Commit b059bdc3 authored by Russell King's avatar Russell King
Browse files

ARM: entry: rejig register allocation in exception entry handlers 



This allows us to avoid moving registers twice to work around the
clobbered registers when we add calls to trace_hardirqs_{on,off}.

Ensure that all SVC handlers return with SPSR in r5 for consistency.

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent fbab1c80

arch/arm/kernel/entry-armv.S

+43 −38
Original line number Diff line number Diff line
@@ -45,7 +45,7 @@ 
	.endm



	.macro	pabt_helper

	mov	r0, r2			@ pass address of aborted instruction.

	mov	r0, r4			@ pass address of aborted instruction.

#ifdef MULTI_PABORT

	ldr	ip, .LCprocfns

	mov	lr, pc
@@ -56,6 +56,8 @@ 
	.endm



	.macro	dabt_helper

	mov	r2, r4

	mov	r3, r5



	@

	@ Call the processor-specific abort handler:
@@ -157,26 +159,26 @@ ENDPROC(__und_invalid) 
 SPFIX(	subeq	sp, sp, #4	)

	stmia	sp, {r1 - r12}



	ldmia	r0, {r1 - r3}

	add	r5, sp, #S_SP - 4	@ here for interlock avoidance

	mov	r4, #-1			@  ""  ""      ""       ""

	add	r0, sp, #(S_FRAME_SIZE + \stack_hole - 4)

 SPFIX(	addeq	r0, r0, #4	)

	str	r1, [sp, #-4]!		@ save the "real" r0 copied

	ldmia	r0, {r3 - r5}

	add	r7, sp, #S_SP - 4	@ here for interlock avoidance

	mov	r6, #-1			@  ""  ""      ""       ""

	add	r2, sp, #(S_FRAME_SIZE + \stack_hole - 4)

 SPFIX(	addeq	r2, r2, #4	)

	str	r3, [sp, #-4]!		@ save the "real" r0 copied

					@ from the exception stack



	mov	r1, lr

	mov	r3, lr



	@

	@ We are now ready to fill in the remaining blanks on the stack:

	@

	@  r0 - sp_svc

	@  r1 - lr_svc

	@  r2 - lr_<exception>, already fixed up for correct return/restart

	@  r3 - spsr_<exception>

	@  r4 - orig_r0 (see pt_regs definition in ptrace.h)

	@  r2 - sp_svc

	@  r3 - lr_svc

	@  r4 - lr_<exception>, already fixed up for correct return/restart

	@  r5 - spsr_<exception>

	@  r6 - orig_r0 (see pt_regs definition in ptrace.h)

	@

	stmia	r5, {r0 - r4}

	stmia	r7, {r2 - r6}

	.endm



	.align	5
@@ -187,7 +189,7 @@ __dabt_svc: 
	@ get ready to re-enable interrupts if appropriate

	@

	mrs	r9, cpsr

	tst	r3, #PSR_I_BIT

	tst	r5, #PSR_I_BIT

	biceq	r9, r9, #PSR_I_BIT



	dabt_helper
@@ -208,8 +210,8 @@ __dabt_svc: 
	@

	@ restore SPSR and restart the instruction

	@

	ldr	r2, [sp, #S_PSR]

	svc_exit r2				@ return from exception

	ldr	r5, [sp, #S_PSR]

	svc_exit r5				@ return from exception

 UNWIND(.fnend		)

ENDPROC(__dabt_svc)
@@ -232,13 +234,13 @@ __irq_svc: 
	tst	r0, #_TIF_NEED_RESCHED

	blne	svc_preempt

#endif

	ldr	r4, [sp, #S_PSR]		@ irqs are already disabled

	ldr	r5, [sp, #S_PSR]

#ifdef CONFIG_TRACE_IRQFLAGS

	@ The parent context IRQs must have been enabled to get here in

	@ the first place, so there's no point checking the PSR I bit.

	bl	trace_hardirqs_on

#endif

	svc_exit r4				@ return from exception

	svc_exit r5				@ return from exception

 UNWIND(.fnend		)

ENDPROC(__irq_svc)
@@ -273,15 +275,16 @@ __und_svc: 
	@  r0 - instruction

	@

#ifndef	CONFIG_THUMB2_KERNEL

	ldr	r0, [r2, #-4]

	ldr	r0, [r4, #-4]

