From: Arnaldo Carvalho de Melo <[email protected]> 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 <[email protected]> Cc: Adrian Hunter <[email protected]> Cc: David Ahern <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Wang Nan <[email protected]> Link: http://lkml.kernel.org/n/[email protected] Signed-off-by: Arnaldo Carvalho de Melo <[email protected]> --- tools/perf/util/machine.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c index 7ba9fadb68af..b277984aaa93 100644 --- a/tools/perf/util/machine.c +++ b/tools/perf/util/machine.c @@ -1135,10 +1135,10 @@ int machine__create_kernel_maps(struct machine *machine) { struct dso *kernel = machine__get_kernel(machine); const char *name; - u64 addr = machine__get_running_kernel_start(machine, &name); + u64 addr; int ret; - if (!addr || kernel == NULL) + if (kernel == NULL) return -1; 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); - if (maps__set_kallsyms_ref_reloc_sym(machine->vmlinux_maps, name, - addr)) { + addr = machine__get_running_kernel_start(machine, &name); + if (!addr) { + } else if (maps__set_kallsyms_ref_reloc_sym(machine->vmlinux_maps, name, addr)) { machine__destroy_kernel_maps(machine); return -1; } -- 2.5.5
