From: Anton Blanchard Date: Thu, 3 Jul 2014 05:52:03 +0000 (+1000) Subject: powerpc/pseries: Use jump labels for hcall tracepoints X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=cc1adb5f32557f10f48e8febbef7278a2db9d593;p=linux-beck.git powerpc/pseries: Use jump labels for hcall tracepoints hcall tracepoints add quite a few instructions to our hcall path: plpar_hcall: mr r2,r2 mfcr r0 stw r0,8(r1) b 164 <---- start ld r12,0(r2) std r12,32(r1) cmpdi r12,0 beq 164 <---- end ... We have an unconditional branch that gets noped out during boot and a load/compare/branch. We also store the tracepoint value to the stack for the hcall_exit path to use. By using jump labels we can simplify this to just a single nop that gets replaced with a branch when the tracepoint is enabled: plpar_hcall: mr r2,r2 mfcr r0 stw r0,8(r1) nop <---- ... If jump labels are not enabled, we fall back to the old method. Signed-off-by: Anton Blanchard Signed-off-by: Benjamin Herrenschmidt --- diff --git a/arch/powerpc/include/asm/jump_label.h b/arch/powerpc/include/asm/jump_label.h index f016bb699b5f..efbf9a322a23 100644 --- a/arch/powerpc/include/asm/jump_label.h +++ b/arch/powerpc/include/asm/jump_label.h @@ -10,6 +10,7 @@ * 2 of the License, or (at your option) any later version. */ +#ifndef __ASSEMBLY__ #include #include @@ -42,4 +43,12 @@ struct jump_entry { jump_label_t key; }; +#else +#define ARCH_STATIC_BRANCH(LABEL, KEY) \ +1098: nop; \ + .pushsection __jump_table, "aw"; \ + FTR_ENTRY_LONG 1098b, LABEL, KEY; \ + .popsection +#endif + #endif /* _ASM_POWERPC_JUMP_LABEL_H */ diff --git a/arch/powerpc/platforms/pseries/hvCall.S b/arch/powerpc/platforms/pseries/hvCall.S index 99ecf0a5a929..2f51abf6afa3 100644 --- a/arch/powerpc/platforms/pseries/hvCall.S +++ b/arch/powerpc/platforms/pseries/hvCall.S @@ -12,9 +12,13 @@ #include #include #include +#include + + .section ".text" #ifdef CONFIG_TRACEPOINTS +#ifndef CONFIG_JUMP_LABEL .section ".toc","aw" .globl hcall_tracepoint_refcount @@ -22,21 +26,13 @@ hcall_tracepoint_refcount: .llong 0 .section ".text" +#endif /* * precall must preserve all registers. use unused STK_PARAM() - * areas to save snapshots and opcode. We branch around this - * in early init (eg when populating the MMU hashtable) by using an - * unconditional cpu feature. + * areas to save snapshots and opcode. */ #define HCALL_INST_PRECALL(FIRST_REG) \ -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; \ std r3,STK_PARAM(R3)(r1); \ std r4,STK_PARAM(R4)(r1); \ @@ -60,22 +56,13 @@ END_FTR_SECTION(0, 1); \ ld r8,STK_PARAM(R8)(r1); \ ld r9,STK_PARAM(R9)(r1); \ ld r10,STK_PARAM(R10)(r1); \ - mtlr r0; \ -1: + mtlr r0 /* * postcall is performed immediately before function return which - * allows liberal use of volatile registers. We branch around this - * in early init (eg when populating the MMU hashtable) by using an - * unconditional cpu feature. + * allows liberal use of volatile registers. */ #define __HCALL_INST_POSTCALL \ -BEGIN_FTR_SECTION; \ - b 1f; \ -END_FTR_SECTION(0, 1); \ - ld r12,32(r1); \ - cmpdi r12,0; \ - beq+ 1f; \ mflr r0; \ ld r6,STK_PARAM(R3)(r1); \ std r3,STK_PARAM(R3)(r1); \ @@ -87,8 +74,7 @@ END_FTR_SECTION(0, 1); \ addi r1,r1,STACK_FRAME_OVERHEAD; \ ld r0,16(r1); \ ld r3,STK_PARAM(R3)(r1); \ - mtlr r0; \ -1: + mtlr r0 #define HCALL_INST_POSTCALL_NORETS \ li r5,0; \ @@ -98,37 +84,62 @@ END_FTR_SECTION(0, 1); \ mr r5,BUFREG; \ __HCALL_INST_POSTCALL +#ifdef CONFIG_JUMP_LABEL +#define HCALL_BRANCH(LABEL) \ + ARCH_STATIC_BRANCH(LABEL, hcall_tracepoint_key) +#else + +/* + * We branch around this in early init (eg when populating the MMU + * hashtable) by using an unconditional cpu feature. + */ +#define HCALL_BRANCH(LABEL) \ +BEGIN_FTR_SECTION; \ + b 1f; \ +END_FTR_SECTION(0, 1); \ + ld r12,hcall_tracepoint_refcount@toc(r2); \ + std r12,32(r1); \ + cmpdi r12,0; \ + bne- LABEL; \ +1: +#endif + #else #define HCALL_INST_PRECALL(FIRST_ARG) #define