to sample machine state on interrupt

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Enable capture of interrupted machine state for each sample.

Registers to sample are passed per event in the sample_regs_intr bitmask.

To sample interrupt machine state, the PERF_SAMPLE_INTR_REGS must be passed in
sample_type.

The list of available registers is arch dependent and provided by asm/perf_regs.h

Registers are laid out as u64 in the order of the bit order of sample_intr_regs.

This patch also adds a new ABI version PERF_ATTR_SIZE_VER4 because we extend
the perf_event_attr struct with a new u64 field.

Reviewed-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: cebbert.lkml@gmail.com
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-api@vger.kernel.org
Link: http://lkml.kernel.org/r/1411559322-16548-2-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Stephane Eranian 2014-09-24 13:48:37 +02:00 • committed by Ingo Molnar
commit 60e2364e60
3 changed files with 63 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

7
include/linux/perf_event.h
View file

@ -79,7 +79,7 @@ struct perf_branch_stack {
struct perf_branch_entry entries[0];
};
struct perf_regs_user {
struct perf_regs {
__u64 abi;
struct pt_regs *regs;
};
@ -600,7 +600,8 @@ struct perf_sample_data {
struct perf_callchain_entry *callchain;
struct perf_raw_record *raw;
struct perf_branch_stack *br_stack;
struct perf_regs_user regs_user;
struct perf_regs regs_user;
struct perf_regs regs_intr;
u64 stack_user_size;
u64 weight;
/*
@ -630,6 +631,8 @@ static inline void perf_sample_data_init(struct perf_sample_data *data,
data->weight = 0;
data->data_src.val = PERF_MEM_NA;
data->txn = 0;
data->regs_intr.abi = PERF_SAMPLE_REGS_ABI_NONE;
data->regs_intr.regs = NULL;
}
extern void perf_output_sample(struct perf_output_handle *handle,

15
include/uapi/linux/perf_event.h
View file

@ -137,8 +137,9 @@ enum perf_event_sample_format {
PERF_SAMPLE_DATA_SRC = 1U << 15,
PERF_SAMPLE_IDENTIFIER = 1U << 16,
PERF_SAMPLE_TRANSACTION = 1U << 17,
PERF_SAMPLE_REGS_INTR = 1U << 18,
PERF_SAMPLE_MAX = 1U << 18, /* non-ABI */
PERF_SAMPLE_MAX = 1U << 19, /* non-ABI */
};
/*
@ -238,6 +239,7 @@ enum perf_event_read_format {
#define PERF_ATTR_SIZE_VER2 80 /* add: branch_sample_type */
#define PERF_ATTR_SIZE_VER3 96 /* add: sample_regs_user */
/* add: sample_stack_user */
#define PERF_ATTR_SIZE_VER4 104 /* add: sample_regs_intr */
/*
* Hardware event_id to monitor via a performance monitoring event:
@ -334,6 +336,15 @@ struct perf_event_attr {
/* Align to u64. */
__u32 __reserved_2;
/*
* Defines set of regs to dump for each sample
* state captured on:
* - precise = 0: PMU interrupt
* - precise > 0: sampled instruction
*
* See asm/perf_regs.h for details.
*/
__u64 sample_regs_intr;
};
#define perf_flags(attr) (*(&(attr)->read_format + 1))
@ -686,6 +697,8 @@ enum perf_event_type {
* { u64 weight; } && PERF_SAMPLE_WEIGHT
* { u64 data_src; } && PERF_SAMPLE_DATA_SRC
* { u64 transaction; } && PERF_SAMPLE_TRANSACTION
* { u64 abi; # enum perf_sample_regs_abi
* u64 regs[weight(mask)]; } && PERF_SAMPLE_REGS_INTR
* };
*/
PERF_RECORD_SAMPLE = 9,

46
kernel/events/core.c
View file

@ -4460,7 +4460,7 @@ perf_output_sample_regs(struct perf_output_handle *handle,
}
}
static void perf_sample_regs_user(struct perf_regs_user *regs_user,
static void perf_sample_regs_user(struct perf_regs *regs_user,
struct pt_regs *regs)
{
if (!user_mode(regs)) {
@ -4476,6 +4476,14 @@ static void perf_sample_regs_user(struct perf_regs_user *regs_user,
}
}
static void perf_sample_regs_intr(struct perf_regs *regs_intr,
struct pt_regs *regs)
{
regs_intr->regs = regs;
regs_intr->abi = perf_reg_abi(current);
}
/*
* Get remaining task size from user stack pointer.
*
@ -4857,6 +4865,23 @@ void perf_output_sample(struct perf_output_handle *handle,
if (sample_type & PERF_SAMPLE_TRANSACTION)
perf_output_put(handle, data->txn);
if (sample_type & PERF_SAMPLE_REGS_INTR) {
u64 abi = data->regs_intr.abi;
/*
* If there are no regs to dump, notice it through
* first u64 being zero (PERF_SAMPLE_REGS_ABI_NONE).
*/
perf_output_put(handle, abi);
if (abi) {
u64 mask = event->attr.sample_regs_intr;
perf_output_sample_regs(handle,
data->regs_intr.regs,
mask);
}
}
if (!event->attr.watermark) {
int wakeup_events = event->attr.wakeup_events;
@ -4943,7 +4968,7 @@ void perf_prepare_sample(struct perf_event_header *header,
* 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;
struct perf_regs *uregs = &data->regs_user;
u16 stack_size = event->attr.sample_stack_user;
u16 size = sizeof(u64);
@ -4964,6 +4989,21 @@ void perf_prepare_sample(struct perf_event_header *header,
data->stack_user_size = stack_size;
header->size += size;
}
if (sample_type & PERF_SAMPLE_REGS_INTR) {
/* regs dump ABI info */
int size = sizeof(u64);
perf_sample_regs_intr(&data->regs_intr, regs);
if (data->regs_intr.regs) {
u64 mask = event->attr.sample_regs_intr;
size += hweight64(mask) * sizeof(u64);
}
header->size += size;
}
}
static void perf_event_output(struct perf_event *event,
@ -7151,6 +7191,8 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr,
ret = -EINVAL;
}
if (attr->sample_type & PERF_SAMPLE_REGS_INTR)
ret = perf_reg_validate(attr->sample_regs_intr);
out:
return ret;