linux-kernel - [PATCH 01/20] exit/doublefault: Remove apparently bogus comment about rewind_stack_do

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Message-Id: <20211020174406.17889-1-ebiederm@xmission.com>
Date:   Wed, 20 Oct 2021 12:43:47 -0500
From:   "Eric W. Biederman" <ebiederm@...ssion.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-arch@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Oleg Nesterov <oleg@...hat.com>,
        Al Viro <viro@...IV.linux.org.uk>,
        Kees Cook <keescook@...omium.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Andy Lutomirski <luto@...nel.org>
Subject: [PATCH 01/20] exit/doublefault: Remove apparently bogus comment about rewind_stack_do_exit

I do not see panic calling rewind_stack_do_exit anywhere, nor can I
find anywhere in the history where doublefault_shim has called
rewind_stack_do_exit.  So I don't think this comment was ever actually
correct.

Cc: Andy Lutomirski <luto@...nel.org>
Fixes: 7d8d8cfdee9a ("x86/doublefault/32: Rewrite the x86_32 #DF handler and unify with 64-bit")
Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
---
 arch/x86/kernel/doublefault_32.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/arch/x86/kernel/doublefault_32.c b/arch/x86/kernel/doublefault_32.c
index d1d49e3d536b..3b58d8703094 100644
--- a/arch/x86/kernel/doublefault_32.c
+++ b/arch/x86/kernel/doublefault_32.c
@@ -77,9 +77,6 @@ asmlinkage noinstr void __noreturn doublefault_shim(void)
 	 * some way to reconstruct CR3.  We could make a credible guess based
 	 * on cpu_tlbstate, but that would be racy and would not account for
 	 * PTI.
-	 *
-	 * Instead, don't bother.  We can return through
-	 * rewind_stack_do_exit() instead.
 	 */
 	panic("cannot return from double fault\n");
 }
-- 
2.20.1