From: Steven Rostedt <rostedt@goodmis.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>,
"Matthew Wilcox" <mawilcox@microsoft.com>,
virtualization@lists.linux-foundation.org,
"David Howells" <dhowells@redhat.com>,
"Paul Gortmaker" <paul.gortmaker@windriver.com>,
"Pavel Machek" <pavel@ucw.cz>, "H . Peter Anvin" <hpa@zytor.com>,
kernel-hardening@lists.openwall.com,
"Andrey Ryabinin" <aryabinin@virtuozzo.com>,
"Christoph Lameter" <cl@linux.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Chris Metcalf" <cmetcalf@mellanox.com>,
x86@kernel.org, "Herbert Xu" <herbert@gondor.apana.org.au>
Subject: Re: [RFC v3 20/27] x86/ftrace: Adapt function tracing for PIE support
Date: Thu, 5 Oct 2017 09:06:33 -0400 [thread overview]
Message-ID: <20171005090633.5a6ce840@gandalf.local.home> (raw)
In-Reply-To: <20171004212003.28296-21-thgarnie@google.com>
On Wed, 4 Oct 2017 14:19:56 -0700
Thomas Garnier <thgarnie@google.com> wrote:
> When using -fPIE/PIC with function tracing, the compiler generates a
> call through the GOT (call *__fentry__@GOTPCREL). This instruction
> takes 6 bytes instead of 5 on the usual relative call.
>
> With this change, function tracing supports 6 bytes on traceable
> function and can still replace relative calls on the ftrace assembly
> functions.
>
> Position Independent Executable (PIE) support will allow to extended the
> KASLR randomization range below the -2G memory limit.
Question: This 6 bytes is only the initial call that gcc creates. When
function tracing is enabled, the calls are back to the normal call to
the ftrace trampoline?
-- Steve
next prev parent reply other threads:[~2017-10-05 13:06 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-04 21:19 x86: PIE support and option to extend KASLR randomization Thomas Garnier
2017-10-04 21:19 ` [RFC v3 01/27] x86/crypto: Adapt assembly for PIE support Thomas Garnier
2017-10-04 21:19 ` [RFC v3 02/27] x86: Use symbol name on bug table " Thomas Garnier
2017-10-04 21:19 ` [RFC v3 03/27] x86: Use symbol name in jump " Thomas Garnier
2017-10-04 21:19 ` [RFC v3 04/27] x86: Add macro to get symbol address " Thomas Garnier
2017-10-04 21:19 ` [RFC v3 05/27] x86: relocate_kernel - Adapt assembly " Thomas Garnier
2017-10-04 21:19 ` [RFC v3 06/27] x86/entry/64: " Thomas Garnier
2017-10-04 21:19 ` [RFC v3 07/27] x86: pm-trace - " Thomas Garnier
2017-10-04 21:19 ` [RFC v3 08/27] x86/CPU: " Thomas Garnier
2017-10-04 21:19 ` [RFC v3 09/27] x86/acpi: " Thomas Garnier
2017-10-04 21:19 ` [RFC v3 10/27] x86/boot/64: " Thomas Garnier
2017-10-04 21:19 ` [RFC v3 11/27] x86/power/64: " Thomas Garnier
2017-10-04 21:19 ` [RFC v3 12/27] x86/paravirt: " Thomas Garnier
2017-10-04 21:19 ` [RFC v3 13/27] x86/boot/64: Use _text in a global " Thomas Garnier
2017-10-04 21:19 ` [RFC v3 14/27] x86/percpu: Adapt percpu " Thomas Garnier
2017-10-04 21:19 ` [RFC v3 15/27] compiler: Option to default to hidden symbols Thomas Garnier
2017-10-04 21:19 ` [RFC v3 16/27] x86/relocs: Handle PIE relocations Thomas Garnier
2017-10-04 21:19 ` [RFC v3 17/27] xen: Adapt assembly for PIE support Thomas Garnier
2017-10-04 21:19 ` [RFC v3 18/27] kvm: " Thomas Garnier
2017-10-04 21:19 ` [RFC v3 19/27] x86: Support global stack cookie Thomas Garnier
2017-10-04 21:19 ` [RFC v3 20/27] x86/ftrace: Adapt function tracing for PIE support Thomas Garnier
2017-10-05 13:06 ` Steven Rostedt [this message]
2017-10-05 16:01 ` Thomas Garnier
2017-10-05 16:11 ` Steven Rostedt
2017-10-05 16:14 ` Thomas Garnier
2017-10-04 21:19 ` [RFC v3 21/27] x86/mm/dump_pagetables: Fix address markers index on x86_64 Thomas Garnier
2017-10-04 21:19 ` [RFC v3 22/27] x86/modules: Add option to start module section after kernel Thomas Garnier
2017-10-04 21:19 ` [RFC v3 23/27] x86/modules: Adapt module loading for PIE support Thomas Garnier
2017-10-04 21:20 ` [RFC v3 24/27] x86/mm: Make the x86 GOT read-only Thomas Garnier
2017-10-04 21:20 ` [RFC v3 25/27] x86/pie: Add option to build the kernel as PIE Thomas Garnier
2017-10-04 21:20 ` [RFC v3 26/27] x86/relocs: Add option to generate 64-bit relocations Thomas Garnier
2017-10-04 21:20 ` [RFC v3 27/27] x86/kaslr: Add option to extend KASLR range from 1GB to 3GB Thomas Garnier
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