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Commit 09bfafac authored by Rabin Vincent's avatar Rabin Vincent Committed by Russell King
Browse files

ARM: 6314/1: ftrace: allow build without frame pointers on ARM 



With a new enough GCC, ARM function tracing can be supported without the
need for frame pointers.  This is essential for Thumb-2 support, since
frame pointers aren't available then.

Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarRabin Vincent <rabin@rab.in>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 7e9501fd

arch/arm/Kconfig.debug

+5 −0
Original line number Diff line number Diff line
@@ -27,6 +27,11 @@ config ARM_UNWIND 
	  the performance is not affected. Currently, this feature

	  only works with EABI compilers. If unsure say Y.



config OLD_MCOUNT

	bool

	depends on FUNCTION_TRACER && FRAME_POINTER

	default y



config DEBUG_USER

	bool "Verbose user fault messages"

	help

arch/arm/kernel/armksyms.c

+2 −0
Original line number Diff line number Diff line
@@ -165,6 +165,8 @@ EXPORT_SYMBOL(_find_next_bit_be); 
#endif



#ifdef CONFIG_FUNCTION_TRACER

#ifdef CONFIG_OLD_MCOUNT

EXPORT_SYMBOL(mcount);

#endif

EXPORT_SYMBOL(__gnu_mcount_nc);

#endif

arch/arm/kernel/entry-common.S

+14 −0
Original line number Diff line number Diff line
@@ -128,6 +128,13 @@ ENDPROC(ret_from_fork) 
 * allows it to be clobbered in subroutines and doesn't use it to hold

 * parameters.)

 */



#ifndef CONFIG_OLD_MCOUNT

#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4))

#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0.

#endif

#endif



#ifdef CONFIG_DYNAMIC_FTRACE

ENTRY(mcount)

	stmdb	sp!, {r0-r3, lr}
@@ -173,6 +180,12 @@ gnu_trace: 
	ldmia	sp!, {r0-r3, ip, lr}

	mov	pc, ip



#ifdef CONFIG_OLD_MCOUNT

/*

 * This is under an ifdef in order to force link-time errors for people trying

 * to build with !FRAME_POINTER with a GCC which doesn't use the new-style

 * mcount.

 */

ENTRY(mcount)

	stmdb	sp!, {r0-r3, lr}

	ldr	r0, =ftrace_trace_function
@@ -191,6 +204,7 @@ trace: 
	mov	pc, r2

	ldr	lr, [fp, #-4]			@ restore lr

	ldmia	sp!, {r0-r3, pc}

#endif



#endif /* CONFIG_DYNAMIC_FTRACE */

kernel/trace/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -121,7 +121,7 @@ if FTRACE 
config FUNCTION_TRACER

	bool "Kernel Function Tracer"

	depends on HAVE_FUNCTION_TRACER

	select FRAME_POINTER

	select FRAME_POINTER if (!ARM_UNWIND)

	select KALLSYMS

	select GENERIC_TRACER

	select CONTEXT_SWITCH_TRACER