Commit 831a469b authored by Ard Biesheuvel's avatar Ard Biesheuvel
Browse files

ARM: entry: preserve thread_info pointer in switch_to 



Tweak the UP stack protector handling code so that the thread info
pointer is preserved in R7 until set_current is called. This is needed
for a subsequent patch that implements THREAD_INFO_IN_TASK and
set_current for UP as well.

This also means we will prefer the per-task protector on UP systems that
implement the thread ID registers, so tweak the preprocessor
conditionals to reflect this.

Acked-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Acked-by: default avatarNicolas Pitre <nico@fluxnic.net>
Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Tested-by: default avatarMarc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
parent 52d24087

arch/arm/kernel/entry-armv.S

+9 −8
Original line number Diff line number Diff line
@@ -806,16 +806,16 @@ ENTRY(__switch_to) 
	ldr	r6, [r2, #TI_CPU_DOMAIN]

#endif

	switch_tls r1, r4, r5, r3, r7

#if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_SMP)

	ldr	r7, [r2, #TI_TASK]

#if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_SMP) && \

    !defined(CONFIG_STACKPROTECTOR_PER_TASK)

	ldr	r9, [r2, #TI_TASK]

	ldr	r8, =__stack_chk_guard

	.if (TSK_STACK_CANARY > IMM12_MASK)

	add	r7, r7, #TSK_STACK_CANARY & ~IMM12_MASK

	add	r9, r9, #TSK_STACK_CANARY & ~IMM12_MASK

	.endif

	ldr	r7, [r7, #TSK_STACK_CANARY & IMM12_MASK]

#elif defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO)

	mov	r7, r2				@ Preserve 'next'

	ldr	r9, [r9, #TSK_STACK_CANARY & IMM12_MASK]

#endif

	mov	r7, r2				@ Preserve 'next'

#ifdef CONFIG_CPU_USE_DOMAINS

	mcr	p15, 0, r6, c3, c0, 0		@ Set domain register

#endif
@@ -824,8 +824,9 @@ ENTRY(__switch_to) 
	ldr	r0, =thread_notify_head

	mov	r1, #THREAD_NOTIFY_SWITCH

	bl	atomic_notifier_call_chain

#if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_SMP)

	str	r7, [r8]

#if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_SMP) && \

    !defined(CONFIG_STACKPROTECTOR_PER_TASK)

	str	r9, [r8]

#endif

	mov	r0, r5

#if !defined(CONFIG_THUMB2_KERNEL) && !defined(CONFIG_VMAP_STACK)