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Commit 5bb7d508 authored by Stefan Agner's avatar Stefan Agner Committed by Greg Kroah-Hartman
Browse files

UPSTREAM: ARM: 8788/1: ftrace: remove old mcount support 



Commit cafa0010 ("Raise the minimum required gcc version to 4.6")
raised the minimum GCC version to 4.6. Old mcount is only required for
GCC versions older than 4.4.0. Hence old mcount support can be dropped
too.

Signed-off-by: default avatarStefan Agner <stefan@agner.ch>
Signed-off-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
(cherry picked from commit d3c61619568c88d48eccd5e74b4f84faa1440652)
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@google.com>
Change-Id: I036c04a6d06c8e8afb954d02f222047af838803d
parent 27e286f3

arch/arm/Kconfig.debug

+0 −5
Original line number Diff line number Diff line
@@ -70,11 +70,6 @@ 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/include/asm/ftrace.h

+0 −3
Original line number Diff line number Diff line
@@ -16,9 +16,6 @@ extern void __gnu_mcount_nc(void); 


#ifdef CONFIG_DYNAMIC_FTRACE

struct dyn_arch_ftrace {

#ifdef CONFIG_OLD_MCOUNT

	bool	old_mcount;

#endif

#ifdef CONFIG_ARM_MODULE_PLTS

	struct module *mod;

#endif

arch/arm/kernel/armksyms.c

+0 −3
Original line number Diff line number Diff line
@@ -167,9 +167,6 @@ 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-ftrace.S

+4 −71
Original line number Diff line number Diff line
@@ -15,23 +15,8 @@ 
 * start of every function.  In mcount, apart from the function's address (in

 * lr), we need to get hold of the function's caller's address.

 *

 * Older GCCs (pre-4.4) inserted a call to a routine called mcount like this:

 *

 *	bl	mcount

 *

 * These versions have the limitation that in order for the mcount routine to

 * be able to determine the function's caller's address, an APCS-style frame

 * pointer (which is set up with something like the code below) is required.

 *

 *	mov     ip, sp

 *	push    {fp, ip, lr, pc}

 *	sub     fp, ip, #4

 *

 * With EABI, these frame pointers are not available unless -mapcs-frame is

 * specified, and if building as Thumb-2, not even then.

 *

 * Newer GCCs (4.4+) solve this problem by introducing a new version of mcount,

 * with call sites like:

 * Newer GCCs (4.4+) solve this problem by using a version of mcount with call

 * sites like:

 *

 *	push	{lr}

 *	bl	__gnu_mcount_nc
@@ -46,17 +31,10 @@ 
 * allows it to be clobbered in subroutines and doesn't use it to hold

 * parameters.)

 *

 * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0"

 * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see

 * arch/arm/kernel/ftrace.c).

 * When using dynamic ftrace, we patch out the mcount call by a "pop {lr}"

 * instead of the __gnu_mcount_nc call (see arch/arm/kernel/ftrace.c).

 */



#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



.macro mcount_adjust_addr rd, rn

	bic	\rd, \rn, #1		@ clear the Thumb bit if present

	sub	\rd, \rd, #MCOUNT_INSN_SIZE
@@ -209,51 +187,6 @@ ftrace_graph_call\suffix: 
	mcount_exit

.endm



#ifdef CONFIG_OLD_MCOUNT

/*

 * mcount

 */



.macro mcount_enter

	stmdb	sp!, {r0-r3, lr}

.endm



.macro mcount_get_lr reg

	ldr	\reg, [fp, #-4]

.endm



.macro mcount_exit

	ldr	lr, [fp, #-4]

	ldmia	sp!, {r0-r3, pc}

.endm



ENTRY(mcount)

#ifdef CONFIG_DYNAMIC_FTRACE

	stmdb	sp!, {lr}

	ldr	lr, [fp, #-4]

	ldmia	sp!, {pc}

#else

	__mcount _old

#endif

ENDPROC(mcount)



#ifdef CONFIG_DYNAMIC_FTRACE

ENTRY(ftrace_caller_old)

	__ftrace_caller _old

ENDPROC(ftrace_caller_old)

#endif



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

ENTRY(ftrace_graph_caller_old)

	__ftrace_graph_caller

ENDPROC(ftrace_graph_caller_old)

#endif



.purgem mcount_enter

.purgem mcount_get_lr

.purgem mcount_exit

#endif



/*

 * __gnu_mcount_nc

 */

arch/arm/kernel/ftrace.c

+0 −51
Original line number Diff line number Diff line
@@ -47,30 +47,6 @@ void arch_ftrace_update_code(int command) 
	stop_machine(__ftrace_modify_code, &command, NULL);

}



#ifdef CONFIG_OLD_MCOUNT

#define OLD_MCOUNT_ADDR	((unsigned long) mcount)

#define OLD_FTRACE_ADDR ((unsigned long) ftrace_caller_old)



#define	OLD_NOP		0xe1a00000	/* mov r0, r0 */



static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)

{

	return rec->arch.old_mcount ? OLD_NOP : NOP;

}



static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)

{

	if (!rec->arch.old_mcount)

		return addr;



	if (addr == MCOUNT_ADDR)

		addr = OLD_MCOUNT_ADDR;

	else if (addr == FTRACE_ADDR)

		addr = OLD_FTRACE_ADDR;



	return addr;

}

#else

static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)

{

	return NOP;
@@ -80,7 +56,6 @@ static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr) 
{

	return addr;

}

#endif



int ftrace_arch_code_modify_prepare(void)

{
@@ -151,15 +126,6 @@ int ftrace_update_ftrace_func(ftrace_func_t func) 
	}

#endif



#ifdef CONFIG_OLD_MCOUNT

	if (!ret) {

		pc = (unsigned long)&ftrace_call_old;

		new = ftrace_call_replace(pc, (unsigned long)func, true);



		ret = ftrace_modify_code(pc, 0, new, false);

	}

#endif



	return ret;

}
@@ -233,16 +199,6 @@ int ftrace_make_nop(struct module *mod, 
	new = ftrace_nop_replace(rec);

	ret = ftrace_modify_code(ip, old, new, true);



#ifdef CONFIG_OLD_MCOUNT

	if (ret == -EINVAL && addr == MCOUNT_ADDR) {

		rec->arch.old_mcount = true;



		old = ftrace_call_replace(ip, adjust_address(rec, addr), true);

		new = ftrace_nop_replace(rec);

		ret = ftrace_modify_code(ip, old, new, true);

	}

#endif



	return ret;

}
@@ -305,13 +261,6 @@ static int ftrace_modify_graph_caller(bool enable) 
#endif





#ifdef CONFIG_OLD_MCOUNT

	if (!ret)

		ret = __ftrace_modify_caller(&ftrace_graph_call_old,

					     ftrace_graph_caller_old,

					     enable);

#endif



	return ret;

}