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SubjectRe: [PATCH v2] perf machine: Fix load kernel symbol with '-k' option
On Fri, Mar 09, 2018 at 02:05:23PM +0800, Leo Yan wrote:
> On Hikey arm64 octa A53 platform, when use command './perf report -v
> -k vmlinux --stdio' it outputs below error info, and it skips to load
> kernel symbol and doesn't print symbol for event:
> Failed to open [kernel.kallsyms]_text, continuing without symbols.
>
> The regression is introduced by commit ("8c7f1bb37b29 perf machine: Move
> kernel mmap name into struct machine"), which changes the logic for
> machine mmap_name by removing function machine__mmap_name() and always
> use 'machine->mmap_name'. Comparing difference between
> machine__mmap_name() and 'machine->mmap_name', the later one includes
> the string for specified kernel vmlinux string with option '-k' in
> command, but the old function machine__mmap_name() ignores vmlinux
> path string. As result, event's mmap file name doesn't match with
> machine mmap file name anymore and it skips to load kernel symbol from
> vmlinux file.
>
> To resolve this issue, this patch adds extra checking for
> 'symbol_conf.vmlinux_name', when it has been set string so we can know
> it includes vmlinux path string specified for option '-k'. For this
> case it sets 'is_kernel_mmap' to true and run into flow to load kernel
> symbol from vmlinux.
>
> This patch has been verified with two commands: './perf report -v
> -k vmlinux --stdio' and './perf script -v -F cpu,event,ip,sym,symoff
> -k vmlinux'.
>
> Suggested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> Signed-off-by: Leo Yan <leo.yan@linaro.org>
> ---
> 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 12b7427..3125871 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -1299,9 +1299,18 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
> else
> kernel_type = DSO_TYPE_GUEST_KERNEL;
>
> - is_kernel_mmap = memcmp(event->mmap.filename,
> - machine->mmap_name,
> - strlen(machine->mmap_name) - 1) == 0;
> + /*
> + * When symbol_conf.vmlinux_name is not NULL, it includes the specified
> + * kernel vmlinux path with option '-k'. So set 'is_kernel_mmap' to
> + * true for creating machine symbol map.
> + */
> + if (symbol_conf.vmlinux_name)
> + is_kernel_mmap = true;
> + else
> + is_kernel_mmap = memcmp(event->mmap.filename,
> + machine->mmap_name,
> + strlen(machine->mmap_name) - 1) == 0;
> +
> if (event->mmap.filename[0] == '/' ||
> (!is_kernel_mmap && event->mmap.filename[0] == '[')) {
> map = machine__findnew_module_map(machine, event->mmap.start,

right, the mmap gets confused with the vmlinux path, but I wonder
the fix should be not to include symbol_conf.vmlinux_name in the
mmap_name like below.. untested

thanks,
jirka


---
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 43fbbee409ec..f0cb72022177 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -51,15 +51,9 @@ static void machine__threads_init(struct machine *machine)
static int machine__set_mmap_name(struct machine *machine)
{
if (machine__is_host(machine)) {
- if (symbol_conf.vmlinux_name)
- machine->mmap_name = strdup(symbol_conf.vmlinux_name);
- else
- machine->mmap_name = strdup("[kernel.kallsyms]");
+ machine->mmap_name = strdup("[kernel.kallsyms]");
} else if (machine__is_default_guest(machine)) {
- if (symbol_conf.default_guest_vmlinux_name)
- machine->mmap_name = strdup(symbol_conf.default_guest_vmlinux_name);
- else
- machine->mmap_name = strdup("[guest.kernel.kallsyms]");
+ machine->mmap_name = strdup("[guest.kernel.kallsyms]");
} else {
if (asprintf(&machine->mmap_name, "[guest.kernel.kallsyms.%d]",
machine->pid) < 0)
@@ -794,9 +788,15 @@ static struct dso *machine__get_kernel(struct machine *machine)
struct dso *kernel;

if (machine__is_host(machine)) {
+ if (symbol_conf.vmlinux_name)
+ vmlinux_name = symbol_conf.vmlinux_name;
+
kernel = machine__findnew_kernel(machine, vmlinux_name,
"[kernel]", DSO_TYPE_KERNEL);
} else {
+ if (symbol_conf.default_guest_vmlinux_name)
+ vmlinux_name = symbol_conf.default_guest_vmlinux_name;
+
kernel = machine__findnew_kernel(machine, vmlinux_name,
"[guest.kernel]",
DSO_TYPE_GUEST_KERNEL);
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