linux-kernel - Re: [PATCH v2 1/1] mseal: remove can_do

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Message-ID: <607a69bb-9b6f-4d0e-83aa-1ec6903c34a5@lucifer.local>
Date: Fri, 6 Dec 2024 19:56:54 +0000
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: jeffxu@...omium.org
Cc: akpm@...ux-foundation.org, vbabka@...e.cz, Liam.Howlett@...cle.com,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org,
        linux-mm@...ck.org, jorgelo@...omium.org, keescook@...omium.org,
        pedro.falcato@...il.com, rdunlap@...radead.org
Subject: Re: [PATCH v2 1/1] mseal: remove can_do_mseal()

On Fri, Dec 06, 2024 at 07:48:39PM +0000, jeffxu@...omium.org wrote:
> From: Jeff Xu <jeffxu@...omium.org>
>
> No code logic change.
>
> can_do_mseal() is called exclusively by mseal.c, and mseal.c is compiled
> only when CONFIG_64BIT flag is set in makefile.  Therefore, it is
> unnecessary to have 32 bit stub function in the header file, remove
> this function and merge the logic into do_mseal().
>
> Link: https://lkml.kernel.org/r/20241206013934.2782793-1-jeffxu@google.com
> Signed-off-by: Jeff Xu <jeffxu@...omium.org>

LGTM,

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>

> Cc: Jorge Lucangeli Obes <jorgelo@...omium.org>
> Cc: Kees Cook <keescook@...omium.org>
> Cc: Liam R. Howlett <Liam.Howlett@...cle.com>
> Cc: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
> Cc: Pedro Falcato <pedro.falcato@...il.com>
> Cc: Randy Dunlap <rdunlap@...radead.org>
> Cc: Vlastimil Babka <vbabka@...e.cz>
> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>

Not sure you should be submitting a S-o-b for Andrew :P I'm thinking this
is a copy/paste mistake.

> ---
>  mm/internal.h | 16 ----------------
>  mm/mseal.c    |  6 +++---
>  2 files changed, 3 insertions(+), 19 deletions(-)
>
> diff --git a/mm/internal.h b/mm/internal.h
> index 74dc1c48fa31..5e4ef5ce9c0a 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -1457,22 +1457,6 @@ void __meminit __init_single_page(struct page *page, unsigned long pfn,
>  unsigned long shrink_slab(gfp_t gfp_mask, int nid, struct mem_cgroup *memcg,
>  			  int priority);
>
> -#ifdef CONFIG_64BIT
> -static inline int can_do_mseal(unsigned long flags)
> -{
> -	if (flags)
> -		return -EINVAL;
> -
> -	return 0;
> -}
> -
> -#else
> -static inline int can_do_mseal(unsigned long flags)
> -{
> -	return -EPERM;
> -}
> -#endif
> -
>  #ifdef CONFIG_SHRINKER_DEBUG
>  static inline __printf(2, 0) int shrinker_debugfs_name_alloc(
>  			struct shrinker *shrinker, const char *fmt, va_list ap)
> diff --git a/mm/mseal.c b/mm/mseal.c
> index 81d6e980e8a9..c27197ac04e8 100644
> --- a/mm/mseal.c
> +++ b/mm/mseal.c
> @@ -217,9 +217,9 @@ int do_mseal(unsigned long start, size_t len_in, unsigned long flags)
>  	unsigned long end;
>  	struct mm_struct *mm = current->mm;
>
> -	ret = can_do_mseal(flags);
> -	if (ret)
> -		return ret;
> +	/* Verify flags not set. */
> +	if (flags)
> +		return -EINVAL;
>
>  	start = untagged_addr(start);
>  	if (!PAGE_ALIGNED(start))
> --
> 2.47.0.338.g60cca15819-goog
>