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: NVincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: NThomas 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

GCC 5.5.0 sometimes cleverly hoists reads of the pvclock and/or hvclock
pages before the vclock mode checks.  This creates a path through
vclock_gettime() in which no vclock is enabled at all (due to disabled
TSC on old CPUs, for example) but the pvclock or hvclock page
nevertheless read.  This will segfault on bare metal.

This fixes commit 459e3a21 ("gcc-9: properly declare the
{pv,hv}clock_page storage") in the sense that, before that commit, GCC
didn't seem to generate the offending code.  There was nothing wrong
with that commit per se, and -stable maintainers should backport this to
all supported kernels regardless of whether the offending commit was
present, since the same crash could just as easily be triggered by the
phase of the moon.

On GCC 9.1.1, this doesn't seem to affect the generated code at all, so
I'm not too concerned about performance regressions from this fix.

Cc: stable@vger.kernel.org
Cc: x86@kernel.org
Cc: Borislav Petkov <bp@alien8.de>
Reported-by: NDuncan Roe <duncan_roe@optusnet.com.au>
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Based on 1 normalized pattern(s):

  subject to the gnu public license v 2

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 9 file(s).
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NAllison Randal <allison@lohutok.net>
Reviewed-by: NAlexios Zavras <alexios.zavras@intel.com>
Reviewed-by: NSteve Winslow <swinslow@gmail.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190528171440.130801526@linutronix.deSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Based on 1 normalized pattern(s):

  subject to the gpl v 2

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 2 file(s).
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NAllison Randal <allison@lohutok.net>
Reviewed-by: NSteve Winslow <swinslow@gmail.com>
Reviewed-by: NAlexios Zavras <alexios.zavras@intel.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190528171439.372657724@linutronix.deSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This trivial cleanup finalizes the removal of vDSO HPET support.

Fixes: 1ed95e52 ("x86/vdso: Remove direct HPET access through the vDSO")
Signed-off-by: Jia Zhang <zhang.jia@linux.alibaba.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: luto@kernel.org
Cc: bp@alien8.de
Link: https://lkml.kernel.org/r/20190401114045.7280-1-zhang.jia@linux.alibaba.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

The pvlock_page and hvclock_page variables are (as the name implies)
addresses to pages, created by the linker script.

But we declared them as just "extern u8" variables, which _works_, but
now that gcc does some more bounds checking, it causes warnings like

    warning: array subscript 1 is outside array bounds of ‘u8[1]’

when we then access more than one byte from those variables.

Fix this by simply making the declaration of the variables match
reality, which makes the compiler happy too.
Signed-off-by: NLinus Torvalds <torvalds@-linux-foundation.org>

The go32() and go64() functions has an argument and a local variable called ‘name’.
Rename both to clarify the code and to fix a warning with -Wshadow.
Signed-off-by: NLeonardo Brás <leobras.c@gmail.com>
Acked-by: NAndy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: David.Laight@aculab.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: helen@koikeco.de
Cc: linux-kbuild@vger.kernel.org
Cc: lkcamp@lists.libreplanetbr.org
Link: http://lkml.kernel.org/r/20181023011022.GA6574@WindFlashSigned-off-by: NIngo Molnar <mingo@kernel.org>

$(call if_changed,...) must have FORCE as a prerequisite.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1554280212-10578-1-git-send-email-yamada.masahiro@socionext.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Commit

  379d98dd ("x86: vdso: Use $LD instead of $CC to link")

accidentally broke unwinding from userspace, because ld would strip the
.eh_frame sections when linking.

Originally, the compiler would implicitly add --eh-frame-hdr when
invoking the linker, but when this Makefile was converted from invoking
ld via the compiler, to invoking it directly (like vmlinux does),
the flag was missed. (The EH_FRAME section is important for the VDSO
shared libraries, but not for vmlinux.)

Fix the problem by explicitly specifying --eh-frame-hdr, which restores
parity with the old method.

