Greenlet issues on Solaris sparc 64-bit

[sfv880]

Hello,

I hope you are well!

We use Greenlet 3.0.3 and 0.4.15 on Solaris 11.4 sparc 64-bit platform and in some cases it failed with:

• SIGBUS (Bus Error) - access to unaligned memory address

status: process terminated by SIGBUS (Bus Error), addr=4f00e0070bf0000a
python:core> $c
_greenlet.cpython-311.so`slp_restore_state_trampoline+0x74(ffffffff7fff8f71, 0, 0, ffffffffffffffff, ffffffff7dfdf470, 
ffffffff7f227060)
_greenlet.cpython-311.so`slp_switch+0x18(ffffffffffffffff, 7ffface0da78, ffffffff7f5a06c0, 8, ffffffff7fff97f0, 
ffffffff7fff8f71)
_greenlet.cpython-311.so`_ZN8greenlet8Greenlet13g_switchstackEv+0x17c(ffffffff7fff9998, ffffffff7dfdf470, 
ffffffff7fff99a8, ffffffff7e166de0, ffffffff7f227030, 7fffa631a2b8)

• SIGSEGV (Segmentation Fault) - access to unmapped memory address

status: process terminated by SIGSEGV (Segmentation Fault), addr=18
python:core> $c
greenlet-0.4.15-py3.8-sola`slp_save_state+0x50(ffffffff7fff3f31, 0, ffffffff7e9e8c80, 7fffb0d069a8, ffffffffffffffff, 0)
greenlet-0.4.15-py3.8-sola`slp_switch+0x18(ffffffffffffffff, 0, 20, 100106140, 0, ffffffff7fff3f31)
greenlet-0.4.15-py3.8-sola`g_switchstack+0x54(ffffffff7f272540, ffffffff7fff49d8, e60, 0, 7fffb0d06998, ffffffff7d2c2e10)
greenlet-0.4.15-py3.8-sola`g_switch+0x12c(ffffffff7e961540, ffffffff7fff4948, 7fffb0d069a8, 7fffb0d06988, 7fffb0d06998, 
7fffb0d06990)

But in all cases it happened after the slp_switch call.
I read the src/greenlet/platform/switch_sparc_sun_gcc.h source code and I have a questions:

• https://github.com/python-greenlet/greenlet/blob/master/src/greenlet/platform/switch_sparc_sun_gcc.h#L37C9-L37C20

#define STACK_MAGIC 0

Is it correct value for the sparcv9 platform ?
According to the https://docs.oracle.com/cd/E37838_01/html/E66175/advanced-2.html

6.1 SPARC V9 ABI Features
6.1.1 Stack Bias

An important feature of the SPARC V9 ABI for developers is the stack bias.
For 64-bit SPARC programs, a stack bias of 2047 bytes must be added to both
the frame pointer and the stack pointer to get to the actual data of the stack frame. 

• I tried to build Greenlet 3.0.3 without optimization (using -O0) and in this case it constantly failed on BUS error:

creating build/temp.solaris-2.11-sun4v.64bit-3.11/src/greenlet
gcc -fPIC -m64 -pthread -c src/greenlet/greenlet.cpp -o build/temp.solaris-2.11-sun4v.64bit-3.11/src/greenlet/greenlet.o -O0
...
# python3 -m unittest discover -v greenlet.tests
test_break_ctxvars (greenlet.tests.test_contextvars.ContextVarsTests.test_break_ctxvars) ...
Bus Error               (core dumped) python3 -m unittest discover -v greenlet.tests
...
status: process terminated by SIGBUS (Bus Error), addr=fffffd2621cb0ce1
python3.11:core> $c
_greenlet.cpython-311.so`_ZN8greenlet10StackState18copy_heap_to_stackERKS0_+0x60(7feae8c1f4530, 7feae8d1693e0, 
7feae8d1693e0, 0, 0, 0)
_greenlet.cpython-311.so`_ZN8greenlet8Greenlet17slp_restore_stateEv+0x68(7feae8c1f4500, fffffd2621cb0621, 7feae8f4306c0, 
8, 7feae8ed0d978, 7feae8c1f4530)
_greenlet.cpython-311.so`slp_restore_state_trampoline+0x2c(fffffd2621cb0ce1, 7feae893fb100, 7feae8f4306c0, 8, 
7feae89491840, fffffd2621cb1598)
_greenlet.cpython-311.so`slp_switch+0x24(0, 7feae8ed0d978, 7feae8f4306c0, 8, 0, 7feae8c1344b0)
_greenlet.cpython-311.so`_ZN8greenlet8Greenlet13g_switchstackEv+0x204(fffffd2621cb1910, 7feae8d1693b0, 7feae8c1f4530, 8, 
7feae89480180, 7feae8c1344b0)
...

Please help me debug this issue - how can I check/validate the correct value of the Greenlet stack ?

Thank you very much!