On Wed, May 31, 2017 at 09:01:03PM +0900, Namhyung Kim wrote: > When perf processes build-id event, it creates DSOs with the build-id. > But it didn't set the module short name (like '[module-name]') so when > processing a kernel mmap event of the module, it cannot found the DSO as > it only checks the short names. > > That leads for perf to create a same DSO without the build-id info and > it'll lookup the system path even if the DSO is already in the build-id > cache. After kernel was updated, perf cannot find the DSO and cannot show > symbols in it anymore. > > You can see this if you have an old data file (w/ old kernel version): > > $ perf report -i perf.data.old -v |& grep scsi_mod > build id event received for > /lib/modules/3.19.2-1-ARCH/kernel/drivers/scsi/scsi_mod.ko.gz : > cafe1ce6ca13a98a5d9ed3425cde249e57a27fc1 > Failed to open > /lib/modules/3.19.2-1-ARCH/kernel/drivers/scsi/scsi_mod.ko.gz, continuing > without symbols > ... > > The second message didn't show the build-id. With this patch: > > $ perf report -i perf.data.old -v |& grep scsi_mod > build id event received for > /lib/modules/3.19.2-1-ARCH/kernel/drivers/scsi/scsi_mod.ko.gz: > cafe1ce6ca13a98a5d9ed3425cde249e57a27fc1 > /lib/modules/3.19.2-1-ARCH/kernel/drivers/scsi/scsi_mod.ko.gz with build id > cafe1ce6ca13a98a5d9ed3425cde249e57a27fc1 not found, continuing without symbols > ... > > Now it shows the build-id but still cannot load the symbol table. This > is a different problem which will be fixed in the next patch. > > Signed-off-by: Namhyung Kim <[email protected]>
for all 3: Acked-by: Jiri Olsa <[email protected]> thanks, jirka
