Commit eac828ea authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

x86/ftrace: Remove ftrace_epilogue() 



Remove the weird jumps to RET and simply use RET.

This then promotes ftrace_stub() to a real function; which becomes
important for kcfi.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111148.719080593@infradead.org
parent b2e9dfe5

arch/x86/kernel/ftrace_64.S

+6 −15
Original line number Diff line number Diff line
@@ -172,20 +172,14 @@ SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL) 
	 */

SYM_INNER_LABEL(ftrace_caller_end, SYM_L_GLOBAL)

	ANNOTATE_NOENDBR



	jmp ftrace_epilogue

	RET

SYM_FUNC_END(ftrace_caller);

STACK_FRAME_NON_STANDARD_FP(ftrace_caller)



SYM_FUNC_START(ftrace_epilogue)

/*

 * This is weak to keep gas from relaxing the jumps.

 */

SYM_INNER_LABEL_ALIGN(ftrace_stub, SYM_L_WEAK)

SYM_FUNC_START(ftrace_stub)

	UNWIND_HINT_FUNC

	ENDBR

	RET

SYM_FUNC_END(ftrace_epilogue)

SYM_FUNC_END(ftrace_stub)



SYM_FUNC_START(ftrace_regs_caller)

	/* Save the current flags before any operations that can change them */
@@ -262,14 +256,11 @@ SYM_INNER_LABEL(ftrace_regs_caller_jmp, SYM_L_GLOBAL) 
	popfq



	/*

	 * 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.

	 * The trampoline will add the return.

	 */

SYM_INNER_LABEL(ftrace_regs_caller_end, SYM_L_GLOBAL)

	ANNOTATE_NOENDBR

	jmp ftrace_epilogue

	RET



	/* Swap the flags with orig_rax */

1:	movq MCOUNT_REG_SIZE(%rsp), %rdi
@@ -280,7 +271,7 @@ SYM_INNER_LABEL(ftrace_regs_caller_end, SYM_L_GLOBAL) 
	/* Restore flags */

	popfq

	UNWIND_HINT_FUNC

	jmp	ftrace_epilogue

	RET



SYM_FUNC_END(ftrace_regs_caller)

STACK_FRAME_NON_STANDARD_FP(ftrace_regs_caller)