[src/trunk]: src/sys/arch/powerpc/powerpc When trying to figure out which cod...

[matt <matt%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/6c0af1fa7237
branches:  trunk
changeset: 565350:6c0af1fa7237
user:      matt <matt%NetBSD.org@localhost>
date:      Sun Apr 04 22:20:44 2004 +0000

description:
When trying to figure out which code to return, use the exception enable
bits to mask out the undesired exceptions.  (Thanks to Todd Whitesel for
the idea).

diffstat:

 sys/arch/powerpc/powerpc/fpu.c |  48 +++++++++++++++++++++--------------------
 1 files changed, 25 insertions(+), 23 deletions(-)

diffs (103 lines):

diff -r 6cc6bd69d05c -r 6c0af1fa7237 sys/arch/powerpc/powerpc/fpu.c
--- a/sys/arch/powerpc/powerpc/fpu.c    Sun Apr 04 20:17:27 2004 +0000
+++ b/sys/arch/powerpc/powerpc/fpu.c    Sun Apr 04 22:20:44 2004 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: fpu.c,v 1.13 2004/04/04 19:21:36 matt Exp $    */
+/*     $NetBSD: fpu.c,v 1.14 2004/04/04 22:20:44 matt Exp $    */
 
 /*
  * Copyright (C) 1996 Wolfgang Solfrank.
@@ -32,7 +32,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: fpu.c,v 1.13 2004/04/04 19:21:36 matt Exp $");
+__KERNEL_RCSID(0, "$NetBSD: fpu.c,v 1.14 2004/04/04 22:20:44 matt Exp $");
 
 #include "opt_multiprocessor.h"
 
@@ -226,9 +226,9 @@
 }
 
 #define        STICKYBITS      (FPSCR_VX|FPSCR_OX|FPSCR_UX|FPSCR_ZX|FPSCR_XX)
-#if STICKYBITS & (PCB_FE0|PCB_FE1|PCB_VEC|PCB_FPU)
-#error PCB flags overlap FPSCR STICKYBITS
-#endif
+#define        STICKYSHIFT     25
+#define        MASKBITS        (FPSCR_VE|FPSCR_OE|FPSCR_UE|FPSCR_ZE|FPSCR_XE)
+#define        MASKSHIFT       3
 
 int
 get_fpu_fault_code(void)
@@ -236,21 +236,22 @@
 #ifdef DIAGNOSTIC
        struct cpu_info *ci = curcpu();
 #endif
-       struct lwp *l = curlwp;
-       struct pcb *pcb = &l->l_addr->u_pcb;
+       struct pcb *pcb = curpcb;
        register_t msr;
-       uint64_t tmp;
-       uint32_t fpscr;
+       uint64_t tmp, fpscr64;
+       uint32_t fpscr, ofpscr;
        int code;
 
        KASSERT(pcb->pcb_fpcpu == ci);
        KASSERT(pcb->pcb_flags & PCB_FPU);
-       KASSERT(ci->ci_fpulwp == l);
+       KASSERT(ci->ci_fpulwp == curlwp);
        msr = mfmsr();
         mtmsr((msr & ~PSL_EE) | PSL_FP);
        __asm __volatile ("isync");
        __asm __volatile (
                "stfd   0,0(%0)\n"      /* save f0 */
+               "mffs   0\n"            /* get FPSCR */
+               "stfd   0,0(%2)\n"      /* store a temp copy */
                "mtfsb0 0\n"            /* clear FPSCR_FX */
                "mtfsb0 24\n"           /* clear FPSCR_VE */
                "mtfsb0 25\n"           /* clear FPSCR_OE */
@@ -260,29 +261,30 @@
                "mffs   0\n"            /* get FPSCR */
                "stfd   0,0(%1)\n"      /* store it */
                "lfd    0,0(%0)\n"      /* restore f0 */
-           :: "b"(&tmp), "b"(&pcb->pcb_fpu.fpscr));
+           :: "b"(&tmp), "b"(&pcb->pcb_fpu.fpscr), "b"(&fpscr64));
         mtmsr(msr);
        __asm __volatile ("isync");
        /*
-        * Now determine the fault type.  First we see if any of the sticky
-        * bits have changed since the FP exception.  If so, we only want
-        * to return the code for the new exception.  If not, we look at all
-        * the bits.
+        * Now determine the fault type.  First we test to see if any of sticky
+        * bits correspond to the enabled exceptions.  If so, we only test
+        * those bits.  If not, we look at all the bits.  (In reality, we only
+        * could get an exception if FPSCR_FEX changed state.  So we should
+        * have at least one bit that corresponds).
         */
+       ofpscr = (uint32_t)fpscr64;
+       ofpscr &= ofpscr << (STICKYSHIFT - MASKSHIFT);
        fpscr = (uint32_t)(*(uint64_t *)&pcb->pcb_fpu.fpscr);
-       if ((fpscr & ~pcb->pcb_flags) & STICKYBITS)
-               fpscr &= ~pcb->pcb_flags;
+       if (fpscr & ofpscr & STICKYBITS)
+               fpscr &= ofpscr;
+
+       /*
+        * Let's determine what the appropriate code is.
+        */
        if (fpscr & FPSCR_VX)           code = FPE_FLTINV;
        else if (fpscr & FPSCR_OX)      code = FPE_FLTOVF;
        else if (fpscr & FPSCR_UX)      code = FPE_FLTUND;
        else if (fpscr & FPSCR_ZX)      code = FPE_FLTDIV;
        else if (fpscr & FPSCR_XX)      code = FPE_FLTRES;
        else                            code = 0;
-       /*
-        * Now we save the latest set of sticky bits.  This is so we can see
-        * what's changed on the next SIGFPE.
-        */
-       pcb->pcb_flags &= ~STICKYBITS;
-       pcb->pcb_flags |= fpscr & STICKYBITS;
        return code;
 }