From f1b92bb6b5a4e17b508f128b084fa00e0eda590c Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Tue, 16 Feb 2016 09:43:21 +0100 Subject: [PATCH] x86/ftrace, x86/asm: Kill ftrace_caller_end label One of ftrace_caller_end and ftrace_return is redundant so unify them. Rename ftrace_return to ftrace_epilogue to mean that everything after that label represents, like an afterword, work which happens *after* the ftrace call, e.g., the function graph tracer for one. Steve wants this to rather mean "[a]n event which reflects meaningfully on a recently ended conflict or struggle." I can imagine that ftrace can be a struggle sometimes. Anyway, beef up the comment about the code contents and layout before ftrace_epilogue label. Signed-off-by: Borislav Petkov Reviewed-by: Steven Rostedt Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1455612202-14414-4-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- arch/x86/kernel/ftrace.c | 11 +++++------ arch/x86/kernel/mcount_64.S | 14 ++++++++------ 2 files changed, 13 insertions(+), 12 deletions(-) diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index 29408d6d6626..04f9641e0cb6 100644 --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -697,9 +697,8 @@ static inline void tramp_free(void *tramp) { } #endif /* Defined as markers to the end of the ftrace default trampolines */ -extern void ftrace_caller_end(void); extern void ftrace_regs_caller_end(void); -extern void ftrace_return(void); +extern void ftrace_epilogue(void); extern void ftrace_caller_op_ptr(void); extern void ftrace_regs_caller_op_ptr(void); @@ -746,7 +745,7 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size) op_offset = (unsigned long)ftrace_regs_caller_op_ptr; } else { start_offset = (unsigned long)ftrace_caller; - end_offset = (unsigned long)ftrace_caller_end; + end_offset = (unsigned long)ftrace_epilogue; op_offset = (unsigned long)ftrace_caller_op_ptr; } @@ -754,7 +753,7 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size) /* * Allocate enough size to store the ftrace_caller code, - * the jmp to ftrace_return, as well as the address of + * the jmp to ftrace_epilogue, as well as the address of * the ftrace_ops this trampoline is used for. */ trampoline = alloc_tramp(size + MCOUNT_INSN_SIZE + sizeof(void *)); @@ -772,8 +771,8 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size) ip = (unsigned long)trampoline + size; - /* The trampoline ends with a jmp to ftrace_return */ - jmp = ftrace_jmp_replace(ip, (unsigned long)ftrace_return); + /* The trampoline ends with a jmp to ftrace_epilogue */ + jmp = ftrace_jmp_replace(ip, (unsigned long)ftrace_epilogue); memcpy(trampoline + size, jmp, MCOUNT_INSN_SIZE); /* diff --git a/arch/x86/kernel/mcount_64.S b/arch/x86/kernel/mcount_64.S index 87e1762e2bca..ed48a9f465f8 100644 --- a/arch/x86/kernel/mcount_64.S +++ b/arch/x86/kernel/mcount_64.S @@ -168,12 +168,14 @@ GLOBAL(ftrace_call) restore_mcount_regs /* - * The copied trampoline must call ftrace_return as it + * The copied trampoline must call ftrace_epilogue as it * still may need to call the function graph tracer. + * + * The code up to this label is copied into trampolines so + * think twice before adding any new code or changing the + * layout here. */ -GLOBAL(ftrace_caller_end) - -GLOBAL(ftrace_return) +GLOBAL(ftrace_epilogue) #ifdef CONFIG_FUNCTION_GRAPH_TRACER GLOBAL(ftrace_graph_call) @@ -244,14 +246,14 @@ GLOBAL(ftrace_regs_call) popfq /* - * As this jmp to ftrace_return can be a short jump + * As this jmp to ftrace_epilogue can be a short jump * it must not be copied into the trampoline. * The trampoline will add the code to jump * to the return. */ GLOBAL(ftrace_regs_caller_end) - jmp ftrace_return + jmp ftrace_epilogue END(ftrace_regs_caller)