On Wed, 27 Oct 2010, wu zhangjin wrote:
> will this help?
>
> typedef struct {
> Elf64_Addr r_offset; /* Address */
> union {
> struct {
> Elf64_Word r_sym;
> myElf64_byte r_ssym; /* Special sym:
> gp-relative, etc. */
> myElf64_byte r_type3;
> myElf64_byte r_type2;
> myElf64_byte r_type;
> } r_info;
> Elf64_Xword gABI_r_info;
> };
> Elf64_Sxword r_addend; /* Addend */
> } MIPS64_Rela;
More or less, although you need to give your union a name to access its
members. ;) It may be simpler to refer to r_info only, e.g. something
along these lines:
typedef uint8_t myElf64_Byte;
union mips_r_info {
Elf64_Xword r_info;
struct {
Elf64_Word r_sym;
myElf64_Byte r_ssym;
myElf64_Byte r_type3;
myElf64_Byte r_type2;
myElf64_Byte r_type;
} r_mips;
};
static uint64_t MIPS64_r_sym(Elf64_Rel const *rp)
{
return w(((union mips_r_info){ .r_info = rp->r_info }).r_mips.r_sym);
}
static void MIPS64_r_info(Elf64_Rel *const rp,
unsigned int sym, unsigned int type)
{
rp->r_info = ((union mips_r_info){
.r_mips = { .r_sym = w(sym), .r_type = type }
}).r_info;
}
Untested, but GCC 4.1.2 seems to turn it into decent big-endian code:
tmp.o: file format elf64-tradbigmips
Disassembly of section .text:
0000000000000000 <MIPS64_r_sym>:
0: 03e00008 jr ra
4: 9c820008 lwu v0,8(a0)
0000000000000008 <MIPS64_r_info>:
8: 30c600ff andi a2,a2,0xff
c: 0005283c dsll32 a1,a1,0x0
10: 00a62825 or a1,a1,a2
14: 03e00008 jr ra
18: fc850008 sd a1,8(a0)
and not so decent little-endian code (too many shifts):
tmpel.o: file format elf64-tradlittlemips
Disassembly of section .text:
0000000000000000 <MIPS64_r_sym>:
0: dc820008 ld v0,8(a0)
4: 00021000 sll v0,v0,0x0
8: 0002103c dsll32 v0,v0,0x0
c: 03e00008 jr ra
10: 0002103e dsrl32 v0,v0,0x0
0000000000000018 <MIPS64_r_info>:
18: 0005283c dsll32 a1,a1,0x0
1c: 0006363c dsll32 a2,a2,0x18
20: 0005283e dsrl32 a1,a1,0x0
24: 00a62825 or a1,a1,a2
28: 03e00008 jr ra
2c: fc850008 sd a1,8(a0)
GCC may have been fixed/improved since though (I'd expect so, but didn't
have the resources to upgrade yet, so check yourself).
Here's my sign-off mark if you'd like to use the code above.
Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxxxxx>
Maciej
