From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ard Biesheuvel Date: Mon, 14 Aug 2017 13:53:47 +0100 Message-Id: <20170814125411.22604-7-ard.biesheuvel@linaro.org> In-Reply-To: <20170814125411.22604-1-ard.biesheuvel@linaro.org> References: <20170814125411.22604-1-ard.biesheuvel@linaro.org> Subject: [kernel-hardening] [PATCH 06/30] ARM: kernel: use relative references for UP/SMP alternatives To: kernel-hardening@lists.openwall.com Cc: linux-arm-kernel@lists.infradead.org, Ard Biesheuvel , Arnd Bergmann , Nicolas Pitre , Russell King , Kees Cook , Thomas Garnier , Marc Zyngier , Mark Rutland , Tony Lindgren , Matt Fleming , Dave Martin List-ID: 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 Signed-off-by: Ard Biesheuvel --- 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