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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Anvin <h.peter.anvin@intel.com>,
	kernel test robot <xiaolong.ye@intel.com>,
	Andrew Lutomirski <luto@kernel.org>,
	Borislav Petkov <bp@alien8.de>, Brian Gerst <brgerst@gmail.com>,
	Denys Vlasenko <dvlasenk@redhat.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Peter Anvin <hpa@zytor.com>, tipbuild@zytor.com, LKP <lkp@01.org>,
	"the arch/x86 maintainers" <x86@kernel.org>
Subject: Re: [PATCH v2] x86/asm: Pad assembly functions with INT3 instructions
Date: Tue, 15 May 2018 16:28:58 -0700	[thread overview]
Message-ID: <CA+55aFySWuQvnJ=27GUbz+h=Jop6F2TYFqnALAaeXXiPivLtqQ@mail.gmail.com> (raw)
In-Reply-To: <20180515225845.GB21902@avx2>

On Tue, May 15, 2018 at 3:58 PM Alexey Dobriyan <adobriyan@gmail.com> wrote:
>          jb      resume_kernel                   # not returning to v8086
or userspace
> -
> -ENTRY(resume_userspace)

I went back in history, and we used to have multiple "jmp resume_userspace"
including even the vm86.c code (in a different file) doing that, so there
*used* to be a reason for this being a global symbol (and yes, we had a
fall-through to that global symbol even in those days).

That said, I also look at "resume_kernel". There's no reason to make that
globally visible afaik. It looks local to entry_32.S, and should look like
restore_all rather than resume_userspace.

So we probably should remove the ENTRY() for that too, and just make it be

          ALIGN
         resume_kernel:

instead?

I guess the reason for removing that other ENTRY() is different from this
case, though..

                Linus

WARNING: multiple messages have this Message-ID (diff)
From: Linus Torvalds <torvalds@linux-foundation.org>
To: lkp@lists.01.org
Subject: Re: [PATCH v2] x86/asm: Pad assembly functions with INT3 instructions
Date: Tue, 15 May 2018 16:28:58 -0700	[thread overview]
Message-ID: <CA+55aFySWuQvnJ=27GUbz+h=Jop6F2TYFqnALAaeXXiPivLtqQ@mail.gmail.com> (raw)
In-Reply-To: <20180515225845.GB21902@avx2>

[-- Attachment #1: Type: text/plain, Size: 934 bytes --]

On Tue, May 15, 2018 at 3:58 PM Alexey Dobriyan <adobriyan@gmail.com> wrote:
>          jb      resume_kernel                   # not returning to v8086
or userspace
> -
> -ENTRY(resume_userspace)

I went back in history, and we used to have multiple "jmp resume_userspace"
including even the vm86.c code (in a different file) doing that, so there
*used* to be a reason for this being a global symbol (and yes, we had a
fall-through to that global symbol even in those days).

That said, I also look at "resume_kernel". There's no reason to make that
globally visible afaik. It looks local to entry_32.S, and should look like
restore_all rather than resume_userspace.

So we probably should remove the ENTRY() for that too, and just make it be

          ALIGN
         resume_kernel:

instead?

I guess the reason for removing that other ENTRY() is different from this
case, though..

                Linus

  reply	other threads:[~2018-05-15 23:29 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-15  8:00 [lkp-robot] [x86/asm] 51bad67ffb: int3:#[##] kernel test robot
2018-05-15  8:00 ` kernel test robot
2018-05-15 21:07 ` Alexey Dobriyan
2018-05-15 21:07   ` Alexey Dobriyan
2018-05-15 21:25   ` Anvin, H Peter
2018-05-15 21:43     ` Alexey Dobriyan
2018-05-15 21:43       ` Alexey Dobriyan
2018-05-15 22:22       ` Josh Poimboeuf
2018-05-15 22:22         ` Josh Poimboeuf
2018-05-15 22:26         ` Thomas Gleixner
2018-05-15 22:26           ` Thomas Gleixner
2018-05-15 22:28         ` Linus Torvalds
2018-05-15 22:28           ` Linus Torvalds
2018-05-15 22:43           ` Josh Poimboeuf
2018-05-15 22:43             ` Josh Poimboeuf
2018-05-15 22:52             ` Linus Torvalds
2018-05-15 22:52               ` Linus Torvalds
2018-05-15 23:05               ` Linus Torvalds
2018-05-15 23:05                 ` Linus Torvalds
2018-05-16  3:30                 ` Josh Poimboeuf
2018-05-16  3:30                   ` Josh Poimboeuf
2018-05-17 13:49                   ` [PATCH] objtool: Detect assembly code falling through to INT3 padding Josh Poimboeuf
2018-05-17 13:49                     ` Josh Poimboeuf
2018-05-17 14:01                     ` Peter Zijlstra
2018-05-17 14:01                       ` Peter Zijlstra
2018-05-18  7:24                       ` Ingo Molnar
2018-05-18  7:24                         ` Ingo Molnar
2018-05-18  7:18                     ` Ingo Molnar
2018-05-18  7:18                       ` Ingo Molnar
2018-05-18  7:27                       ` H. Peter Anvin
2018-05-18 16:06                         ` Borislav Petkov
2018-05-18 16:06                           ` Borislav Petkov
2018-05-18  7:27                       ` Ingo Molnar
2018-05-18  7:27                         ` Ingo Molnar
2018-05-18 17:51                       ` Alexey Dobriyan
2018-05-18 17:51                         ` Alexey Dobriyan
2018-05-19  8:18                         ` hpa
2018-05-19  7:00                 ` "interesting" entry in hibernation code was Re: [lkp-robot] [x86/asm] 51bad67ffb: int3:#[##] Pavel Machek
2018-05-19  7:00                   ` Pavel Machek
2018-05-19  8:35                   ` Rafael J. Wysocki
2018-05-19  8:35                     ` Rafael J. Wysocki
2018-05-18  7:15               ` Ingo Molnar
2018-05-18  7:15                 ` Ingo Molnar
2018-05-15 22:25       ` Thomas Gleixner
2018-05-15 22:25         ` Thomas Gleixner
2018-05-15 22:29         ` Andy Lutomirski
2018-05-15 22:29           ` Andy Lutomirski
2018-05-15 22:27       ` Linus Torvalds
2018-05-15 22:27         ` Linus Torvalds
2018-05-15 22:50         ` Alexey Dobriyan
2018-05-15 22:50           ` Alexey Dobriyan
2018-05-15 22:58           ` [PATCH v2] x86/asm: Pad assembly functions with INT3 instructions Alexey Dobriyan
2018-05-15 22:58             ` Alexey Dobriyan
2018-05-15 23:28             ` Linus Torvalds [this message]
2018-05-15 23:28               ` Linus Torvalds
2018-05-18  7:36             ` Ingo Molnar
2018-05-18  7:36               ` Ingo Molnar
2018-05-18 13:02               ` Josh Poimboeuf
2018-05-18 13:02                 ` Josh Poimboeuf
2018-05-18 17:34                 ` Alexey Dobriyan
2018-05-18 17:34                   ` Alexey Dobriyan

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