| Message ID | 1481233595-22112-1-git-send-email-abelvesa@linux.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Dec 08, 2016 at 09:46:35PM +0000, Abel Vesa wrote: > From: Jean-Jacques Hiblot <jjhiblot@traphandler.com> > > From: Jean-Jacques Hiblot <jjhiblot@traphandler.com> From statement twice in the commit message. Will resend. > > The DYNAMIC_FTRACE_WITH_REGS configuration makes it possible for a ftrace > operation to specify if registers need to saved/restored by the ftrace handler. > This is needed by kgraft and possibly other ftrace-based tools, and the ARM > architecture is currently lacking this feature. It would also be the first step > to support the "Kprobes-on-ftrace" optimization on ARM. > > This patch introduces a new ftrace handler that stores the registers on the > stack before calling the next stage. The registers are restored from the stack > before going back to the instrumented function. > > A side-effect of this patch is to activate the support for ftrace_modify_call() > as it defines ARCH_SUPPORTS_FTRACE_OPS for the ARM architecture > > Signed-off-by: Jean-Jacques Hiblot <jjhiblot@traphandler.com> > Signed-off-by: Abel Vesa <abelvesa@linux.com> > --- > arch/arm/Kconfig | 2 ++ > arch/arm/include/asm/ftrace.h | 4 +++ > arch/arm/kernel/entry-ftrace.S | 78 ++++++++++++++++++++++++++++++++++++++++++ > arch/arm/kernel/ftrace.c | 33 ++++++++++++++++++ > 4 files changed, 117 insertions(+) > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index b5d529f..87f1a9f 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -50,6 +50,7 @@ config ARM > select HAVE_DMA_API_DEBUG > select HAVE_DMA_CONTIGUOUS if MMU > select HAVE_DYNAMIC_FTRACE if (!XIP_KERNEL) && !CPU_ENDIAN_BE32 && MMU > + select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE > select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU > select HAVE_EXIT_THREAD > select HAVE_FTRACE_MCOUNT_RECORD if (!XIP_KERNEL) > @@ -90,6 +91,7 @@ config ARM > select PERF_USE_VMALLOC > select RTC_LIB > select SYS_SUPPORTS_APM_EMULATION > + select FRAME_POINTER if DYNAMIC_FTRACE_WITH_REGS && FUNCTION_GRAPH_TRACER > # Above selects are sorted alphabetically; please add new ones > # according to that. Thanks. > help > diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h > index bfe2a2f..f434ce9 100644 > --- a/arch/arm/include/asm/ftrace.h > +++ b/arch/arm/include/asm/ftrace.h > @@ -1,6 +1,10 @@ > #ifndef _ASM_ARM_FTRACE > #define _ASM_ARM_FTRACE > > +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS > +#define ARCH_SUPPORTS_FTRACE_OPS 1 > +#endif > + > #ifdef CONFIG_FUNCTION_TRACER > #define MCOUNT_ADDR ((unsigned long)(__gnu_mcount_nc)) > #define MCOUNT_INSN_SIZE 4 /* sizeof mcount call */ > diff --git a/arch/arm/kernel/entry-ftrace.S b/arch/arm/kernel/entry-ftrace.S > index c73c403..fd75bae 100644 > --- a/arch/arm/kernel/entry-ftrace.S > +++ b/arch/arm/kernel/entry-ftrace.S > @@ -92,12 +92,73 @@ > 2: mcount_exit > .endm > > +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS > + > +.macro __ftrace_regs_caller > + > + add ip, sp, #4 @ move in IP the value of SP as it was > + @ before the push {lr} of the mcount mechanism > + stmdb sp!, {ip,lr,pc} > + stmdb sp!, {r0-r11,lr} > + > + @ stack content at this point: > + @ 0 4 44 48 52 56 60 64 > + @ RO | R1 | ... | R11 | LR | SP + 4 | LR | PC | previous LR | > + > + mov r3, sp @ struct pt_regs* > + ldr r2, =function_trace_op > + ldr r2, [r2] @ pointer to the current > + @ function tracing op > + ldr r1, [sp, #64] @ lr of instrumented func > + mcount_adjust_addr r0, lr @ instrumented function > + > + .globl ftrace_regs_call > +ftrace_regs_call: > + bl ftrace_stub > + > +#ifdef CONFIG_FUNCTION_GRAPH_TRACER > + .globl ftrace_graph_regs_call > +ftrace_graph_regs_call: > + mov r0, r0 > +#endif > + ldr lr, [sp, #64] @ get the