HCALL_INST_POSTCALL_NORETS #define HCALL_INST_POSTCALL(BUFREG) +#define HCALL_BRANCH(LABEL) #endif - .text - _GLOBAL_TOC(plpar_hcall_norets) HMT_MEDIUM mfcr r0 stw r0,8(r1) - - HCALL_INST_PRECALL(R4) - + HCALL_BRANCH(plpar_hcall_norets_trace) HVSC /* invoke the hypervisor */ - HCALL_INST_POSTCALL_NORETS - lwz r0,8(r1) mtcrf 0xff,r0 blr /* return r3 = status */ +#ifdef CONFIG_TRACEPOINTS +plpar_hcall_norets_trace: + HCALL_INST_PRECALL(R4) + HVSC + HCALL_INST_POSTCALL_NORETS + lwz r0,8(r1) + mtcrf 0xff,r0 + blr +#endif + _GLOBAL_TOC(plpar_hcall) HMT_MEDIUM mfcr r0 stw r0,8(r1) - HCALL_INST_PRECALL(R5) + HCALL_BRANCH(plpar_hcall_trace) std r4,STK_PARAM(R4)(r1) /* Save ret buffer */ @@ -147,12 +158,40 @@ _GLOBAL_TOC(plpar_hcall) std r6, 16(r12) std r7, 24(r12) + lwz r0,8(r1) + mtcrf 0xff,r0 + + blr /* return r3 = status */ + +#ifdef CONFIG_TRACEPOINTS +plpar_hcall_trace: + HCALL_INST_PRECALL(R5) + + std r4,STK_PARAM(R4)(r1) + mr r0,r4 + + mr r4,r5 + mr r5,r6 + mr r6,r7 + mr r7,r8 + mr r8,r9 + mr r9,r10 + + HVSC + + ld r12,STK_PARAM(R4)(r1) + std r4,0(r12) + std r5,8(r12) + std r6,16(r12) + std r7,24(r12) + HCALL_INST_POSTCALL(r12) lwz r0,8(r1) mtcrf 0xff,r0 - blr /* return r3 = status */ + blr +#endif /* * plpar_hcall_raw can be called in real mode. kexec/kdump need some @@ -194,7 +233,7 @@ _GLOBAL_TOC(plpar_hcall9) mfcr r0 stw r0,8(r1) - HCALL_INST_PRECALL(R5) + HCALL_BRANCH(plpar_hcall9_trace) std r4,STK_PARAM(R4)(r1) /* Save ret buffer */ @@ -222,12 +261,49 @@ _GLOBAL_TOC(plpar_hcall9) std r11,56(r12) std r0, 64(r12) + lwz r0,8(r1) + mtcrf 0xff,r0 + + blr /* return r3 = status */ + +#ifdef CONFIG_TRACEPOINTS +plpar_hcall9_trace: + HCALL_INST_PRECALL(R5) + + std r4,STK_PARAM(R4)(r1) + mr r0,r4 + + mr r4,r5 + mr r5,r6 + mr r6,r7 + mr r7,r8 + mr r8,r9 + mr r9,r10 + ld r10,STK_PARAM(R11)(r1) + ld r11,STK_PARAM(R12)(r1) + ld r12,STK_PARAM(R13)(r1) + + HVSC + + mr r0,r12 + ld r12,STK_PARAM(R4)(r1) + std r4,0(r12) + std r5,8(r12) + std r6,16(r12) + std r7,24(r12) + std r8,32(r12) + std r9,40(r12) + std r10,48(r12) + std r11,56(r12) + std r0,64(r12) + HCALL_INST_POSTCALL(r12) lwz r0,8(r1) mtcrf 0xff,r0 - blr /* return r3 = status */ + blr +#endif /* See plpar_hcall_raw to see why this is needed */ _GLOBAL(plpar_hcall9_raw) diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c index b02af9ef3ff6..fbfcef514aa7 100644 --- a/arch/powerpc/platforms/pseries/lpar.c +++ b/arch/powerpc/platforms/pseries/lpar.c @@ -26,6 +26,7 @@ #include #include #include +#include #include #include #include @@ -649,6 +650,19 @@ EXPORT_SYMBOL(arch_free_page); #endif #ifdef CONFIG_TRACEPOINTS +#ifdef CONFIG_JUMP_LABEL +struct static_key hcall_tracepoint_key = STATIC_KEY_INIT; + +void hcall_tracepoint_regfunc(void) +{ + static_key_slow_inc(&hcall_tracepoint_key); +} + +void hcall_tracepoint_unregfunc(void) +{ + static_key_slow_dec(&hcall_tracepoint_key); +} +#else /* * We optimise our hcall path by placing hcall_tracepoint_refcount * directly in the TOC so we can check if the hcall tracepoints are @@ -658,13 +672,6 @@ EXPORT_SYMBOL(arch_free_page); /* NB: reg/unreg are called while guarded with the tracepoints_mutex */ extern long hcall_tracepoint_refcount; -/* - * Since the tracing code might execute hcalls we need to guard against - * recursion. One example of this are spinlocks calling H_YIELD on - * shared processor partitions. - */ -static DEFINE_PER_CPU(unsigned int, hcall_trace_depth); - void hcall_tracepoint_regfunc(void) { hcall_tracepoint_refcount++; @@ -674,6 +681,15 @@ void hcall_tracepoint_unregfunc(void) { hcall_tracepoint_refcount--; } +#endif + +/* + * Since the tracing code might execute hcalls we need to guard against + * recursion. One example of this are spinlocks calling H_YIELD on + * shared processor partitions. + */ +static DEFINE_PER_CPU(unsigned int, hcall_trace_depth); + void __trace_hcall_entry(unsigned long opcode, unsigned long *args) {