From: Arnaldo Carvalho de Melo acme@redhat.com
commit f068435d9bb2d825d59e3c101bc579f09315ee01 upstream.
At some point in the past we needed to make sure we would get the long name of modules and not just what we get from /proc/modules, but that need, as described in the cset that introduced the adjustment function:
Fixes: c03d5184f0e9 ("perf machine: Adjust dso->long_name for offline module")
Without using the buildid-cache:
# lsmod | grep trusted # insmod trusted.ko # lsmod | grep trusted trusted 24576 0 # strace -e open,openat perf probe -m ./trusted.ko key_seal |& grep trusted openat(AT_FDCWD, "/sys/module/trusted/notes/.note.gnu.build-id", O_RDONLY) = 4 openat(AT_FDCWD, "/sys/module/trusted/notes/.note.gnu.build-id", O_RDONLY) = 7 openat(AT_FDCWD, "/root/trusted.ko", O_RDONLY) = 3 openat(AT_FDCWD, "/root/.debug/root/trusted.ko/dd3d355d567394d540f527e093e0f64b95879584/probes", O_RDWR|O_CREAT, 0644) = 3 openat(AT_FDCWD, "/usr/lib/debug/root/trusted.ko.debug", O_RDONLY) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/usr/lib/debug/root/trusted.ko", O_RDONLY) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/root/.debug/trusted.ko", O_RDONLY) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/root/trusted.ko", O_RDONLY) = 3 openat(AT_FDCWD, "trusted.ko.debug", O_RDONLY) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, ".debug/trusted.ko.debug", O_RDONLY) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "trusted.ko.debug", O_RDONLY) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/root/trusted.ko", O_RDONLY) = 3 openat(AT_FDCWD, "/root/trusted.ko", O_RDONLY) = 3 openat(AT_FDCWD, "/root/trusted.ko", O_RDONLY) = 4 openat(AT_FDCWD, "/root/trusted.ko", O_RDONLY) = 3 probe:key_seal (on key_seal in trusted) # perf probe -l probe:key_seal (on key_seal in trusted) #
No attempt at opening '[trusted]'.
Now using the build-id cache:
# rmmod trusted # perf buildid-cache --add ./trusted.ko # insmod trusted.ko # strace -e open,openat perf probe -m ./trusted.ko key_seal |& grep trusted openat(AT_FDCWD, "/sys/module/trusted/notes/.note.gnu.build-id", O_RDONLY) = 4 openat(AT_FDCWD, "/sys/module/trusted/notes/.note.gnu.build-id", O_RDONLY) = 7 openat(AT_FDCWD, "/root/trusted.ko", O_RDONLY) = 3 openat(AT_FDCWD, "/root/.debug/root/trusted.ko/dd3d355d567394d540f527e093e0f64b95879584/probes", O_RDWR|O_CREAT, 0644) = 3 openat(AT_FDCWD, "/usr/lib/debug/root/trusted.ko.debug", O_RDONLY) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/usr/lib/debug/root/trusted.ko", O_RDONLY) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/root/.debug/trusted.ko", O_RDONLY) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/root/trusted.ko", O_RDONLY) = 3 openat(AT_FDCWD, "trusted.ko.debug", O_RDONLY) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, ".debug/trusted.ko.debug", O_RDONLY) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "trusted.ko.debug", O_RDONLY) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/root/trusted.ko", O_RDONLY) = 3 openat(AT_FDCWD, "/root/trusted.ko", O_RDONLY) = 3 openat(AT_FDCWD, "/root/trusted.ko", O_RDONLY) = 4 openat(AT_FDCWD, "/root/trusted.ko", O_RDONLY) = 3 #
Again, no attempt at reading '[trusted]'.
