Opened 6 years ago
Closed 6 years ago
#6571 closed defect (fixed)
SIGBUS on ARM in h264idct_neon.S when compiled with binutils 2.29
| Reported by: | James Cowgill | Owned by: | |
|---|---|---|---|
| Priority: | normal | Component: | avcodec |
| Version: | git-master | Keywords: | h264 arm |
| Cc: | Blocked By: | ||
| Blocking: | Reproduced by developer: | no | |
| Analyzed by developer: | no |
Description
Summary of the bug:
Binutils 2.29 changes the behavior of the ADR instruction when loading Thumb functions. This causes some of the optimizations to crash.
See:
https://bugs.debian.org/870622
https://sourceware.org/bugzilla/show_bug.cgi?id=21458
There is a suggestion on how to fix this in message 25 in the Debian bug report, while still allowing the code to work with old and new binutils. I don't know ARM assembly very well so I don't know how well it works. It looks reasonably sensible however.
How to reproduce:
Build ffmpeg 3.3.3 on ARMv7 using binutils 2.29
Run:
$ ffmpeg -f lavfi -i testsrc=s=32x32:d=0.1 -strict -2 -c:v libx264rgb -f avi libx264rgb.avi -y -hide_banner -nostdin $ ffmpeg -strict -2 -i libx264rgb.avi -t 1 -c:v rawvideo -c:a pcm_s32le -f nut /dev/null -y -hide_banner -nostdin
The second command will crash with SIGBUS.
Change History (2)
comment:1 by , 6 years ago
| Keywords: | h264 arm added |
|---|---|
| Version: | unspecified → git-master |
comment:2 by , 6 years ago
| Resolution: | → fixed |
|---|---|
| Status: | new → closed |
Fixed since 640073ecebc46040f966fe3b52c10f3c5b11d66f, sorry about this: Reviews are still less important than merges.
Did you send the patch to the FFmpeg development mailing list?
Regarding sparc64: I can reproduce the build failure of libavcodec/vp9dsp_12bpp.o with gcc-7 and toolchain=hardened, but not with gcc-6 and not without -fstack-protector-all so I suspect another gcc-7 bug.