Re: [PATCH 26/35] perf tools: Handle injected guest kernel mmap event

Ian Rogers
2022-07-20T01:09:46Z

On Mon, Jul 11, 2022 at 2:33 AM Adrian Hunter <adrian.hunter@intel.com> wrote:
>
> If a kernel mmap event was recorded inside a guest and injected into a host
> perf.data file, then it will match a host mmap_name not a guest mmap_name,
> see machine__set_mmap_name(). So try matching a host mmap_name in that
> case.
>
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>

Acked-by: Ian Rogers <irogers@google.com>

Thanks,
Ian

> ---
> tools/perf/util/machine.c | 15 ++++++++++++---
> 1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index 27d1a38f44c3..8f657225fb02 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -1742,6 +1742,7 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
> struct map *map;
> enum dso_space_type dso_space;
> bool is_kernel_mmap;
> + const char *mmap_name = machine->mmap_name;
>
> /* If we have maps from kcore then we do not need or want any others */
> if (machine__uses_kcore(machine))
> @@ -1752,8 +1753,16 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
> else
> dso_space = DSO_SPACE__KERNEL_GUEST;
>
> - is_kernel_mmap = memcmp(xm->name, machine->mmap_name,
> - strlen(machine->mmap_name) - 1) == 0;
> + is_kernel_mmap = memcmp(xm->name, mmap_name, strlen(mmap_name) - 1) == 0;
> + if (!is_kernel_mmap && !machine__is_host(machine)) {
> + /*
> + * If the event was recorded inside the guest and injected into
> + * the host perf.data file, then it will match a host mmap_name,
> + * so try that - see machine__set_mmap_name().
> + */
> + mmap_name = "[kernel.kallsyms]";
> + is_kernel_mmap = memcmp(xm->name, mmap_name, strlen(mmap_name) - 1) == 0;
> + }
> if (xm->name[0] == '/' ||
> (!is_kernel_mmap && xm->name[0] == '[')) {
> map = machine__addnew_module_map(machine, xm->start,
> @@ -1767,7 +1776,7 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
> dso__set_build_id(map->dso, bid);
>
> } else if (is_kernel_mmap) {
> - const char *symbol_name = (xm->name + strlen(machine->mmap_name));
> + const char *symbol_name = xm->name + strlen(mmap_name);
> /*
> * Should be there already, from the build-id table in
> * the header.
> --
> 2.25.1
>