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Message-ID: <87bkajlphj.fsf@mail.lhotse>
Date: Thu, 21 Dec 2023 23:16:56 +1100
From: Michael Ellerman <mpe@...erman.id.au>
To: Christophe Leroy <christophe.leroy@...roup.eu>, Nicholas Piggin
<npiggin@...il.com>, Arnd Bergmann <arnd@...db.de>, Luis Chamberlain
<mcgrof@...nel.org>
Cc: Christophe Leroy <christophe.leroy@...roup.eu>,
linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-modules@...r.kernel.org, Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH 1/3] init: Declare rodata_enabled and mark_rodata_ro()
at all time
Cc +Kees
Christophe Leroy <christophe.leroy@...roup.eu> writes:
> Declaring rodata_enabled and mark_rodata_ro() at all time
> helps removing related #ifdefery in C files.
>
> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
> ---
> include/linux/init.h | 4 ----
> init/main.c | 21 +++++++--------------
> 2 files changed, 7 insertions(+), 18 deletions(-)
>
> diff --git a/include/linux/init.h b/include/linux/init.h
> index 01b52c9c7526..d2b47be38a07 100644
> --- a/include/linux/init.h
> +++ b/include/linux/init.h
> @@ -168,12 +168,8 @@ extern initcall_entry_t __initcall_end[];
>
> extern struct file_system_type rootfs_fs_type;
>
> -#if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX)
> extern bool rodata_enabled;
> -#endif
> -#ifdef CONFIG_STRICT_KERNEL_RWX
> void mark_rodata_ro(void);
> -#endif
>
> extern void (*late_time_init)(void);
>
> diff --git a/init/main.c b/init/main.c
> index e24b0780fdff..807df08c501f 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -1396,10 +1396,9 @@ static int __init set_debug_rodata(char *str)
> early_param("rodata", set_debug_rodata);
> #endif
>
> -#ifdef CONFIG_STRICT_KERNEL_RWX
> static void mark_readonly(void)
> {
> - if (rodata_enabled) {
> + if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX) && rodata_enabled) {
> /*
> * load_module() results in W+X mappings, which are cleaned
> * up with call_rcu(). Let's make sure that queued work is
> @@ -1409,20 +1408,14 @@ static void mark_readonly(void)
> rcu_barrier();
> mark_rodata_ro();
> rodata_test();
> - } else
> + } else if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)) {
> pr_info("Kernel memory protection disabled.\n");
> + } else if (IS_ENABLED(CONFIG_ARCH_HAS_STRICT_KERNEL_RWX)) {
> + pr_warn("Kernel memory protection not selected by kernel config.\n");
> + } else {
> + pr_warn("This architecture does not have kernel memory protection.\n");
> + }
> }
> -#elif defined(CONFIG_ARCH_HAS_STRICT_KERNEL_RWX)
> -static inline void mark_readonly(void)
> -{
> - pr_warn("Kernel memory protection not selected by kernel config.\n");
> -}
> -#else
> -static inline void mark_readonly(void)
> -{
> - pr_warn("This architecture does not have kernel memory protection.\n");
> -}
> -#endif
>
> void __weak free_initmem(void)
> {
> --
> 2.41.0
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