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authorH. Peter Anvin <hpa@zytor.com>2008-12-22 17:56:05 -0800
committerH. Peter Anvin <hpa@zytor.com>2008-12-22 18:00:18 -0800
commitadf77bac052bb5bf0722b2ce2af9fefc5b2d2a71 (patch)
treeaceffee150411ffe1e93b4f78f4660028d44ecd8
parent55dac3a5553b13891f0ae4bbd11920619b5436d4 (diff)
x86: prioritize the FPU traps for the error code
In the case of multiple FPU errors, prioritize the error codes, instead of returning __SI_FAULT, which ends up pushing a 0 as the error code to userspace, a POSIX violation. For i386, we will simply return if there are no errors at all; for x86-64 this is probably a "can't happen" (and the code should be unified), but for this patch, return __SI_FAULT|SI_KERNEL if this ever happens. Signed-off-by: H. Peter Anvin <hpa@zytor.com>
-rw-r--r--arch/x86/kernel/traps.c34
1 files changed, 15 insertions, 19 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 04d242ab016..c320c29255c 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -664,7 +664,7 @@ void math_error(void __user *ip)
{
struct task_struct *task;
siginfo_t info;
- unsigned short cwd, swd;
+ unsigned short cwd, swd, err;
/*
* Save the info for the exception handler and clear the error.
@@ -675,7 +675,6 @@ void math_error(void __user *ip)
task->thread.error_code = 0;
info.si_signo = SIGFPE;
info.si_errno = 0;
- info.si_code = __SI_FAULT;
info.si_addr = ip;
/*
* (~cwd & swd) will mask out exceptions that are not set to unmasked
@@ -689,34 +688,31 @@ void math_error(void __user *ip)
*/
cwd = get_fpu_cwd(task);
swd = get_fpu_swd(task);
- switch (swd & ~cwd & 0x3f) {
- case 0x000: /* No unmasked exception */
-#ifdef CONFIG_X86_32
+
+ err = swd & ~cwd & 0x3f;
+
+#if CONFIG_X86_32
+ if (!err)
return;
#endif
- default: /* Multiple exceptions */
- break;
- case 0x001: /* Invalid Op */
+
+ if (err & 0x001) { /* Invalid op */
/*
* swd & 0x240 == 0x040: Stack Underflow
* swd & 0x240 == 0x240: Stack Overflow
* User must clear the SF bit (0x40) if set
*/
info.si_code = FPE_FLTINV;
- break;
- case 0x002: /* Denormalize */
- case 0x010: /* Underflow */
- info.si_code = FPE_FLTUND;
- break;
- case 0x004: /* Zero Divide */
+ } else if (err & 0x004) { /* Divide by Zero */
info.si_code = FPE_FLTDIV;
- break;
- case 0x008: /* Overflow */
+ } else if (err & 0x008) { /* Overflow */
info.si_code = FPE_FLTOVF;
- break;
- case 0x020: /* Precision */
+ } else if (err & 0x012) { /* Denormal, Underflow */
+ info.si_code = FPE_FLTUND;
+ } else if (err & 0x020) { /* Precision */
info.si_code = FPE_FLTRES;
- break;
+ } else {
+ info.si_code = __SI_FAULT|SI_KERNEL; /* WTF? */
}
force_sig_info(SIGFPE, &info, task);
}