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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2017-01-11 14:54:53 +0000
committerCatalin Marinas <catalin.marinas@arm.com>2017-01-12 18:10:52 +0000
commit41c066f2c4d436c535616fe182331766c57838f0 (patch)
treea805b9567c20c7d8b3853d57b6915b80ca7c5b49
parent69d012345a1a32d3f03957f14d972efccc106a98 (diff)
arm64: assembler: make adr_l work in modules under KASLR
When CONFIG_RANDOMIZE_MODULE_REGION_FULL=y, the offset between loaded modules and the core kernel may exceed 4 GB, putting symbols exported by the core kernel out of the reach of the ordinary adrp/add instruction pairs used to generate relative symbol references. So make the adr_l macro emit a movz/movk sequence instead when executing in module context. While at it, remove the pointless special case for the stack pointer. Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
-rw-r--r--arch/arm64/include/asm/assembler.h36
1 files changed, 27 insertions, 9 deletions
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index 446f6c46d4b1..3a4301163e04 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -164,22 +164,25 @@ lr .req x30 // link register
/*
* Pseudo-ops for PC-relative adr/ldr/str <reg>, <symbol> where
- * <symbol> is within the range +/- 4 GB of the PC.
+ * <symbol> is within the range +/- 4 GB of the PC when running
+ * in core kernel context. In module context, a movz/movk sequence
+ * is used, since modules may be loaded far away from the kernel
+ * when KASLR is in effect.
*/
/*
* @dst: destination register (64 bit wide)
* @sym: name of the symbol
- * @tmp: optional scratch register to be used if <dst> == sp, which
- * is not allowed in an adrp instruction
*/
- .macro adr_l, dst, sym, tmp=
- .ifb \tmp
+ .macro adr_l, dst, sym
+#ifndef MODULE
adrp \dst, \sym
add \dst, \dst, :lo12:\sym
- .else
- adrp \tmp, \sym
- add \dst, \tmp, :lo12:\sym
- .endif
+#else
+ movz \dst, #:abs_g3:\sym
+ movk \dst, #:abs_g2_nc:\sym
+ movk \dst, #:abs_g1_nc:\sym
+ movk \dst, #:abs_g0_nc:\sym
+#endif
.endm
/*
@@ -190,6 +193,7 @@ lr .req x30 // link register
* the address
*/
.macro ldr_l, dst, sym, tmp=
+#ifndef MODULE
.ifb \tmp
adrp \dst, \sym
ldr \dst, [\dst, :lo12:\sym]
@@ -197,6 +201,15 @@ lr .req x30 // link register
adrp \tmp, \sym
ldr \dst, [\tmp, :lo12:\sym]
.endif
+#else
+ .ifb \tmp
+ adr_l \dst, \sym
+ ldr \dst, [\dst]
+ .else
+ adr_l \tmp, \sym
+ ldr \dst, [\tmp]
+ .endif
+#endif
.endm
/*
@@ -206,8 +219,13 @@ lr .req x30 // link register
* while <src> needs to be preserved.
*/
.macro str_l, src, sym, tmp
+#ifndef MODULE
adrp \tmp, \sym
str \src, [\tmp, :lo12:\sym]
+#else
+ adr_l \tmp, \sym
+ str \src, [\tmp]
+#endif
.endm
/*