From: Thomas Garnier <thgarnie@google.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Kernel Hardening <kernel-hardening@lists.openwall.com>,
Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
"H . Peter Anvin" <hpa@zytor.com>,
"the arch/x86 maintainers" <x86@kernel.org>,
Francis Deslauriers <francis.deslauriers@efficios.com>,
Greg KH <gregkh@linuxfoundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Guenter Roeck <linux@roeck-us.net>,
nixiaoming <nixiaoming@huawei.com>,
James Hogan <jhogan@kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4 21/27] x86/ftrace: Adapt function tracing for PIE support
Date: Mon, 4 Jun 2018 14:06:03 -0700 [thread overview]
Message-ID: <CAJcbSZG1dVBVeOjEDeTm4mwXS60wMi-5ej_FB+YyS7iwXoebOQ@mail.gmail.com> (raw)
In-Reply-To: <20180604161612.6d48d8d2@gandalf.local.home>
On Mon, Jun 4, 2018 at 1:16 PM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Tue, 29 May 2018 15:15:22 -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.
> >
> > If PIE is enabled, replace the 6th byte of the GOT call by a 1-byte nop
> > so ftrace can handle the previous 5-bytes as before.
> >
> > Position Independent Executable (PIE) support will allow to extend the
> > KASLR randomization range 0xffffffff80000000.
>
> I thought you were going to write a update to recordmcount.c to handle
> this at compile time?
I can correctly calculate the start of the call instruction with
recordmcount (no need for addr-1) but I still need to handle the
different size of the instructions. I don't think I can completely
replace the GOT call with a relative call. Maybe I am missing
something on the way recordmcount is used? Should it replace all
mcount locations with a nop slide? Why is it done at runtime too then?
>
> -- Steve
>
> >
> > Signed-off-by: Thomas Garnier <thgarnie@google.com>
> > ---
> >
--
Thomas
next prev parent reply other threads:[~2018-06-04 21:06 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20180529221625.33541-1-thgarnie@google.com>
2018-05-29 22:15 ` [PATCH v4 01/27] x86/crypto: Adapt assembly for PIE support Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 02/27] x86: Use symbol name on bug table " Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 03/27] x86: Use symbol name in jump " Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 04/27] x86: Add macro to get symbol address " Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 05/27] x86: relocate_kernel - Adapt assembly " Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 06/27] x86/entry/64: " Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 07/27] x86: pm-trace - " Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 08/27] x86/CPU: " Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 09/27] x86/acpi: " Thomas Garnier
2018-05-30 8:19 ` Rafael J. Wysocki
2018-05-29 22:15 ` [PATCH v4 10/27] x86/boot/64: " Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 11/27] x86/power/64: " Thomas Garnier
2018-05-30 8:20 ` Rafael J. Wysocki
2018-05-29 22:15 ` [PATCH v4 12/27] x86/paravirt: " Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 13/27] x86/boot/64: Build head64.c as mcmodel large when PIE is enabled Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 14/27] x86/percpu: Adapt percpu for PIE support Thomas Garnier
2018-05-29 22:46 ` Christopher Lameter
2018-05-29 23:08 ` Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 15/27] compiler: Option to default to hidden symbols Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 16/27] compiler: Option to add PROVIDE_HIDDEN replacement for weak symbols Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 17/27] x86/relocs: Handle PIE relocations Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 18/27] xen: Adapt assembly for PIE support Thomas Garnier
2018-06-01 15:44 ` Boris Ostrovsky
2018-06-01 15:53 ` Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 19/27] kvm: " Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 20/27] x86: Support global stack cookie Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 21/27] x86/ftrace: Adapt function tracing for PIE support Thomas Garnier
2018-06-04 20:16 ` Steven Rostedt
2018-06-04 21:06 ` Thomas Garnier [this message]
2018-06-04 21:44 ` Steven Rostedt
2018-06-05 16:56 ` Thomas Garnier
2018-06-05 21:19 ` Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 22/27] x86/modules: Add option to start module section after kernel Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 23/27] x86/modules: Adapt module loading for PIE support Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 24/27] x86/mm: Make the x86 GOT read-only Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 25/27] x86/pie: Add option to build the kernel as PIE Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 26/27] x86/relocs: Add option to generate 64-bit relocations Thomas Garnier
2018-05-29 22:15 ` [PATCH v4 27/27] x86/kaslr: Add option to extend KASLR range from 1GB to 3GB Thomas Garnier
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