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Message-Id: <20170814125411.22604-11-ard.biesheuvel@linaro.org> Date: Mon, 14 Aug 2017 13:53:51 +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 10/30] ARM: head.S: use PC relative insn sequence to calculate PHYS_OFFSET Replace the open coded arithmetic with a simple adr_l/sub pair. This ensures these quantities are invariant under runtime relocation. Cc: Russell King <linux@...linux.org.uk> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org> --- arch/arm/kernel/head.S | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S index f607e290ef4b..62c961849035 100644 --- a/arch/arm/kernel/head.S +++ b/arch/arm/kernel/head.S @@ -106,10 +106,8 @@ ENTRY(stext) #endif #ifndef CONFIG_XIP_KERNEL - adr r3, 2f - ldmia r3, {r4, r8} - sub r4, r3, r4 @ (PHYS_OFFSET - PAGE_OFFSET) - add r8, r8, r4 @ PHYS_OFFSET + adr_l r8, _text @ __pa(_text) + sub r8, r8, #TEXT_OFFSET @ PHYS_OFFSET #else ldr r8, =PLAT_PHYS_OFFSET @ always constant in this case #endif @@ -161,10 +159,6 @@ ENTRY(stext) 1: b __enable_mmu ENDPROC(stext) .ltorg -#ifndef CONFIG_XIP_KERNEL -2: .long . - .long PAGE_OFFSET -#endif /* * Setup the initial page tables. We only setup the barest -- 2.11.0
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