* [PATCH v3] scripts: Create objdump-func helper script
@ 2022-04-20 17:16 Josh Poimboeuf
2022-04-20 18:35 ` Borislav Petkov
2022-04-21 8:52 ` Peter Zijlstra
0 siblings, 2 replies; 5+ messages in thread
From: Josh Poimboeuf @ 2022-04-20 17:16 UTC (permalink / raw)
To: Peter Zijlstra; +Cc: linux-kernel, x86, Miroslav Benes, Borislav Petkov
Add a simple script which disassembles a single function from an object
file. Comes in handy for objtool warnings and kernel stack traces.
Originally-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
v3:
- Add usage
- Fix vmlinux
scripts/objdump-func | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
create mode 100755 scripts/objdump-func
diff --git a/scripts/objdump-func b/scripts/objdump-func
new file mode 100755
index 000000000000..0908f9f616c3
--- /dev/null
+++ b/scripts/objdump-func
@@ -0,0 +1,25 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Disassemble a single function.
+#
+# usage: objdump-func <file> <func>
+
+set -o errexit
+set -o nounset
+
+OBJDUMP="${CROSS_COMPILE:-}objdump"
+
+command -v gawk >/dev/null 2>&1 || die "gawk isn't installed"
+
+usage() {
+ echo "usage: objdump-func <file> <func>" >&2
+ exit 1
+}
+
+[[ $# -ne 2 ]] && usage
+
+OBJ=$1; shift
+FUNC=$1; shift
+
+${OBJDUMP} -wdr $OBJ | gawk -M -v f=$FUNC '/^$/ { P=0; } $0 ~ "<" f ">:" { P=1; O=strtonum("0x" $1); } { if (P) { o=strtonum("0x" $1); printf("%04x ", o-O); print $0; } }'
--
2.34.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v3] scripts: Create objdump-func helper script
2022-04-20 17:16 [PATCH v3] scripts: Create objdump-func helper script Josh Poimboeuf
@ 2022-04-20 18:35 ` Borislav Petkov
2022-04-21 8:52 ` Peter Zijlstra
1 sibling, 0 replies; 5+ messages in thread
From: Borislav Petkov @ 2022-04-20 18:35 UTC (permalink / raw)
To: Josh Poimboeuf; +Cc: Peter Zijlstra, linux-kernel, x86, Miroslav Benes
On Wed, Apr 20, 2022 at 10:16:36AM -0700, Josh Poimboeuf wrote:
> Add a simple script which disassembles a single function from an object
> file. Comes in handy for objtool warnings and kernel stack traces.
>
> Originally-by: Peter Zijlstra <peterz@infradead.org>
> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> ---
> v3:
> - Add usage
Thanks!
Acked-by: Borislav Petkov <bp@suse.de>
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v3] scripts: Create objdump-func helper script
2022-04-20 17:16 [PATCH v3] scripts: Create objdump-func helper script Josh Poimboeuf
2022-04-20 18:35 ` Borislav Petkov
@ 2022-04-21 8:52 ` Peter Zijlstra
2022-04-21 17:37 ` Josh Poimboeuf
1 sibling, 1 reply; 5+ messages in thread
From: Peter Zijlstra @ 2022-04-21 8:52 UTC (permalink / raw)
To: Josh Poimboeuf; +Cc: linux-kernel, x86, Miroslav Benes, Borislav Petkov
On Wed, Apr 20, 2022 at 10:16:36AM -0700, Josh Poimboeuf wrote:
> +${OBJDUMP} -wdr $OBJ | gawk -M -v f=$FUNC '/^$/ { P=0; } $0 ~ "<" f ">:" { P=1; O=strtonum("0x" $1); } { if (P) { o=strtonum("0x" $1); printf("%04x ", o-O); print $0; } }'
Two noteworthy changes:
- $@ went missing, I've occasionally abused that to add extra argument
to objdump.
- you removed the glob after FUNC, I had that so that .cold and
.constprop etc.. variants of the function also show up.
