linux-kernel - Re: [PATCH v2 59/62] livepatch/klp-build: Introduce klp-build script for generating livepatch modules

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Message-ID: <c7bifa7n7ybhqxxwbcl7o5743gl6ezd2odx63qc3nmqwcqpxiy@64oztd4qm3um>
Date: Wed, 11 Jun 2025 12:08:52 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: Joe Lawrence <joe.lawrence@...hat.com>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, 
	Petr Mladek <pmladek@...e.com>, Miroslav Benes <mbenes@...e.cz>, live-patching@...r.kernel.org, 
	Song Liu <song@...nel.org>, laokz <laokz@...mail.com>, Jiri Kosina <jikos@...nel.org>, 
	Marcos Paulo de Souza <mpdesouza@...e.com>, Weinan Liu <wnliu@...gle.com>, 
	Fazla Mehrab <a.mehrab@...edance.com>, Chen Zhongjin <chenzhongjin@...wei.com>, 
	Puranjay Mohan <puranjay@...nel.org>
Subject: Re: [PATCH v2 59/62] livepatch/klp-build: Introduce klp-build script
 for generating livepatch modules

On Wed, Jun 11, 2025 at 02:44:35PM -0400, Joe Lawrence wrote:
> > +get_patch_files() {
> > +	local patch="$1"
> > +
> > +	grep0 -E '^(--- |\+\+\+ )' "$patch"			\
> > +		| gawk '{print $2}'				\
> 
> If we split the rest of this line on the tab character and print the
> first part of $2:
> 
>   gawk '{ split($2, a, "\t"); print a[1] }'
> 
> then it can additionally handle patches generated by `diff -Nupr` with a
> timepstamp ("--- <filepath>\t<timestamp>").

Hm?  The default gawk behavior is to treat both tabs and groups of
spaces as field separators:

  https://www.gnu.org/software/gawk/manual/html_node/Default-Field-Splitting.html

And it works for me:

  $ diff -Nupr /tmp/meminfo.c fs/proc/meminfo.c > /tmp/a.patch
  $ grep -E '^(--- |\+\+\+ )' /tmp/a.patch | gawk '{print $2}'
  /tmp/meminfo.c
  fs/proc/meminfo.c

Or did I miss something?

> > +# Refresh the patch hunk headers, specifically the line numbers and counts.
> > +refresh_patch() {
> > +	local patch="$1"
> > +	local tmpdir="$PATCH_TMP_DIR"
> > +	local files=()
> > +
> > +	rm -rf "$tmpdir"
> > +	mkdir -p "$tmpdir/a"
> > +	mkdir -p "$tmpdir/b"
> > +
> > +	# Find all source files affected by the patch
> > +	grep0 -E '^(--- |\+\+\+ )[^ /]+' "$patch"	|
> > +		sed -E 's/(--- |\+\+\+ )[^ /]+\///'	|
> > +		sort | uniq | mapfile -t files
> > +
> 
> Should just call `get_patch_files() here?

Indeed.

-- 
Josh