This patch is from Craig Chaney <[EMAIL PROTECTED]>.
This patch moves the restoring of the stack pointer in the system call
exit path to after the point where we clear the RI (recoverable
interrupt) bit in the MSR. Normally, loading the stack pointer before
clearing RI doesn't cause any problem because there is no trap that
can normally occur in between. But if we are tracing the code using a
tool that single-steps instructions, this can cause a problem. In
this case, clearing RI serves as an indication that the following code
can't be safely single-stepped.
Signed-off-by: Craig Chaney <[EMAIL PROTECTED]>
Signed-off-by: Paul Mackerras <[EMAIL PROTECTED]>
diff -Naur clean/arch/ppc64/kernel/entry.S edited/arch/ppc64/kernel/entry.S
--- clean/arch/ppc64/kernel/entry.S 2004-09-26 14:24:27.000000000 +0000
+++ edited/arch/ppc64/kernel/entry.S 2004-09-27 14:36:29.221308744 +0000
@@ -185,10 +185,10 @@
beq- 1f /* only restore r13 if */
ld r13,GPR13(r1) /* returning to usermode */
1: ld r2,GPR2(r1)
- ld r1,GPR1(r1)
li r12,MSR_RI
andc r10,r10,r12
mtmsrd r10,1 /* clear MSR.RI */
+ ld r1,GPR1(r1)
mtlr r4
mtcr r5
mtspr SRR0,r7
-
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