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On AMD64, provide siginfo.si_code for floating point errors when error

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occurs using the SSE math processor.  Update comments describing the
handling of the exception status bits in coprocessors control words.

Remove GET_FPU_CW and GET_FPU_SW macros which were used only once.
Prefer to use curpcb to access pcb_save over the longer path of
referencing pcb through the thread structure.

Based on the submission by:	Ed Alley <wea llnl gov>
PR:	  amd64/169927
Reviewed by:	bde
MFC after:	3 weeks
This commit is contained in:
Konstantin Belousov 2012-07-18 15:43:47 +00:00
parent a81f9fed5d
commit bc84db6267
3 changed files with 34 additions and 15 deletions
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40
sys/amd64/amd64/fpu.c
View file

@ -115,9 +115,6 @@ void xsave(char *addr, uint64_t mask);
#define start_emulating() load_cr0(rcr0() | CR0_TS)
#define stop_emulating() clts()
#define GET_FPU_CW(thread) ((thread)->td_pcb->pcb_save->sv_env.en_cw)
#define GET_FPU_SW(thread) ((thread)->td_pcb->pcb_save->sv_env.en_sw)
CTASSERT(sizeof(struct savefpu) == 512);
CTASSERT(sizeof(struct xstate_hdr) == 64);
CTASSERT(sizeof(struct savefpu_ymm) == 832);
@ -516,11 +513,15 @@ static char fpetable[128] = {
};
/*
* Preserve the FP status word, clear FP exceptions, then generate a SIGFPE.
* Preserve the FP status word, clear FP exceptions for x87, then
* generate a SIGFPE.
*
* Clearing exceptions is necessary mainly to avoid IRQ13 bugs. We now
* depend on longjmp() restoring a usable state. Restoring the state
* or examining it might fail if we didn't clear exceptions.
* Clearing exceptions was necessary mainly to avoid IRQ13 bugs and is
* engraved in our i386 ABI. We now depend on longjmp() restoring a
* usable state. Restoring the state or examining it might fail if we
* didn't clear exceptions.
*
* For SSE exceptions, the exceptions are not cleared.
*
* The error code chosen will be one of the FPE_... macros. It will be
* sent as the second argument to old BSD-style signal handlers and as
@ -533,8 +534,9 @@ static char fpetable[128] = {
* solution for signals other than SIGFPE.
*/
int
fputrap()
fputrap_x87(void)
{
struct savefpu *pcb_save;
u_short control, status;
critical_enter();
@ -545,19 +547,33 @@ fputrap()
* wherever they are.
*/
if (PCPU_GET(fpcurthread) != curthread) {
control = GET_FPU_CW(curthread);
status = GET_FPU_SW(curthread);
pcb_save = PCPU_GET(curpcb)->pcb_save;
control = pcb_save->sv_env.en_cw;
status = pcb_save->sv_env.en_sw;
} else {
fnstcw(&control);
fnstsw(&status);
fnclex();
}
if (PCPU_GET(fpcurthread) == curthread)
fnclex();
critical_exit();
return (fpetable[status & ((~control & 0x3f) | 0x40)]);
}
int
fputrap_sse(void)
{
u_int mxcsr;
critical_enter();
if (PCPU_GET(fpcurthread) != curthread)
mxcsr = PCPU_GET(curpcb)->pcb_save->sv_env.en_mxcsr;
else
stmxcsr(&mxcsr);
critical_exit();
return (fpetable[(mxcsr & (~mxcsr >> 7)) & 0x3f]);
}
/*
* Implement device not available (DNA) exception
*

6
sys/amd64/amd64/trap.c
View file

@ -328,7 +328,7 @@ trap(struct trapframe *frame)
break;
case T_ARITHTRAP: /* arithmetic trap */
ucode = fputrap();
ucode = fputrap_x87();
if (ucode == -1)
goto userout;
i = SIGFPE;
@ -442,7 +442,9 @@ trap(struct trapframe *frame)
break;
case T_XMMFLT: /* SIMD floating-point exception */
ucode = 0; /* XXX */
ucode = fputrap_sse();
if (ucode == -1)
goto userout;
i = SIGFPE;
break;
}

3
sys/amd64/include/fpu.h
View file

@ -62,7 +62,8 @@ int fpusetregs(struct thread *td, struct savefpu *addr,
char *xfpustate, size_t xfpustate_size);
int fpusetxstate(struct thread *td, char *xfpustate,
size_t xfpustate_size);
int fputrap(void);
int fputrap_sse(void);
int fputrap_x87(void);
void fpuuserinited(struct thread *td);
struct fpu_kern_ctx *fpu_kern_alloc_ctx(u_int flags);
void fpu_kern_free_ctx(struct fpu_kern_ctx *ctx);