32-bit userspace will now always see the same vDSO, which is
exactly what used to be the int80 vDSO.  Subsequent patches will
clean it up and make it support SYSENTER and SYSCALL using
alternatives.
Signed-off-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: 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: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/e7e6b3526fa442502e6125fe69486aab50813c32.1444091584.git.luto@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

Putting the vvar area after the vdso text is rather complicated: it
only works of the total length of the vdso text mapping is known at
vdso link time, and the linker doesn't allow symbol addresses to
depend on the sizes of non-allocatable data after the PT_LOAD
segment.

Moving the vvar area before the vdso text will allow is to safely
map non-allocatable data after the vdso text, which is a nice
simplification.
Signed-off-by: NAndy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/156c78c0d93144ff1055a66493783b9e56813983.1405040914.git.luto@amacapital.netSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Using arch_vma_name to give special mappings a name is awkward.  x86
currently implements it by comparing the start address of the vma to
the expected address of the vdso.  This requires tracking the start
address of special mappings and is probably buggy if a special vma
is split or moved.

Improve _install_special_mapping to just name the vma directly.  Use
it to give the x86 vvar area a name, which should make CRIU's life
easier.

As a side effect, the vvar area will show up in core dumps.  This
could be considered weird and is fixable.

[hpa: I say we accept this as-is but be prepared to deal with knocking
 out the vvars from core dumps if this becomes a problem.]

Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: NAndy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/276b39b6b645fb11e345457b503f17b83c2c6fd0.1400538962.git.luto@amacapital.netSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

This unifies the vdso mapping code and teaches it how to map special
pages at addresses corresponding to symbols in the vdso image.  The
new code is used for all vdso variants, but so far only the 32-bit
variants use the new vvar page position.
Signed-off-by: NAndy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/b6d7858ad7b5ac3fd3c29cab6d6d769bc45d195e.1399317206.git.luto@amacapital.netSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Currently, vdso.so files are prepared and analyzed by a combination
of objcopy, nm, some linker script tricks, and some simple ELF
parsers in the kernel.  Replace all of that with plain C code that
runs at build time.

All five vdso images now generate .c files that are compiled and
linked in to the kernel image.

This should cause only one userspace-visible change: the loaded vDSO
images are stripped more heavily than they used to be.  Everything
outside the loadable segment is dropped.  In particular, this causes
the section table and section name strings to be missing.  This
should be fine: real dynamic loaders don't load or inspect these
tables anyway.  The result is roughly equivalent to eu-strip's
--strip-sections option.

The purpose of this change is to enable the vvar and hpet mappings
to be moved to the page following the vDSO load segment.  Currently,
it is possible for the section table to extend into the page after
the load segment, so, if we map it, it risks overlapping the vvar or
hpet page.  This happens whenever the load segment is just under a
multiple of PAGE_SIZE.

The only real subtlety here is that the old code had a C file with
inline assembler that did 'call VDSO32_vsyscall' and a linker script
that defined 'VDSO32_vsyscall = __kernel_vsyscall'.  This most
likely worked by accident: the linker script entry defines a symbol
associated with an address as opposed to an alias for the real
dynamic symbol __kernel_vsyscall.  That caused ld to relocate the
reference at link time instead of leaving an interposable dynamic
relocation.  Since the VDSO32_vsyscall hack is no longer needed, I
now use 'call __kernel_vsyscall', and I added -Bsymbolic to make it
work.  vdso2c will generate an error and abort the build if the
resulting image contains any dynamic relocations, so we won't
silently generate bad vdso images.

(Dynamic relocations are a problem because nothing will even attempt
to relocate the vdso.)
Signed-off-by: NAndy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/2c4fcf45524162a34d87fdda1eb046b2a5cecee7.1399317206.git.luto@amacapital.netSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

It's a declaration of a nonexistent symbol.  We can get rid of the
64-bit versions, too, but that's more intrusive.
Signed-off-by: NAndy Lutomirski <luto@amacapital.net>
Cc: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/2ce2ce18447d8a0b78d44a278a066b6c0af06b32.1395366931.git.luto@amacapital.netSigned-off-by: NH. Peter Anvin <hpa@zytor.com>

This fixes the Xen build and gets rid of a silly header file.
Signed-off-by: NAndy Lutomirski <luto@amacapital.net>
Cc: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/1df77311795aff75f5742c787d277518314a38d3.1395366931.git.luto@amacapital.netSigned-off-by: NH. Peter Anvin <hpa@zytor.com>

This replaces a decent amount of incomprehensible and buggy code
with much more straightforward code.  It also brings the 32-bit vdso
more in line with the 64-bit vdsos, so maybe someday they can share
even more code.

