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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: Stefan Agner <stefan@agner.ch>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Stefan Agner 2015-06-02 20:43:24 +01:00 committed by Russell King
parent 05c9ca8843
commit 970d96f9a8
1 changed files with 8 additions and 13 deletions
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21
arch/arm/kernel/head-nommu.S
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@ -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