See relevant bug reports for additional info:

  https://bugzilla.kernel.org/show_bug.cgi?id=201741
  https://bugzilla.redhat.com/show_bug.cgi?id=1659295

Fixes: 379d98dd ("x86: vdso: Use $LD instead of $CC to link")
Reported-by: NFlorian Weimer <fweimer@redhat.com>
Reported-by: NCarlos O'Donell <carlos@redhat.com>
Reported-by: N"H. J. Lu" <hjl.tools@gmail.com>
Signed-off-by: NAlistair Strachan <astrachan@google.com>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Tested-by: NLaura Abbott <labbott@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Carlos O'Donell <carlos@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: kernel-team@android.com
Cc: Laura Abbott <labbott@redhat.com>
Cc: stable <stable@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: X86 ML <x86@kernel.org>
Link: https://lkml.kernel.org/r/20181214223637.35954-1-astrachan@google.com

GNU linker's -z common-page-size's default value is based on the target
architecture. arch/x86/entry/vdso/Makefile sets it to the architecture
default, which is implicit and redundant. Drop it.

Fixes: 2aae950b ("x86_64: Add vDSO for x86-64 with gettimeofday/clock_gettime/getcpu")
Reported-by: NDmitry Golovin <dima@golovin.in>
Reported-by: NBill Wendling <morbo@google.com>
Suggested-by: NDmitry Golovin <dima@golovin.in>
Suggested-by: NRui Ueyama <ruiu@google.com>
Signed-off-by: NNick Desaulniers <ndesaulniers@google.com>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Acked-by: NAndy Lutomirski <luto@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Fangrui Song <maskray@google.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20181206191231.192355-1-ndesaulniers@google.com
Link: https://bugs.llvm.org/show_bug.cgi?id=38774
Link: https://github.com/ClangBuiltLinux/linux/issues/31

Once upon a time, vdso2c aggressively stripped data from the vDSO
image when generating the final userspace image.  This included
stripping the .altinstructions and .altinstr_replacement sections.
Eventually, the stripping process reverted to "objdump -S" and no
longer removed the aforementioned sections, but the comment remained.

Keeping the .alt* sections at the end of the PT_LOAD segment is no
longer necessary, but there's no harm in doing so and it's a helpful
reminder that they don't need to be included in the final vDSO image,
i.e. someone may want to take another stab at zapping/stripping the
unneeded sections.
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Acked-by: NAndy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: da861e18 ("x86, vdso: Get rid of the fake section mechanism")
Link: http://lkml.kernel.org/r/20181204212600.28090-3-sean.j.christopherson@intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

At one point the vDSO image was manually stripped down by vdso2c in an
attempt to minimize the size of the image mapped into userspace.  Part
of that stripping process involved building a fake section table so as
not to break userspace processes that parse the section table.  Memory
for the fake section table was reserved in the .rodata section so that
vdso2c could simply copy the entire PT_LOAD segment into the userspace
image after building the fake table.

Eventually, the entire fake section table approach was dropped in favor
of stripping the vdso "the old fashioned way", i.e. via objdump -S.
But, the reservation in .rodata for the fake table was left behind.
Remove the reserveration along with a few other related defines and
section entries.

Removing the fake section table placeholder zaps a whopping 0x340 bytes
from the 64-bit vDSO image, which drops the current image's size to
under 4k, i.e. reduces the effective size of the userspace vDSO mapping
by a full page.
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Acked-by: NAndy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: da861e18 ("x86, vdso: Get rid of the fake section mechanism")
Link: http://lkml.kernel.org/r/20181204212600.28090-2-sean.j.christopherson@intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Go over arch/x86/ and fix common typos in comments,
and a typo in an actual function argument name.

No change in functionality intended.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Return vm_fault_t codes directly from the appropriate mm routines instead
of converting from errnos ourselves.  Fixes a minor bug where we'd return
SIGBUS instead of the correct OOM code if we ran out of memory allocating
page tables.

