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PATCH New [email protected] 1 participant 1 message Aug 11, 2003

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From Dave Richards ([email protected])

While diagnosing an MMX/FPU problem I found a minor problem in the code which diagnoses and generates signals for FPU exceptions. On x86 Stack Fault Exception are a subclass of Invalid Operation. Thus, the FPU status register will have both the SF and IF bits set when a stack fault occurs. The code which turns FPU exceptions into signals was assuming IF would be clear:

arch/i386/kernel/traps.c +3 -2
diff -urpN --exclude-from=/home/davej/.exclude bk-linus/arch/i386/kernel/traps.c linux-2.5/arch/i386/kernel/traps.c
@@ -629,9 +629,10 @@ void math_error(void *eip)
 		default:
 			break;
 		case 0x001: /* Invalid Op */
-		case 0x040: /* Stack Fault */
-		case 0x240: /* Stack Fault | Direction */
+		case 0x041: /* Stack Fault */
+		case 0x241: /* Stack Fault | Direction */
 			info.si_code = FPE_FLTINV;
+			/* Should we clear the SF or let user space do it ???? */
 			break;
 		case 0x002: /* Denormalize */
 		case 0x010: /* Underflow */