previous LR value from stack > + ldmia sp, {r0-r11, ip, sp} @ pop the saved registers INCLUDING > + @ the stack pointer > + ret ip > +.endm > + > +#ifdef CONFIG_FUNCTION_GRAPH_TRACER > +.macro __ftrace_graph_regs_caller > + > + sub r0, fp, #4 @ lr of instrumented routine (parent) > + > + @ called from __ftrace_regs_caller > + ldr r1, [sp, #56] @ instrumented routine (func) > + mcount_adjust_addr r1, r1 > + > + mov r2, fp @ frame pointer > + bl prepare_ftrace_return > + > + ldr lr, [fp, #-4] @ restore lr from the stack > + ldmia sp, {r0-r11, ip, sp} @ restore r0 through sp > + ret ip > +.endm > +#endif > +#endif > + > .macro __ftrace_caller suffix > mcount_enter > > mcount_get_lr r1 @ lr of instrumented func > mcount_adjust_addr r0, lr @ instrumented function > > +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS > + ldr r2, =function_trace_op > + ldr r2, [r2] @ pointer to the current > + @ function tracing op > + mov r3, #0 @ regs is NULL > +#endif > + > .globl ftrace_call\suffix > ftrace_call\suffix: > bl ftrace_stub > @@ -212,6 +273,15 @@ UNWIND(.fnstart) > __ftrace_caller > UNWIND(.fnend) > ENDPROC(ftrace_caller) > + > +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS > +ENTRY(ftrace_regs_caller) > +UNWIND(.fnstart) > + __ftrace_regs_caller > +UNWIND(.fnend) > +ENDPROC(ftrace_regs_caller) > +#endif > + > #endif > > #ifdef CONFIG_FUNCTION_GRAPH_TRACER > @@ -220,6 +290,14 @@ UNWIND(.fnstart) > __ftrace_graph_caller > UNWIND(.fnend) > ENDPROC(ftrace_graph_caller) > + > +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS > +ENTRY(ftrace_graph_regs_caller) > +UNWIND(.fnstart) > + __ftrace_graph_regs_caller > +UNWIND(.fnend) > +ENDPROC(ftrace_graph_regs_caller) > +#endif > #endif > > .purgem mcount_enter > diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c > index 3f17594..d8d4753 100644 > --- a/arch/arm/kernel/ftrace.c > +++ b/arch/arm/kernel/ftrace.c > @@ -139,6 +139,15 @@ int ftrace_update_ftrace_func(ftrace_func_t func) > > ret = ftrace_modify_code(pc, 0, new, false); > > +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS > + if (!ret) { > + pc = (unsigned long)&ftrace_regs_call; > + new = ftrace_call_replace(pc, (unsigned long)func); > + > + ret = ftrace_modify_code(pc, 0, new, false); > + } > +#endif > + > #ifdef CONFIG_OLD_MCOUNT > if (!ret) { > pc = (unsigned long)&ftrace_call_old; > @@ -157,6 +166,20 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) > unsigned long ip = rec->ip; > > old = ftrace_nop_replace(rec); > + > + new = ftrace_call_replace(ip, adjust_address(rec, addr)); > + > + return ftrace_modify_code(rec->ip, old, new, true); > +} > + > +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, > + unsigned long addr) > +{ > + unsigned long new, old; > + unsigned long ip = rec->ip; > + > + old = ftrace_call_replace(ip, adjust_address(rec, old_addr)); > + > new = ftrace_call_replace(ip, adjust_address(rec, addr)); > > return ftrace_modify_code(rec->ip, old, new, true); > @@ -229,6 +252,8 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, > extern unsigned long ftrace_graph_call; > extern unsigned long ftrace_graph_call_old; > extern void ftrace_graph_caller_old(void); > +extern unsigned long ftrace_graph_regs_call; > +extern void ftrace_graph_regs_caller(void); > > static int __ftrace_modify_caller(unsigned long *callsite, > void (*func) (void), bool enable) > @@ -251,6 +276,14 @@ static int ftrace_modify_graph_caller(bool enable) > ftrace_graph_caller, > enable); > > +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS > + if (!ret) > + ret = __ftrace_modify_caller(&ftrace_graph_regs_call, > + ftrace_graph_regs_caller, > + enable); > +#endif > + > + > #ifdef CONFIG_OLD_MCOUNT > if (!ret) > ret = __ftrace_modify_caller(&ftrace_graph_call_old, > -- > 2.7.4 >