I don't suppose either one are super important, but esp. that latter one
has been convenient.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v3] scripts: Create objdump-func helper script
2022-04-21 8:52 ` Peter Zijlstra
@ 2022-04-21 17:37 ` Josh Poimboeuf
2022-04-21 20:39 ` Peter Zijlstra
0 siblings, 1 reply; 5+ messages in thread
From: Josh Poimboeuf @ 2022-04-21 17:37 UTC (permalink / raw)
To: Peter Zijlstra; +Cc: linux-kernel, x86, Miroslav Benes, Borislav Petkov
On Thu, Apr 21, 2022 at 10:52:44AM +0200, Peter Zijlstra wrote:
> On Wed, Apr 20, 2022 at 10:16:36AM -0700, Josh Poimboeuf wrote:
>
> > +${OBJDUMP} -wdr $OBJ | gawk -M -v f=$FUNC '/^$/ { P=0; } $0 ~ "<" f ">:" { P=1; O=strtonum("0x" $1); } { if (P) { o=strtonum("0x" $1); printf("%04x ", o-O); print $0; } }'
>
> Two noteworthy changes:
>
> - $@ went missing, I've occasionally abused that to add extra argument
> to objdump.
Just to clarify, you'd add the extra arg at the end like this, right?
objdump-func <file> <func> -Mintel
> - you removed the glob after FUNC, I had that so that .cold and
> .constprop etc.. variants of the function also show up.
Sure, I'll match ".whatever" if there's a period, but not other
substring matches, e.g. "put_page" shouldn't match "put_pages_list".
{OBJDUMP} -wdr $@ $OBJ | gawk -M -v f=$FUNC '/^$/ { P=0; } $0 ~ "<" f "(\\..*)?>:" { P=1; O=strtonum("0x" $1); } { if (P) { o=strtonum("0x" $1); printf("%04x ", o-O); print $0; } }'
--
Josh
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v3] scripts: Create objdump-func helper script
2022-04-21 17:37 ` Josh Poimboeuf
@ 2022-04-21 20:39 ` Peter Zijlstra
0 siblings, 0 replies; 5+ messages in thread
From: Peter Zijlstra @ 2022-04-21 20:39 UTC (permalink / raw)
To: Josh Poimboeuf; +Cc: linux-kernel, x86, Miroslav Benes, Borislav Petkov
On Thu, Apr 21, 2022 at 10:37:59AM -0700, Josh Poimboeuf wrote:
> On Thu, Apr 21, 2022 at 10:52:44AM +0200, Peter Zijlstra wrote:
> > On Wed, Apr 20, 2022 at 10:16:36AM -0700, Josh Poimboeuf wrote:
> >
> > > +${OBJDUMP} -wdr $OBJ | gawk -M -v f=$FUNC '/^$/ { P=0; } $0 ~ "<" f ">:" { P=1; O=strtonum("0x" $1); } { if (P) { o=strtonum("0x" $1); printf("%04x ", o-O); print $0; } }'
> >
> > Two noteworthy changes:
> >
> > - $@ went missing, I've occasionally abused that to add extra argument
> > to objdump.
>
> Just to clarify, you'd add the extra arg at the end like this, right?
>
> objdump-func <file> <func> -Mintel
Yeah, highly awkward, but it worked ;-)
> > - you removed the glob after FUNC, I had that so that .cold and
> > .constprop etc.. variants of the function also show up.
>
> Sure, I'll match ".whatever" if there's a period, but not other
> substring matches, e.g. "put_page" shouldn't match "put_pages_list".
>
> {OBJDUMP} -wdr $@ $OBJ | gawk -M -v f=$FUNC '/^$/ { P=0; } $0 ~ "<" f "(\\..*)?>:" { P=1; O=strtonum("0x" $1); } { if (P) { o=strtonum("0x" $1); printf("%04x ", o-O); print $0; } }'
Ah, good thinking requiring that '.' in there. I just ignored the extra
gunk on the very rare occasion I got it.
^ permalink raw reply [flat|nested] 5+ messages in thread
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2022-04-20 17:16 [PATCH v3] scripts: Create objdump-func helper script Josh Poimboeuf
2022-04-20 18:35 ` Borislav Petkov
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2022-04-21 17:37 ` Josh Poimboeuf
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