x86/vdso: Add time napespace page

To support time namespaces in the VDSO with a minimal impact on regular non
time namespace affected tasks, the namespace handling needs to be hidden in
a slow path.

The most obvious place is vdso_seq_begin(). If a task belongs to a time
namespace then the VVAR page which contains the system wide VDSO data is
replaced with a namespace specific page which has the same layout as the
VVAR page. That page has vdso_data->seq set to 1 to enforce the slow path
and vdso_data->clock_mode set to VCLOCK_TIMENS to enforce the time
namespace handling path.

The extra check in the case that vdso_data->seq is odd, e.g. a concurrent
update of the VDSO data is in progress, is not really affecting regular
tasks which are not part of a time namespace as the task is spin waiting
for the update to finish and vdso_data->seq to become even again.

If a time namespace task hits that code path, it invokes the corresponding
time getter function which retrieves the real VVAR page, reads host time
and then adds the offset for the requested clock which is stored in the
special VVAR page.

Allocate the time namespace page among VVAR pages and place vdso_data on
it. Provide __arch_get_timens_vdso_data() helper for VDSO code to get the
code-relative position of VVARs on that special page.

Co-developed-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20191112012724.250792-23-dima@arista.com

x86/vdso: Provide vdso_data offset on vvar_page

VDSO support for time namespaces needs to set up a page with the same
layout as VVAR. That timens page will be placed on position of VVAR page
inside namespace. That page has vdso_data->seq set to 1 to enforce
the slow path and vdso_data->clock_mode set to VCLOCK_TIMENS to enforce
the time namespace handling path.

To prepare the time namespace page the kernel needs to know the vdso_data
offset. Provide arch_get_vdso_data() helper for locating vdso_data on VVAR
page.

Co-developed-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20191112012724.250792-22-dima@arista.com

x86/vdso: Switch to generic vDSO implementation

The x86 vDSO library requires some adaptations to take advantage of the
newly introduced generic vDSO library.

Introduce the following changes:
- Modification of vdso.c to be compliant with the common vdso datapage
- Use of lib/vdso for gettimeofday

[ tglx: Massaged changelog and cleaned up the function signature formatting ]

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mips@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Huw Davies <huw@codeweavers.com>
Cc: Shijith Thotton <sthotton@marvell.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Link: https://lkml.kernel.org/r/20190621095252.32307-23-vincenzo.frascino@arm.com

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 180

Based on 1 normalized pattern(s):

subject to the gnu general public license version 2

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steve Winslow <swinslow@gmail.com>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190528170026.343113277@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

x86,vdso: Use LSL unconditionally for vgetcpu

LSL is faster than RDTSCP and works everywhere; there's no need to
switch between them depending on CPU.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Andi Kleen <andi@firstfloor.org>
Link: http://lkml.kernel.org/r/72f73d5ec4514e02bba345b9759177ef03742efb.1414706021.git.luto@amacapital.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

x86_64/vdso: Remove jiffies from the vvar page

I think that the jiffies vvar was once used for the vgetcpu
cache. That code is long gone, so let's just make jiffies be a
normal variable.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/fcfee6f8749af14d96373a9e2656354ad0b95499.1411494540.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>

x86, vdso: Move the vvar and hpet mappings next to the 64-bit vDSO

This makes the 64-bit and x32 vdsos use the same mechanism as the
32-bit vdso. Most of the churn is deleting all the old fixmap code.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/8af87023f57f6bb96ec8d17fce3f88018195b49b.1399317206.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

x86, vdso: Add 32 bit VDSO time support for 64 bit kernel

This patch add the VDSO time support for the IA32 Emulation Layer.

Due the nature of the kernel headers and the LP64 compiler where the
size of a long and a pointer differs against a 32 bit compiler, there
is some type hacking necessary for optimal performance.

