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at 2024-08-29T07:36:36-07:00

Use os_set_sigcontext_fpu_modes to reset modes

x86-vm.lisp defines `(setf sigcontext-floating-point-modes)` to set
the modes in the sigcontext.  Use this in `sigfpe-handler` to reset
trap bit for the exception that was signaled.

However, there's no implementation of `os_set_sigcontext_fpu_modes`,
so implement one in solaris-os.c.

Works somewhat better than before in that we don't resignal the
exception again when we restart.  But still have problems with divide
by zero and invalid.  And we're left in a weird FP trap state where we
can't read 1d300 anymore---an overflow?

@@ -481,6 +481,7 @@
  	   (type system-area-pointer scp))
    (let* ((modes (sigcontext-floating-point-modes
  		 (alien:sap-alien scp (* unix:sigcontext)))))
 +    (format t "Current modes:         ~32,'0b~%" modes)
      (multiple-value-bind (fop operands)
  	(let ((sym (find-symbol "GET-FP-OPERANDS" "VM")))
  	  (if (fboundp sym)
@@ -503,6 +504,7 @@
  	;;
  	;; Clear out the status for any enabled traps.  If we don't
  	;; then when we return, the exception gets signaled again.
 +	#+nil
  	(let* ((trap-bit (third (assoc code +fpe-code-info-alist+)))
  	       (current-x87-modes (vm::x87-floating-point-modes))
  	       (current-sse2-modes (vm::sse2-floating-point-modes))
@@ -525,7 +527,16 @@
  	    (setf (vm::x87-floating-point-modes) new-x87-modes))
  	  (format t "new x87 modes:         ~32,'0b~%" (vm::x87-floating-point-modes))
 -	  (format t "new sse2 modes:        ~32,'0b~%" (vm::sse2-floating-point-modes)))))))
 +	  (format t "new sse2 modes:        ~32,'0b~%" (vm::sse2-floating-point-modes)))
 +	(let* ((trap-bit (third (assoc code +fpe-code-info-alist+)))
 +	       (new-modes
 +		(dpb (logandc2 (ldb float-exceptions-byte modes)
 +			       trap-bit)
 +		     float-exceptions-byte modes)))
 +	  (format t "New modes:             ~32,'0b~%" new-modes)
 +	  (setf (sigcontext-floating-point-modes)
 +		(alien:sap-alien scp (* unix:sigcontext))
 +		new-modes))))))
  (macrolet
      ((with-float-traps (name merge-traps docstring)

@@ -637,6 +637,45 @@ os_sigcontext_fpu_modes(ucontext_t *scp)
      return modes;
+ }
 +unsigned int
 +os_set_sigcontext_fpu_modes(ucontext_t *scp, uint32_t modes)
 +{
 +    unsigned short cw, sw;
 +    fpregset_t *fpr;
 +    unsigned int state;
++
 +    fpr = &scp->uc_mcontext.fpregs;
++
 +    cw = modes & 0x3f;
 +    sw = (modes >> 7) &0x3f;
++
 +    DPRINTF(1, (stderr, "modes = 0x%08x\n", modes));
 +    DPRINTF(1, (stderr, "cw = 0x%04x\n", cw));
 +    DPRINTF(1, (stderr, "sw = 0x%04x\n", sw));
++
 +    fpr->fp_reg_set.fpchip_state.state[0] = cw;
 +    fpr->fp_reg_set.fpchip_state.state[1] = sw;
++
 +#ifdef FEATURE_SSE2
 +    /*
 +     * Add in the SSE2 part, if we're running the sse2 core.
 +     */
 +    if (fpu_mode == SSE2) {
 +	unsigned long mxcsr = modes & 0xffff;
++
 +        DPRINTF(1, (stderr, "SSE2 modes = %08lx\n", mxcsr));
 +        fpr->fp_reg_set.fpchip_state.mxcsr = mxcsr;
++
 +	modes |= mxcsr;
 +    }
 +#endif
++
 +    modes ^= (0x3f << 7);
 +    return modes;
 +}
++
++
++
  boolean
  os_support_sse2()
+ {

Raymond Toy pushed to branch issue-355-solaris-x86-fp-trap-handler at cmucl / cmucl

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2 changed files:

Changes: