x86/bugs: Rename CONFIG_RETHUNK => CONFIG_MITIGATION_RETHUNK

Step 10/10 of the namespace unification of CPU mitigations related Kconfig options.

[ mingo: Added one more case. ]

Suggested-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20231121160740.1249350-11-leitao@debian.org

x86/bugs: Rename CONFIG_SLS => CONFIG_MITIGATION_SLS

Step 6/10 of the namespace unification of CPU mitigations related Kconfig options.

Suggested-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20231121160740.1249350-7-leitao@debian.org

x86/bugs: Rename CONFIG_RETPOLINE => CONFIG_MITIGATION_RETPOLINE

Step 5/10 of the namespace unification of CPU mitigations related Kconfig options.

[ mingo: Converted a few more uses in comments/messages as well. ]

Suggested-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Ariel Miculas <amiculas@cisco.com>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20231121160740.1249350-6-leitao@debian.org

x86/asm: Fix build of UML with KASAN

Building UML with KASAN fails since commit 69d4c0d32186 ("entry, kasan,
x86: Disallow overriding mem*() functions") with the following errors:

$ tools/testing/kunit/kunit.py run --kconfig_add CONFIG_KASAN=y
...
ld: mm/kasan/shadow.o: in function `memset':
shadow.c:(.text+0x40): multiple definition of `memset';
arch/x86/lib/memset_64.o:(.noinstr.text+0x0): first defined here
ld: mm/kasan/shadow.o: in function `memmove':
shadow.c:(.text+0x90): multiple definition of `memmove';
arch/x86/lib/memmove_64.o:(.noinstr.text+0x0): first defined here
ld: mm/kasan/shadow.o: in function `memcpy':
shadow.c:(.text+0x110): multiple definition of `memcpy';
arch/x86/lib/memcpy_64.o:(.noinstr.text+0x0): first defined here

UML does not use GENERIC_ENTRY and is still supposed to be allowed to
override the mem*() functions, so use weak aliases in that case.

Fixes: 69d4c0d32186 ("entry, kasan, x86: Disallow overriding mem*() functions")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20230918-uml-kasan-v3-1-7ad6db477df6@axis.com

x86/ibt: Suppress spurious ENDBR

It was reported that under certain circumstances GCC emits ENDBR
instructions for _THIS_IP_ usage. Specifically, when it appears at the
start of a basic block -- but not elsewhere.

Since _THIS_IP_ is never used for control flow, these ENDBR
instructions are completely superfluous. Override the _THIS_IP_
definition for x86_64 to avoid this.

Less ENDBR instructions is better.

Fixes: 156ff4a544ae ("x86/ibt: Base IBT bits")
Reported-by: David Kaplan <David.Kaplan@amd.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230802110323.016197440@infradead.org

x86/linkage: Fix typo of BUILD_VDSO in asm/linkage.h

The BUILD_VDSO macro was incorrectly spelled as BULID_VDSO in
asm/linkage.h. This causes the !defined(BULID_VDSO) directive to always
evaluate to true.

Correct the spelling to BUILD_VDSO.

Fixes: bea75b33895f ("x86/Kconfig: Introduce function padding")
Signed-off-by: Jinghao Jia <jinghao@linux.ibm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Cc: <stable@kernel.org>
Link: https://lore.kernel.org/r/20230808182353.76218-1-jinghao@linux.ibm.com

x86/linkage: Fix padding for typed functions

CFI typed functions are failing to get padded properly for
CONFIG_CALL_PADDING.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/721f0da48d2a49fe907225711b8b76a2b787f9a8.1681331135.git.jpoimboe@kernel.org

x86/ibt: Implement FineIBT

Implement an alternative CFI scheme that merges both the fine-grained
nature of kCFI but also takes full advantage of the coarse grained
hardware CFI as provided by IBT.

To contrast:

kCFI is a pure software CFI scheme and relies on being able to read
text -- specifically the instruction *before* the target symbol, and
does the hash validation *before* doing the call (otherwise control
flow is compromised already).

FineIBT is a software and hardware hybrid scheme; by ensuring every
branch target starts with a hash validation it is possible to place
the hash validation after the branch. This has several advantages:

o the (hash) load is avoided; no memop; no RX requirement.

o IBT WAIT-FOR-ENDBR state is a speculation stop; by placing
the hash validation in the immediate instruction after
the branch target there is a minimal speculation window
and the whole is a viable defence against SpectreBHB.

o Kees feels obliged to mention it is slightly more vulnerable
when the attacker can write code.