Finally, adding a probe to that function and then using:
[root@quaco ~]# perf trace -e probe_perf:*/max-stack=16/ --max-events=2 0.000 perf/13456 probe_perf:dso__adjust_kmod_long_name(__probe_ip: 5492263) dso__adjust_kmod_long_name (/home/acme/bin/perf) machine__process_kernel_mmap_event (/home/acme/bin/perf) machine__process_mmap_event (/home/acme/bin/perf) perf_event__process_mmap (/home/acme/bin/perf) machines__deliver_event (/home/acme/bin/perf) perf_session__deliver_event (/home/acme/bin/perf) perf_session__process_event (/home/acme/bin/perf) process_simple (/home/acme/bin/perf) reader__process_events (/home/acme/bin/perf) __perf_session__process_events (/home/acme/bin/perf) perf_session__process_events (/home/acme/bin/perf) process_buildids (/home/acme/bin/perf) record__finish_output (/home/acme/bin/perf) __cmd_record (/home/acme/bin/perf) cmd_record (/home/acme/bin/perf) run_builtin (/home/acme/bin/perf) 0.055 perf/13456 probe_perf:dso__adjust_kmod_long_name(__probe_ip: 5492263) dso__adjust_kmod_long_name (/home/acme/bin/perf) machine__process_kernel_mmap_event (/home/acme/bin/perf) machine__process_mmap_event (/home/acme/bin/perf) perf_event__process_mmap (/home/acme/bin/perf) machines__deliver_event (/home/acme/bin/perf) perf_session__deliver_event (/home/acme/bin/perf) perf_session__process_event (/home/acme/bin/perf) process_simple (/home/acme/bin/perf) reader__process_events (/home/acme/bin/perf) __perf_session__process_events (/home/acme/bin/perf) perf_session__process_events (/home/acme/bin/perf) process_buildids (/home/acme/bin/perf) record__finish_output (/home/acme/bin/perf) __cmd_record (/home/acme/bin/perf) cmd_record (/home/acme/bin/perf) run_builtin (/home/acme/bin/perf) #
This was the only path I could find using the perf tools that reach at this function, then as of november/2019, if we put a probe in the line where the actuall setting of the dso->long_name is done:
# perf trace -e probe_perf:* ^C[root@quaco ~] # perf stat -e probe_perf:* -I 2000 2.000404265 0 probe_perf:dso__adjust_kmod_long_name 4.001142200 0 probe_perf:dso__adjust_kmod_long_name 6.001704120 0 probe_perf:dso__adjust_kmod_long_name 8.002398316 0 probe_perf:dso__adjust_kmod_long_name 10.002984010 0 probe_perf:dso__adjust_kmod_long_name 12.003597851 0 probe_perf:dso__adjust_kmod_long_name 14.004113303 0 probe_perf:dso__adjust_kmod_long_name 16.004582773 0 probe_perf:dso__adjust_kmod_long_name 18.005176373 0 probe_perf:dso__adjust_kmod_long_name 20.005801605 0 probe_perf:dso__adjust_kmod_long_name 22.006467540 0 probe_perf:dso__adjust_kmod_long_name ^C 23.683261941 0 probe_perf:dso__adjust_kmod_long_name
#
Its not being used at all.
To further test this I used kvm.ko as the offline module, i.e. removed if from the buildid-cache by nuking it completely (rm -rf ~/.debug) and moved it from the normal kernel distro path, removed the modules, stoped the kvm guest, and then installed it manually, etc.
# rmmod kvm-intel # rmmod kvm # lsmod | grep kvm # modprobe kvm-intel modprobe: ERROR: ctx=0x55d3b1722260 path=/lib/modules/5.3.8-200.fc30.x86_64/kernel/arch/x86/kvm/kvm.ko.xz error=No such file or directory modprobe: ERROR: ctx=0x55d3b1722260 path=/lib/modules/5.3.8-200.fc30.x86_64/kernel/arch/x86/kvm/kvm.ko.xz error=No such file or directory modprobe: ERROR: could not insert 'kvm_intel': Unknown symbol in module, or unknown parameter (see dmesg) # insmod ./kvm.ko # modprobe kvm-intel modprobe: ERROR: ctx=0x562f34026260 path=/lib/modules/5.3.8-200.fc30.x86_64/kernel/arch/x86/kvm/kvm.ko.xz error=No such file or directory modprobe: ERROR: ctx=0x562f34026260 path=/lib/modules/5.3.8-200.fc30.x86_64/kernel/arch/x86/kvm/kvm.ko.xz error=No such file or directory # lsmod | grep kvm kvm_intel 299008 0 kvm 765952 1 kvm_intel irqbypass 16384 1 kvm # # perf probe -x ~/bin/perf machine__findnew_module_map:12 mname=m.name:string filename=filename:string 'dso_long_name=map->dso->long_name:string' 'dso_name=map->dso->name:string' # perf probe -l probe_perf:machine__findnew_module_map (on machine__findnew_module_map:12@util/machine.c in /home/acme/bin/perf with mname filename dso_long_name dso_name) # perf record ^C[ perf record: Woken up 2 times to write data ] [ perf record: Captured and wrote 3.416 MB perf.data (33956 samples) ] # perf trace -e probe_perf:machine* <SNIP> 6.322 perf/23099 probe_perf:machine__findnew_module_map(__probe_ip: 5492493, mname: "[salsa20_generic]", filename: "/lib/modules/5.3.8-200.fc30.x86_64/kernel/crypto/salsa20_generic.ko.xz", dso_long_name: "/lib/modules/5.3.8-200.fc30.x86_64/kernel/crypto/salsa20_generic.ko.xz", dso_name: "[salsa20_generic]") 6.375 perf/23099 probe_perf:machine__findnew_module_map(__probe_ip: 5492493, mname: "[kvm]", filename: "[kvm]", dso_long_name: "[kvm]", dso_name: "[kvm]") <SNIP>
The filename doesn't come with the path, no point in trying to set the dso->long_name.