This wastes a small amount of kernel .data and .text space, but it
avoids a couple of allocations on startup, so it should be more or
less a wash memory-wise.
Signed-off-by: NAndy Lutomirski <luto@amacapital.net>
Cc: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/b8093933fad09ce181edb08a61dcd5d2592e9814.1395352498.git.luto@amacapital.netSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

This patch add the time support for 32 bit a VDSO to a 32 bit kernel.

For 32 bit programs running on a 32 bit kernel, the same mechanism is
used as for 64 bit programs running on a 64 bit kernel.
Reviewed-by: NAndy Lutomirski <luto@amacapital.net>
Signed-off-by: NStefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/1395094933-14252-10-git-send-email-stefani@seibold.netSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

We need the alternatives mechanism for rdtsc_barrier() to work.
Signed-off-by: NStefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/1395094933-14252-9-git-send-email-stefani@seibold.netSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

The compat vDSO is a complicated hack that's needed to maintain
compatibility with a small range of glibc versions.

This removes it and replaces it with a much simpler hack: a config
option to disable the 32-bit vDSO by default.

This also changes the default value of CONFIG_COMPAT_VDSO to n --
users configuring kernels from scratch almost certainly want that
choice.
Signed-off-by: NAndy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/4bb4690899106eb11430b1186d5cc66ca9d1660c.1394751608.git.luto@amacapital.netSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

The address calculated by VDSO32_SYMBOL() is a pointer into
userland. Add the __user annotation to fix related sparse
warnings in its users.
Signed-off-by: NMathias Krause <minipli@googlemail.com>
Cc: Andy Lutomirski <luto@MIT.EDU>
Link: http://lkml.kernel.org/r/1346621506-30857-3-git-send-email-minipli@googlemail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

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: NAndy 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%3ESigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Change header guards named "ASM_X86__*" to "_ASM_X86_*" since:

a. the double underscore is ugly and pointless.
b. no leading underscore violates namespace constraints.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

This patch is the result of an automatic script that consolidates the
format of all the headers in include/asm-x86/.

The format:

1. No leading underscore. Names with leading underscores are reserved.
2. Pathname components are separated by two underscores. So we can
   distinguish between mm_types.h and mm/types.h.
3. Everything except letters and numbers are turned into single
   underscores.
Signed-off-by: NVegard Nossum <vegard.nossum@gmail.com>

AMD only supports "syscall" from 32-bit compat usermode.
Intel and Centaur(?) only support "sysenter" from 32-bit compat usermode.

Set the X86 feature bits accordingly, and set up the vdso in
accordance with those bits.  On the offchance we run on in a 64-bit
environment which supports neither syscall nor sysenter from 32-bit
mode, then fall back to the int $0x80 vdso.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Before:
   total: 0 errors, 3 warnings, 685 lines checked
After:
   total: 0 errors, 1 warnings, 678 lines checked

No code changed:

arch/x86/kernel/signal_32.o:

   text	   data	    bss	    dec	    hex	filename
   5333	      0	      4	   5337	   14d9	signal_32.o.before
   5333	      0	      4	   5337	   14d9	signal_32.o.after

md5:
   c279e98012a2808e90cfa2a7787e42a4  signal_32.o.before.asm
   c279e98012a2808e90cfa2a7787e42a4  signal_32.o.after.asm
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This makes the i386 kernel use the new vDSO build in arch/x86/vdso/vdso32/
to replace the old one from arch/x86/kernel/.
Signed-off-by: NRoland McGrath <roland@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

This patch changes the kernel's references to addresses in the vDSO image
to be based on the symbols defined by vdso-syms.lds instead of the old
vdso-syms.o symbols.  This is all wrapped up in a macro defined by the new
asm-x86/vdso.h header; that's the only place in the kernel source that has
to know the details of the scheme for getting vDSO symbol values.
Signed-off-by: NRoland McGrath <roland@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>