NetBSD Problem Report #59343

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Date: Wed, 23 Apr 2025 02:28:24 +0000 (UTC)
From: campbell+netbsd@mumble.net
Reply-To: campbell+netbsd@mumble.net
To: gnats-bugs@NetBSD.org
Subject: compat_sigsetjmp.S: missing RESTORE_GP64
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>Number:         59343
>Category:       port-mips
>Synopsis:       compat_sigsetjmp.S: missing RESTORE_GP64
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-mips-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Apr 23 02:30:00 +0000 2025
>Last-Modified:  Thu Apr 24 12:55:02 +0000 2025
>Originator:     Taylor R Campbell
>Release:        current, 10, 9, 8, 7, 6, ...
>Organization:
The CompatBSD Mipsglobalization
>Environment:
>Description:
The compat13 sigsetjmp function uses SAVE_GP and SAVE_GP64 to save gp on ABIs where gp is callee-saves (n32, n64), so it can restore gp when it returns.  Except it doesn't actually restore gp -- it does a tail call to _setjmp or setjmp, but doesn't return gp before (or after, making it a non-tail call).

     61 LEAF(sigsetjmp)
     62 	SETUP_GP
     63 	SETUP_GP64(t0, sigsetjmp)
     64 	INT_S	a1, _SC_MASK13(a0)		# save "savemask"
     65 	bne	a1, 0x0, 1f			# do saving of signal mask?
     66 	PTR_LA	t9, _C_LABEL(_setjmp)
     67 	jr	t9
     68 
     69 1:	PTR_LA	t9, _C_LABEL(setjmp)
     70 	jr	t9
     71 END(sigsetjmp)

https://nxr.netbsd.org/xref/src/lib/libc/compat/arch/mips/gen/compat_sigsetjmp.S?r=1.3#61

It's OK for longjmp to not restore gp -- it doesn't return.  But setjmp definitely does return.
>How-To-Repeat:
run a binary that uses compat13 sigsetjmp and siglongjmp
>Fix:
RESTORE_GP64

>Audit-Trail:
From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/59343 CVS commit: src/tests/lib/libc/setjmp
Date: Thu, 24 Apr 2025 01:41:01 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Thu Apr 24 01:41:01 UTC 2025

 Modified Files:
 	src/tests/lib/libc/setjmp: t_setjmp.c

 Log Message:
 t_setjmp: Tidy up.

 - KNF.
 - Nix trailing whitespace.
 - Use RL from h_macros.h.
 - Use enum and case.

 No functional change intended.

 Preparation for extending these tests to the compat13 functions,
 prompted by:

 PR port-mips/59285: _longjmp(..., 0) makes setjmp return 0, not 1
 PR port-mips/59342: compat_setjmp.S is confused about delay slots
 PR port-mips/59343: compat_sigsetjmp.S: missing RESTORE_GP64


 To generate a diff of this commit:
 cvs rdiff -u -r1.5 -r1.6 src/tests/lib/libc/setjmp/t_setjmp.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/59343 CVS commit: src/tests/lib/libc/setjmp
Date: Thu, 24 Apr 2025 01:41:48 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Thu Apr 24 01:41:48 UTC 2025

 Modified Files:
 	src/tests/lib/libc/setjmp: t_setjmp.c t_sigstack.c

 Log Message:
 t_setjmp, t_sigstack: Test compat13 setjmp/sigsetjmp too.

 PR port-mips/59342: compat_setjmp.S is confused about delay slots
 PR port-mips/59343: compat_sigsetjmp.S: missing RESTORE_GP64


 To generate a diff of this commit:
 cvs rdiff -u -r1.6 -r1.7 src/tests/lib/libc/setjmp/t_setjmp.c
 cvs rdiff -u -r1.13 -r1.14 src/tests/lib/libc/setjmp/t_sigstack.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/59343 CVS commit: src
Date: Thu, 24 Apr 2025 01:42:38 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Thu Apr 24 01:42:38 UTC 2025

 Modified Files:
 	src/lib/libc/compat/arch/mips/gen: compat_sigsetjmp.S
 	src/tests/lib/libc/setjmp: t_setjmp.c t_sigstack.c

 Log Message:
 mips/compat_sigsetjmp: Add missing RESTORE_GP64.

