Commit abaf1f42 authored by Josh Poimboeuf's avatar Josh Poimboeuf
Browse files

livepatch/klp-build: Introduce fix-patch-lines script to avoid __LINE__ diff noise 



The __LINE__ macro creates challenges for binary diffing.  When a .patch
file adds or removes lines, it shifts the line numbers for all code
below it.

This can cause the code generation of functions using __LINE__ to change
due to the line number constant being embedded in a MOV instruction,
despite there being no semantic difference.

Avoid such false positives by adding a fix-patch-lines script which can
be used to insert a #line directive in each patch hunk affecting the
line numbering.  This script will be used by klp-build, which will be
introduced in a subsequent patch.

Acked-by: default avatarPetr Mladek <pmladek@suse.com>
Tested-by: default avatarJoe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
parent f2c356d1

MAINTAINERS

+1 −0
Original line number Diff line number Diff line
@@ -14443,6 +14443,7 @@ F: include/linux/livepatch*.h 
F:	kernel/livepatch/

F:	kernel/module/livepatch.c

F:	samples/livepatch/

F:	scripts/livepatch/

F:	tools/testing/selftests/livepatch/









LLC (802.2)
































scripts/livepatch/fix-patch-lines
0 → 100755



+79
−0






























Original line number
Diff line number
Diff line









#!/usr/bin/awk -f









# SPDX-License-Identifier: GPL-2.0









#









# Use #line directives to preserve original __LINE__ numbers across patches to









# avoid unwanted compilation changes.



















BEGIN {









	in_hunk = 0









	skip    = 0









}



















/^--- / {









	skip = $2 !~ /\.(c|h)$/









	print









	next









}



















/^@@/ {









	if (skip) {









		print









		next









	}



















	in_hunk = 1



















	# for @@ -1,3 +1,4 @@:









	#   1: line number in old file









	#   3: how many lines the hunk covers in old file









	#   1: line number in new file









	#   4: how many lines the hunk covers in new file



















	match($0, /^@@ -([0-9]+)(,([0-9]+))? \+([0-9]+)(,([0-9]+))? @@/, m)



















	# Set 'cur' to the old file's line number at the start of the hunk.  It









	# gets incremented for every context line and every line removal, so









	# that it always represents the old file's current line number.









	cur = m[1]



















	# last = last line number of current hunk









	last = cur + (m[3] ? m[3] : 1) - 1



















	need_line_directive = 0



















	print









	next









}



















{









	if (skip || !in_hunk || $0 ~ /^\\ No newline at end of file/) {









		print









		next









	}



















	# change line









	if ($0 ~ /^[+-]/) {









		# inject #line after this group of changes









		need_line_directive = 1



















		if ($0 ~ /^-/)









			cur++



















		print









		next









	}



















	# If this is the first context line after a group of changes, inject









	# the #line directive to force the compiler to correct the line









	# numbering to match the original file.









	if (need_line_directive) {









		print "+#line " cur









		need_line_directive = 0









	}



















	if (cur == last)









		in_hunk = 0



















	cur++









	print









}