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ARM: entry: preserve thread_info pointer in switch_to

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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: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com> # ARMv7M
This commit is contained in:
Ard Biesheuvel 2021-11-24 12:09:48 +01:00
parent 52d2408717
commit 831a469bc1
1 changed files with 9 additions and 8 deletions
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17
arch/arm/kernel/entry-armv.S
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@ -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)