On Thu 2016-12-08 22:46:55, Abel Vesa wrote: > On Thu, Dec 08, 2016 at 09:46:35PM +0000, Abel Vesa wrote: > > From: Jean-Jacques Hiblot <jjhiblot@traphandler.com> > > > > From: Jean-Jacques Hiblot <jjhiblot@traphandler.com> > > >From statement twice in the commit message. Will resend. > > > > The DYNAMIC_FTRACE_WITH_REGS configuration makes it possible for a ftrace > > operation to specify if registers need to saved/restored by the ftrace handler. > > This is needed by kgraft and possibly other ftrace-based tools, and the ARM > > architecture is currently lacking this feature. It would also be the first step > > to support the "Kprobes-on-ftrace" optimization on ARM. > > > > This patch introduces a new ftrace handler that stores the registers on the > > stack before calling the next stage. The registers are restored from the stack > > before going back to the instrumented function. > > > > A side-effect of this patch is to activate the support for ftrace_modify_call() > > as it defines ARCH_SUPPORTS_FTRACE_OPS for the ARM architecture > > > > Signed-off-by: Jean-Jacques Hiblot <jjhiblot@traphandler.com> > > Signed-off-by: Abel Vesa <abelvesa@linux.com> > > --- > > arch/arm/Kconfig | 2 ++ > > arch/arm/include/asm/ftrace.h | 4 +++ > > arch/arm/kernel/entry-ftrace.S | 78 ++++++++++++++++++++++++++++++++++++++++++ > > arch/arm/kernel/ftrace.c | 33 ++++++++++++++++++ > > 4 files changed, 117 insertions(+) > > > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > > index b5d529f..87f1a9f 100644 > > --- a/arch/arm/Kconfig > > +++ b/arch/arm/Kconfig > > @@ -50,6 +50,7 @@ config ARM > > select HAVE_DMA_API_DEBUG > > select HAVE_DMA_CONTIGUOUS if MMU > > select HAVE_DYNAMIC_FTRACE if (!XIP_KERNEL) && !CPU_ENDIAN_BE32 && MMU > > + select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE > > select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU > > select HAVE_EXIT_THREAD > > select HAVE_FTRACE_MCOUNT_RECORD if (!XIP_KERNEL) > > @@ -90,6 +91,7 @@ config ARM > > select PERF_USE_VMALLOC > > select RTC_LIB > > select SYS_SUPPORTS_APM_EMULATION > > + select FRAME_POINTER if DYNAMIC_FTRACE_WITH_REGS && FUNCTION_GRAPH_TRACER FRAME_POINTER is not for free. It takes space on the stack. Also there is a performance penalty. Do we really need to depend on it? If so, it might be worth a note in the commit message. I made only a quick look at the patch. It looks reasonable. But I do not have enough knowledge about the arm architecture, assembly, and ftrace-specifics. Also I cannot test it easily. So issues might be hidden to my eyes. Best Regards, Petr
On Tue, Jan 10, 2017 at 04:51:12PM +0100, Petr Mladek wrote: > On Thu 2016-12-08 22:46:55, Abel Vesa wrote: > > On Thu, Dec 08, 2016 at 09:46:35PM +0000, Abel Vesa wrote: > > > From: Jean-Jacques Hiblot <jjhiblot@traphandler.com> > > > > > > From: Jean-Jacques Hiblot <jjhiblot@traphandler.com> > > > > >From statement twice in the commit message. Will resend. > > > > > > The DYNAMIC_FTRACE_WITH_REGS configuration makes it possible for a ftrace > > > operation to specify if registers need to saved/restored by the ftrace handler. > > > This is needed by kgraft and possibly other ftrace-based tools, and the ARM > > > architecture is currently lacking this feature. It would also be the first step > > > to support the "Kprobes-on-ftrace" optimization on ARM. > > > > > > This patch introduces a new ftrace handler that stores the registers on the > > > stack before calling the next stage. The registers are restored from the stack > > > before going back to the instrumented function. > > > > > > A side-effect of this patch is to activate the support for ftrace_modify_call() > > > as it defines ARCH_SUPPORTS_FTRACE_OPS for the ARM architecture > > > > > > Signed-off-by: Jean-Jacques Hiblot <jjhiblot@traphandler.com> > > > Signed-off-by: Abel Vesa <abelvesa@linux.com> > > > --- > > > arch/arm/Kconfig | 2 ++ > > > arch/arm/include/asm/ftrace.h | 4 +++ > > > arch/arm/kernel/entry-ftrace.S | 78 ++++++++++++++++++++++++++++++++++++++++++ > > > arch/arm/kernel/ftrace.c | 33 ++++++++++++++++++ > > > 4 files changed, 117 insertions(+) > > > > > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > > > index b5d529f..87f1a9f 100644 > > > --- a/arch/arm/Kconfig > > > +++ b/arch/arm/Kconfig > > > @@ -50,6 +50,7 @@ config ARM > > > select HAVE_DMA_API_DEBUG > > > select HAVE_DMA_CONTIGUOUS if MMU > > > select HAVE_DYNAMIC_FTRACE if (!XIP_KERNEL) && !CPU_ENDIAN_BE32 && MMU > > > + select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE > > > select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU > > > select HAVE_EXIT_THREAD > > > select HAVE_FTRACE_MCOUNT_RECORD if (!XIP_KERNEL) > > > @@ -90,6 +91,7 @@ config ARM > > > select PERF_USE_VMALLOC > > > select RTC_LIB > > > select SYS_SUPPORTS_APM_EMULATION > > > + select FRAME_POINTER if DYNAMIC_FTRACE_WITH_REGS && FUNCTION_GRAPH_TRACER Hi Petr, > > FRAME_POINTER is not for free. It takes space on the stack. Also there > is a performance penalty. Do we really need to depend on it? If so, > it might be worth a note in the commit message. I was trying to create my own patch when I found this work done by Jean-Jacques, so I haven't looked specifically for the FRAME_POINTER part. I looked now at it and you seem to be right, FRAME_POINTER is not needed. I will get rid of the FRAME_POINTER part, change the authorship and send it again in the following days. > > I made only a quick look at the patch. It looks reasonable. But I do > not have enough knowledge about the arm architecture, assembly, and > ftrace-specifics. Also I cannot test it easily. So issues might > be hidden to my eyes. > > Best Regards, > Petr Thanks, Abel
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index b5d529f..87f1a9f 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -50,6 +50,7 @@ config ARM select HAVE_DMA_API_DEBUG select HAVE_DMA_CONTIGUOUS if MMU select HAVE_DYNAMIC_FTRACE if (!XIP_KERNEL) && !CPU_ENDIAN_BE32 && MMU + select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE select HAVE_EFFICIENT_UNALIGNED_ACCESS if (CPU_V6 || CPU_V6K || CPU_V7) && MMU select HAVE_EXIT_THREAD select HAVE_FTRACE_MCOUNT_RECORD if (!XIP_KERNEL) @@ -90,6 +91,7 @@ config ARM select PERF_USE_VMALLOC select RTC_LIB select SYS_SUPPORTS_APM_EMULATION + select FRAME_POINTER if DYNAMIC_FTRACE_WITH_REGS && FUNCTION_GRAPH_TRACER # Above selects are sorted alphabetically; please add new ones # according to that. Thanks. help diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h index bfe2a2f..f434ce9 100644 --- a/arch/arm/include/asm/ftrace.h +++ b/arch/arm/include/asm/ftrace.h @@ -1,6 +1,10 @@ #ifndef _ASM_ARM_FTRACE #define _ASM_ARM_FTRACE +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS +#define ARCH_SUPPORTS_FTRACE_OPS 1 +#endif + #ifdef CONFIG_FUNCTION_TRACER #define MCOUNT_ADDR ((unsigned long)(__gnu_mcount_nc)) #define MCOUNT_INSN_SIZE 4 /* sizeof mcount call */ diff --git a/arch/arm/kernel/entry-ftrace.S b/arch/arm/kernel/entry-ftrace.S index c73c403..fd75bae 100644 --- a/arch/arm/kernel/entry-ftrace.S +++ b/arch/arm/kernel/entry-ftrace.S @@ -92,12 +92,73 @@ 2: mcount_exit .endm +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS + +.macro __ftrace_regs_caller + + add ip, sp, #4 @ move in IP the value of SP as it was + @ before the push {lr} of the mcount mechanism + stmdb sp!, {ip,lr,pc} + stmdb sp!, {r0-r11,lr} + + @ stack content at this point: + @ 0 4 44 48 52 56 60 64 + @ RO | R1 | ... | R11 | LR | SP + 4 | LR | PC | previous LR | + + mov r3, sp @ struct pt_regs* + ldr r2, =function_trace_op + ldr r2, [r2] @ pointer to the current + @ function tracing op + ldr