Obviously this patch relies on kCFI, but additionally it also relies
on the padding from the call-depth-tracking patches. It uses this
padding to place the hash-validation while the call-sites are
re-written to modify the indirect target to be 16 bytes in front of
the original target, thus hitting this new preamble.

Notably, there is no hardware that needs call-depth-tracking (Skylake)
and supports IBT (Tigerlake and onwards).

Suggested-by: Joao Moreira (Intel) <joao@overdrivepizza.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221027092842.634714496@infradead.org

x86/Kconfig: Introduce function padding

Now that all functions are 16 byte aligned, add 16 bytes of NOP
padding in front of each function. This prepares things for software
call stack tracking and kCFI/FineIBT.

This significantly increases kernel .text size, around 5.1% on a
x86_64-defconfig-ish build.

However, per the random access argument used for alignment, these 16
extra bytes are code that wouldn't be used. Performance measurements
back this up by showing no significant performance regressions.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111146.950884492@infradead.org

x86/asm: Differentiate between code and function alignment

Create SYM_F_ALIGN to differentiate alignment requirements between
SYM_CODE and SYM_FUNC.

This distinction is useful later when adding padding in front of
functions; IOW this allows following the compiler's
patchable-function-entry option.

[peterz: Changelog]

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111143.824822743@infradead.org

arch: Introduce CONFIG_FUNCTION_ALIGNMENT

Generic function-alignment infrastructure.

Architectures can select FUNCTION_ALIGNMENT_xxB symbols; the
FUNCTION_ALIGNMENT symbol is then set to the largest such selected
size, 0 otherwise.

From this the -falign-functions compiler argument and __ALIGN macro
are set.

This incorporates the DEBUG_FORCE_FUNCTION_ALIGN_64B knob and future
alignment requirements for x86_64 (later in this series) into a single
place.

NOTE: also removes the 0x90 filler byte from the generic __ALIGN
primitive, that value makes no sense outside of x86.

NOTE: .balign 0 reverts to a no-op.

Requested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111143.719248727@infradead.org

x86: Add types to indirectly called assembly functions

With CONFIG_CFI_CLANG, assembly functions indirectly called
from C code must be annotated with type identifiers to pass CFI
checking. Define the __CFI_TYPE helper macro to match the compiler
generated function preamble, and ensure SYM_TYPED_FUNC_START also
emits ENDBR with IBT.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220908215504.3686827-21-samitolvanen@google.com

x86/retbleed: Add fine grained Kconfig knobs

Do fine-grained Kconfig for all the various retbleed parts.

NOTE: if your compiler doesn't support return thunks this will
silently 'upgrade' your mitigation to IBPB, you might not like this.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>

x86: Use return-thunk in asm code

Use the return thunk in asm code. If the thunk isn't needed, it will
get patched into a RET instruction during boot by apply_returns().

Since alternatives can't handle relocations outside of the first
instruction, putting a 'jmp __x86_return_thunk' in one is not valid,
therefore carve out the memmove ERMS path into a separate label and jump
to it.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>

x86/linkage: Add ENDBR to SYM_FUNC_START*()

Ensure the ASM functions have ENDBR on for IBT builds, this follows
the ARM64 example. Unlike ARM64, we'll likely end up overwriting them
with poison.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154317.992708941@infradead.org

x86: Add straight-line-speculation mitigation

Make use of an upcoming GCC feature to mitigate
straight-line-speculation for x86:

https://gcc.gnu.org/g:53a643f8568067d7700a9f2facc8ba39974973d3
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102952
https://bugs.llvm.org/show_bug.cgi?id=52323

It's built tested on x86_64-allyesconfig using GCC-12 and GCC-11.

Maintenance overhead of this should be fairly low due to objtool
validation.

Size overhead of all these additional int3 instructions comes to:

text data bss dec hex filename
22267751 6933356 2011368 31212475 1dc43bb defconfig-build/vmlinux
22804126 6933356 1470696 31208178 1dc32f2 defconfig-build/vmlinux.sls

Or roughly 2.4% additional text.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211204134908.140103474@infradead.org

x86: Prepare inline-asm for straight-line-speculation

Replace all ret/retq instructions with ASM_RET in preparation of
making it more than a single instruction.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20211204134907.964635458@infradead.org

x86/asm: Remove the last GLOBAL user and remove the macro

Convert the remaining 32bit users and remove the GLOBAL macro finally.
In particular, this means to use SYM_ENTRY for the singlestepping hack
region.

