From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
commit 41c066f2c4d436c535616fe182331766c57838f0 upstream
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@xxxxxxx>
Acked-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
[ dannf: backported to v4.4 by replacing the 3-arg adr_l macro in head.S
with it's output, as this commit drops the 3-arg variant ]
Fixes: c042dd600f4e ("crypto: arm64/sha - avoid non-standard inline asm tricks")
Signed-off-by: dann frazier <dann.frazier@xxxxxxxxxxxxx>
---
arch/arm64/include/asm/assembler.h | 36 +++++++++++++++++++++++++++---------
arch/arm64/kernel/head.S | 3 ++-
2 files changed, 29 insertions(+), 10 deletions(-)
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index f68abb1..7c28791 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -148,22 +148,25 @@ 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
/*
@@ -174,6 +177,7 @@ 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]
@@ -181,6 +185,15 @@ 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
/*
@@ -190,8 +203,13 @@ 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
/*
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 6299a8a..504bcc3 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -424,7 +424,8 @@ __mmap_switched:
str xzr, [x6], #8 // Clear BSS
b 1b
2:
- adr_l sp, initial_sp, x4
+ adrp x4, initial_sp
+ add sp, x4, :lo12:initial_sp
str_l x21, __fdt_pointer, x5 // Save FDT pointer
str_l x24, memstart_addr, x6 // Save PHYS_OFFSET
mov x29, #0
--
2.7.4
