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Commit 970d96f9 authored by Stefan Agner's avatar Stefan Agner Committed by Russell King
Browse files

ARM: 8383/1: nommu: avoid deprecated source register on mov 



In Thumb2 mode, the stack register r13 is deprecated if the
destination register is the program counter (r15). Similar to
head.S, head-nommu.S uses r13 to store the return address used
after configuring the CPU's CP15 register. However, since we do
not enable a MMU, there will be no address switch and it is
possible to use branch with link instruction to call
__after_proc_init.

Avoid using r13 completely by using bl to call __after_proc_init
and get rid of __secondary_switched.

Beside removing unnecessary complexity, this also fixes a
compiler warning when compiling a !MMU kernel:
Warning: Use of r13 as a source register is deprecated when r15
is the destination register.

Tested-?by: Maxime Coquelin <mcoquelin.stm32@gmail.com>

Signed-off-by: default avatarStefan Agner <stefan@agner.ch>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 05c9ca88

arch/arm/kernel/head-nommu.S

+8 −13
Original line number Diff line number Diff line
@@ -77,13 +77,13 @@ ENTRY(stext) 
	orr	r6, r6, #(1 << MPU_RSR_EN)	@ Set region enabled bit

	bl	__setup_mpu

#endif

	ldr	r13, =__mmap_switched		@ address to jump to after

						@ initialising sctlr



	badr	lr, 1f				@ return (PIC) address

	ldr	r12, [r10, #PROCINFO_INITFUNC]

	add	r12, r12, r10

	ret	r12

 1:	b	__after_proc_init

1:	bl	__after_proc_init

	b	__mmap_switched

ENDPROC(stext)



#ifdef CONFIG_SMP
@@ -106,8 +106,7 @@ ENTRY(secondary_startup) 
	movs	r10, r5				@ invalid processor?

	beq	__error_p			@ yes, error 'p'



	adr	r4, __secondary_data

	ldmia	r4, {r7, r12}

	ldr	r7, __secondary_data



#ifdef CONFIG_ARM_MPU

	/* Use MPU region info supplied by __cpu_up */
@@ -115,23 +114,19 @@ ENTRY(secondary_startup) 
	bl      __setup_mpu			@ Initialize the MPU

#endif



	badr	lr, __after_proc_init		@ return address

	mov	r13, r12			@ __secondary_switched address

	badr	lr, 1f				@ return (PIC) address

	ldr	r12, [r10, #PROCINFO_INITFUNC]

	add	r12, r12, r10

	ret	r12

ENDPROC(secondary_startup)



ENTRY(__secondary_switched)

1:	bl	__after_proc_init

	ldr	sp, [r7, #12]			@ set up the stack pointer

	mov	fp, #0

	b	secondary_start_kernel

ENDPROC(__secondary_switched)

ENDPROC(secondary_startup)



	.type	__secondary_data, %object

__secondary_data:

	.long	secondary_data

	.long	__secondary_switched

#endif /* CONFIG_SMP */



/*
@@ -164,7 +159,7 @@ __after_proc_init: 
#endif

	mcr	p15, 0, r0, c1, c0, 0		@ write control reg

#endif /* CONFIG_CPU_CP15 */

	ret	r13

	ret	lr

ENDPROC(__after_proc_init)

	.ltorg