x86: Prepare asm files for straight-line-speculation

Replace all ret/retq instructions with RET in preparation of making
RET a macro. Since AS is case insensitive it's a big no-op without
RET defined.

find arch/x86/ -name \*.S | while read file
do
sed -i 's/\<ret[q]*\>/RET/' $file
done

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211204134907.905503893@infradead.org

x86/alternative: Merge include files

Merge arch/x86/include/asm/alternative-asm.h into
arch/x86/include/asm/alternative.h in order to make it easier to use
common definitions later.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210311142319.4723-2-jgross@suse.com

x86/asm/32: Change all ENTRY+ENDPROC to SYM_FUNC_*

These are all functions which are invoked from elsewhere, so annotate
them as global using the new SYM_FUNC_START and their ENDPROC's by
SYM_FUNC_END.

Now, ENTRY/ENDPROC can be forced to be undefined on X86, so do so.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Allison Randal <allison@lohutok.net>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Andy Shevchenko <andy@infradead.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Bill Metzenthen <billm@melbpc.org.au>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Darren Hart <dvhart@infradead.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-arch@vger.kernel.org
Cc: linux-crypto@vger.kernel.org
Cc: linux-efi <linux-efi@vger.kernel.org>
Cc: linux-efi@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: platform-driver-x86@vger.kernel.org
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20191011115108.12392-28-jslaby@suse.cz

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

x86/debug: Remove perpetually broken, unmaintainable dwarf annotations

So the dwarf2 annotations in low level assembly code have
become an increasing hindrance: unreadable, messy macros
mixed into some of the most security sensitive code paths
of the Linux kernel.

These debug info annotations don't even buy the upstream
kernel anything: dwarf driven stack unwinding has caused
problems in the past so it's out of tree, and the upstream
kernel only uses the much more robust framepointers based
stack unwinding method.

In addition to that there's a steady, slow bitrot going
on with these annotations, requiring frequent fixups.
There's no tooling and no functionality upstream that
keeps it correct.

So burn down the sick forest, allowing new, healthier growth:

27 files changed, 350 insertions(+), 1101 deletions(-)

Someone who has the willingness and time to do this
properly can attempt to reintroduce dwarf debuginfo in x86
assembly code plus dwarf unwinding from first principles,
with the following conditions:

- it should be maximally readable, and maximally low-key to
'ordinary' code reading and maintenance.

- find a build time method to insert dwarf annotations
automatically in the most common cases, for pop/push
instructions that manipulate the stack pointer. This could
be done for example via a preprocessing step that just
looks for common patterns - plus special annotations for
the few cases where we want to depart from the default.
We have hundreds of CFI annotations, so automating most of
that makes sense.

- it should come with build tooling checks that ensure that
CFI annotations are sensible. We've seen such efforts from
the framepointer side, and there's no reason it couldn't be
done on the dwarf side.

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: Frédéric Weisbecker <fweisbec@gmail.com
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jan Beulich <JBeulich@suse.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.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
Signed-off-by: Ingo Molnar <mingo@kernel.org>

x86/asm: Introduce push/pop macros which generate CFI_REL_OFFSET and CFI_RESTORE

Sequences:

pushl_cfi %reg
CFI_REL_OFFSET reg, 0

and:

popl_cfi %reg
CFI_RESTORE reg

happen quite often. This patch adds macros which generate them.

No assembly changes (verified with objdump -dr vmlinux.o).

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1421017655-25561-1-git-send-email-dvlasenk@redhat.com
Link: http://lkml.kernel.org/r/2202eb90f175cf45d1b2d1c64dbb5676a8ad07ad.1424989793.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>

x86: atomic64 assembly improvements

In the "xchg" implementation, %ebx and %ecx don't need to be copied
into %eax and %edx respectively (this is only necessary when desiring
to only read the stored value).

In the "add_unless" implementation, swapping the use of %ecx and %esi
for passing arguments allows %esi to become an input only (i.e.
permitting the register to be re-used to address the same object
without reload).

In "{add,sub}_return", doing the initial read64 through the passed in
%ecx decreases a register dependency.

In "inc_not_zero", a branch can be eliminated by or-ing together the
two halves of the current (64-bit) value, and code size can be further
reduced by adjusting the arithmetic slightly.

v2: Undo the folding of "xchg" and "set".

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Link: http://lkml.kernel.org/r/4F19A2BC020000780006E0DC@nat28.tlf.novell.com
Cc: Luca Barbieri <luca@luca-barbieri.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

x86: Use {push,pop}_cfi in more places

Cleaning up and shortening code...

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Alexander van Heukelum <heukelum@fastmail.fm>
LKML-Reference: <4D6BD35002000078000341DA@vpn.id2.novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

x86-32: Fix atomic64_inc_not_zero return value convention

atomic64_inc_not_zero must return 1 if it perfomed the add and 0 otherwise.
It was doing the opposite thing.

Signed-off-by: Luca Barbieri <luca@luca-barbieri.com>
LKML-Reference: <1267469749-11878-6-git-send-email-luca@luca-barbieri.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

x86-32: Fix atomic64_add_unless return value convention

atomic64_add_unless must return 1 if it perfomed the add and 0 otherwise.
The implementation did the opposite thing.

Reported-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Luca Barbieri <luca@luca-barbieri.com>
LKML-Reference: <1267469749-11878-3-git-send-email-luca@luca-barbieri.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

x86-32: Rewrite 32-bit atomic64 functions in assembly

This patch replaces atomic64_32.c with two assembly implementations,
one for 386/486 machines using pushf/cli/popf and one for 586+ machines
using cmpxchg8b.

The cmpxchg8b implementation provides the following advantages over the
current one:

1. Implements atomic64_add_unless, atomic64_dec_if_positive and
atomic64_inc_not_zero

2. Uses the ZF flag changed by cmpxchg8b instead of doing a comparison

3. Uses custom register calling conventions that reduce or eliminate
register moves to suit cmpxchg8b

4. Reads the initial value instead of using cmpxchg8b to do that.
Currently we use lock xaddl and movl, which seems the fastest.

5. Does not use the lock prefix for atomic64_set
64-bit writes are already atomic, so we don't need that.
We still need it for atomic64_read to avoid restoring a value
changed in the meantime.

6. Allocates registers as well or better than gcc

The 386 implementation provides support for 386 and 486 machines.
386/486 SMP is not supported (we dropped it), but such support can be
added easily if desired.

A pure assembly implementation is required due to the custom calling
conventions, and desire to use %ebp in atomic64_add_return (we need
7 registers...), as well as the ability to use pushf/popf in the 386
code without an intermediate pop/push.

The parameter names are changed to match the convention in atomic_64.h

Changes in v3 (due to rebasing to tip/x86/asm):
- Patches atomic64_32.h instead of atomic_32.h
- Uses the CALL alternative mechanism from commit
1b1d9258181bae199dc940f4bd0298126b9a73d9

Changes in v2:
- Merged 386 and cx8 support in the same patch
- 386 support now done in assembly, C code no longer used at all
- cmpxchg64 is used for atomic64_cmpxchg
- stop using macros, use one-line inline functions instead
- miscellanous changes and improvements

Signed-off-by: Luca Barbieri <luca@luca-barbieri.com>
LKML-Reference: <1267005265-27958-5-git-send-email-luca@luca-barbieri.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>