From 10dec7dbd50ab0be96dda085d625d54ce800e426 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Fri, 15 Aug 2014 13:01:46 +0200 Subject: [PATCH] s390/ftrace: add HAVE_DYNAMIC_FTRACE_WITH_REGS support This code is based on a patch from Vojtech Pavlik. http://marc.info/?l=linux-s390&m=140438885114413&w=2 The actual implementation now differs significantly: Instead of adding a second function "ftrace_regs_caller" which would be nearly identical to the existing ftrace_caller function, the current ftrace_caller function is now an alias to ftrace_regs_caller and always passes the needed pt_regs structure and function_trace_op parameters unconditionally. Besides that also use asm offsets to correctly allocate and access the new struct pt_regs on the stack. While at it we can make use of new instruction to get rid of some indirect loads if compiled for new machines. The passed struct pt_regs can be changed by the called function and it's new contents will replace the current contents. Note: to change the return address the embedded psw member of the pt_regs structure must be changed. The psw member is right now incomplete, since the mask part is missing. For all current use cases this should be sufficent. Providing and restoring a sane mask would mean we need to add an epsw/lpswe pair to the mcount code. Only these two instruction would cost us ~120 cycles which currently seems not necessary. Cc: Vojtech Pavlik Cc: Jiri Kosina Cc: Jiri Slaby Cc: Steven Rostedt Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- arch/s390/Kconfig | 1 + arch/s390/include/asm/ftrace.h | 4 ++++ arch/s390/kernel/ftrace.c | 7 ++++++ arch/s390/kernel/mcount64.S | 43 ++++++++++++++++++++++++---------- 4 files changed, 43 insertions(+), 12 deletions(-) diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 05c78bb5f570..3f845fc02ac4 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -114,6 +114,7 @@ config S390 select HAVE_C_RECORDMCOUNT select HAVE_DEBUG_KMEMLEAK select HAVE_DYNAMIC_FTRACE + select HAVE_DYNAMIC_FTRACE_WITH_REGS if 64BIT select HAVE_FTRACE_MCOUNT_RECORD select HAVE_FUNCTION_GRAPH_TRACER select HAVE_FUNCTION_TRACER diff --git a/arch/s390/include/asm/ftrace.h b/arch/s390/include/asm/ftrace.h index 7b8e456d76c9..1759d73fb95b 100644 --- a/arch/s390/include/asm/ftrace.h +++ b/arch/s390/include/asm/ftrace.h @@ -24,4 +24,8 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr) #define MCOUNT_INSN_SIZE 22 #endif +#ifdef CONFIG_64BIT +#define ARCH_SUPPORTS_FTRACE_OPS 1 +#endif + #endif /* _ASM_S390_FTRACE_H */ diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c index de55efa5b64e..14b61954d5a8 100644 --- a/arch/s390/kernel/ftrace.c +++ b/arch/s390/kernel/ftrace.c @@ -107,6 +107,13 @@ asm( #endif /* CONFIG_64BIT */ +#ifdef CONFIG_64BIT +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, + unsigned long addr) +{ + return 0; +} +#endif int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) diff --git a/arch/s390/kernel/mcount64.S b/arch/s390/kernel/mcount64.S index 5b33c83adde9..4a65dabae851 100644 --- a/arch/s390/kernel/mcount64.S +++ b/arch/s390/kernel/mcount64.S @@ -8,28 +8,47 @@ #include #include #include +#include .section .kprobes.text, "ax" ENTRY(ftrace_stub) br %r14 +#define STACK_FRAME_SIZE (STACK_FRAME_OVERHEAD + __PT_SIZE) +#define STACK_PARENT_IP (STACK_FRAME_SIZE + 8) +#define STACK_PTREGS (STACK_FRAME_OVERHEAD) +#define STACK_PTREGS_GPRS (STACK_PTREGS + __PT_GPRS) +#define STACK_PTREGS_PSW (STACK_PTREGS + __PT_PSW) + ENTRY(_mcount) #ifdef CONFIG_DYNAMIC_FTRACE br %r14 ENTRY(ftrace_caller) + .globl ftrace_regs_caller + .set ftrace_regs_caller,ftrace_caller #endif - stmg %r2,%r5,32(%r15) - stg %r14,112(%r15) lgr %r1,%r15 - aghi %r15,-160 + aghi %r15,-STACK_FRAME_SIZE stg %r1,__SF_BACKCHAIN(%r15) + stg %r1,(STACK_PTREGS_GPRS+15*8)(%r15) + stmg %r0,%r13,STACK_PTREGS_GPRS(%r15) + stg %r14,(STACK_PTREGS_PSW+8)(%r15) +#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES + aghik %r2,%r14,-MCOUNT_INSN_SIZE + lgrl %r4,function_trace_op + lgrl %r14,ftrace_trace_function +#else lgr %r2,%r14 - lg %r3,168(%r15) aghi %r2,-MCOUNT_INSN_SIZE + larl %r4,function_trace_op + lg %r4,0(%r4) larl %r14,ftrace_trace_function lg %r14,0(%r14) +#endif + lg %r3,STACK_PARENT_IP(%r15) + la %r5,STACK_PTREGS(%r15) basr %r14,%r14 #ifdef CONFIG_FUNCTION_GRAPH_TRACER # The j instruction gets runtime patched to a nop instruction. @@ -37,16 +56,16 @@ ENTRY(ftrace_caller) # j .+4 ENTRY(ftrace_graph_caller) j ftrace_graph_caller_end - lg %r2,168(%r15) - lg %r3,272(%r15) + lg %r2,STACK_PARENT_IP(%r15) + lg %r3,(STACK_PTREGS_PSW+8)(%r15) brasl %r14,prepare_ftrace_return - stg %r2,168(%r15) + stg %r2,STACK_PARENT_IP(%r15) ftrace_graph_caller_end: .globl ftrace_graph_caller_end #endif - aghi %r15,160 - lmg %r2,%r5,32(%r15) - lg %r14,112(%r15) + lmg %r0,%r13,STACK_PTREGS_GPRS(%r15) + lg %r14,(STACK_PTREGS_PSW+8)(%r15) + aghi %r15,STACK_FRAME_SIZE br %r14 #ifdef CONFIG_FUNCTION_GRAPH_TRACER @@ -54,10 +73,10 @@ ftrace_graph_caller_end: ENTRY(return_to_handler) stmg %r2,%r5,32(%r15) lgr %r1,%r15 - aghi %r15,-160 + aghi %r15,-STACK_FRAME_OVERHEAD stg %r1,__SF_BACKCHAIN(%r15) brasl %r14,ftrace_return_to_handler - aghi %r15,160 + aghi %r15,STACK_FRAME_OVERHEAD lgr %r14,%r2 lmg %r2,%r5,32(%r15) br %r14 -- 2.39.2