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

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>

diff --git a/arch/arm/kernel/kprobes-test.c b/arch/arm/kernel/kprobes-test.c
index 08d7312..b206d77 100644 (file)
--- a/arch/arm/kernel/kprobes-test.c
+++ b/arch/arm/kernel/kprobes-test.c
@@ -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;
 

diff --git a/arch/arm/kernel/kprobes-test.h b/arch/arm/kernel/kprobes-test.h
index eecc90a..4430990 100644 (file)
--- a/arch/arm/kernel/kprobes-test.h
+++ b/arch/arm/kernel/kprobes-test.h
@@ -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"   \