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authorTaras Kondratiuk <taras.kondratiuk@linaro.org>2013-11-08 19:29:29 +0100
committerTaras Kondratiuk <taras@ti.com>2014-04-01 15:48:27 +0200
commit41b5368f31f86a1c2be2bb16a1cf18d23f1223d4 (patch)
tree19bb9fd519dba304852611c94aa2aedb288309ba /arch
parentARM: kprobes-test: use <asm/opcodes.h> for Thumb instruction building (diff)
downloadlinux-41b5368f31f86a1c2be2bb16a1cf18d23f1223d4.tar.xz
linux-41b5368f31f86a1c2be2bb16a1cf18d23f1223d4.zip
ARM: kprobes-test: Workaround GAS .align bug
By default if no fill symbol is given to .align directive in a code section it fills gap with NOPs. If previous fragment is not instruction-aligned, additional pre-alignment is done by zero bytes before NOPs. These zero bytes are marked as data by special symbol $d in symbol table. Unfortunately GAS assumes that there is only code in the code section so it "puts back" code symbol $a at the end of this pre-alignment. So if there is some data after alignment it will be interpreted as code and will be swapped back to LE for BE8 system during a final linking. If explicit fill value is given to .align, the NOP-padding code is skipped and symbol table does not get messed-up. So the workaround for this issue: Use explicit fill value if data should be aligned in the code section. Acked-by: Ben Dooks <ben.dooks@codethink.co.uk> Acked-by: Jon Medhurst <tixy@linaro.org> Signed-off-by: Taras Kondratiuk <taras.kondratiuk@linaro.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/kernel/kprobes-test.c2
-rw-r--r--arch/arm/kernel/kprobes-test.h2
2 files changed, 2 insertions, 2 deletions
diff --git a/arch/arm/kernel/kprobes-test.c b/arch/arm/kernel/kprobes-test.c
index 6e60a349aed9..379639998d5a 100644
--- a/arch/arm/kernel/kprobes-test.c
+++ b/arch/arm/kernel/kprobes-test.c
@@ -113,7 +113,7 @@
* @ start of inline data...
* .ascii "mov r0, r7" @ text title for test case
* .byte 0
- * .align 2
+ * .align 2, 0
*
* @ TEST_ARG_REG
* .byte ARG_TYPE_REG
diff --git a/arch/arm/kernel/kprobes-test.h b/arch/arm/kernel/kprobes-test.h
index e28a869b1ae4..eecc90a0fd91 100644
--- a/arch/arm/kernel/kprobes-test.h
+++ b/arch/arm/kernel/kprobes-test.h
@@ -115,7 +115,7 @@ struct test_arg_end {
/* multiple strings to be concatenated. */ \
".ascii "#title" \n\t" \
".byte 0 \n\t" \
- ".align 2 \n\t"
+ ".align 2, 0 \n\t"
#define TEST_ARG_REG(reg, val) \
".byte "__stringify(ARG_TYPE_REG)" \n\t" \