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Message-Id: <1502801449-29246-11-git-send-email-mark.rutland@arm.com>
Date: Tue, 15 Aug 2017 13:50:45 +0100
From: Mark Rutland <mark.rutland@....com>
To: linux-arm-kernel@...ts.infradead.org
Cc: ard.biesheuvel@...aro.org,
catalin.marinas@....com,
james.morse@....com,
labbott@...hat.com,
linux-kernel@...r.kernel.org,
luto@...capital.net,
mark.rutland@....com,
matt@...eblueprint.co.uk,
will.deacon@....com,
kernel-hardening@...ts.openwall.com,
keescook@...omium.org
Subject: [PATCHv2 10/14] arm64: assembler: allow adr_this_cpu to use the stack pointer
From: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Given that adr_this_cpu already requires a temp register in addition
to the destination register, tweak the instruction sequence so that sp
may be used as well.
This will simplify switching to per-cpu stacks in subsequent patches. While
this limits the range of adr_this_cpu, to +/-4GiB, we don't currently use
adr_this_cpu in modules, and this is not problematic for the main kernel image.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
[Mark: add more commit text]
Signed-off-by: Mark Rutland <mark.rutland@....com>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: James Morse <james.morse@....com>
Cc: Laura Abbott <labbott@...hat.com>
Cc: Will Deacon <will.deacon@....com>
---
arch/arm64/include/asm/assembler.h | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index 610a420..2f2bd51 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -230,12 +230,18 @@
.endm
/*
- * @dst: Result of per_cpu(sym, smp_processor_id())
+ * @dst: Result of per_cpu(sym, smp_processor_id()), can be SP for
+ * non-module code
* @sym: The name of the per-cpu variable
* @tmp: scratch register
*/
.macro adr_this_cpu, dst, sym, tmp
+#ifndef MODULE
+ adrp \tmp, \sym
+ add \dst, \tmp, #:lo12:\sym
+#else
adr_l \dst, \sym
+#endif
mrs \tmp, tpidr_el1
add \dst, \dst, \tmp
.endm
--
1.9.1
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