From: Ingo Molnar <mingo@kernel.org>
To: Thomas Garnier <thgarnie@google.com>
Cc: "Nicolas Pitre" <nicolas.pitre@linaro.org>,
"Michal Hocko" <mhocko@suse.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
linux-doc@vger.kernel.org, "Daniel Micay" <danielmicay@gmail.com>,
"Len Brown" <len.brown@intel.com>,
"Peter Zijlstra" <peterz@infradead.org>,
"Christopher Li" <sparse@chrisli.org>,
"Jan H . Schönherr" <jschoenh@amazon.de>,
"Alexei Starovoitov" <ast@kernel.org>,
virtualization@lists.linux-foundation.org,
"David Howells" <dhowells@redhat.com>,
"Paul Gortmaker" <paul.gortmaker@windriver.com>,
"Waiman Long" <longman@redhat.com>, "Pavel Machek" <pavel@ucw.cz>,
"H . Peter Anvin" <hpa@zytor.com>,
"Kernel Hardening" <kernel-hardening@lists.openwall.com>,
"Christoph Lameter" <cl@linux.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"the arch/x86 maintainers" <x86@kernel.org>,
"Herbert Xu" <herbert@gondor.apana.org.au>,
"Daniel Borkmann" <daniel@iogearbox.net>
Subject: Re: [PATCH v1 06/27] x86/entry/64: Adapt assembly for PIE support
Date: Fri, 20 Oct 2017 17:20:28 +0200 [thread overview]
Message-ID: <20171020152028.syq6woeet6it3z3h@gmail.com> (raw)
In-Reply-To: <CAJcbSZFScsqOORMGXFQdsqcN5xbfHWpzSHGdxQB=45zgSDryLw@mail.gmail.com>
* Thomas Garnier <thgarnie@google.com> wrote:
> >> */
> >> - cmpq $.Lentry_SYSCALL_64_after_fastpath_call, (%rsp)
> >> + leaq .Lentry_SYSCALL_64_after_fastpath_call(%rip), %r11
> >> + cmpq %r11, (%rsp)
> >> jne 1f
> > This patch seems to add extra overhead to the syscall fast-path even when PIE is
> > disabled, right?
>
> It does add extra instructions when one is not possible, I preferred
> that over ifdefing but I can change it.
So my problem is, this pattern repeats in many other places as well, but sprinking
various pieces of assembly code with #ifdefs would be very bad as well.
I have no good idea how to solve this.
Thanks,
Ingo
next prev parent reply other threads:[~2017-10-20 15:20 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-11 20:30 [PATCH v1 00/27] x86: PIE support and option to extend KASLR randomization Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 01/27] x86/crypto: Adapt assembly for PIE support Thomas Garnier
2017-10-20 8:24 ` Ingo Molnar
2017-10-20 8:28 ` Ard Biesheuvel
2017-10-20 14:48 ` Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 02/27] x86: Use symbol name on bug table " Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 03/27] x86: Use symbol name in jump " Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 04/27] x86: Add macro to get symbol address " Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 05/27] x86: relocate_kernel - Adapt assembly " Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 06/27] x86/entry/64: " Thomas Garnier
2017-10-20 8:26 ` Ingo Molnar
2017-10-20 14:47 ` Thomas Garnier
2017-10-20 15:20 ` Ingo Molnar [this message]
2017-10-20 16:27 ` Andy Lutomirski
2017-10-20 17:52 ` Andy Lutomirski
2017-10-11 20:30 ` [PATCH v1 07/27] x86: pm-trace - " Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 08/27] x86/CPU: " Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 09/27] x86/acpi: " Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 10/27] x86/boot/64: " Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 11/27] x86/power/64: " Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 12/27] x86/paravirt: " Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 13/27] x86/boot/64: Use _text in a global " Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 14/27] x86/percpu: Adapt percpu " Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 15/27] compiler: Option to default to hidden symbols Thomas Garnier
2017-10-12 20:02 ` Luis R. Rodriguez
2017-10-18 23:15 ` Thomas Garnier
2017-10-19 19:38 ` Luis R. Rodriguez
2017-10-11 20:30 ` [PATCH v1 16/27] x86/relocs: Handle PIE relocations Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 17/27] xen: Adapt assembly for PIE support Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 18/27] kvm: " Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 19/27] x86: Support global stack cookie Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 20/27] x86/ftrace: Adapt function tracing for PIE support Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 21/27] x86/mm/dump_pagetables: Fix address markers index on x86_64 Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 22/27] x86/modules: Add option to start module section after kernel Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 23/27] x86/modules: Adapt module loading for PIE support Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 24/27] x86/mm: Make the x86 GOT read-only Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 25/27] x86/pie: Add option to build the kernel as PIE Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 26/27] x86/relocs: Add option to generate 64-bit relocations Thomas Garnier
2017-10-11 20:30 ` [PATCH v1 27/27] x86/kaslr: Add option to extend KASLR range from 1GB to 3GB Thomas Garnier
2017-10-11 21:34 ` [PATCH v1 00/27] x86: PIE support and option to extend KASLR randomization Tom Lendacky
2017-10-12 15:34 ` Thomas Garnier
2017-10-12 15:51 ` Markus Trippelsdorf
2017-10-12 16:28 ` Tom Lendacky
2017-10-18 23:17 ` Thomas Garnier
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