From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <jan@vrany.io>
Received: from mail-4323.proton.ch (mail-4323.proton.ch [185.70.43.23])
 by sourceware.org (Postfix) with ESMTPS id D0A0A385803E
 for <gdb@sourceware.org>; Fri, 29 Apr 2022 13:10:39 +0000 (GMT)
DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org D0A0A385803E
Date: Fri, 29 Apr 2022 13:10:31 +0000
To: Simon Marchi <simark@simark.ca>, GDB mailing list <gdb@sourceware.org>
From: Jan Vrany <jan@vrany.io>
Reply-To: Jan Vrany <jan@vrany.io>
Subject: Re: Hand-written assembly and Python API
Message-ID: <bcfcef52f22cde038ddc1e2bbab4a090693fa591.camel@vrany.io>
In-Reply-To: <daed9d7d-8957-e5ad-ab10-fd615a6ef4f6@simark.ca>
References: <5dce3fb2110facb58974d1ee546c43b6db20b6f4.camel@vrany.io>
 <daed9d7d-8957-e5ad-ab10-fd615a6ef4f6@simark.ca>
Feedback-ID: 40767693:user:proton
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
X-Spam-Status: No, score=-2.8 required=5.0 tests=BAYES_00, DKIM_SIGNED,
 DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, SPF_HELO_NONE, SPF_PASS,
 TXREP autolearn=ham autolearn_force=no version=3.4.4
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on
 server2.sourceware.org
X-BeenThere: gdb@sourceware.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Gdb mailing list <gdb.sourceware.org>
List-Unsubscribe: <https://sourceware.org/mailman/options/gdb>,
 <mailto:gdb-request@sourceware.org?subject=unsubscribe>
List-Archive: <https://sourceware.org/pipermail/gdb/>
List-Post: <mailto:gdb@sourceware.org>
List-Help: <mailto:gdb-request@sourceware.org?subject=help>
List-Subscribe: <https://sourceware.org/mailman/listinfo/gdb>,
 <mailto:gdb-request@sourceware.org?subject=subscribe>
X-List-Received-Date: Fri, 29 Apr 2022 13:10:42 -0000

On Fri, 2022-04-29 at 08:54 -0400, Simon Marchi wrote:
> On 2022-04-29 08:32, Jan Vrany via Gdb wrote:
> > Hi folks,
> >
> > I'm trying to debug a code that uses a handful of
> > hand-written assembly routines. For example, one of
> > them looks like (its RISC-V but that does not matter):
> >
> >     .text
> >     .globl returnFromJIT1
> >     .type returnFromJIT1,function
> >     .align 2
> > returnFromJIT1:
> >     .cfi_startproc
> >     sd a0,248(s10)
> >     sd s11,32(s10)
> >     li a0, 17
> >     li a1, 1
> >     j cInterpreterFromJIT
> >     .cfi_endproc
> >     .size   returnFromJIT1, .-returnFromJIT1
> >
> >    .text
> >    .globl ...
> >
> > GDB clealy knows "something" about the assembly routines, it shows
> > the source properly and 'info symbol' works too:
> >
> >    (gdb) info symbol 0x3ff75eca24
> >    returnFromJIT1 in section .text of /opt/riscv/sysroot/tmp/jdk/lib/de=
fault/libj9jit29.so
> >
> > The problem is how to figure out I'm in (say) `returnFromJIT1` routine
> > using Python API:
> >
> >    (gdb) py print(gdb.block_for_pc(0x3ff75eca24).function)
> >    None
> >
> > The only way I can think of is to parse value of `gdb.format_address()`=
:
> >
> >    (gdb) py print(gdb.format_address(0x3ff75eca24))
> >    0x3ff75eca24 <returnFromJIT1>
> >
> > which is bit awkward (but doable!).
> >
> > Question is: is there a better way? I can modify the assembly source
> > too if there's some directive that may help GDB (.cfi_startproc / .cfi_=
endproc
> > is clearly not enough). Or do I have to roll up sleeves and implement p=
ython
> > API for minimal symbols?
>
> I was going to say "returnFromJIT1" is a minimal symbol, but you clearly
> know that already.  There is DWARF debug info for assembly when building
> with -g (at least when building with gcc / gas), but it only contains
> line statements, which allows GDB to show where you are in the source
> file (instead of showing disassembly).  You won't be able to look up a
> block from that.
>
> I don't know of a way to do it with the current API, unfortunately.
>
> Simon

Thanks!=C2=A0
I was secretly hoping you might know some trick I'm not aware of...

Jan