Josh Poimboeuf c485c94c0b x86/retpoline: Make sure there are no unconverted return thunks due to KCSAN ... [ Upstream commit 2d7ce49f58 ] Enabling CONFIG_KCSAN leads to unconverted, default return thunks to remain after patching. As David Kaplan describes in his debugging of the issue, it is caused by a couple of KCSAN-generated constructors which aren't processed by objtool: "When KCSAN is enabled, GCC generates lots of constructor functions named _sub_I_00099_0 which call __tsan_init and then return. The returns in these are generally annotated normally by objtool and fixed up at runtime. But objtool runs on vmlinux.o and vmlinux.o does not include a couple of object files that are in vmlinux, like init/version-timestamp.o and .vmlinux.export.o, both of which contain _sub_I_00099_0 functions. As a result, the returns in these functions are not annotated, and the panic occurs when we call one of them in do_ctors and it uses the default return thunk. This difference can be seen by counting the number of these functions in the object files: $ objdump -d vmlinux.o|grep -c "<_sub_I_00099_0>:" 2601 $ objdump -d vmlinux|grep -c "<_sub_I_00099_0>:" 2603 If these functions are only run during kernel boot, there is no speculation concern." Fix it by disabling KCSAN on version-timestamp.o and .vmlinux.export.o so the extra functions don't get generated. KASAN and GCOV are already disabled for those files. [ bp: Massage commit message. ] Closes: https://lore.kernel.org/lkml/20231016214810.GA3942238@dev-arch.thelio-3990X/ Reported-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Acked-by: Marco Elver <elver@google.com> Tested-by: Nathan Chancellor <nathan@kernel.org> Link: https://lore.kernel.org/r/20231017165946.v4i2d4exyqwqq3bx@treble Signed-off-by: Sasha Levin <sashal@kernel.org>		2023-11-28 17:14:40 +00:00
..
.gitignore	kbuild: build init/built-in.a just once	2022-09-29 04:40:15 +09:00
build-version	kbuild: build init/built-in.a just once	2022-09-29 04:40:15 +09:00
calibrate.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
do_mounts_initrd.c	init: pass root_device_name explicitly	2023-06-05 10:55:20 -06:00
do_mounts_rd.c	init: add an init_unlink helper	2020-07-31 08:17:52 +02:00
do_mounts.c	- Arnd Bergmann has fixed a bunch of -Wmissing-prototypes in	2023-06-28 10:59:38 -07:00
do_mounts.h	init: pass root_device_name explicitly	2023-06-05 10:55:20 -06:00
init_task.c	rcu-tasks: Add data structures for lightweight grace periods	2022-06-20 09:22:28 -07:00
initramfs.c	init/initramfs: Fix argument forwarding to panic() in panic_show_mem()	2023-04-16 17:37:01 +09:00
Kconfig	sched/psi: Select KERNFS as needed	2023-09-13 09:52:59 +02:00
main.c	- Arnd Bergmann has fixed a bunch of -Wmissing-prototypes in	2023-06-28 10:59:38 -07:00
Makefile	x86/retpoline: Make sure there are no unconverted return thunks due to KCSAN	2023-11-28 17:14:40 +00:00
noinitramfs.c	init: move usermodehelper_enable() to populate_rootfs()	2021-09-08 11:50:27 -07:00
version-timestamp.c	init/version-timestamp.c: remove unneeded #include <linux/version.h>	2023-01-09 07:34:38 +09:00
version.c	init/version.c: remove #include <generated/utsrelease.h>	2022-12-10 10:33:20 +09:00