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Commit 59481062 authored by Jon Medhurst's avatar Jon Medhurst Committed by Tixy
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ARM: Thumb-2: Fix exception return sequence to restore stack correctly 



The implementation of svc_exit didn't take into account any stack hole
created by svc_entry; as happens with the undef handler when kprobes are
configured. The fix is to read the saved value of SP rather than trying
to calculate it.

Signed-off-by: default avatarJon Medhurst <tixy@yxit.co.uk>
Acked-by: default avatarNicolas Pitre <nicolas.pitre@linaro.org>
parent 620917de

arch/arm/kernel/entry-header.S

+5 −7
Original line number Diff line number Diff line
@@ -121,15 +121,13 @@ 
	.endm

#else	/* CONFIG_THUMB2_KERNEL */

	.macro	svc_exit, rpsr

	ldr	lr, [sp, #S_SP]			@ top of the stack

	ldrd	r0, r1, [sp, #S_LR]		@ calling lr and pc

	clrex					@ clear the exclusive monitor

	ldr	r0, [sp, #S_SP]			@ top of the stack

	ldr	r1, [sp, #S_PC]			@ return address

	tst	r0, #4				@ orig stack 8-byte aligned?

	stmdb	r0, {r1, \rpsr}			@ rfe context

	stmdb	lr!, {r0, r1, \rpsr}		@ calling lr and rfe context

	ldmia	sp, {r0 - r12}

	ldr	lr, [sp, #S_LR]

	addeq	sp, sp, #S_FRAME_SIZE - 8	@ aligned

	addne	sp, sp, #S_FRAME_SIZE - 4	@ not aligned

	mov	sp, lr

	ldr	lr, [sp], #4

	rfeia	sp!

	.endm