Exclude the global definition of GLOBAL from x86 too.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-arch@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20191011115108.12392-20-jslaby@suse.cz

linkage: Introduce new macros for assembler symbols

Introduce new C macros for annotations of functions and data in
assembly. There is a long-standing mess in macros like ENTRY, END,
ENDPROC and similar. They are used in different manners and sometimes
incorrectly.

So introduce macros with clear use to annotate assembly as follows:

a) Support macros for the ones below
SYM_T_FUNC -- type used by assembler to mark functions
SYM_T_OBJECT -- type used by assembler to mark data
SYM_T_NONE -- type used by assembler to mark entries of unknown type

They are defined as STT_FUNC, STT_OBJECT, and STT_NOTYPE
respectively. According to the gas manual, this is the most portable
way. I am not sure about other assemblers, so this can be switched
back to %function and %object if this turns into a problem.
Architectures can also override them by something like ", @function"
if they need.

SYM_A_ALIGN, SYM_A_NONE -- align the symbol?
SYM_L_GLOBAL, SYM_L_WEAK, SYM_L_LOCAL -- linkage of symbols

b) Mostly internal annotations, used by the ones below
SYM_ENTRY -- use only if you have to (for non-paired symbols)
SYM_START -- use only if you have to (for paired symbols)
SYM_END -- use only if you have to (for paired symbols)

c) Annotations for code
SYM_INNER_LABEL_ALIGN -- only for labels in the middle of code
SYM_INNER_LABEL -- only for labels in the middle of code

SYM_FUNC_START_LOCAL_ALIAS -- use where there are two local names for
one function
SYM_FUNC_START_ALIAS -- use where there are two global names for one
function
SYM_FUNC_END_ALIAS -- the end of LOCAL_ALIASed or ALIASed function

SYM_FUNC_START -- use for global functions
SYM_FUNC_START_NOALIGN -- use for global functions, w/o alignment
SYM_FUNC_START_LOCAL -- use for local functions
SYM_FUNC_START_LOCAL_NOALIGN -- use for local functions, w/o
alignment
SYM_FUNC_START_WEAK -- use for weak functions
SYM_FUNC_START_WEAK_NOALIGN -- use for weak functions, w/o alignment
SYM_FUNC_END -- the end of SYM_FUNC_START_LOCAL, SYM_FUNC_START,
SYM_FUNC_START_WEAK, ...

For functions with special (non-C) calling conventions:
SYM_CODE_START -- use for non-C (special) functions
SYM_CODE_START_NOALIGN -- use for non-C (special) functions, w/o
alignment
SYM_CODE_START_LOCAL -- use for local non-C (special) functions
SYM_CODE_START_LOCAL_NOALIGN -- use for local non-C (special)
functions, w/o alignment
SYM_CODE_END -- the end of SYM_CODE_START_LOCAL or SYM_CODE_START

d) For data
SYM_DATA_START -- global data symbol
SYM_DATA_START_LOCAL -- local data symbol
SYM_DATA_END -- the end of the SYM_DATA_START symbol
SYM_DATA_END_LABEL -- the labeled end of SYM_DATA_START symbol
SYM_DATA -- start+end wrapper around simple global data
SYM_DATA_LOCAL -- start+end wrapper around simple local data

==========

The macros allow to pair starts and ends of functions and mark functions
correctly in the output ELF objects.

All users of the old macros in x86 are converted to use these in further
patches.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-arch@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Cc: x86-ml <x86@kernel.org>
Cc: xen-devel@lists.xenproject.org
Link: https://lkml.kernel.org/r/20191011115108.12392-2-jslaby@suse.cz

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

x86/entry/32: Remove asmlinkage_protect()

Now that syscalls are called from C code, which copies the args to
new stack slots instead of overlaying pt_regs, asmlinkage_protect()
is no longer needed.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
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>
Link: http://lkml.kernel.org/r/1462416278-11974-4-git-send-email-brgerst@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

ix86: Tighten asmlinkage_protect() constraints

While the description of the commit that originally introduced
asmlinkage_protect() validly says that this doesn't guarantee
clobbering of the function arguments, using "m" constraints
rather than "g" ones reduces the risk (by making it less
attractive to the compiler to move those variables into
registers) and generally results in better code (because we know
the arguments are in memory anyway, and are frequently - if not
always - used just once, with the second [compiler visible] use
in asmlinkage_protect() itself being a fake one).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: <roland@hack.frob.com>
Cc: <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/50FE84EC02000078000B83B7@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

x86: Get rid of asmregparm

As UML does no longer need asmregparm we can remove it.