Link: http://lkml.kernel.org/r/20180828145728.11873-5-willy@infradead.orgSigned-off-by: NMatthew Wilcox <willy@infradead.org>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

So:

 - use 'extern' consistently for APIs

 - fix weird header guard

 - clarify code comments

 - reorder APIs by type

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chang S. Bae <chang.seok.bae@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Markus T Metzger <markus.t.metzger@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1537312139-5580-2-git-send-email-chang.seok.bae@intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

We have a special segment descriptor entry in the GDT, whose sole purpose is to
encode the CPU and node numbers in its limit (size) field. There are user-space
instructions that allow the reading of the limit field, which gives us a really
fast way to read the CPU and node IDs from the vDSO for example.

But the naming of related functionality does not make this clear, at all:

	VDSO_CPU_SIZE
	VDSO_CPU_MASK
	__CPU_NUMBER_SEG
	GDT_ENTRY_CPU_NUMBER
	vdso_encode_cpu_node
	vdso_read_cpu_node

There's a number of problems:

 - The 'VDSO_CPU_SIZE' doesn't really make it clear that these are number
   of bits, nor does it make it clear which 'CPU' this refers to, i.e.
   that this is about a GDT entry whose limit encodes the CPU and node number.

 - Furthermore, the 'CPU_NUMBER' naming is actively misleading as well,
   because the segment limit encodes not just the CPU number but the
   node ID as well ...

So use a better nomenclature all around: name everything related to this trick
as 'CPUNODE', to make it clear that this is something special, and add
_BITS to make it clear that these are number of bits, and propagate this to
every affected name:

	VDSO_CPU_SIZE         =>  VDSO_CPUNODE_BITS
	VDSO_CPU_MASK         =>  VDSO_CPUNODE_MASK
	__CPU_NUMBER_SEG      =>  __CPUNODE_SEG
	GDT_ENTRY_CPU_NUMBER  =>  GDT_ENTRY_CPUNODE
	vdso_encode_cpu_node  =>  vdso_encode_cpunode
	vdso_read_cpu_node    =>  vdso_read_cpunode

This, beyond being less confusing, also makes it easier to grep for all related
functionality:

  $ git grep -i cpunode arch/x86

Also, while at it, fix "return is not a function" style sloppiness in vdso_encode_cpunode().

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chang S. Bae <chang.seok.bae@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Markus T Metzger <markus.t.metzger@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/1537312139-5580-2-git-send-email-chang.seok.bae@intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Currently the CPU/node NR segment descriptor (GDT_ENTRY_CPU_NUMBER) is
initialized relatively late during CPU init, from the vCPU code, which
has a number of disadvantages, such as hotplug CPU notifiers and SMP
cross-calls.

Instead just initialize it much earlier, directly in cpu_init().

This reduces complexity and increases robustness.

[ mingo: Wrote new changelog. ]
Suggested-by: NH. Peter Anvin <hpa@zytor.com>
Suggested-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NChang S. Bae <chang.seok.bae@intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Markus T Metzger <markus.t.metzger@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1537312139-5580-9-git-send-email-chang.seok.bae@intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Clean up the CPU/node number related code a bit, to make it more apparent
how we are encoding/extracting the CPU and node fields from the
segment limit.

No change in functionality intended.

[ mingo: Wrote new changelog. ]
Suggested-by: NAndy Lutomirski <luto@kernel.org>
Suggested-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NChang S. Bae <chang.seok.bae@intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Markus T Metzger <markus.t.metzger@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: Rik van Riel <riel@surriel.com>
Link: http://lkml.kernel.org/r/1537312139-5580-8-git-send-email-chang.seok.bae@intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

The old 'per CPU' naming was misleading: 64-bit kernels don't use this
GDT entry for per CPU data, but to store the CPU (and node) ID.

[ mingo: Wrote new changelog. ]
Suggested-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NChang S. Bae <chang.seok.bae@intel.com>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NAndy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Markus T Metzger <markus.t.metzger@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: Rik van Riel <riel@surriel.com>
Link: http://lkml.kernel.org/r/1537312139-5580-7-git-send-email-chang.seok.bae@intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

vgetcyc() is full of barriers, so fetching values out of the vvar
page before vgetcyc() for use after vgetcyc() results in poor code
generation.  Put vgetcyc() first to avoid this problem.

