Commit dc2eb928 authored by Dave Martin's avatar Dave Martin Committed by Russell King
Browse files

ARM: 6938/1: fiq: Refactor {get,set}_fiq_regs() for Thumb-2 



 * To remove the risk of inconvenient register allocation decisions
   by the compiler, these functions are separated out as pure
   assembler.

 * The apcs frame manipulation code is not applicable for Thumb-2
   (and also not easily compatible).  Since it's not essential to
   have a full frame on these leaf assembler functions, the frame
   manipulation is removed, in the interests of simplicity.

 * Split up ldm/stm instructions to be compatible with Thumb-2,
   as well as avoiding instruction forms deprecated on >= ARMv7.

Signed-off-by: default avatarDave Martin <dave.martin@linaro.org>
Reviewed-by: default avatarNicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 4db70f73

arch/arm/include/asm/fiq.h

+14 −2
Original line number Diff line number Diff line
@@ -29,9 +29,21 @@ struct fiq_handler { 
extern int claim_fiq(struct fiq_handler *f);

extern void release_fiq(struct fiq_handler *f);

extern void set_fiq_handler(void *start, unsigned int length);

extern void set_fiq_regs(struct pt_regs *regs);

extern void get_fiq_regs(struct pt_regs *regs);

extern void enable_fiq(int fiq);

extern void disable_fiq(int fiq);



/* helpers defined in fiqasm.S: */

extern void __set_fiq_regs(unsigned long const *regs);

extern void __get_fiq_regs(unsigned long *regs);



static inline void set_fiq_regs(struct pt_regs const *regs)

{

	__set_fiq_regs(&regs->ARM_r8);

}



static inline void get_fiq_regs(struct pt_regs *regs)

{

	__get_fiq_regs(&regs->ARM_r8);

}



#endif

arch/arm/kernel/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -24,7 +24,7 @@ obj-$(CONFIG_OC_ETM) += etm.o 


obj-$(CONFIG_ISA_DMA_API)	+= dma.o

obj-$(CONFIG_ARCH_ACORN)	+= ecard.o 

obj-$(CONFIG_FIQ)		+= fiq.o

obj-$(CONFIG_FIQ)		+= fiq.o fiqasm.o

obj-$(CONFIG_MODULES)		+= armksyms.o module.o

obj-$(CONFIG_ARTHUR)		+= arthur.o

obj-$(CONFIG_ISA_DMA)		+= dma-isa.o

arch/arm/kernel/fiq.c

+2 −43
Original line number Diff line number Diff line
@@ -89,47 +89,6 @@ void set_fiq_handler(void *start, unsigned int length) 
		flush_icache_range(0x1c, 0x1c + length);

}



/*

 * Taking an interrupt in FIQ mode is death, so both these functions

 * disable irqs for the duration.  Note - these functions are almost

 * entirely coded in assembly.

 */

void __naked set_fiq_regs(struct pt_regs *regs)

{

	register unsigned long tmp;

	asm volatile (

	"mov	ip, sp\n\

	stmfd	sp!, {fp, ip, lr, pc}\n\

	sub	fp, ip, #4\n\

	mrs	%0, cpsr\n\

	msr	cpsr_c, %2	@ select FIQ mode\n\

	mov	r0, r0\n\

	ldmia	%1, {r8 - r14}\n\

	msr	cpsr_c, %0	@ return to SVC mode\n\

	mov	r0, r0\n\

	ldmfd	sp, {fp, sp, pc}"

	: "=&r" (tmp)

	: "r" (&regs->ARM_r8), "I" (PSR_I_BIT | PSR_F_BIT | FIQ_MODE));

}



void __naked get_fiq_regs(struct pt_regs *regs)

{

	register unsigned long tmp;

	asm volatile (

	"mov	ip, sp\n\

	stmfd	sp!, {fp, ip, lr, pc}\n\

	sub	fp, ip, #4\n\

	mrs	%0, cpsr\n\

	msr	cpsr_c, %2	@ select FIQ mode\n\

	mov	r0, r0\n\

	stmia	%1, {r8 - r14}\n\

	msr	cpsr_c, %0	@ return to SVC mode\n\

	mov	r0, r0\n\

	ldmfd	sp, {fp, sp, pc}"

	: "=&r" (tmp)

	: "r" (&regs->ARM_r8), "I" (PSR_I_BIT | PSR_F_BIT | FIQ_MODE));

}



int claim_fiq(struct fiq_handler *f)

{

	int ret = 0;
@@ -174,8 +133,8 @@ void disable_fiq(int fiq) 
}



EXPORT_SYMBOL(set_fiq_handler);

EXPORT_SYMBOL(set_fiq_regs);

EXPORT_SYMBOL(get_fiq_regs);

EXPORT_SYMBOL(__set_fiq_regs);	/* defined in fiqasm.S */

EXPORT_SYMBOL(__get_fiq_regs);	/* defined in fiqasm.S */

EXPORT_SYMBOL(claim_fiq);

EXPORT_SYMBOL(release_fiq);

EXPORT_SYMBOL(enable_fiq);

arch/arm/kernel/fiqasm.S

0 → 100644
+49 −0
Original line number Diff line number Diff line 
/*

 *  linux/arch/arm/kernel/fiqasm.S

 *

 *  Derived from code originally in linux/arch/arm/kernel/fiq.c:

 *

 *  Copyright (C) 1998 Russell King

 *  Copyright (C) 1998, 1999 Phil Blundell

 *  Copyright (C) 2011, Linaro Limited

 *

 *  FIQ support written by Philip Blundell <philb@gnu.org>, 1998.

 *

 *  FIQ support re-written by Russell King to be more generic

 *

 *  v7/Thumb-2 compatibility modifications by Linaro Limited, 2011.

 */



#include <linux/linkage.h>

#include <asm/assembler.h>



/*

 * Taking an interrupt in FIQ mode is death, so both these functions

 * disable irqs for the duration.

 */



ENTRY(__set_fiq_regs)

	mov	r2, #PSR_I_BIT | PSR_F_BIT | FIQ_MODE

	mrs	r1, cpsr

	msr	cpsr_c, r2	@ select FIQ mode

	mov	r0, r0		@ avoid hazard prior to ARMv4

	ldmia	r0!, {r8 - r12}

	ldr	sp, [r0], #4

	ldr	lr, [r0]

	msr	cpsr_c, r1	@ return to SVC mode

	mov	r0, r0		@ avoid hazard prior to ARMv4

	mov	pc, lr

ENDPROC(__set_fiq_regs)



ENTRY(__get_fiq_regs)

	mov	r2, #PSR_I_BIT | PSR_F_BIT | FIQ_MODE

	mrs	r1, cpsr

	msr	cpsr_c, r2	@ select FIQ mode

	mov	r0, r0		@ avoid hazard prior to ARMv4

	stmia	r0!, {r8 - r12}

	str	sp, [r0], #4

	str	lr, [r0]

	msr	cpsr_c, r1	@ return to SVC mode

	mov	r0, r0		@ avoid hazard prior to ARMv4

	mov	pc, lr

ENDPROC(__get_fiq_regs)

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