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Date: Mon, 14 Aug 2017 13:54:01 +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 20/30] ARM: kernel: use PC relative symbol references in suspend/resume code

Replace some unnecessary absolute references with relative ones. Also,
to prepare for runtime relocation, which occurs with the caches on,
defer taking the absolute address of cpu_resume_after_mmu() until after
the MMU is enabled.

Cc: Russell King <linux@...linux.org.uk>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
---
 arch/arm/kernel/sleep.S | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S
index 3026b119d3ff..9efd1c7d3552 100644
--- a/arch/arm/kernel/sleep.S
+++ b/arch/arm/kernel/sleep.S
@@ -60,18 +60,17 @@
 ENTRY(__cpu_suspend)
 	stmfd	sp!, {r4 - r11, lr}
 #ifdef MULTI_CPU
-	ldr	r10, =processor
-	ldr	r4, [r10, #CPU_SLEEP_SIZE] @ size of CPU sleep state
+	ldr_l	r4, processor + CPU_SLEEP_SIZE	@ size of CPU sleep state
 #else
-	ldr	r4, =cpu_suspend_size
+	adr_l	r4, cpu_suspend_size
 #endif
 	mov	r5, sp			@ current virtual SP
 	add	r4, r4, #12		@ Space for pgd, virt sp, phys resume fn
 	sub	sp, sp, r4		@ allocate CPU state on stack
-	ldr	r3, =sleep_save_sp
+	adr_l	r3, sleep_save_sp
 	stmfd	sp!, {r0, r1}		@ save suspend func arg and pointer
 	ldr	r3, [r3, #SLEEP_SAVE_SP_VIRT]
-	ALT_SMP(ldr r0, =mpidr_hash)
+	ALT_SMP(adr_l r0, mpidr_hash)
 	ALT_UP_B(1f)
 	/* This ldmia relies on the memory layout of the mpidr_hash struct */
 	ldmia	r0, {r1, r6-r8}	@ r1 = mpidr mask (r6,r7,r8) = l[0,1,2] shifts
@@ -100,13 +99,13 @@ ENDPROC(cpu_suspend_abort)
 	.align	5
 	.pushsection	.idmap.text,"ax"
 ENTRY(cpu_resume_mmu)
-	ldr	r3, =cpu_resume_after_mmu
 	instr_sync
 	mcr	p15, 0, r0, c1, c0, 0	@ turn on MMU, I-cache, etc
 	mrc	p15, 0, r0, c0, c0, 0	@ read id reg
 	instr_sync
 	mov	r0, r0
 	mov	r0, r0
+	ldr	r3, =cpu_resume_after_mmu
 	ret	r3			@ jump to virtual address
 ENDPROC(cpu_resume_mmu)
 	.popsection
-- 
2.11.0

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