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 <[email protected]>
diff -urN linux-2.5/arch/ppc/kernel/traps.c pmac-2.5/arch/ppc/kernel/traps.c
--- linux-2.5/arch/ppc/kernel/traps.c 2005-03-29 16:24:53.000000000 +1000
+++ pmac-2.5/arch/ppc/kernel/traps.c 2005-03-31 08:37:53.000000000 +1000
@@ -805,6 +828,13 @@
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) {
-
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