The patch titled
Subject: kcov: remove stale RANDOMIZE_BASE text
has been added to the -mm mm-nonmm-unstable branch. Its filename is
kcov-remove-stale-randomize_base-text.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kcov-remove-stale-randomize_base-text.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Mark Rutland <mark.rutland@xxxxxxx>
Subject: kcov: remove stale RANDOMIZE_BASE text
Date: Mon, 4 Dec 2023 17:18:07 +0000
The Kconfig help text for CONFIG_KCOV describes that recorded PC values
will not be stable across machines or reboots when RANDOMIZE_BASE is
selected. This was the case when KCOV was introduced in commit:
5c9a8750a6409c63 ("kernel: add kcov code coverage")
However, this changed in commit:
4983f0ab7ffaad1e ("kcov: make kcov work properly with KASLR enabled")
Since that commit KCOV always subtracts the KASLR offset from PC values,
which ensures that these are stable across machines and across reboots
even when RANDOMIZE_BASE is selected.
Unfortunately, that commit failed to update the Kconfig help text, which
still suggests disabling RANDOMIZE_BASE even though this is no longer
necessary.
Remove the stale Kconfig text.
Link: https://lkml.kernel.org/r/20231204171807.3313022-1-mark.rutland@xxxxxxx
Reported-by: Borislav Petkov <bp@xxxxxxxxx>
Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
Reviewed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Alexander Popov <alex.popov@xxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/Kconfig.debug | 4 ----
1 file changed, 4 deletions(-)
--- a/lib/Kconfig.debug~kcov-remove-stale-randomize_base-text
+++ a/lib/Kconfig.debug
@@ -2103,10 +2103,6 @@ config KCOV
KCOV exposes kernel code coverage information in a form suitable
for coverage-guided fuzzing (randomized testing).
- If RANDOMIZE_BASE is enabled, PC values will not be stable across
- different machines and across reboots. If you need stable PC values,
- disable RANDOMIZE_BASE.
-
For more details, see Documentation/dev-tools/kcov.rst.
config KCOV_ENABLE_COMPARISONS
_
Patches currently in -mm which might be from mark.rutland@xxxxxxx are
kcov-remove-stale-randomize_base-text.patch
