From: Pavel Machek <pavel@ucw.cz>
To: Linus Torvalds <torvalds@linux-foundation.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
Alexey Dobriyan <adobriyan@gmail.com>,
Peter Anvin <h.peter.anvin@intel.com>,
kernel test robot <xiaolong.ye@intel.com>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Andrew Lutomirski <luto@kernel.org>,
Borislav Petkov <bp@alien8.de>, Brian Gerst <brgerst@gmail.com>,
Denys Vlasenko <dvlasenk@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>
Subject: "interesting" entry in hibernation code was Re: [lkp-robot] [x86/asm] 51bad67ffb: int3:#[##]
Date: Sat, 19 May 2018 09:00:08 +0200 [thread overview]
Message-ID: <20180519070008.GC30676@amd> (raw)
In-Reply-To: <CA+55aFwrT-BAvdujUonX5MvB=8GFopQJT4x6xMhtjNN2G0AxSw@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 1342 bytes --]
Hi!
> Side note: doing some grepping, I find some other sequences that are a bit
> scary, like this:
>
> arch/x86/kernel/acpi/wakeup_32.S-.data
> arch/x86/kernel/acpi/wakeup_32.S-ALIGN
> arch/x86/kernel/acpi/wakeup_32.S:ENTRY(saved_magic) .long 0
> arch/x86/kernel/acpi/wakeup_32.S:ENTRY(saved_eip) .long 0
>
> so apparently people are using ENTRY() for data too (the same pattern
> exists in wakeup_64.S).
>
> So we end up having those odd 0x90 bytes (now 0xcc) in the data section as
> "padding" between those two values. Crazy.
Sorry about that. I'm pretty sure intention was simply to use the
variable from C code.. and ENTRY() worked. I was not aware that it has
side effect of padding...
Let me see how this can be improved... (untested).
diff --git a/arch/x86/kernel/acpi/wakeup_32.S b/arch/x86/kernel/acpi/wakeup_32.S
index 0c26b1b..d6f477f 100644
--- a/arch/x86/kernel/acpi/wakeup_32.S
+++ b/arch/x86/kernel/acpi/wakeup_32.S
@@ -89,8 +89,8 @@ ret_point:
.data
ALIGN
-ENTRY(saved_magic) .long 0
-ENTRY(saved_eip) .long 0
+GLOBAL(saved_magic) .long 0
+saved_eip: .long 0
# saved registers
saved_idt: .long 0,0
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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WARNING: multiple messages have this Message-ID (diff)
From: Pavel Machek <pavel@ucw.cz>
To: lkp@lists.01.org
Subject: "interesting" entry in hibernation code was Re: [lkp-robot] [x86/asm] 51bad67ffb: int3:#[##]
Date: Sat, 19 May 2018 09:00:08 +0200 [thread overview]
Message-ID: <20180519070008.GC30676@amd> (raw)
In-Reply-To: <CA+55aFwrT-BAvdujUonX5MvB=8GFopQJT4x6xMhtjNN2G0AxSw@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 1342 bytes --]
Hi!
> Side note: doing some grepping, I find some other sequences that are a bit
> scary, like this:
>
> arch/x86/kernel/acpi/wakeup_32.S-.data
> arch/x86/kernel/acpi/wakeup_32.S-ALIGN
> arch/x86/kernel/acpi/wakeup_32.S:ENTRY(saved_magic) .long 0
> arch/x86/kernel/acpi/wakeup_32.S:ENTRY(saved_eip) .long 0
>
> so apparently people are using ENTRY() for data too (the same pattern
> exists in wakeup_64.S).
>
> So we end up having those odd 0x90 bytes (now 0xcc) in the data section as
> "padding" between those two values. Crazy.
Sorry about that. I'm pretty sure intention was simply to use the
variable from C code.. and ENTRY() worked. I was not aware that it has
side effect of padding...
Let me see how this can be improved... (untested).
diff --git a/arch/x86/kernel/acpi/wakeup_32.S b/arch/x86/kernel/acpi/wakeup_32.S
index 0c26b1b..d6f477f 100644
--- a/arch/x86/kernel/acpi/wakeup_32.S
+++ b/arch/x86/kernel/acpi/wakeup_32.S
@@ -89,8 +89,8 @@ ret_point:
.data
ALIGN
-ENTRY(saved_magic) .long 0
-ENTRY(saved_eip) .long 0
+GLOBAL(saved_magic) .long 0
+saved_eip: .long 0
# saved registers
saved_idt: .long 0,0
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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next prev parent reply other threads:[~2018-05-19 7:00 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 ` Pavel Machek [this message]
2018-05-19 7:00 ` "interesting" entry in hibernation code was Re: [lkp-robot] [x86/asm] 51bad67ffb: int3:#[##] 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
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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