Hi There is no problem when I use aarch64_be(gcc v10.2). Because gcc v10.2 use __patchable_function_entries instead of __mcount. I am not sure when the change happened.
Regards, Chen Jun -----邮件原件----- 发件人: Chen Jun [mailto:chenjun...@huawei.com] 发送时间: 2021年2月22日 21:59 收件人: linux-kernel@vger.kernel.org 抄送: gregory.herr...@oracle.com; catalin.mari...@arm.com; rost...@goodmis.org; Xiangrui (Euler) <rui.xi...@huawei.com> 主题: [PATCH] recordmcount: use w8 to read relp->r_info in arm64_is_fake_mcount On little endian system, Use aarch64_be(gcc v7.3) downloaded from linaro.org to build image with CONFIG_CPU_BIG_ENDIAN = y, CONFIG_FTRACE = y, CONFIG_DYNAMIC_FTRACE = y. gcc will create symbols of _mcount but recordmcount can not create mcount_loc for *.o. aarch64_be-linux-gnu-objdump -r fs/namei.o | grep mcount 00000000000000d0 R_AARCH64_CALL26 _mcount ... 0000000000007190 R_AARCH64_CALL26 _mcount The reason is than funciton arm64_is_fake_mcount can not work correctly. A symbol of _mcount in *.o compiled with big endian compiler likes: 00 00 00 2d 00 00 01 1b w(rp->r_info) will return 0x2d instead of 0x011b. Because w() takes uint32_t as parameter, which truncates rp->r_info. Use w8() instead w() to read relp->r_info Fixes: ea0eada45632 ("recordmcount: only record relocation of type R_AARCH64_CALL26 on arm64.") Signed-off-by: Chen Jun <chenjun...@huawei.com> --- scripts/recordmcount.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c index b9c2ee7ab43f..cce12e1971d8 100644 --- a/scripts/recordmcount.c +++ b/scripts/recordmcount.c @@ -438,7 +438,7 @@ static int arm_is_fake_mcount(Elf32_Rel const *rp) static int arm64_is_fake_mcount(Elf64_Rel const *rp) { - return ELF64_R_TYPE(w(rp->r_info)) != R_AARCH64_CALL26; + return ELF64_R_TYPE(w8(rp->r_info)) != R_AARCH64_CALL26; } /* 64-bit EM_MIPS has weird ELF64_Rela.r_info. -- 2.25.0