Signed-off-by: Richard Weinberger <richard@nod.at>
Cc: namhyung@gmail.com
Cc: davem@davemloft.net
Cc: fweisbec@gmail.com
Cc: dhowells@redhat.com
Link: http://lkml.kernel.org/r/%3C1306189085-29896-1-git-send-email-richard%40nod.at%3E
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

x86: shrink __ALIGN and __ALIGN_STR definitions

Impact: cleanup

1) .p2align 4 and .align 16 are the same meaning
(until a.out format for i386 is used which is
not our case for CONFIG_X86_ALIGNMENT_16 anyway)

2) having 15 as max allowed bytes to be skipped
does not make sense on modulo 16

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
LKML-Reference: <20090309171951.GE9945@localhost>
[ small cleanup, use __stringify(), etc. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

x86: linkage.h - guard assembler specifics by __ASSEMBLY__

Stephen Rothwell reported:

|Today's linux-next build (x86_64 allmodconfig) produced this warning:
|
|In file included from drivers/char/epca.c:49:
|drivers/char/digiFep1.h:7:1: warning: "GLOBAL" redefined
|In file included from include/linux/linkage.h:5,
| from include/linux/kernel.h:11,
| from arch/x86/include/asm/system.h:10,
| from arch/x86/include/asm/processor.h:17,
| from include/linux/prefetch.h:14,
| from include/linux/list.h:6,
| from include/linux/module.h:9,
| from drivers/char/epca.c:29:
|arch/x86/include/asm/linkage.h:55:1: warning: this is the location of the previous definition
|
|Probably introduced by commit 95695547a7db44b88a7ee36cf5df188de267e99e
|("x86: asm linkage - introduce GLOBAL macro") from the x86 tree.

Any assembler specific snippets being placed in headers
are to be protected by __ASSEMBLY__. Fixed.

Also move __ALIGN definition under the same protection as well.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
LKML-Reference: <20090306160833.GB7420@localhost>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

x86: linkage - get rid of _X86 macros

Impact: cleanup

There was an attempt to bring build-time checking for
missed ENTRY_X86/END_X86 and KPROBE... pairs. Using
them will add messy in code. Get just rid of them.
This commit could be easily restored if the need appear
in future.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

x86: asm linkage - introduce GLOBAL macro

If the code is time critical and this entry is called
from other places we use ENTRY to have it globally defined
and especially aligned.

Contrary we have some snippets which are size
critical. So we use plane ".globl name; name:"
directive. Introduce GLOBAL macro for this.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

x86: use regparm(3) for passed-in pt_regs pointer

Some syscalls need to access the pt_regs structure, either to copy
user register state or to modifiy it. This patch adds stubs to load
the address of the pt_regs struct into the %eax register, and changes
the syscalls to take the pointer as an argument instead of relying on
the assumption that the pt_regs structure overlaps the function
arguments.

Drop the use of regparm(1) due to concern about gcc bugs, and to move
in the direction of the eventual removal of regparm(0) for asmlinkage.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

x86: pass in pt_regs pointer for syscalls that need it

Some syscalls need to access the pt_regs structure, either to copy
user register state or to modifiy it. This patch adds stubs to load
the address of the pt_regs struct into the %eax register, and changes
the syscalls to regparm(1) to receive the pt_regs pointer as the
first argument.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

x86: introduce ENTRY(KPROBE_ENTRY)_X86 assembly helpers to catch unbalanced declaration v3

Impact: make ENTRY()/END() macros more capable

It's usefull to catch unbalanced or messed or mixed declarations of ENTRY and
KPROBES. These macros would help a bit.

For example the following code would compile without problems

ENTRY_X86(mcount)
retq
END_X86(mcount)

But if you forget and mess the following form

ENTRY_X86(mcount)
retq
END(mcount)

ENTRY_X86(ftrace_caller)

The assembler will issue the following message:
Error: ENTRY_X86/KPROBE_X86 unbalanced,missed,mixed

Actually the checking is performed at every _X86 macro
so maybe it's good idea to put ENTRY_KPROBE_FINAL_X86
at the end of .S file to be sure you didn't miss anything.

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Alexander van Heukelum <heukelum@mailshack.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

x86: Fix ASM_X86__ header guards

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: H. Peter Anvin <hpa@zytor.com>

x86, um: ... and asm-x86 move

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