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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 <ard.biesheuvel@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
[kees: Adjust commit log slightly]
Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Arnd Bergmann 2017-06-30 18:03:59 +02:00 committed by Kees Cook
parent 1854c19cae
commit ffa47aa678
3 changed files with 10 additions and 7 deletions
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2
arch/arm/include/asm/assembler.h
View File

@ -87,6 +87,8 @@
#define CALGN(code...)
#endif
#define IMM12_MASK 0xfff
/*
* Enable and disable interrupts
*/

5
arch/arm/kernel/entry-armv.S
View File

@ -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

10
arch/arm/mm/proc-macros.S
View File

@ -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
/*