Also, pull the tv_sec division into the loop and put all the ts
writes together.  The old code wrote ts->tv_sec on each iteration
before the syscall fallback check and then added in the offset
afterwards, which forced the compiler to pointlessly copy base->sec
to ts->tv_sec on each iteration.  The new version seems to generate
sensible code.

Saves several cycles.  With this patch applied, the result is faster
than before the clock_gettime() rewrite.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/3c05644d010b72216aa286a6d20b5078d5fae5cd.1538762487.git.luto@kernel.org

When a vDSO clock function falls back to the syscall, no special
barriers or ordering is needed, and the syscall fallbacks don't
clobber any memory that is not explicitly listed in the asm
constraints.  Remove the "memory" clobber.

This causes minor changes to the generated code, but otherwise has
no obvious performance impact.  I think it's nice to have, though,
since it may help the optimizer in the future.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/3a7438f5fb2422ed881683d2ccffd7f987b2dc44.1538689401.git.luto@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

Dereferencing gtod->cycle_last all over the place and foing the cycles <
last comparison in the vclock read functions generates horrible code. Doing
it at the call site is much better and gains a few cycles both for TSC and
pvclock.

Caveat: This adds the comparison to the hyperv vclock as well, but I have
no way to test that.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NAndy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Matt Rickard <matt@softrans.com.au>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: devel@linuxdriverproject.org
Cc: virtualization@lists.linux-foundation.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Juergen Gross <jgross@suse.com>
Link: https://lkml.kernel.org/r/20180917130707.741440803@linutronix.de

The code flow for the vclocks is convoluted as it requires the vclocks
which can be invalidated separately from the vsyscall_gtod_data sequence to
store the fact in a separate variable. That's inefficient.

Restructure the code so the vclock readout returns cycles and the
conversion to nanoseconds is handled at the call site.

If the clock gets invalidated or vclock is already VCLOCK_NONE, return
U64_MAX as the cycle value, which is invalid for all clocks and leave the
sequence loop immediately in that case by calling the fallback function
directly.

This allows to remove the gettimeofday fallback as it now uses the
clock_gettime() fallback and does the nanoseconds to microseconds
conversion in the same way as it does when the vclock is functional. It
does not make a difference whether the division by 1000 happens in the
kernel fallback or in userspace.

Generates way better code and gains a few cycles back.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NAndy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Matt Rickard <matt@softrans.com.au>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: devel@linuxdriverproject.org
Cc: virtualization@lists.linux-foundation.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Juergen Gross <jgross@suse.com>
Link: https://lkml.kernel.org/r/20180917130707.657928937@linutronix.de

Now that the time getter functions use the clockid as index into the
storage array for the base time access, the switch case can be replaced.

- Check for clockid >= MAX_CLOCKS and for negative clockid (CPU/FD) first
  and call the fallback function right away.

- After establishing that clockid is < MAX_CLOCKS, convert the clockid to a
  bitmask

- Check for the supported high resolution and coarse functions by anding
  the bitmask of supported clocks and check whether a bit is set.

This completely avoids jump tables, reduces the number of conditionals and
makes the VDSO extensible for other clock ids.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NAndy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Matt Rickard <matt@softrans.com.au>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: devel@linuxdriverproject.org
Cc: virtualization@lists.linux-foundation.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Juergen Gross <jgross@suse.com>
Link: https://lkml.kernel.org/r/20180917130707.574315796@linutronix.de

do_realtime_coarse() and do_monotonic_coarse() are now the same except for
the storage array index. Hand the index in as an argument and collapse the
functions.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NAndy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Matt Rickard <matt@softrans.com.au>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: devel@linuxdriverproject.org
Cc: virtualization@lists.linux-foundation.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Juergen Gross <jgross@suse.com>
Link: https://lkml.kernel.org/r/20180917130707.490733779@linutronix.de

do_realtime() and do_monotonic() are now the same except for the storage
array index. Hand the index in as an argument and collapse the functions.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NAndy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Matt Rickard <matt@softrans.com.au>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: devel@linuxdriverproject.org
Cc: virtualization@lists.linux-foundation.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Juergen Gross <jgross@suse.com>
Link: https://lkml.kernel.org/r/20180917130707.407955860@linutronix.de

It's desired to support more clocks in the VDSO, e.g. CLOCK_TAI. This
results either in indirect calls due to the larger switch case, which then
requires retpolines or when the compiler is forced to avoid jump tables it
results in even more conditionals.

