From: Andi Kleen <andi@firstfloor.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Michal Marek <mmarek@suse.cz>,
Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
x86@kernel.org, live-patching@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 00/10] x86/asm: Compile-time asm code validation
Date: Wed, 10 Jun 2015 17:04:12 +0200 [thread overview]
Message-ID: <20150610150412.GR19417@two.firstfloor.org> (raw)
In-Reply-To: <20150610143209.GA28843@treble.redhat.com>
> > > - duplicate the destination code inside the function
> > > - convert the jump to a call
> >
> > That all won't work for a lot of cases.
>
> Hm, could you give an example?
Just a standard *_user exception handler.
>
> Well, I don't see how that's really a logical conclusion.
What's special about assembler code?
> But we're
> probably being too vague here... Do you have any examples where you
> really need to jump outside of a callable function?
It's not needed, but it's an optimization to optimize icache usage.
It is optional (-freorder-blocks-and-partition)
In this case gcc splits the function into two (hot and cold)
It's actually a nice optimization and it would be sad from stopping
the kernel from using it.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2015-06-10 15:04 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-10 12:06 [PATCH v5 00/10] x86/asm: Compile-time asm code validation Josh Poimboeuf
2015-06-10 12:06 ` [PATCH v5 01/10] x86/asm: Add FP_SAVE/RESTORE frame pointer macros Josh Poimboeuf
2015-06-10 18:17 ` Pavel Machek
2015-06-10 18:24 ` Josh Poimboeuf
2015-06-11 4:22 ` Jiri Kosina
2015-06-11 6:46 ` Pavel Machek
2015-06-11 12:06 ` Jiri Kosina
2015-06-11 14:18 ` Josh Poimboeuf
2015-06-10 12:06 ` [PATCH v5 02/10] x86: Compile-time asm code validation Josh Poimboeuf
2015-06-10 17:21 ` Andy Lutomirski
2015-06-10 17:53 ` Josh Poimboeuf
2015-06-10 18:15 ` Andy Lutomirski
2015-06-10 18:58 ` Josh Poimboeuf
2015-06-10 22:17 ` Josh Poimboeuf
2015-06-11 6:08 ` Ingo Molnar
2015-06-11 14:01 ` Josh Poimboeuf
2015-06-11 6:10 ` Ingo Molnar
2015-06-11 14:10 ` Josh Poimboeuf
2015-06-12 11:18 ` Pedro Alves
2015-06-12 14:10 ` Josh Poimboeuf
2015-06-12 16:00 ` Pedro Alves
2015-06-12 16:41 ` Josh Poimboeuf
2015-06-10 18:16 ` Vojtech Pavlik
2015-06-10 18:18 ` Andy Lutomirski
2015-06-10 12:06 ` [PATCH v5 03/10] x86/asm/entry: Fix asmvalidate warnings for entry_64_compat.S Josh Poimboeuf
2015-06-10 12:06 ` [PATCH v5 04/10] x86/asm/crypto: Fix asmvalidate warnings for aesni-intel_asm.S Josh Poimboeuf
2015-06-10 12:06 ` [PATCH v5 05/10] x86/asm/crypto: Fix asmvalidate warnings for ghash-clmulni-intel_asm.S Josh Poimboeuf
2015-06-10 12:06 ` [PATCH v5 06/10] x86/asm/efi: Fix asmvalidate warnings for efi_stub_64.S Josh Poimboeuf
2015-06-11 13:14 ` Matt Fleming
2015-06-12 19:24 ` Borislav Petkov
2015-06-10 12:06 ` [PATCH v5 07/10] x86/asm/acpi: Fix asmvalidate warnings for wakeup_64.S Josh Poimboeuf
2015-06-10 13:19 ` Pavel Machek
2015-06-10 14:08 ` Josh Poimboeuf
2015-06-11 12:36 ` Pavel Machek
2015-06-10 13:21 ` Pavel Machek
2015-06-10 14:13 ` Josh Poimboeuf
2015-06-11 6:13 ` Ingo Molnar
2015-06-10 12:06 ` [PATCH v5 08/10] x86/asm/head: Fix asmvalidate warnings for head_64.S Josh Poimboeuf
2015-06-10 12:06 ` [PATCH v5 09/10] x86/asm/lib: Fix asmvalidate warnings for lib functions Josh Poimboeuf
2015-06-10 12:06 ` [PATCH v5 10/10] x86/asm/lib: Fix asmvalidate warnings for rwsem.S Josh Poimboeuf
2015-06-10 12:16 ` [PATCH v5 00/10] x86/asm: Compile-time asm code validation Josh Poimboeuf
2015-06-10 13:08 ` Andi Kleen
2015-06-10 13:52 ` Josh Poimboeuf
2015-06-10 14:11 ` Andi Kleen
2015-06-10 14:32 ` Josh Poimboeuf
2015-06-10 15:04 ` Andi Kleen [this message]
2015-06-10 15:31 ` Josh Poimboeuf
2015-06-10 16:50 ` Josh Poimboeuf
2015-06-10 18:41 ` Andi Kleen
2015-06-10 19:43 ` Josh Poimboeuf
2015-06-10 18:40 ` Andi Kleen
2015-06-10 19:36 ` Josh Poimboeuf
2015-06-10 19:38 ` Andy Lutomirski
2015-06-10 19:51 ` Josh Poimboeuf
2015-06-10 13:42 ` Pavel Machek
2015-06-10 14:20 ` Josh Poimboeuf
2015-06-10 18:24 ` Andy Lutomirski
2015-06-10 20:26 ` Josh Poimboeuf
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