Hi Lijiang,
On Mon, Aug 29, 2022 at 8:54 PM lijiang <lijiang@xxxxxxxxxx> wrote:
>
> On Wed, Aug 24, 2022 at 3:54 PM <crash-utility-request@xxxxxxxxxx> wrote:
>>
>> Date: Wed, 24 Aug 2022 12:10:35 +0800
>> From: Tao Liu <ltao@xxxxxxxxxx>
>> To: crash-utility@xxxxxxxxxx
>> Subject: [PATCH 2/2] x86_64: Correct the identifier
>> when locating the call instruction
>> Message-ID: <20220824041033.40559-2-ltao@xxxxxxxxxx>
>> Content-Type: text/plain; charset="US-ASCII"; x-default=true
>>
>> The previous implementation to locate the call instruction is
>> to strstr "call", then check whether the previous char is ' '
>> or '\t'. The implementation is problematic. For example it
>> cannot resolve the following disassembly string:
>>
>> "0xffffffffc06e6399 <nfs_callback_up+118>:\tcall 0xffffffff9ac8792f <printk>"
>>
>> strstr will locate the "_call" and char check fails,
>> as a result, extract_hex fail to get the calling address.
>>
>
> This looks like a potential corner bug. Did you see if it can be reproduced without the [PATCH 1/2]?
>
No, I didn't encounter the corner bug without patch1. I admit patch2
deals with a different issue to patch1, but I encountered this when
testing patch1, so I sent the 2 patches together...
Thanks,
Tao Liu
> Thanks.
> Lianbo
>
>> This patch fix the issue by strstr "\tcall" and " call", to
>> locate the correct call instruction.
>>
>> Signed-off-by: Tao Liu <ltao@xxxxxxxxxx>
>> ---
>> x86_64.c | 3 +--
>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/x86_64.c b/x86_64.c
>> index dfada48..74bd1bb 100644
>> --- a/x86_64.c
>> +++ b/x86_64.c
>> @@ -4432,8 +4432,7 @@ x86_64_function_called_by(ulong rip)
>> if (gdb_pass_through(buf, pc->tmpfile2, GNU_RETURN_ON_ERROR)) {
>> rewind(pc->tmpfile2);
>> while (fgets(buf, BUFSIZE, pc->tmpfile2)) {
>> - if ((p1 = strstr(buf, "call")) &&
>> - whitespace(*(p1-1))) {
>> + if ((p1 = strstr(buf, " call")) || (p1 = strstr(buf, "\tcall"))) {
>>
>> if (extract_hex(p1, &value, NULLCHAR, TRUE))
>> break;
>> }
>> --
>> 2.33.1
--
Crash-utility mailing list
Crash-utility@xxxxxxxxxx
https://listman.redhat.com/mailman/listinfo/crash-utility
Contribution Guidelines: https://github.com/crash-utility/crash/wiki
