On 2020-12-12 23:30, Alexander Bluhm wrote:
> On Fri, Dec 11, 2020 at 03:14:52PM -0500, Johan Huldtgren wrote:
> > init: single user shell terminated, restarting
> > init: single user shell terminated, restarting
>
> The problem is that libc setjmp tries to save the MXCSR register.
>
> > cpu0: Geode(TM) Integrated Processor by AMD PCS ("AuthenticAMD" 586-class)
> > 500 MHz, 05-0a-02
> > cpu0: FPU,DE,PSE,TSC,MSR,CX8,SEP,PGE,CMOV,CFLUSH,MMX,MMXX,3DNOW2,3DNOW
>
> This processor has no SSE support, so accessing MXCSR fails.
>
> I tried several variants to detect SSE support during runtime in
> libc. None of them was working in a nice way. So I suggest to
> remove the MXCSR bits. For regress/lib/libc/setjmp-fpu it is enough
> to save the FPU CW register.
>
> i386 compiler does not use SSE by default. There is some code in
> libm/arch/i387/fenv.c that may access MXCSR. Can we assume that
> programs working with MXCSR will care about the state itself or not
> use setjmp?
sorry for the late reponse, I had to wait for new snaps and then
time ran away, but I can confirm that with this change in snaps
i can once again boot and run my i386s boxes normally. Thank you
for the quick fix.
.jh
> ok?
>
> bluhm
>
> Index: lib/libc/arch/i386/gen/_setjmp.S
> ===================================================================
> RCS file: /mount/openbsd/cvs/src/lib/libc/arch/i386/gen/_setjmp.S,v
> retrieving revision 1.8
> diff -u -p -r1.8 _setjmp.S
> --- lib/libc/arch/i386/gen/_setjmp.S 6 Dec 2020 18:13:15 -0000 1.8
> +++ lib/libc/arch/i386/gen/_setjmp.S 12 Dec 2020 22:03:57 -0000
> @@ -63,7 +63,6 @@ ENTRY(_setjmp)
> movl %ecx,(_JB_EBP * 4)(%eax)
> movl %esi,(_JB_ESI * 4)(%eax)
> movl %edi,(_JB_EDI * 4)(%eax)
> - stmxcsr (_JB_MXCSR * 4)(%eax)
> fnstcw (_JB_FCW * 4)(%eax)
> xorl %eax,%eax
> ret
> @@ -75,7 +74,6 @@ ENTRY(_longjmp)
> addl $__jmpxor-1b,%ecx # load cookie address
> movl 4(%esp),%edx # parameter, pointer to env
> movl 8(%esp),%eax # parameter, val
> - ldmxcsr (_JB_MXCSR * 4)(%edx)
> fldcw (_JB_FCW * 4)(%edx)
> movl (_JB_EBX * 4)(%edx),%ebx
> movl (_JB_ESP * 4)(%edx),%esi
> Index: lib/libc/arch/i386/gen/setjmp.S
> ===================================================================
> RCS file: /mount/openbsd/cvs/src/lib/libc/arch/i386/gen/setjmp.S,v
> retrieving revision 1.13
> diff -u -p -r1.13 setjmp.S
> --- lib/libc/arch/i386/gen/setjmp.S 6 Dec 2020 18:13:15 -0000 1.13
> +++ lib/libc/arch/i386/gen/setjmp.S 12 Dec 2020 22:04:01 -0000
> @@ -78,7 +78,6 @@ ENTRY(setjmp)
> movl 8(%edx),%edx # load eip cookie over cookie address
> xorl 0(%esp),%edx # caller address
> movl %edx,(_JB_EIP * 4)(%ecx)
> - stmxcsr (_JB_MXCSR * 4)(%ecx)
> fnstcw (_JB_FCW * 4)(%ecx)
> xorl %eax,%eax
> ret
> @@ -97,7 +96,6 @@ ENTRY(longjmp)
>
> movl 4(%esp),%edx # parameter, pointer to env
> movl 8(%esp),%eax # parameter, val
> - ldmxcsr (_JB_MXCSR * 4)(%edx)
> fldcw (_JB_FCW * 4)(%edx)
> movl (_JB_EBX * 4)(%edx),%ebx
> movl (_JB_ESP * 4)(%edx),%esi
> Index: lib/libc/arch/i386/gen/sigsetjmp.S
> ===================================================================
> RCS file: /mount/openbsd/cvs/src/lib/libc/arch/i386/gen/sigsetjmp.S,v
> retrieving revision 1.12
> diff -u -p -r1.12 sigsetjmp.S
> --- lib/libc/arch/i386/gen/sigsetjmp.S 6 Dec 2020 18:13:15 -0000
> 1.12
> +++ lib/libc/arch/i386/gen/sigsetjmp.S 12 Dec 2020 22:04:05 -0000
> @@ -67,7 +67,6 @@ ENTRY(sigsetjmp)
> movl 4(%edx),%edx # load eip cookie over cookie address
> xorl 0(%esp),%edx
> movl %edx,(_JB_EIP * 4)(%ecx)
> - stmxcsr (_JB_MXCSR * 4)(%ecx)
> fnstcw (_JB_FCW * 4)(%ecx)
> xorl %eax,%eax
> ret
> @@ -91,7 +90,6 @@ ENTRY(siglongjmp)
>
> movl 4(%esp),%edx # reload in case sigprocmask failed
> movl 8(%esp),%eax # parameter, val
> - ldmxcsr (_JB_MXCSR * 4)(%edx)
> fldcw (_JB_FCW * 4)(%edx)
> movl (_JB_EBX * 4)(%edx),%ebx
> movl (_JB_ESP * 4)(%edx),%esi
> Index: sys/arch/i386/include/setjmp.h
> ===================================================================
> RCS file: /mount/openbsd/cvs/src/sys/arch/i386/include/setjmp.h,v
> retrieving revision 1.3
> diff -u -p -r1.3 setjmp.h
> --- sys/arch/i386/include/setjmp.h 6 Dec 2020 15:31:30 -0000 1.3
> +++ sys/arch/i386/include/setjmp.h 12 Dec 2020 22:04:32 -0000
> @@ -13,7 +13,6 @@
> #define _JB_EDI 5
> #define _JB_SIGMASK 6
> #define _JB_SIGFLAG 7
> -#define _JB_MXCSR 8
> -#define _JB_FCW 9
> +#define _JB_FCW 8
>
> #define _JBLEN 10 /* size, in longs, of a jmp_buf */
