On Tue, 23 Aug 2005 11:55:21 -0700 (PDT), Linus Torvalds wrote:
> Wouldn't this simpler patch result in exactly the same behaviour?
I thought the extra code would be good documentation, but the comments
work just as well. This is a little clearer (hand edited patch:)
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -803,15 +803,17 @@ void math_error(void __user *eip)
*/
cwd = get_fpu_cwd(task);
swd = get_fpu_swd(task);
- switch (((~cwd) & swd & 0x3f) | (swd & 0x240)) {
+ switch (swd & ~cwd & 0x3f) {
case 0x000:
default:
break;
case 0x001: /* Invalid Op */
- case 0x041: /* Stack Fault */
- case 0x241: /* Stack Fault | Direction */
+ /*
+ * swd & 0x240 == 0x040: Stack Underflow
+ * swd & 0x240 == 0x240: Stack Overflow
+ * User must clear the SF bit (0x40) if set
+ */
info.si_code = FPE_FLTINV;
- /* Should we clear the SF or let user space do it ????
*/
break;
case 0x002: /* Denormalize */
case 0x010: /* Underflow */
__
Chuck
-
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