Re: [PATCH v7 1/6] perf: add ability to sample machine state on interrupt

From: Arnaldo Carvalho de Melo
Date: Tue Dec 09 2014 - 08:30:42 EST

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Em Fri, Nov 21, 2014 at 07:26:31PM -0200, Arnaldo Carvalho de Melo escreveu:
> Em Wed, Sep 24, 2014 at 01:48:37PM +0200, Stephane Eranian escreveu:
> > 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.

I think this problem is also related to this changeset:

[root@zoo ~]# perf test 15
15: struct perf_event_attr setup :FAILED
'/home/acme/libexec/perf-core/tests/attr/test-stat-default' - match
failure
Ok
[root@zoo ~]# perf test -v 15
15: struct perf_event_attr setup :
--- start ---
test child forked, pid 17464
running
'/home/acme/libexec/perf-core/tests/attr/test-record-branch-filter-hv'
unsupp
'/home/acme/libexec/perf-core/tests/attr/test-record-branch-filter-hv'
running '/home/acme/libexec/perf-core/tests/attr/test-record-count'
unsupp '/home/acme/libexec/perf-core/tests/attr/test-record-count'
running '/home/acme/libexec/perf-core/tests/attr/test-record-basic'
unsupp '/home/acme/libexec/perf-core/tests/attr/test-record-basic'
running '/home/acme/libexec/perf-core/tests/attr/test-stat-default'
expected size=96, got 104
FAILED '/home/acme/libexec/perf-core/tests/attr/test-stat-default' -
match failure
test child finished with 0
---- end ----
struct perf_event_attr setup: Ok
[root@zoo ~]# uname -r
3.17.3-200.fc20.x86_64
[root@zoo ~]#

Checking if this is just a matter of updating the test entry.

- Arnaldo

>
> So, trying to bisect a problem with how the TUI hist_entries browser
> renders callchains I got stuck with:
>
> [root@zoo acme]# perf report
> incompatible file format (rerun with -v to learn more)
>
> [root@zoo acme]# perf report -v
> file uses a more recent and unsupported ABI (8 bytes extra)
>
> Because the perf.data file was generated with HEAD of perf/core and
> probably the above warning comes from a simple check against the ABI
> version...
>
> I wonder if we can't just check that there are no sample_types that we
> don't know and if not, just process the file anyway, i.e. the sample
> will be parseable, no?
>
> For now, in this case, I'll just regenerate the perf.data file with an
> older tool...
>
> - Arnaldo
>
> > Reviewed-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> > Reviewed-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> > Signed-off-by: Stephane Eranian <eranian@xxxxxxxxxx>
> > ---
> > include/linux/perf_event.h | 7 ++++--
> > include/uapi/linux/perf_event.h | 15 ++++++++++++-
> > kernel/events/core.c | 46 +++++++++++++++++++++++++++++++++++++--
> > 3 files changed, 63 insertions(+), 5 deletions(-)
> >
> > diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> > index 893a0d0..68d46d5 100644
> > --- a/include/linux/perf_event.h
> > +++ b/include/linux/perf_event.h
> > @@ -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,
> > diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
> > index 9269de2..48d4a01 100644
> > --- a/include/uapi/linux/perf_event.h
> > +++ b/include/uapi/linux/perf_event.h
> > @@ -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,
> > diff --git a/kernel/events/core.c b/kernel/events/core.c
> > index eaa636e..7941343 100644
> > --- a/kernel/events/core.c
> > +++ b/kernel/events/core.c
> > @@ -4430,7 +4430,7 @@ 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)) {
> > @@ -4446,6 +4446,14 @@ 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.
> > *
> > @@ -4827,6 +4835,23 @@ 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;
> >
> > @@ -4913,7 +4938,7 @@ 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);
> >
> > @@ -4934,6 +4959,21 @@ 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,
> > @@ -7134,6 +7174,8 @@ 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;
> >
> > --
> > 1.7.9.5
--
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Next message: Cyrille Pitchen: "[PATCH 0/5] tty/serial: at91: fix atmel_serial_probe(), dma_sync_* and the Hardware Handshaking support"
Previous message: Ingo Molnar: "[GIT PULL] x86/microcode tree changes for v3.19"
Next in thread: Arnaldo Carvalho de Melo: "Re: [PATCH v7 1/6] perf: add ability to sample machine state on interrupt"
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