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Subject[PATCH] powerpc: fix altivec_unavailable_exception Oopses
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altivec_unavailable_exception is called without setting r3... it looks like
the r3 that actually gets passed in as struct pt_regs *regs is the
undisturbed value of r3 at the time the altivec instruction was encountered.
The user actually gets to choose the pt_regs printed in the Oops!

After applying the following patch to 2.6.16-rc4, I can no longer cause an
Oops by executing an altivec instruction with CONFIG_ALTIVEC=n. The same
change would probably also be good for arch/ppc/kernel/head.S to fix the same
Oops in 2.6.15.4, though I haven't tested that.

--- arch/powerpc/kernel/head_32.S.orig 2006-02-21 15:58:18.000000000 -0500
+++ arch/powerpc/kernel/head_32.S 2006-02-21 15:59:23.000000000 -0500
@@ -714,6 +714,7 @@
#ifdef CONFIG_ALTIVEC
bne load_up_altivec /* if from user, just load it up */
#endif /* CONFIG_ALTIVEC */
+ addi r3,r1,STACK_FRAME_OVERHEAD
EXC_XFER_EE_LITE(0xf20, altivec_unavailable_exception)

PerformanceMonitor:
-
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