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Message-Id: <20170814125411.22604-7-ard.biesheuvel@linaro.org>
Date: Mon, 14 Aug 2017 13:53:47 +0100
From: Ard Biesheuvel <ard.biesheuvel@...aro.org>
To: kernel-hardening@...ts.openwall.com
Cc: linux-arm-kernel@...ts.infradead.org,
Ard Biesheuvel <ard.biesheuvel@...aro.org>,
Arnd Bergmann <arnd@...db.de>,
Nicolas Pitre <nico@...aro.org>,
Russell King <linux@...linux.org.uk>,
Kees Cook <keescook@...omium.org>,
Thomas Garnier <thgarnie@...gle.com>,
Marc Zyngier <marc.zyngier@....com>,
Mark Rutland <mark.rutland@....com>,
Tony Lindgren <tony@...mide.com>,
Matt Fleming <matt@...eblueprint.co.uk>,
Dave Martin <dave.martin@....com>
Subject: [PATCH 06/30] ARM: kernel: use relative references for UP/SMP alternatives
To avoid absolute references that are subject to runtime relocation
when running a kernel built with CONFIG_RELOCATABLE=y, use relative
references in the smp.alt entries.
Cc: Russell King <linux@...linux.org.uk>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
---
arch/arm/include/asm/assembler.h | 4 ++--
arch/arm/include/asm/processor.h | 2 +-
arch/arm/kernel/head.S | 10 +++++-----
3 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index 516ebaf4ff38..3176bf7dcbd9 100644
--- a/arch/arm/include/asm/assembler.h
+++ b/arch/arm/include/asm/assembler.h
@@ -260,7 +260,7 @@
*/
#define ALT_UP(instr...) \
.pushsection ".alt.smp.init", "a" ;\
- .long 9998b ;\
+ .long 9998b - . ;\
9997: instr ;\
.if . - 9997b == 2 ;\
nop ;\
@@ -272,7 +272,7 @@
#define ALT_UP_B(label) \
.equ up_b_offset, label - 9998b ;\
.pushsection ".alt.smp.init", "a" ;\
- .long 9998b ;\
+ .long 9998b - . ;\
W(b) . + up_b_offset ;\
.popsection
#else
diff --git a/arch/arm/include/asm/processor.h b/arch/arm/include/asm/processor.h
index c3d5fc124a05..3667b395bb17 100644
--- a/arch/arm/include/asm/processor.h
+++ b/arch/arm/include/asm/processor.h
@@ -92,7 +92,7 @@ unsigned long get_wchan(struct task_struct *p);
#define __ALT_SMP_ASM(smp, up) \
"9998: " smp "\n" \
" .pushsection \".alt.smp.init\", \"a\"\n" \
- " .long 9998b\n" \
+ " .long 9998b - .\n" \
" " up "\n" \
" .popsection\n"
#else
diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index 6e9df3663a57..ec22f42fd8bb 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -548,14 +548,15 @@ smp_on_up:
__do_fixup_smp_on_up:
cmp r4, r5
reths lr
- ldmia r4!, {r0, r6}
- ARM( str r6, [r0, r3] )
- THUMB( add r0, r0, r3 )
+ ldmia r4, {r0, r6}
+ ARM( str r6, [r0, r4] )
+ THUMB( add r0, r0, r4 )
+ add r4, r4, #8
#ifdef __ARMEB__
THUMB( mov r6, r6, ror #16 ) @ Convert word order for big-endian.
#endif
THUMB( strh r6, [r0], #2 ) @ For Thumb-2, store as two halfwords
- THUMB( mov r6, r6, lsr #16 ) @ to be robust against misaligned r3.
+ THUMB( mov r6, r6, lsr #16 ) @ to be robust against misaligned r0.
THUMB( strh r6, [r0] )
b __do_fixup_smp_on_up
ENDPROC(__do_fixup_smp_on_up)
@@ -564,7 +565,6 @@ ENTRY(fixup_smp)
stmfd sp!, {r4 - r6, lr}
mov r4, r0
add r5, r0, r1
- mov r3, #0
bl __do_fixup_smp_on_up
ldmfd sp!, {r4 - r6, pc}
ENDPROC(fixup_smp)
--
2.11.0
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