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powerpc: Fix unpaired __trace_hcall_entry and __trace_hcall_exit 

Unpaired calling of __trace_hcall_entry and __trace_hcall_exit could
 cause incorrect preempt count. And it might happen as the global
 variable hcall_tracepoint_refcount is checked separately before calling
 them.

 Instead, store the value that was used on entry in the stack frame
 and retreive it from there after the call

Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Li Zhong 2012-01-07 17:54:52 +00:00 committed by Benjamin Herrenschmidt
parent a5ccfee05a
commit ebb7f616ab
1 changed files with 2 additions and 1 deletions
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3
arch/powerpc/platforms/pseries/hvCall.S
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@ -36,6 +36,7 @@ BEGIN_FTR_SECTION; \
b 1f; \
END_FTR_SECTION(0, 1); \
ld r12,hcall_tracepoint_refcount@toc(r2); \
std r12,32(r1); \
cmpdi r12,0; \
beq+ 1f; \
mflr r0; \
@ -74,7 +75,7 @@ END_FTR_SECTION(0, 1); \
BEGIN_FTR_SECTION; \
b 1f; \
END_FTR_SECTION(0, 1); \
ld r12,hcall_tracepoint_refcount@toc(r2); \
ld r12,32(r1); \
cmpdi r12,0; \
beq+ 1f; \
mflr r0; \