To avoid both variants which are bad for performance the high resolution
functions and the coarse grained functions will be collapsed into one for
each. That requires to store the clock specific base time in an array.

Introcude struct vgtod_ts for storage and convert the data store, the
update function and the individual clock functions over to use it.

The new storage does not longer use gtod_long_t for seconds depending on 32
or 64 bit compile because this needs to be the full 64bit value even for
32bit when a Y2038 function is added. No point in keeping the distinction
alive in the internal representation.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NAndy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Matt Rickard <matt@softrans.com.au>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: devel@linuxdriverproject.org
Cc: virtualization@lists.linux-foundation.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Juergen Gross <jgross@suse.com>
Link: https://lkml.kernel.org/r/20180917130707.324679401@linutronix.de

The sequence count in vgtod_data is unsigned int, but the call sites use
unsigned long, which is a pointless exercise. Fix the call sites and
replace 'unsigned' with unsinged 'int' while at it.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NAndy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Matt Rickard <matt@softrans.com.au>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: devel@linuxdriverproject.org
Cc: virtualization@lists.linux-foundation.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Juergen Gross <jgross@suse.com>
Link: https://lkml.kernel.org/r/20180917130707.236250416@linutronix.de

All VDSO clock sources are TSC based and use CLOCKSOURCE_MASK(64). There is
no point in masking with all FF. Get rid of it and enforce the mask in the
sanity checker.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NAndy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Matt Rickard <matt@softrans.com.au>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: devel@linuxdriverproject.org
Cc: virtualization@lists.linux-foundation.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Juergen Gross <jgross@suse.com>
Link: https://lkml.kernel.org/r/20180917130707.151963007@linutronix.de

When I added the missing memory outputs, I failed to update the
index of the first argument (ebx) on 32-bit builds, which broke the
fallbacks.  Somehow I must have screwed up my testing or gotten
lucky.

Add another test to cover gettimeofday() as well.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Fixes: 715bd9d1 ("x86/vdso: Fix asm constraints on vDSO syscall fallbacks")
Link: http://lkml.kernel.org/r/21bd45ab04b6d838278fa5bebfa9163eceffa13c.1538608971.git.luto@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

When I fixed the vDSO build to use inline retpolines, I messed up
the Makefile logic and made it unconditional.  It should have
depended on CONFIG_RETPOLINE and on the availability of compiler
support.  This broke the build on some older compilers.

Reported-by: nikola.ciprich@linuxbox.cz
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Rickard <matt@softrans.com.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: jason.vas.dias@gmail.com
Cc: stable@vger.kernel.org
Fixes: 2e549b2e ("x86/vdso: Fix vDSO build if a retpoline is emitted")
Link: http://lkml.kernel.org/r/08a1f29f2c238dd1f493945e702a521f8a5aa3ae.1538540801.git.luto@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

The syscall fallbacks in the vDSO have incorrect asm constraints.
They are not marked as writing to their outputs -- instead, they are
marked as clobbering "memory", which is useless.  In particular, gcc
is smart enough to know that the timespec parameter hasn't escaped,
so a memory clobber doesn't clobber it.  And passing a pointer as an
asm *input* does not tell gcc that the pointed-to value is changed.

Add in the fact that the asm instructions weren't volatile, and gcc
was free to omit them entirely unless their sole output (the return
value) is used.  Which it is (phew!), but that stops happening with
some upcoming patches.

As a trivial example, the following code:

void test_fallback(struct timespec *ts)
{
	vdso_fallback_gettime(CLOCK_MONOTONIC, ts);
}

compiles to:

00000000000000c0 <test_fallback>:
  c0:   c3                      retq

To add insult to injury, the RCX and R11 clobbers on 64-bit
builds were missing.