 Otherwise, compat13 sigsetjmp clobbers the caller's gp when it
 returns (the first time around, anyway), which leads to a lovely
 display of fireworks.

 PR port-mips/59343: compat_sigsetjmp.S: missing RESTORE_GP64


 To generate a diff of this commit:
 cvs rdiff -u -r1.3 -r1.4 src/lib/libc/compat/arch/mips/gen/compat_sigsetjmp.S
 cvs rdiff -u -r1.8 -r1.9 src/tests/lib/libc/setjmp/t_setjmp.c
 cvs rdiff -u -r1.15 -r1.16 src/tests/lib/libc/setjmp/t_sigstack.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

From: "Taylor R Campbell" <riastradh@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/59343 CVS commit: src/sys/arch/mips/mips
Date: Thu, 24 Apr 2025 12:54:43 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Thu Apr 24 12:54:43 UTC 2025

 Modified Files:
 	src/sys/arch/mips/mips: compat_13_machdep.c

 Log Message:
 mips: Fix compat_13_sys_sigreturn locking.

 This had been broken back in rev. 1.13.20.1 (on the newlock2 branch,
 merged into HEAD as 1.14) in 2007.

 Should fix:

    lib/libc/setjmp/t_setjmp (261/985): 10 test cases
        _longjmp_zero: [0.078125s] Passed.
        _setjmp: [0.093750s] Passed.
        compat13_longjmp_zero: [ 7875.3945352] panic: kernel diagnostic assertion "mutex_owned(l->l_proc->p_lock)" failed: file "/tmp/build/2025.04.24.01.52.38-pmax/src/sys/kern/sys_sig.c", line 590
    [ 7875.3984415] cpu0: Begin traceback...
    [ 7875.4062540] pid -2135532376 not found
    [ 7875.4140665] cpu0: End traceback...
    [ 7875.6093790] 0x80b65c90: cpu_reboot+0x3c (0x80b64000,0,0x866e5400,0x805b6440) ra 0x803197c0 sz 24
    [ 7875.7109415] 0x80b65ca8: kern_reboot+0xb0 (0x80b64000,0,0x866e5400,0x805b6440) ra 0x80369c80 sz 40
    [ 7875.7109415] 0x80b65cd0: vpanic+0x1dc (0x80b64000,0,0x866e5400,0x805b6440) ra 0x804c085c sz 48
    [ 7875.7109415] 0x80b65d00: kern_assert+0x3c (0x80b64000,0x804e6a3c,0x8051f7a8,0x8052e330) ra 0x8038df4c sz 32
    [ 7875.7265665] 0x80b65d20: sigprocmask1+0x224 (0x80b64000,0x804e6a3c,0x8051f7a8,0x8052e330) ra 0x800616f0 sz 48
    [ 7875.7265665] 0x80b65d50: compat_13_sys_sigreturn+0x1f0 (0x80b64000,0x804e6a3c,0x8051f7a8,0x8052e330) ra 0x80055178 sz 376
    [ 7875.7265665] 0x80b65ec8: syscall+0x158 (0x80b64000,0x804e6a3c,0x8051f7a8,0x8052e330) ra 0x800450ac sz 128
    [ 7875.7265665] 0x80b65f48: mips1_systemcall+0xec (0x80b64000,0x804e6a3c,0x8051f7a8,0x8052e330) ra 0x7923d090 sz 0
    [ 7875.7265665] PC 0x7923d090: not in kernel space
    [ 7875.7265665] 0x80b65f48: 0+0x7923d090 (0x80b64000,0x804e6a3c,0x8051f7a8,0x8052e330) ra 0 sz 0
    [ 7875.7265665] User-level: pid 17290.17290

 https://releng.netbsd.org/b5reports/pmax/2025/2025.04.24.01.52.38/test.log

 (Probably won't do anything about `pid -2135532376 not found',
 though!)

 Prompted by adding tests for compat13 for:

 PR port-mips/59285: _longjmp(..., 0) makes setjmp return 0, not 1
 PR port-mips/59342: compat_setjmp.S is confused about delay slots
 PR port-mips/59343: compat_sigsetjmp.S: missing RESTORE_GP64


 To generate a diff of this commit:
 cvs rdiff -u -r1.22 -r1.23 src/sys/arch/mips/mips/compat_13_machdep.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

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