linux-kernel - [PATCH] x86: mm: refer to the intended config STRICT

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Date:   Wed, 22 Dec 2021 13:53:47 +0100
From:   Lukas Bulwahn <lukas.bulwahn@...il.com>
To:     Dave Hansen <dave.hansen@...ux.intel.com>,
        Kees Cook <keescook@...omium.org>
Cc:     Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H . Peter Anvin" <hpa@...or.com>,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org,
        Lukas Bulwahn <lukas.bulwahn@...il.com>
Subject: [PATCH] x86: mm: refer to the intended config STRICT_DEVMEM in a comment

Commit a4866aa81251 ("mm: Tighten x86 /dev/mem with zeroing reads") adds a
comment to the function devmem_is_allowed() referring to a non-existing
config STRICT_IOMEM, whereas the comment very likely intended to refer to
the config STRICT_DEVMEM, as the commit adds some behavior for the config
STRICT_DEVMEM.

Most of the initial analysis was actually done by Dave Hansen in the
email thread below (see Link).

Refer to the intended and existing config STRICT_DEVMEM.

Link: https://lore.kernel.org/r/f9074e8d-9314-9d7d-7bf5-5b5538c8be8d@intel.com/

Suggested-by: Dave Hansen <dave.hansen@...el.com>
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@...il.com>
---
 arch/x86/mm/init.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 4ba024d5b63a..64ac8a5e928a 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -847,7 +847,7 @@ int devmem_is_allowed(unsigned long pagenr)
 
 	/*
 	 * This must follow RAM test, since System RAM is considered a
-	 * restricted resource under CONFIG_STRICT_IOMEM.
+	 * restricted resource under CONFIG_STRICT_DEVMEM.
 	 */
 	if (iomem_is_exclusive(pagenr << PAGE_SHIFT)) {
 		/* Low 1MB bypasses iomem restrictions. */
-- 
2.17.1