Re: [Crash-utility] [PATCH 2/2] x86_64: Correct the identifier when locating the call instruction

On Wed, Aug 24, 2022 at 3:54 PM <crash-utility-request(a)redhat.com&gt; wrote: > > Date: Wed, 24 Aug 2022 12:10:35 +0800 > From: Tao Liu <ltao(a)redhat.com&gt; > To: crash-utility(a)redhat.com > Subject: [Crash-utility] [PATCH 2/2] x86_64: Correct the identifier > when locating the call instruction > Message-ID: <20220824041033.40559-2-ltao(a)redhat.com&gt; > 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]?

Thanks. Lianbo > This patch fix the issue by strstr "\tcall" and " call", to > locate the correct call instruction. > > Signed-off-by: Tao Liu <ltao(a)redhat.com&gt; > --- > 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