From: Paul Mackerras <paulus@samba.org>
If we should happen to get an altivec assist exception while executing in
the kernel, we will currently try to handle it and fail, and end up oopsing
with (apparently) a segfault. (An altivec assist exception occurs for
floating-point altivec instructions with denormalized inputs or outputs if
the altivec unit is in java mode.)
This patch checks explicitly if we are in user mode and prints a useful
message if not.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/arch/ppc/kernel/traps.c | 7 +++++++
1 files changed, 7 insertions(+)
diff -puN arch/ppc/kernel/traps.c~ppc32-oops-on-kernel-altivec-assist-exceptions arch/ppc/kernel/traps.c
--- 25/arch/ppc/kernel/traps.c~ppc32-oops-on-kernel-altivec-assist-exceptions 2005-04-04 01:59:47.000000000 -0700
+++ 25-akpm/arch/ppc/kernel/traps.c 2005-04-04 01:59:47.000000000 -0700
@@ -805,6 +805,13 @@ void AltivecAssistException(struct pt_re
if (regs->msr & MSR_VEC)
giveup_altivec(current);
preempt_enable();
+ if (!user_mode(regs)) {
+ printk(KERN_ERR "altivec assist exception in kernel mode"
+ " at %lx\n", regs->nip);
+ debugger(regs);
+ die("altivec assist exception", regs, SIGFPE);
+ return;
+ }
err = emulate_altivec(regs);
if (err == 0) {
_