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) { _