#else

	ldrh	r0, [r2, #-2]			@ Thumb instruction at LR - 2

	ldrh	r0, [r4, #-2]			@ Thumb instruction at LR - 2

	and	r9, r0, #0xf800

	cmp	r9, #0xe800			@ 32-bit instruction if xx >= 0

	ldrhhs	r9, [r2]			@ bottom 16 bits

	ldrhhs	r9, [r4]			@ bottom 16 bits

	orrhs	r0, r9, r0, lsl #16

#endif

	adr	r9, BSYM(1f)

	mov	r2, r4

	bl	call_fpe



	mov	r0, sp				@ struct pt_regs *regs
@@ -295,8 +298,8 @@ __und_svc: 
	@

	@ restore SPSR and restart the instruction

	@

	ldr	r2, [sp, #S_PSR]		@ Get SVC cpsr

	svc_exit r2				@ return from exception

	ldr	r5, [sp, #S_PSR]		@ Get SVC cpsr

	svc_exit r5				@ return from exception

 UNWIND(.fnend		)

ENDPROC(__und_svc)
@@ -308,7 +311,7 @@ __pabt_svc: 
	@ re-enable interrupts if appropriate

	@

	mrs	r9, cpsr

	tst	r3, #PSR_I_BIT

	tst	r5, #PSR_I_BIT

	biceq	r9, r9, #PSR_I_BIT



	pabt_helper
@@ -325,8 +328,8 @@ __pabt_svc: 
	@

	@ restore SPSR and restart the instruction

	@

	ldr	r2, [sp, #S_PSR]

	svc_exit r2				@ return from exception

	ldr	r5, [sp, #S_PSR]

	svc_exit r5				@ return from exception

 UNWIND(.fnend		)

ENDPROC(__pabt_svc)
@@ -357,23 +360,23 @@ ENDPROC(__pabt_svc) 
 ARM(	stmib	sp, {r1 - r12}	)

 THUMB(	stmia	sp, {r0 - r12}	)



	ldmia	r0, {r1 - r3}

	ldmia	r0, {r3 - r5}

	add	r0, sp, #S_PC		@ here for interlock avoidance

	mov	r4, #-1			@  ""  ""     ""        ""

	mov	r6, #-1			@  ""  ""     ""        ""



	str	r1, [sp]		@ save the "real" r0 copied

	str	r3, [sp]		@ save the "real" r0 copied

					@ from the exception stack



	@

	@ We are now ready to fill in the remaining blanks on the stack:

	@

	@  r2 - lr_<exception>, already fixed up for correct return/restart

	@  r3 - spsr_<exception>

	@  r4 - orig_r0 (see pt_regs definition in ptrace.h)

	@  r4 - lr_<exception>, already fixed up for correct return/restart

	@  r5 - spsr_<exception>

	@  r6 - orig_r0 (see pt_regs definition in ptrace.h)

	@

	@ Also, separately save sp_usr and lr_usr

	@

	stmia	r0, {r2 - r4}

	stmia	r0, {r4 - r6}

 ARM(	stmdb	r0, {sp, lr}^			)

 THUMB(	store_user_sp_lr r0, r1, S_SP - S_PC	)
@@ -397,7 +400,7 @@ ENDPROC(__pabt_svc) 
	@ if it was interrupted in a critical region.  Here we

	@ perform a quick test inline since it should be false

	@ 99.9999% of the time.  The rest is done out of line.

	cmp	r2, #TASK_SIZE

	cmp	r4, #TASK_SIZE

	blhs	kuser_cmpxchg_fixup

#endif

#endif
@@ -441,6 +444,8 @@ ENDPROC(__irq_usr) 
	.align	5

__und_usr:

	usr_entry

	mov	r2, r4

	mov	r3, r5



	@

	@ fall through to the emulation code, which returns using r9 if
@@ -894,13 +899,13 @@ __kuser_cmpxchg: @ 0xffff0fc0 
	.text

kuser_cmpxchg_fixup:

	@ Called from kuser_cmpxchg_check macro.

	@ r2 = address of interrupted insn (must be preserved).

	@ r4 = address of interrupted insn (must be preserved).

	@ sp = saved regs. r7 and r8 are clobbered.

	@ 1b = first critical insn, 2b = last critical insn.

	@ If r2 >= 1b and r2 <= 2b then saved pc_usr is set to 1b.

	@ If r4 >= 1b and r4 <= 2b then saved pc_usr is set to 1b.

	mov	r7, #0xffff0fff

	sub	r7, r7, #(0xffff0fff - (0xffff0fc0 + (1b - __kuser_cmpxchg)))

	subs	r8, r2, r7

	subs	r8, r4, r7

	rsbcss	r8, r8, #(2b - 1b)

	strcs	r7, [sp, #S_PC]

	mov	pc, lr

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