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ARM: 8179/1: kprobes-test: Fix compile error "bad immediate value for offset"

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When compiling kprobes-test-arm.c the following error has been observed

/tmp/ccoT403o.s:21439: Error: bad immediate value for offset (4168)

This is caused by the compiler spilling it's literal pool too far away
from the site which is trying to reference it with a PC relative load.
This arises because the compiler is underestimating the size of the
inline assembler code present, which apparently it approximates as 4
bytes per line or instruction.

We fix this problem by moving the operations which generate more than
4 bytes out of the text section. Specifically, moving the .ascii
directives to the .rodata section.

Signed-off-by: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Jon Medhurst 2014-09-30 10:25:10 +01:00 committed by Russell King
parent 9cc6d9e5da
commit ad684dce87
2 changed files with 13 additions and 8 deletions
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16
arch/arm/kernel/kprobes-test.c
View File

@ -110,10 +110,13 @@
*
* @ TESTCASE_START
* bl __kprobes_test_case_start
* @ start of inline data...
* .pushsection .rodata
* "10:
* .ascii "mov r0, r7" @ text title for test case
* .byte 0
* .align 2, 0
* .popsection
* @ start of inline data...
* .word 10b @ pointer to title in .rodata section
*
* @ TEST_ARG_REG
* .byte ARG_TYPE_REG
@ -971,7 +974,7 @@ void __naked __kprobes_test_case_start(void)
__asm__ __volatile__ (
"stmdb sp!, {r4-r11} \n\t"
"sub sp, sp, #"__stringify(TEST_MEMORY_SIZE)"\n\t"
"bic r0, lr, #1 @ r0 = inline title string \n\t"
"bic r0, lr, #1 @ r0 = inline data \n\t"
"mov r1, sp \n\t"
"bl kprobes_test_case_start \n\t"
"bx r0 \n\t"
@ -1349,15 +1352,14 @@ static unsigned long next_instruction(unsigned long pc)
return pc + 4;
}
static uintptr_t __used kprobes_test_case_start(const char *title, void *stack)
static uintptr_t __used kprobes_test_case_start(const char **title, void *stack)
{
struct test_arg *args;
struct test_arg_end *end_arg;
unsigned long test_code;
args = (struct test_arg *)PTR_ALIGN(title + strlen(title) + 1, 4);
current_title = title;
current_title = *title++;
args = (struct test_arg *)title;
current_args = args;
current_stack = stack;

5
arch/arm/kernel/kprobes-test.h
View File

@ -111,11 +111,14 @@ struct test_arg_end {
#define TESTCASE_START(title) \
__asm__ __volatile__ ( \
"bl __kprobes_test_case_start \n\t" \
".pushsection .rodata \n\t" \
"10: \n\t" \
/* don't use .asciz here as 'title' may be */ \
/* multiple strings to be concatenated. */ \
".ascii "#title" \n\t" \
".byte 0 \n\t" \
".align 2, 0 \n\t"
".popsection \n\t" \
".word 10b \n\t"
#define TEST_ARG_REG(reg, val) \
".byte "__stringify(ARG_TYPE_REG)" \n\t" \