[root@quaco ~]# strace -e open,openat perf probe -m ./kvm.ko kvm_apic_local_deliver |& egrep 'open.*kvm' openat(AT_FDCWD, "/sys/module/kvm_intel/notes/.note.gnu.build-id", O_RDONLY) = 4 openat(AT_FDCWD, "/sys/module/kvm/notes/.note.gnu.build-id", O_RDONLY) = 4 openat(AT_FDCWD, "/lib/modules/5.3.8-200.fc30.x86_64/kernel/arch/x86/kvm", O_RDONLY|O_NONBLOCK|O_CLOEXEC|O_DIRECTORY) = 7 openat(AT_FDCWD, "/sys/module/kvm_intel/notes/.note.gnu.build-id", O_RDONLY) = 8 openat(AT_FDCWD, "/root/kvm.ko", O_RDONLY) = 3 openat(AT_FDCWD, "/root/.debug/root/kvm.ko/5955f426cb93f03f30f3e876814be2db80ab0b55/probes", O_RDWR|O_CREAT, 0644) = 3 openat(AT_FDCWD, "/usr/lib/debug/root/kvm.ko.debug", O_RDONLY) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/usr/lib/debug/root/kvm.ko", O_RDONLY) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/root/.debug/kvm.ko", O_RDONLY) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/root/kvm.ko", O_RDONLY) = 3 openat(AT_FDCWD, "kvm.ko.debug", O_RDONLY) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, ".debug/kvm.ko.debug", O_RDONLY) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "kvm.ko.debug", O_RDONLY) = -1 ENOENT (No such file or directory) openat(AT_FDCWD, "/root/kvm.ko", O_RDONLY) = 3 openat(AT_FDCWD, "/root/kvm.ko", O_RDONLY) = 3 openat(AT_FDCWD, "/root/kvm.ko", O_RDONLY) = 4 openat(AT_FDCWD, "/root/kvm.ko", O_RDONLY) = 3 [root@quaco ~]#
Cc: Adrian Hunter adrian.hunter@intel.com Cc: Andi Kleen ak@linux.intel.com Cc: Jiri Olsa jolsa@kernel.org Cc: Namhyung Kim namhyung@kernel.org Cc: Wang Nan wangnan0@huawei.com Link: https://lkml.kernel.org/n/tip-jlfew3lyb24d58egrp0o72o2@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- tools/perf/util/machine.c | 27 +-------------------------- 1 file changed, 1 insertion(+), 26 deletions(-)
--- a/tools/perf/util/machine.c +++ b/tools/perf/util/machine.c @@ -767,24 +767,6 @@ int machine__process_ksymbol(struct mach return machine__process_ksymbol_register(machine, event, sample); }
-static void dso__adjust_kmod_long_name(struct dso *dso, const char *filename) -{ - const char *dup_filename; - - if (!filename || !dso || !dso->long_name) - return; - if (dso->long_name[0] != '[') - return; - if (!strchr(filename, '/')) - return; - - dup_filename = strdup(filename); - if (!dup_filename) - return; - - dso__set_long_name(dso, dup_filename, true); -} - struct map *machine__findnew_module_map(struct machine *machine, u64 start, const char *filename) { @@ -796,15 +778,8 @@ struct map *machine__findnew_module_map( return NULL;
map = map_groups__find_by_name(&machine->kmaps, m.name); - if (map) { - /* - * If the map's dso is an offline module, give dso__load() - * a chance to find the file path of that module by fixing - * long_name. - */ - dso__adjust_kmod_long_name(map->dso, filename); + if (map) goto out; - }
dso = machine__findnew_module_dso(machine, &m, filename); if (dso == NULL)