r1, [sp, #64] @ lr of instrumented func + mcount_adjust_addr r0, lr @ instrumented function + + .globl ftrace_regs_call +ftrace_regs_call: + bl ftrace_stub + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + .globl ftrace_graph_regs_call +ftrace_graph_regs_call: + mov r0, r0 +#endif + ldr lr, [sp, #64] @ get the previous LR value from stack + ldmia sp, {r0-r11, ip, sp} @ pop the saved registers INCLUDING + @ the stack pointer + ret ip +.endm + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +.macro __ftrace_graph_regs_caller + + sub r0, fp, #4 @ lr of instrumented routine (parent) + + @ called from __ftrace_regs_caller + ldr r1, [sp, #56] @ instrumented routine (func) + mcount_adjust_addr r1, r1 + + mov r2, fp @ frame pointer + bl prepare_ftrace_return + + ldr lr, [fp, #-4] @ restore lr from the stack + ldmia sp, {r0-r11, ip, sp} @ restore r0 through sp + ret ip +.endm +#endif +#endif + .macro __ftrace_caller suffix mcount_enter mcount_get_lr r1 @ lr of instrumented func mcount_adjust_addr r0, lr @ instrumented function +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS + ldr r2, =function_trace_op + ldr r2, [r2] @ pointer to the current + @ function tracing op + mov r3, #0 @ regs is NULL +#endif + .globl ftrace_call\suffix ftrace_call\suffix: bl ftrace_stub @@ -212,6 +273,15 @@ UNWIND(.fnstart) __ftrace_caller UNWIND(.fnend) ENDPROC(ftrace_caller) + +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS +ENTRY(ftrace_regs_caller) +UNWIND(.fnstart) + __ftrace_regs_caller +UNWIND(.fnend) +ENDPROC(ftrace_regs_caller) +#endif + #endif #ifdef CONFIG_FUNCTION_GRAPH_TRACER @@ -220,6 +290,14 @@ UNWIND(.fnstart) __ftrace_graph_caller UNWIND(.fnend) ENDPROC(ftrace_graph_caller) + +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS +ENTRY(ftrace_graph_regs_caller) +UNWIND(.fnstart) + __ftrace_graph_regs_caller +UNWIND(.fnend) +ENDPROC(ftrace_graph_regs_caller) +#endif #endif .purgem mcount_enter diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c index 3f17594..d8d4753 100644 --- a/arch/arm/kernel/ftrace.c +++ b/arch/arm/kernel/ftrace.c @@ -139,6 +139,15 @@ int ftrace_update_ftrace_func(ftrace_func_t func) ret = ftrace_modify_code(pc, 0, new, false); +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS + if (!ret) { + pc = (unsigned long)&ftrace_regs_call; + new = ftrace_call_replace(pc, (unsigned long)func); + + ret = ftrace_modify_code(pc, 0, new, false); + } +#endif + #ifdef CONFIG_OLD_MCOUNT if (!ret) { pc = (unsigned long)&ftrace_call_old; @@ -157,6 +166,20 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) unsigned long ip = rec->ip; old = ftrace_nop_replace(rec); + + new = ftrace_call_replace(ip, adjust_address(rec, addr)); + + return ftrace_modify_code(rec->ip, old, new, true); +} + +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, + unsigned long addr) +{ + unsigned long new, old; + unsigned long ip = rec->ip; + + old = ftrace_call_replace(ip, adjust_address(rec, old_addr)); + new = ftrace_call_replace(ip, adjust_address(rec, addr)); return ftrace_modify_code(rec->ip, old, new, true); @@ -229,6 +252,8 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, extern unsigned long ftrace_graph_call; extern unsigned long ftrace_graph_call_old; extern void ftrace_graph_caller_old(void); +extern unsigned long ftrace_graph_regs_call; +extern void ftrace_graph_regs_caller(void); static int __ftrace_modify_caller(unsigned long *callsite, void (*func) (void), bool enable) @@ -251,6 +276,14 @@ static int ftrace_modify_graph_caller(bool enable) ftrace_graph_caller, enable); +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS + if (!ret) + ret = __ftrace_modify_caller(&ftrace_graph_regs_call, + ftrace_graph_regs_caller, + enable); +#endif + + #ifdef CONFIG_OLD_MCOUNT if (!ret) ret = __ftrace_modify_caller(&ftrace_graph_call_old,