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Commit f1b92bb6 authored by Borislav Petkov's avatar Borislav Petkov Committed by Ingo Molnar
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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: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1455612202-14414-4-git-send-email-bp@alien8.de


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 4f6c8938

arch/x86/kernel/ftrace.c

+5 −6
Original line number Diff line number Diff line
@@ -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);



	/*

arch/x86/kernel/mcount_64.S

+8 −6
Original line number Diff line number Diff line
@@ -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)