The "memory" clobber is also unnecessary -- no ordering with respect to
other memory operations is needed, but that's going to be fixed in a
separate not-for-stable patch.

Fixes: 2aae950b ("x86_64: Add vDSO for x86-64 with gettimeofday/clock_gettime/getcpu")
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/2c0231690551989d2fafa60ed0e7b5cc8b403908.1538422295.git.luto@kernel.org

Currently, if the vDSO ends up containing an indirect branch or
call, GCC will emit the "external thunk" style of retpoline, and it
will fail to link.

Fix it by building the vDSO with inline retpoline thunks.

I haven't seen any reports of this triggering on an unpatched
kernel.

Fixes: commit 76b04384 ("x86/retpoline: Add initial retpoline support")
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NMatt Rickard <matt@softrans.com.au>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jason Vas Dias <jason.vas.dias@gmail.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/c76538cd3afbe19c6246c2d1715bc6a60bd63985.1534448381.git.luto@kernel.org

The vdso{32,64}.so can fail to link with CC=clang when clang tries to find
a suitable GCC toolchain to link these libraries with.

/usr/bin/ld: arch/x86/entry/vdso/vclock_gettime.o:
  access beyond end of merged section (782)

This happens because the host environment leaked into the cross compiler
environment due to the way clang searches for suitable GCC toolchains.

Clang is a retargetable compiler, and each invocation of it must provide
--target=<something> --gcc-toolchain=<something> to allow it to find the
correct binutils for cross compilation. These flags had been added to
KBUILD_CFLAGS, but the vdso code uses CC and not KBUILD_CFLAGS (for various
reasons) which breaks clang's ability to find the correct linker when cross
compiling.

Most of the time this goes unnoticed because the host linker is new enough
to work anyway, or is incompatible and skipped, but this cannot be reliably
assumed.

This change alters the vdso makefile to just use LD directly, which
bypasses clang and thus the searching problem. The makefile will just use
${CROSS_COMPILE}ld instead, which is always what we want. This matches the
method used to link vmlinux.

This drops references to DISABLE_LTO; this option doesn't seem to be set
anywhere, and not knowing what its possible values are, it's not clear how
to convert it from CC to LD flag.
Signed-off-by: NAlistair Strachan <astrachan@google.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NAndy Lutomirski <luto@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: kernel-team@android.com
Cc: joel@joelfernandes.org
Cc: Andi Kleen <andi.kleen@intel.com>
Link: https://lkml.kernel.org/r/20180803173931.117515-1-astrachan@google.com

The vDSO needs to have a unique build id in a similar manner
to the kernel and modules. Use the build salt macro.
Acked-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NLaura Abbott <labbott@redhat.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

No reason to use 'define' directive here.  Just use the = operator.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1530582614-5173-3-git-send-email-yamada.masahiro@socionext.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Let's put generated files to $(obj)/ rather than $(src)/ although
this is just a matter of taste because both are the same.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: user-mode-linux-devel@lists.sourceforge.net
Cc: user-mode-linux-user@lists.sourceforge.net
Link: http://lkml.kernel.org/r/1526352744-28229-4-git-send-email-yamada.masahiro@socionext.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

CPPFLAGS_vdso.lds is assigned and referenced internally in each
Makefile.  No need to export it.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: user-mode-linux-devel@lists.sourceforge.net
Cc: user-mode-linux-user@lists.sourceforge.net
Link: http://lkml.kernel.org/r/1526352744-28229-3-git-send-email-yamada.masahiro@socionext.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Since commit bfad381c ("x86/vdso: Improve the fake section
headers"), $(vobjs-nox32) is empty.  Therefore, $(vobjs64-for-x32)
is the same as $(vobjs-y).
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1526352744-28229-2-git-send-email-yamada.masahiro@socionext.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

commit da861e18 ("x86, vdso: Get rid of the fake section mechanism")
left this file behind; nothing is using it anymore.
Signed-off-by: NJann Horn <jannh@google.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: hpa@zytor.com
Cc: luto@amacapital.net
Link: https://lkml.kernel.org/r/20180504175935.104085-1-jannh@google.com