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perf machine: Do not bail out if not managing to read ref reloc symbol

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This means the user can't access /proc/kallsyms, for instance, because
/proc/sys/kernel/kptr_restrict is set to 1.

Instead leave the ref_reloc_sym as NULL and code using it will cope.

This allows 'perf trace' to work on such systems for !root, the only
issue would be when trying to resolve kernel symbols, which happens,
for instance, in some libtracevent plugins.  A warning for that case
will be provided in the next patch in this series.

Noticed in Ubuntu 16.04, that comes with kptr_restrict=1.

Reported-by: Milian Wolff <milian.wolff@kdab.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-knpu3z4iyp2dxpdfm798fac4@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Arnaldo Carvalho de Melo 2016-05-17 11:52:26 -03:00
parent a29d5c9b81
commit 45e9005690
1 changed files with 5 additions and 4 deletions
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9
tools/perf/util/machine.c
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@ -1135,10 +1135,10 @@ int machine__create_kernel_maps(struct machine *machine)
{ {
struct dso *kernel = machine__get_kernel(machine); struct dso *kernel = machine__get_kernel(machine);
const char *name; const char *name;
u64 addr = machine__get_running_kernel_start(machine, &name); u64 addr;
int ret; int ret;
if (!addr || kernel == NULL) if (kernel == NULL)
return -1; return -1;
ret = __machine__create_kernel_maps(machine, kernel); ret = __machine__create_kernel_maps(machine, kernel);
@ -1160,8 +1160,9 @@ int machine__create_kernel_maps(struct machine *machine)
*/ */
map_groups__fixup_end(&machine->kmaps); map_groups__fixup_end(&machine->kmaps);
if (maps__set_kallsyms_ref_reloc_sym(machine->vmlinux_maps, name, addr = machine__get_running_kernel_start(machine, &name);
addr)) { if (!addr) {
} else if (maps__set_kallsyms_ref_reloc_sym(machine->vmlinux_maps, name, addr)) {
machine__destroy_kernel_maps(machine); machine__destroy_kernel_maps(machine);
return -1; return -1;
} }