clang does not support -falign-jumps and only recently gained support
for -falign-loops. When one of the configuration options that adds these
flags is enabled, clang warns and all cc-{disable-warning,option} that
follow fail because -Werror gets added to test for the presence of this
warning:
clang-14: warning: optimization flag '-falign-jumps=0' is not supported
[-Wignored-optimization-argument]
To resolve this, add a couple of cc-option calls when building with
clang; gcc has supported these options since 3.2 so there is no point in
testing for their support. -falign-functions was implemented in clang-7,
-falign-loops was implemented in clang-14, and -falign-jumps has not
been implemented yet.
Link: https://lore.kernel.org/r/YSQE2f5teuvKLkON@Ryzen-9-3900X.localdomain/
Link: https://lore.kernel.org/r/20210824022640.2170859-2-nathan@kernel.org/
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
As noted in the comment, -mtune= has been supported since GCC 3.4. The
minimum required version of GCC to build the kernel (as specified in
Documentation/process/changes.rst) is GCC 4.9.
tune is not immediately expanded. Instead it defines a macro that will
test via cc-option later values for -mtune=. But we can skip the test
whether to use -mtune= vs. -mcpu=.
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
The FPU emulation code is old and fragile in places, try to limit its
use to builds for CPUs that actually use it. As far as I can tell,
this is only true for i486sx compatibles, including the Cyrix 486SLC,
AMD Am486SX and ÉLAN SC410, UMC U5S amd DM&P VortexSX86, all of which
were relatively short-lived and got replaced with i486DX compatible
processors soon after introduction, though some of the embedded versions
remained available much longer.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Bill Metzenthen <billm@melbpc.org.au>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20191001142344.1274185-2-arnd@arndb.de
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>
Documentation/kbuild/makefiles.txt says the change for align options
occurred at GCC 3.0, and Documentation/process/changes.rst says the
minimal supported GCC version is 3.2, so it should be safe to hard-code
-falign* options.
Fix the only user arch/x86/Makefile_32.cpu and remove cc-option-align.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
The GCC '-maccumulate-outgoing-args' flag is enabled for most configs,
mostly because of issues which are no longer relevant. For most
configs, and with most recent versions of GCC, it's no longer needed.
Clarify which cases need it, and only enable it for those cases. Also
produce a compile-time error for the ftrace graph + mcount + '-Os' case,
which will otherwise cause runtime failures.
The main benefit of '-maccumulate-outgoing-args' is that it prevents an
ugly prologue for functions which have aligned stacks. But removing the
option also has some benefits: more readable argument saves, smaller
text size, and (presumably) slightly improved performance.
Here are the object size savings for 32-bit and 64-bit defconfig
kernels:
text data bss dec hex filename
10006710 3543328 1773568 15323606 e9d1d6 vmlinux.x86-32.before
9706358 3547424 1773568 15027350 e54c96 vmlinux.x86-32.after
text data bss dec hex filename
10652105 4537576 843776 16033457 f4a6b1 vmlinux.x86-64.before
10639629 4537576 843776 16020981 f475f5 vmlinux.x86-64.after
That comes out to a 3% text size improvement on x86-32 and a 0.1% text
size improvement on x86-64.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew 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: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170316193133.zrj6gug53766m6nn@treble
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently the option resides under X86_EXTENDED_PLATFORM due to historical
nonstandard A20M# handling. However that is no longer the case and so Elan can
be treated as part of the standard processor choice Kconfig option.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Link: http://lkml.kernel.org/r/1302245177.31620.47.camel@localhost.localdomain
Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
On i386 (not x86_64) early implementations of gcc would have a bug
with asm goto causing it to produce code like the following:
(This was noticed by Peter Zijlstra)
56 pushl 0
67 nopl jmp 0x6f
popl
jmp 0x8c
6f mov
test
je 0x8c
8c mov
call *(%esp)
The jump added in the asm goto skipped over the popl that matched
the pushl 0, which lead up to a quick crash of the system when
the jump was enabled. The nopl is defined in the asm goto () statement
and when tracepoints are enabled, the nop changes to a jump to the label
that was specified by the asm goto. asm goto is suppose to tell gcc that
the code in the asm might jump to an external label. Here gcc obviously
fails to make that work.
The bug report for gcc is here:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46226
The bug only appears on x86 when not compiled with
-maccumulate-outgoing-args. This option is always set on x86_64 and it
is also the work around for a function graph tracer i386 bug.
(See commit: 746357d6a5)
This explains why the bug only showed up on i386 when function graph
tracer was not enabled.
This patch now adds a CONFIG_JUMP_LABEL option that is default
off instead of using jump labels by default. When jump labels are
enabled, the -maccumulate-outgoing-args will be used (causing a
slightly larger kernel image on i386). This option will exist
until we have a way to detect if the gcc compiler in use is safe
to use on all configurations without the work around.
Note, there exists such a test, but for now we will keep the enabling
of jump label as a manual option.
