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ihoro
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Avoid calling _callout_stop_safe with a non-sleepable lock held when
detaching by initializing callout_init_rw() with CALLOUT_SHAREDLOCK.
It avoids the following WITNESS warning when stopping the service:
# service ipfilter stop
calling _callout_stop_safe with the following non-sleepable locks held:
shared rw ipf filter load/unload mutex (ipf filter load/unload mutex) r = 0 (0xffff0000417c7530) locked @ /usr/src/sys/netpfil/ipfilter/netinet/fil.c:7926
stack backtrace:
#0 0xffff00000052d394 at witness_debugger+0x60
#1 0xffff00000052e620 at witness_warn+0x404
#2 0xffff0000004d4ffc at _callout_stop_safe+0x8c
#3 0xffff0000f7236674 at ipfdetach+0x3c
#4 0xffff0000f723fa4c at ipf_ipf_ioctl+0x788
#5 0xffff0000f72367e0 at ipfioctl+0x144
#6 0xffff00000034abd8 at devfs_ioctl+0x100
#7 0xffff0000005c66a0 at vn_ioctl+0xbc
#8 0xffff00000034b2cc at devfs_ioctl_f+0x24
#9 0xffff0000005331ec at kern_ioctl+0x2e0
#10 0xffff000000532eb4 at sys_ioctl+0x140
#11 0xffff000000880480 at do_el0_sync+0x604
#12 0xffff0000008579ac at handle_el0_sync+0x4c
PR: 282478
Suggested by: markj
Reviewed by: cy
Approved by: emaste (mentor)
MFC after: 1 week
ihoro
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Jul 17, 2025
Multiple issues existed within the powerpc FP/VSX save/restore functionality, leading to register corruption and loss of register contents in specific scenarios involving high signal load and use of both floating point and VSX instructions. Issue #1 On little endian systems the PCB used the wrong location for the shadowed FP register within the larger VSX register. This appears to have been an attempt to correct issue #2 without understanding how the vector load/store instructions actually operate. Issue #2 On little endian systems, the VSX state save/restore routines swapped 32-bit words within the 64-bit aliased double word for the associated floating point register. This was due to the use of a word-oriented load/store vs. doubleword oriented load/store. Issue #3 The FPU was turned off in the PCB but not in hardware, leading to a potential race condition if the same thread was scheduled immediately after sigreturn. The triggering codebase for this is Go, which makes heavy use of signals and and generates an unusual mix of floating point and VSX assembler. As a result, when combined with th powerpc lazy FPU restore, a condition was repeatedly hit whereby the thread was interrupted in FP+VSX mode, then restored in FP only mode, thus reliably triggering the issues above. Also clean up the associated asm() style issue flagged by GitHub Actions. Signed-off-by: Timothy Pearson <tpearson@raptorengineering.com> MFC after: 1 week Pull Request: freebsd#1756
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