生成常量数据的％pc相对地址

%pc

%pc

const char * filename(void)
{
    static const char _filename[]
            __attribute__((section(".text")))
            = "logfile";
    return _filename;
}

arm-elf-gcc-4.3.2 -nostdlib -c
-O3 -W -Wall logfile.c

00000000 <filename>:
   0:   e59f0000        ldr     r0, [pc, #0]    ; 8 <filename+0x8>
   4:   e12fff1e        bx      lr
   8:   0000000c        .word   0x0000000c

0000000c <_filename.1175>:
   c:   66676f6c        .word   0x66676f6c
  10:   00656c69        .word   0x00656c69

filename:
    add r0, pc, #0
    bx lr
_filename.1175:
    .ascii "logfile00"

%pc

-fPIC

static intptr_t
__attribute__((noinline))
find_offset( void )
{
    uintptr_t pc;
    asm __volatile__ (
            "mov %0, %%pc" : "=&r"(pc)
    );

    return pc - 8 - (uintptr_t) find_offset;
}

filename()

const char * filename(void)
{
    static const char _filename[]
            __attribute__((section(".text")))
            = "logfile";
    return _filename + find_offset();
}