From ffa47aa678cfaa9b88e8a26cfb115b4768325121 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Fri, 30 Jun 2017 18:03:59 +0200 Subject: [PATCH] ARM: Prepare for randomized task_struct With the new task struct randomization, we can run into a build failure for certain random seeds, which will place fields beyond the allow immediate size in the assembly: arch/arm/kernel/entry-armv.S: Assembler messages: arch/arm/kernel/entry-armv.S:803: Error: bad immediate value for offset (4096) Only two constants in asm-offset.h are affected, and I'm changing both of them here to work correctly in all configurations. One more macro has the problem, but is currently unused, so this removes it instead of adding complexity. Suggested-by: Ard Biesheuvel Signed-off-by: Arnd Bergmann [kees: Adjust commit log slightly] Signed-off-by: Kees Cook --- arch/arm/include/asm/assembler.h | 2 ++ arch/arm/kernel/entry-armv.S | 5 ++++- arch/arm/mm/proc-macros.S | 10 ++++------ 3 files changed, 10 insertions(+), 7 deletions(-) diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h index 68b06f9c65de..ad301f107dd2 100644 --- a/arch/arm/include/asm/assembler.h +++ b/arch/arm/include/asm/assembler.h @@ -87,6 +87,8 @@ #define CALGN(code...) #endif +#define IMM12_MASK 0xfff + /* * Enable and disable interrupts */ diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S index 9f157e7c51e7..c731f0d2b2af 100644 --- a/arch/arm/kernel/entry-armv.S +++ b/arch/arm/kernel/entry-armv.S @@ -797,7 +797,10 @@ ENTRY(__switch_to) #if defined(CONFIG_CC_STACKPROTECTOR) && !defined(CONFIG_SMP) ldr r7, [r2, #TI_TASK] ldr r8, =__stack_chk_guard - ldr r7, [r7, #TSK_STACK_CANARY] + .if (TSK_STACK_CANARY > IMM12_MASK) + add r7, r7, #TSK_STACK_CANARY & ~IMM12_MASK + .endif + ldr r7, [r7, #TSK_STACK_CANARY & IMM12_MASK] #endif #ifdef CONFIG_CPU_USE_DOMAINS mcr p15, 0, r6, c3, c0, 0 @ Set domain register diff --git a/arch/arm/mm/proc-macros.S b/arch/arm/mm/proc-macros.S index 0d40c285bd86..f944836da8a2 100644 --- a/arch/arm/mm/proc-macros.S +++ b/arch/arm/mm/proc-macros.S @@ -25,11 +25,6 @@ ldr \rd, [\rn, #VMA_VM_FLAGS] .endm - .macro tsk_mm, rd, rn - ldr \rd, [\rn, #TI_TASK] - ldr \rd, [\rd, #TSK_ACTIVE_MM] - .endm - /* * act_mm - get current->active_mm */ @@ -37,7 +32,10 @@ bic \rd, sp, #8128 bic \rd, \rd, #63 ldr \rd, [\rd, #TI_TASK] - ldr \rd, [\rd, #TSK_ACTIVE_MM] + .if (TSK_ACTIVE_MM > IMM12_MASK) + add \rd, \rd, #TSK_ACTIVE_MM & ~IMM12_MASK + .endif + ldr \rd, [\rd, #TSK_ACTIVE_MM & IMM12_MASK] .endm /* -- 2.20.1