Archs that know the compiler is safe with asm goto, may choose to
select JUMP_LABEL and enable it by default.
Reported-by: Ingo Molnar <mingo@elte.hu>
Cause-discovered-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Baron <jbaron@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: David Daney <ddaney@caviumnetworks.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: David Miller <davem@davemloft.net>
Cc: Richard Henderson <rth@redhat.com>
LKML-Reference: <1288028746.3673.11.camel@laptop>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, mce: don't restart timer if disabled
x86: Use -maccumulate-outgoing-args for sane mcount prologues
x86: Prevent GCC 4.4.x (pentium-mmx et al) function prologue wreckage
x86: AMD Northbridge: Verify NB's node is online
x86 VSDO: Fix Kconfig help
x86: Fix typo in Intel CPU cache size descriptor
x86: Add new Intel CPU cache size descriptors
commit 746357d (x86: Prevent GCC 4.4.x (pentium-mmx et al) function
prologue wreckage) uses -mtune=generic to work around the function
prologue problem with mcount on -march=pentium-mmx and others.
Jakub pointed out that we can use -maccumulate-outgoing-args instead
which is selected by -mtune=generic and prevents the problem without
losing the -march specific optimizations.
Pointed-out-by: Jakub Jelinek <jakub@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: stable@kernel.org
When the kernel is compiled with -pg for tracing GCC 4.4.x inserts
stack alignment of a function _before_ the mcount prologue if the
-march=pentium-mmx is set and -mtune=generic is not set. This breaks
the assumption of the function graph tracer which expects that the
mcount prologue
push %ebp
mov %esp, %ebp
is the first stack operation in a function because it needs to modify
the function return address on the stack to trap into the tracer
before returning to the real caller.
The generated code is:
push %edi
lea 0x8(%esp),%edi
and $0xfffffff0,%esp
pushl -0x4(%edi)
push %ebp
mov %esp,%ebp
so the tracer modifies the copy of the return address which is stored
after the stack alignment and therefor does not trap the return which
in turn breaks the call chain logic of the tracer and leads to a
kernel panic.
Aside of the fact that the generated code is horrible for no good
reason other -march -mtune options generate the expected:
push %ebp
mov %esp,%ebp
and $0xfffffff0,%esp
which does the same and keeps everything intact.
After some experimenting we found out that this problem is restricted
to gcc4.4.x and to the following -march settings:
i586, pentium, pentium-mmx, k6, k6-2, k6-3, winchip-c6, winchip2, c3,
geode
By adding -mtune=generic the code generator produces always the
expected code.
So forcing -mtune=generic when CONFIG_FUNCTION_GRAPH_TRACER=y is not
pretty, but at the moment the only way to prevent that the kernel
trips over gcc-shrooms induced code madness.
Most distro kernels have CONFIG_X86_GENERIC=y anyway which forces
-mtune=generic as well so it will not impact those.
References: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42109http://lkml.org/lkml/2009/11/19/17
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <alpine.LFD.2.00.0911200206570.24119@localhost.localdomain>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
Cc: Jeff Law <law@redhat.com>
Cc: gcc@gcc.gnu.org
Cc: David Daney <ddaney@caviumnetworks.com>
Cc: Andrew Haley <aph@redhat.com>
Cc: Richard Guenther <richard.guenther@gmail.com>
Cc: stable@kernel.org
Add CPU optimizations for AMD Geode LX.
Signed-off-by: Matteo Croce <technoboy85@gmail.com>
LKML-Reference: <40101cc30910010811v5d15ff4cx9dd57c9cc9b4b045@mail.gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Add another option when selecting CPU family so the kernel can be
optimized for Intel Atom CPUs. If GCC supports tuning options for
Intel Atom they will be used.
Signed-off-by: Tobias Doerffel <tobias.doerffel@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
LKML-Reference: <1251018457-19157-1-git-send-email-tobias.doerffel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The Winchip-2 and Winchip-2A cpu choices select the
same options for kernel and compiler.
Merge them to save few bytes and reduce confusion.
Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
binutils, contrary to documented behaviour, will generate long NOPs (a
P6-or-higher instruction which is broken on at least some VIA chips,
Virtual PC/Virtual Server, and some versions of Qemu) depending on the
-mtune= option, which is not supposed to change architectural
behaviour.
Pass an explicit override to the assembler, in case ends up passing
the -mtune= parameter to gas (gcc 4.3.0 does not appear to.)
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Moving the ARCH specific Makefiles for i386 and x86_64
required a litle bit tweaking in the top-lvel Makefile.
SRCARCH is now set in the top-level Makefile
because we need this info to include the correct
arch Makefile.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Nathan Chancellor
Nick Desaulniers
Arnd Bergmann
Greg Kroah-Hartman
Masahiro Yamada
Josh Poimboeuf
H. Peter Anvin
Ian Campbell
Steven Rostedt
Linus Torvalds
Thomas Gleixner
Matteo Croce
Tobias Doerffel
Krzysztof Helt
H. Peter Anvin
Sam Ravnborg