Yu Watanabe
4483a8ffc7
On i386 with musl and libucontext, many tests crash with SIGSEGV
when using fibers implemented on top of ucontext APIs.
For example:
```
929/1498 libsystemd - systemd:test-event-future FAIL 0.97s killed by signal 11 SIGSEGV
/* test_sd_event_run_timer */
run-suspend-timer: Scheduling fiber
/home/pmos/build/src/systemd-261-rc3/tools/test-crash-trace.sh: line 18: 19994 Segmentation fault (core dumped) "$@"
===== exit 139 — replaying under gdb =====
/* test_sd_event_run_timer */
run-suspend-timer: Scheduling fiber
Program received signal SIGSEGV, Segmentation fault.
0xf7d68be3 in sd_event_add_time_relative (e=0xf7ffd3f0, ret=0xf7b01fa0, clock=1, usec=10000, accuracy=0, callback=0x565564ad <inner_timer_handler>, userdata=0xf7b01fa4) at ../src/libsystemd/sd-event/sd-event.c:1455
1455 void *userdata) {
Thread 1 (process 20485 "test-event-futu"):
#0 0xf7d68be3 in sd_event_add_time_relative (e=0xf7ffd3f0, ret=0xf7b01fa0, clock=1, usec=10000, accuracy=0, callback=0x565564ad <inner_timer_handler>, userdata=0xf7b01fa4) at ../src/libsystemd/sd-event/sd-event.c:1455
t = 17868423377094431728
r = <optimized out>
#1 0x565574c7 in sd_event_run_timer_fiber (userdata=0x0) at ../src/libsystemd/sd-event/test-event-future.c:329
inner = 0xf7ffd3f0
source = 0x0
counter = 0
r = <optimized out>
#2 0xf7dab308 in fiber_entry_point () at ../src/libsystemd/sd-future/fiber.c:208
_cleanup_log_unset_prefix_5 = 0x0
__unique_prefix_c6 = 0x5655bb30
f = 0xf7b06840
__func__ = "fiber_entry_point"
fake_stack_save = <optimized out>
#3 0xf7b032ae in setcontext () from /lib/libucontext.so.1
No symbol table info available.
#4 0x00000000 in ?? ()
No symbol table info available.
```
Building systemd with -mstackrealign makes all observed failures
disappear, suggesting a stack alignment issue in the interaction
between compiler-generated code and the ucontext implementation.
This resembles historical stack alignment issues in glibc's i386
makecontext() implementation, which required fixes to preserve the
expected stack alignment.
As a workaround, add -mstackrealign when building on i386 with musl
and libucontext.
Suggested-by: ChatGPT (OpenAI)
System and Service Manager
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