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 <[email protected]>
---
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
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
-----?ʼ?ԭ??-----
??????: Chen Jun [mailto:[email protected]]
????ʱ??: 2021??2??22?? 21:59
?ռ???: [email protected]
????: [email protected]; [email protected]; [email protected]; Xiangrui (Euler) <[email protected]>
????: [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 <[email protected]>
---
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
On Mon, 22 Feb 2021 15:50:19 +0000
"chenjun (AM)" <[email protected]> wrote:
> 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.
But you are still saying that this patch needs to be applied, right?
-- Steve
$B:_(B 2021/2/24 6:26, Steven Rostedt $B<LF;(B:
> On Mon, 22 Feb 2021 15:50:19 +0000
> "chenjun (AM)" <[email protected]> wrote:
>
>> Hi
>>
>> There is no problem when I use aarch64_be(gcc v10.2). Because gcc v10.2 use __patchable_function_entries
>> instead of __mcount. I am not sure when the change happened.
>
> But you are still saying that this patch needs to be applied, right?
>
> -- Steve
> .
>
Yes$B!$(Bthis patch needs to be applied.
--
Regards
Chen Jun