From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ard Biesheuvel Date: Mon, 14 Aug 2017 13:53:45 +0100 Message-Id: <20170814125411.22604-5-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 04/30] ARM: head-common.S: use PC-relative insn sequence for idmap creation 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: Replace the open coded PC relative offset calculations involving __turn_mmu_on and __turn_mmu_on_end with a pair of adr_l invocations. This ensures these quantities are invariant under runtime relocation. Cc: Russell King Signed-off-by: Ard Biesheuvel --- arch/arm/kernel/head.S | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S index 04286fd9e09c..0a98aec0e39d 100644 --- a/arch/arm/kernel/head.S +++ b/arch/arm/kernel/head.S @@ -227,11 +227,8 @@ __create_page_tables: * Create identity mapping to cater for __enable_mmu. * This identity mapping will be removed by paging_init(). */ - adr r0, __turn_mmu_on_loc - ldmia r0, {r3, r5, r6} - sub r0, r0, r3 @ virt->phys offset - add r5, r5, r0 @ phys __turn_mmu_on - add r6, r6, r0 @ phys __turn_mmu_on_end + adr_l r5, __turn_mmu_on @ _pa(__turn_mmu_on) + adr_l r6, __turn_mmu_on_end @ _pa(__turn_mmu_on_end) mov r5, r5, lsr #SECTION_SHIFT mov r6, r6, lsr #SECTION_SHIFT @@ -354,11 +351,6 @@ __create_page_tables: ret lr ENDPROC(__create_page_tables) .ltorg - .align -__turn_mmu_on_loc: - .long . - .long __turn_mmu_on - .long __turn_mmu_on_end #if defined(CONFIG_SMP) .text -- 2.11.0