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Date: Tue, 21 Dec 2021 11:17:03 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Jiri Olsa <jolsa@...hat.com>
Cc: German Gomez <german.gomez@....com>, linux-kernel@...r.kernel.org,
linux-perf-users@...r.kernel.org,
Alexandre Truong <alexandre.truong@....com>,
John Garry <john.garry@...wei.com>,
Will Deacon <will@...nel.org>,
Mathieu Poirier <mathieu.poirier@...aro.org>,
Leo Yan <leo.yan@...aro.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Namhyung Kim <namhyung@...nel.org>,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v5 6/6] perf arm64: inject missing frames if perf-record
used "--call-graph=fp"
Em Tue, Dec 21, 2021 at 10:32:50AM +0100, Jiri Olsa escreveu:
> On Fri, Dec 17, 2021 at 03:45:20PM +0000, German Gomez wrote:
>
> SNIP
>
> > +}
> > +
> > +u64 get_leaf_frame_caller_aarch64(struct perf_sample *sample, struct thread *thread, int usr_idx)
> > +{
> > + int ret;
> > + struct entries entries = {};
> > + struct regs_dump old_regs = sample->user_regs;
> > +
> > + if (!get_leaf_frame_caller_enabled(sample))
> > + return 0;
> > +
> > + /*
> > + * If PC and SP are not recorded, get the value of PC from the stack
> > + * and set its mask. SP is not used when doing the unwinding but it
> > + * still needs to be set to prevent failures.
> > + */
> > +
> > + if (!(sample->user_regs.mask & SMPL_REG_MASK(PERF_REG_ARM64_PC))) {
> > + sample->user_regs.cache_mask |= SMPL_REG_MASK(PERF_REG_ARM64_PC);
> > + sample->user_regs.cache_regs[PERF_REG_ARM64_PC] = sample->callchain->ips[usr_idx+1];
> > + }
> > +
> > + if (!(sample->user_regs.mask & SMPL_REG_MASK(PERF_REG_ARM64_SP))) {
> > + sample->user_regs.cache_mask |= SMPL_REG_MASK(PERF_REG_ARM64_SP);
> > + sample->user_regs.cache_regs[PERF_REG_ARM64_SP] = 0;
> > + }
> > +
> > + ret = unwind__get_entries(add_entry, &entries, thread, sample, 2);
>
> just curious, did you try this with both unwinders libunwind/libdw?
>
> any chance you could add arm specific test for this?
>
> otherwise it looks good to me
Whole patchkit?
> Acked-by: Jiri Olsa <jolsa@...nel.org>
>
> thanks,
> jirka
>
>
> > + sample->user_regs = old_regs;
> > +
> > + if (ret || entries.length != 2)
> > + return ret;
> > +
> > + return callchain_param.order == ORDER_CALLER ? entries.stack[0] : entries.stack[1];
> > +}
> > diff --git a/tools/perf/util/arm64-frame-pointer-unwind-support.h b/tools/perf/util/arm64-frame-pointer-unwind-support.h
> > new file mode 100644
> > index 000000000000..32af9ce94398
> > --- /dev/null
> > +++ b/tools/perf/util/arm64-frame-pointer-unwind-support.h
> > @@ -0,0 +1,10 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +#ifndef __PERF_ARM_FRAME_POINTER_UNWIND_SUPPORT_H
> > +#define __PERF_ARM_FRAME_POINTER_UNWIND_SUPPORT_H
> > +
> > +#include "event.h"
> > +#include "thread.h"
> > +
> > +u64 get_leaf_frame_caller_aarch64(struct perf_sample *sample, struct thread *thread, int user_idx);
> > +
> > +#endif /* __PERF_ARM_FRAME_POINTER_UNWIND_SUPPORT_H */
> > diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> > index 3eddad009f78..a00fd6796b35 100644
> > --- a/tools/perf/util/machine.c
> > +++ b/tools/perf/util/machine.c
> > @@ -34,6 +34,7 @@
> > #include "bpf-event.h"
> > #include <internal/lib.h> // page_size
> > #include "cgroup.h"
> > +#include "arm64-frame-pointer-unwind-support.h"
> >
> > #include <linux/ctype.h>
> > #include <symbol/kallsyms.h>
> > @@ -2710,10 +2711,13 @@ static int find_prev_cpumode(struct ip_callchain *chain, struct thread *thread,
> > return err;
> > }
> >
> > -static u64 get_leaf_frame_caller(struct perf_sample *sample __maybe_unused,
> > - struct thread *thread __maybe_unused, int usr_idx __maybe_unused)
> > +static u64 get_leaf_frame_caller(struct perf_sample *sample,
> > + struct thread *thread, int usr_idx)
> > {
> > - return 0;
> > + if (machine__normalize_is(thread->maps->machine, "arm64"))
> > + return get_leaf_frame_caller_aarch64(sample, thread, usr_idx);
> > + else
> > + return 0;
> > }
> >
> > static int thread__resolve_callchain_sample(struct thread *thread,
> > @@ -3114,14 +3118,19 @@ int machine__set_current_tid(struct machine *machine, int cpu, pid_t pid,
> > }
> >
> > /*
> > - * Compares the raw arch string. N.B. see instead perf_env__arch() if a
> > - * normalized arch is needed.
> > + * Compares the raw arch string. N.B. see instead perf_env__arch() or
> > + * machine__normalize_is() if a normalized arch is needed.
> > */
> > bool machine__is(struct machine *machine, const char *arch)
> > {
> > return machine && !strcmp(perf_env__raw_arch(machine->env), arch);
> > }
> >
> > +bool machine__normalize_is(struct machine *machine, const char *arch)
> > +{
> > + return machine && !strcmp(perf_env__arch(machine->env), arch);
> > +}
> > +
> > int machine__nr_cpus_avail(struct machine *machine)
> > {
> > return machine ? perf_env__nr_cpus_avail(machine->env) : 0;
> > diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
> > index a143087eeb47..665535153411 100644
> > --- a/tools/perf/util/machine.h
> > +++ b/tools/perf/util/machine.h
> > @@ -208,6 +208,7 @@ static inline bool machine__is_host(struct machine *machine)
> > }
> >
> > bool machine__is(struct machine *machine, const char *arch);
> > +bool machine__normalize_is(struct machine *machine, const char *arch);
> > int machine__nr_cpus_avail(struct machine *machine);
> >
> > struct thread *__machine__findnew_thread(struct machine *machine, pid_t pid, pid_t tid);
> > --
> > 2.25.1
> >
--
- Arnaldo
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