The vsyscall_gtod_data struture must be a rearranged to serve 32- and
64-bit code access at the same time:

- The seqcount_t was replaced by an unsigned, this makes the
vsyscall_gtod_data intedepend of kernel configuration and internal functions.
- All kernel internal structures are replaced by fix size elements
which works for 32- and 64-bit access
- The inner struct clock was removed to pack the whole struct.

The "unsigned seq" would be handled by functions derivated from seqcount_t.

Signed-off-by: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/1395094933-14252-11-git-send-email-stefani@seibold.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

x86, vdso: Introduce VVAR marco for vdso32

This patch revamps the vvar.h for introduce the VVAR macro for vdso32.

Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/1395094933-14252-8-git-send-email-stefani@seibold.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

x86, vdso: Make vsyscall_gtod_data handling x86 generic

This patch move the vsyscall_gtod_data handling out of vsyscall_64.c
into an additonal file vsyscall_gtod.c to make the functionality
available for x86 32 bit kernel.

It also adds a new vsyscall_32.c which setup the VVAR page.

Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/1395094933-14252-2-git-send-email-stefani@seibold.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

x86, asmlinkage, vdso: Mark vdso variables __visible

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1375740170-7446-17-git-send-email-andi@firstfloor.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

x86-64: Give vvars their own page

Move vvars out of the vsyscall page into their own page and mark
it NX.

Without this patch, an attacker who can force a daemon to call
some fixed address could wait until the time contains, say,
0xCD80, and then execute the current time.

Signed-off-by: Andy Lutomirski <luto@mit.edu>
Cc: Jesper Juhl <jj@chaosbits.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Jan Beulich <JBeulich@novell.com>
Cc: richard -rw- weinberger <richard.weinberger@gmail.com>
Cc: Mikael Pettersson <mikpe@it.uu.se>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Louis Rilling <Louis.Rilling@kerlabs.com>
Cc: Valdis.Kletnieks@vt.edu
Cc: pageexec@freemail.hu
Link: http://lkml.kernel.org/r/b1460f81dc4463d66ea3f2b5ce240f58d48effec.1307292171.git.luto@mit.edu
Signed-off-by: Ingo Molnar <mingo@elte.hu>

x86-64: Fix alignment of jiffies variable

It's declared __attribute__((aligned(16)) but it's explicitly
not aligned. This is probably harmless but it's a bit
embarrassing.

Signed-off-by: Andy Lutomirski <luto@mit.edu>
Cc: Jesper Juhl <jj@chaosbits.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Jan Beulich <JBeulich@novell.com>
Cc: richard -rw- weinberger <richard.weinberger@gmail.com>
Cc: Mikael Pettersson <mikpe@it.uu.se>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Louis Rilling <Louis.Rilling@kerlabs.com>
Cc: Valdis.Kletnieks@vt.edu
Cc: pageexec@freemail.hu
Link: http://lkml.kernel.org/r/5f3bc5542e9aaa9382d53f153f54373165cdef89.1307292171.git.luto@mit.edu
Signed-off-by: Ingo Molnar <mingo@elte.hu>

x86-64: Clean up vdso/kernel shared variables

Variables that are shared between the vdso and the kernel are
currently a bit of a mess. They are each defined with their own
magic, they are accessed differently in the kernel, the vsyscall page,
and the vdso, and one of them (vsyscall_clock) doesn't even really
exist.

This changes them all to use a common mechanism. All of them are
delcared in vvar.h with a fixed address (validated by the linker
script). In the kernel (as before), they look like ordinary
read-write variables. In the vsyscall page and the vdso, they are
accessed through a new macro VVAR, which gives read-only access.

The vdso is now loaded verbatim into memory without any fixups. As a
side bonus, access from the vdso is faster because a level of
indirection is removed.

While we're at it, pack jiffies and vgetcpu_mode into the same
cacheline.

Signed-off-by: Andy Lutomirski <luto@mit.edu>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Borislav Petkov <bp@amd64.org>
Link: http://lkml.kernel.org/r/%3C7357882fbb51fa30491636a7b6528747301b7ee9.1306156808.git.luto%40mit.edu%3E
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>