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MIPS: Tracing: Fix 32-bit support with -mmcount-ra-address 

For 32-bit kernel the -mmcount-ra-address option of gcc 4.5 emits one
extra instruction before calling to _mcount so we need to use a different
"b 1f" for it.

Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: linux-mips <linux-mips@linux-mips.org>
Cc: David Daney <david.s.daney@gmail.com>
Patchwork: http://patchwork.linux-mips.org/patch/1228/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Wu Zhangjin 2010-05-14 19:08:30 +08:00 committed by Ralf Baechle
parent 56b49cd35f
commit 3a2af2dc1b
1 changed files with 14 additions and 2 deletions
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16
arch/mips/kernel/ftrace.c
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@ -62,14 +62,26 @@ int ftrace_make_nop(struct module *mod,
return -EFAULT;
}
#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT)
/* lui v1, hi_16bit_of_mcount --> b 1f (0x10000005)
* addiu v1, v1, low_16bit_of_mcount
* move at, ra
* move $12, ra_address
* jalr v1
* sub sp, sp, 8
* 1: offset = 5 instructions
*/
new = 0x10000005;
#else
/* lui v1, hi_16bit_of_mcount --> b 1f (0x10000004)
* addiu v1, v1, low_16bit_of_mcount
* move at, ra
* jalr v1
* nop
* 1f: (ip + 12)
* nop | move $12, ra_address | sub sp, sp, 8
* 1: offset = 4 instructions
*/
new = 0x10000004;
#endif
} else {
/* record/calculate it for ftrace_make_call */
if (jal_mcount == 0) {