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SubjectRe: [PATCH v5 6/6] perf arm64: inject missing frames if perf-record used "--call-graph=fp"
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

Acked-by: Jiri Olsa <jolsa@kernel.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
>

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