Messages in this thread Patch in this message | | | Subject | [PATCH powerpc] fix unpaired __trace_hcall_entry and __trace_hcall_exit | From | Li Zhong <> | Date | Mon, 19 Dec 2011 10:06:47 +0800 |
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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.
I don't know much about the powerpc arch. But the idea here is to store the hcall_tracepoint_refcount locally, so __trace_hcall_entry and __trace_hcall_exit will be called or not called in pair by checking the same value.
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> --- arch/powerpc/platforms/pseries/hvCall.S | 20 +++++++++++--------- 1 files changed, 11 insertions(+), 9 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/hvCall.S b/arch/powerpc/platforms/pseries/hvCall.S index fd05fde..1240bd2 100644 --- a/arch/powerpc/platforms/pseries/hvCall.S +++ b/arch/powerpc/platforms/pseries/hvCall.S @@ -14,6 +14,7 @@ #include <asm/ptrace.h> #define STK_PARM(i) (48 + ((i)-3)*8) +#define REG_SIZE (2*8) #ifdef CONFIG_TRACEPOINTS @@ -32,11 +33,12 @@ hcall_tracepoint_refcount: * unconditional cpu feature. */ #define HCALL_INST_PRECALL(FIRST_REG) \ + std r31,-8(r1); \ BEGIN_FTR_SECTION; \ b 1f; \ END_FTR_SECTION(0, 1); \ - ld r12,hcall_tracepoint_refcount@toc(r2); \ - cmpdi r12,0; \ + ld r31,hcall_tracepoint_refcount@toc(r2); \ + cmpdi r31,0; \ beq+ 1f; \ mflr r0; \ std r3,STK_PARM(r3)(r1); \ @@ -49,9 +51,9 @@ END_FTR_SECTION(0, 1); \ std r10,STK_PARM(r10)(r1); \ std r0,16(r1); \ addi r4,r1,STK_PARM(FIRST_REG); \ - stdu r1,-STACK_FRAME_OVERHEAD(r1); \ + stdu r1,-STACK_FRAME_OVERHEAD-REG_SIZE(r1); \ bl .__trace_hcall_entry; \ - addi r1,r1,STACK_FRAME_OVERHEAD; \ + addi r1,r1,STACK_FRAME_OVERHEAD+REG_SIZE; \ ld r0,16(r1); \ ld r3,STK_PARM(r3)(r1); \ ld r4,STK_PARM(r4)(r1); \ @@ -74,8 +76,7 @@ END_FTR_SECTION(0, 1); \ BEGIN_FTR_SECTION; \ b 1f; \ END_FTR_SECTION(0, 1); \ - ld r12,hcall_tracepoint_refcount@toc(r2); \ - cmpdi r12,0; \ + cmpdi r31,0; \ beq+ 1f; \ mflr r0; \ ld r6,STK_PARM(r3)(r1); \ @@ -83,13 +84,14 @@ END_FTR_SECTION(0, 1); \ mr r4,r3; \ mr r3,r6; \ std r0,16(r1); \ - stdu r1,-STACK_FRAME_OVERHEAD(r1); \ + stdu r1,-STACK_FRAME_OVERHEAD-REG_SIZE(r1); \ bl .__trace_hcall_exit; \ - addi r1,r1,STACK_FRAME_OVERHEAD; \ + addi r1,r1,STACK_FRAME_OVERHEAD+REG_SIZE; \ ld r0,16(r1); \ ld r3,STK_PARM(r3)(r1); \ mtlr r0; \ -1: +1: \ + ld r31,-8(r1); #define HCALL_INST_POSTCALL_NORETS \ li r5,0; \ -- 1.7.5.4
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