From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>,
the arch/x86 maintainers <x86@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@kernel.org>,
Alexander Potapenko <glider@google.com>,
Dmitriy Vyukov <dvyukov@google.com>,
Matthias Kaehlcke <mka@chromium.org>,
Arnd Bergmann <arnd@arndb.de>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [RFC PATCH 3/4] x86/asm: Make alternative macro interfaces more clear and consistent
Date: Thu, 14 Sep 2017 12:26:27 -0500 [thread overview]
Message-ID: <20170914172627.sp2yrecpawovvxxy@treble> (raw)
In-Reply-To: <CA+55aFw0K6Ng2PXK0G7XN=BO=CM=rHUu3g5CYhgh0ukwkbgj6Q@mail.gmail.com>
On Thu, Sep 14, 2017 at 10:16:08AM -0700, Linus Torvalds wrote:
> On Thu, Sep 14, 2017 at 7:48 AM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> >
> > As it turns out, the real problem with this option is that it imposes a
> > penalty for CONFIG_FRAME_POINTER=n: even with frame pointers disabled,
> > it forces the frame pointer to be saved for each function which uses the
> > inline asm "call" statements. Our current solution doesn't do that.
>
> But couldn't we make the whole stack pointer clobber be dependent on
> CONFIG_FRAME_POINTER?
>
> The only reason we do it is to make sure the frame pointer is set up
> before the inline asm is emitted, but with frame pointers disabled we
> don't need to.
We could, but then that would mean either:
a) uglifying the 15 or so relevant inline asm locations with ifdefs; or
b) using my ASM_CALL macro, which I think you frowned upon?
--
Josh
next prev parent reply other threads:[~2017-09-14 17:26 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-31 14:11 [RFC PATCH 0/4] x86/asm: Add ASM_CALL() macro for inline asms with call instructions Josh Poimboeuf
2017-08-31 14:11 ` [RFC PATCH 1/4] x86/paravirt: Fix output constraint macro names Josh Poimboeuf
2017-08-31 14:11 ` [RFC PATCH 2/4] x86/asm: Convert some inline asm positional operands to named operands Josh Poimboeuf
2017-08-31 14:11 ` [RFC PATCH 3/4] x86/asm: Make alternative macro interfaces more clear and consistent Josh Poimboeuf
2017-08-31 16:11 ` Linus Torvalds
2017-08-31 17:25 ` Josh Poimboeuf
2017-08-31 17:31 ` Josh Poimboeuf
2017-09-02 10:32 ` Ingo Molnar
2017-09-14 14:48 ` Josh Poimboeuf
2017-09-14 17:16 ` Linus Torvalds
2017-09-14 17:26 ` Josh Poimboeuf [this message]
2017-09-14 17:33 ` Josh Poimboeuf
2017-09-14 18:28 ` Linus Torvalds
2017-09-14 18:45 ` Josh Poimboeuf
2017-09-15 16:10 ` Josh Poimboeuf
2017-09-15 16:53 ` Andrey Ryabinin
2017-09-15 17:20 ` Josh Poimboeuf
2017-09-15 18:01 ` Linus Torvalds
2017-09-15 23:29 ` Josh Poimboeuf
2017-09-16 22:22 ` Andrey Ryabinin
2017-09-18 17:40 ` Josh Poimboeuf
2017-09-19 16:02 ` Josh Poimboeuf
2017-08-31 14:11 ` [RFC PATCH 4/4] x86/asm: Use ASM_CALL() macro for inline asm statements with call instructions Josh Poimboeuf
2017-08-31 14:50 ` Peter Zijlstra
2017-08-31 15:21 ` Josh Poimboeuf
2017-08-31 15:36 ` Dmitry Vyukov
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