tjh.dev / kernel
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
1
fork

Configure Feed

Select the types of activity you want to include in your feed.

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: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

Josh Poimboeuf abaf1f42 f2c356d1

+80
+1
MAINTAINERS
··· 14443 14443 F: kernel/livepatch/ 14444 14444 F: kernel/module/livepatch.c 14445 14445 F: samples/livepatch/ 14446 + F: scripts/livepatch/ 14446 14447 F: tools/testing/selftests/livepatch/ 14447 14448 14448 14449 LLC (802.2)
+79
scripts/livepatch/fix-patch-lines
··· 1 + #!/usr/bin/awk -f 2 + # SPDX-License-Identifier: GPL-2.0 3 + # 4 + # Use #line directives to preserve original __LINE__ numbers across patches to 5 + # avoid unwanted compilation changes. 6 + 7 + BEGIN { 8 + in_hunk = 0 9 + skip = 0 10 + } 11 + 12 + /^--- / { 13 + skip = $2 !~ /\.(c|h)$/ 14 + print 15 + next 16 + } 17 + 18 + /^@@/ { 19 + if (skip) { 20 + print 21 + next 22 + } 23 + 24 + in_hunk = 1 25 + 26 + # for @@ -1,3 +1,4 @@: 27 + # 1: line number in old file 28 + # 3: how many lines the hunk covers in old file 29 + # 1: line number in new file 30 + # 4: how many lines the hunk covers in new file 31 + 32 + match($0, /^@@ -([0-9]+)(,([0-9]+))? \+([0-9]+)(,([0-9]+))? @@/, m) 33 + 34 + # Set 'cur' to the old file's line number at the start of the hunk. It 35 + # gets incremented for every context line and every line removal, so 36 + # that it always represents the old file's current line number. 37 + cur = m[1] 38 + 39 + # last = last line number of current hunk 40 + last = cur + (m[3] ? m[3] : 1) - 1 41 + 42 + need_line_directive = 0 43 + 44 + print 45 + next 46 + } 47 + 48 + { 49 + if (skip || !in_hunk || $0 ~ /^\\ No newline at end of file/) { 50 + print 51 + next 52 + } 53 + 54 + # change line 55 + if ($0 ~ /^[+-]/) { 56 + # inject #line after this group of changes 57 + need_line_directive = 1 58 + 59 + if ($0 ~ /^-/) 60 + cur++ 61 + 62 + print 63 + next 64 + } 65 + 66 + # If this is the first context line after a group of changes, inject 67 + # the #line directive to force the compiler to correct the line 68 + # numbering to match the original file. 69 + if (need_line_directive) { 70 + print "+#line " cur 71 + need_line_directive = 0 72 + } 73 + 74 + if (cur == last) 75 + in_hunk = 0 76 + 77 + cur++ 78 + print 79 + }