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2021-09-19x86/build: Do not add -falign flags unconditionally for clangNathan Chancellor1-3/+9
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>
2021-09-03x86: remove cc-option-yn test for -mtune=Nick Desaulniers1-6/+0
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>
2019-10-03x86/math-emu: Limit MATH_EMULATION to 486SX compatiblesArnd Bergmann1-0/+1
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
2017-11-02License cleanup: add SPDX GPL-2.0 license identifier to files with no licenseGreg Kroah-Hartman1-0/+1
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>
2017-06-25kbuild: remove cc-option-alignMasahiro Yamada1-4/+3
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>
2017-03-30x86/build: Mostly disable '-maccumulate-outgoing-args'Josh Poimboeuf1-18/+0
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>
2012-11-29x86, 386 removal: Remove CONFIG_M386 from KconfigH. Peter Anvin1-1/+0
Remove the CONFIG_M386 symbol from Kconfig so that it cannot be selected. Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Link: http://lkml.kernel.org/r/1354132230-21854-2-git-send-email-hpa@linux.intel.com
2011-04-08x86, cpu: Move AMD Elan Kconfig under "Processor family"Ian Campbell1-1/+1
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>
2010-10-29jump label: Add work around to i386 gcc asm goto bugSteven Rostedt1-1/+12
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: 746357d6a526d6da9d89a2ec645b28406e959c2e) 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>
2009-12-08Merge branch 'x86-fixes-for-linus' of ↵Linus Torvalds1-0/+7
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * '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
2009-11-28x86: Use -maccumulate-outgoing-args for sane mcount prologuesThomas Gleixner1-2/+3
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
2009-11-20x86: Prevent GCC 4.4.x (pentium-mmx et al) function prologue wreckageThomas Gleixner1-0/+6
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=42109 http://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
2009-10-02x86: AMD Geode LX optimizationsMatteo Croce1-1/+1
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>
2009-08-23x86: add specific support for Intel Atom architectureTobias Doerffel1-0/+2
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>
2008-10-13x86: merge winchip-2 and winchip-2a cpu choicesKrzysztof Helt1-1/+0
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>
2008-09-09x86: prevent binutils from being "smart" and generating NOPLs for usH. Peter Anvin1-0/+5
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>
2007-10-25x86: move i386 and x86_64 Makefiles to arch/x86Sam Ravnborg1-0/+47
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>