Commit ebb7f616 authored Jan 07, 2012 by Li Zhong Committed by Benjamin Herrenschmidt Jan 11, 2012

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>

parent a5ccfee0

arch/powerpc/platforms/pseries/hvCall.S

+2 −1

Original line number	Diff line number	Diff line
		@@ -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; \