Re: [PATCH] tools: perf: allow opt-in "no-dso." files in /dev/shm

[Stephen Brennan <stephen.s.brennan@oracle.com>]

On 11/4/26 12:58 PM, Namhyung Kim wrote:
> On Tue, Oct 13, 2026 at 02:38:41PM -0700, Stephen Brennan wrote:
>> Applications can place JIT-compiled code in POSIX shared memory so that
>> multiple processes can execute the same code. On Linux, these shared
>> memory objects appear as file mappings under /dev/shm.
>>
>> Perf uses /tmp/perf-$pid.map to resolve symbols for executable SysV
>> shared memory mappings, but it treats /dev/shm mappings as ordinary
>> DSOs. As a result, applications which provide perf-map symbols for JIT
>> code in POSIX shared memory don't get those symbols resolved, while they
>> do with SysV shared memory.
>>
>> It would be incorrect to classify every /dev/shm mapping as no-DSO
>> memory though, because /dev/shm is just a tmpfs mount, and it can
>> contain ELF files.
>>
>> Add a filename prefix "/dev/shm/no-dso." which is recognized by
>> is_no_dso_memory(). Applications can opt-in by naming their shared
>> memory objects "no-dso.<name>". Executable mappings with this prefix
>> will use the perf-map file, while other /dev/shm mappings will keep the
>> existing behavior. This allows applications that already emit perf maps
>> to use POSIX shared memory for JIT code, without needing to implement
>> jitdump support.
>>
>> Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
> 
> Applied to perf-tools-next, thanks!

Thank you!
Stephen

> Best regards
> Namhyung