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2017-02-20Linux 4.10v4.10Linus Torvalds1-1/+1
2017-02-13Linux 4.10-rc8v4.10-rc8Linus Torvalds1-1/+1
2017-02-06Linux 4.10-rc7v4.10-rc7Linus Torvalds1-1/+1
2017-02-04jump label: pass kbuild_cflags when checking for asm goto supportDavid Lin1-1/+1
Some versions of ARM GCC compiler such as Android toolchain throws in a '-fpic' flag by default. This causes the gcc-goto check script to fail although some config would have '-fno-pic' flag in the KBUILD_CFLAGS. This patch passes the KBUILD_CFLAGS to the check script so that the script does not rely on the default config from different compilers. Link: http://lkml.kernel.org/r/20170120234329.78868-1-dtwlin@google.com Signed-off-by: David Lin <dtwlin@google.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Cc: Michal Marek <mmarek@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-01-30Linux 4.10-rc6v4.10-rc6Linus Torvalds1-2/+2
2017-01-22Linux 4.10-rc5v4.10-rc5Linus Torvalds1-2/+2
2017-01-16Linux 4.10-rc4v4.10-rc4Linus Torvalds1-1/+1
2017-01-09Linux 4.10-rc3v4.10-rc3Linus Torvalds1-1/+1
2017-01-02Linux 4.10-rc2v4.10-rc2Linus Torvalds1-1/+1
2016-12-26Linux 4.10-rc1v4.10-rc1Linus Torvalds1-2/+2
2016-12-11Linux 4.9v4.9Linus Torvalds1-2/+2
2016-12-04Linux 4.9-rc8v4.9-rc8Linus Torvalds1-1/+1
2016-12-03kbuild: fix building bzImage with CONFIG_TRIM_UNUSED_KSYMS enabledNicolas Pitre1-1/+8
When building a specific target such as bzImage, modules aren't normally built. However if CONFIG_TRIM_UNUSED_KSYMS is enabled, no built modules means none of the exported symbols are used and therefore they will all be trimmed away from the final kernel. A subsequent "make modules" will fail because modpost cannot find the needed symbols for those modules in the kernel binary. Let's make sure modules are also built whenever CONFIG_TRIM_UNUSED_KSYMS is enabled and that the kernel binary is properly rebuilt accordingly. Signed-off-by: Nicolas Pitre <nico@linaro.org> Tested-by: Jarod Wilson <jarod@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-01kbuild: make sure autoksyms.h exists earlyNicolas Pitre1-2/+0
Some people are able to trigger a race where autoksyms.h is used before its empty version is even created. Let's create it at the same time as the directory holding it is created. Signed-off-by: Nicolas Pitre <nico@linaro.org> Tested-by: Prarit Bhargava <prarit@redhat.com> Tested-by: Jarod Wilson <jarod@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-28Linux 4.9-rc7v4.9-rc7Linus Torvalds1-1/+1
2016-11-21Linux 4.9-rc6v4.9-rc6Linus Torvalds1-1/+1
2016-11-19Merge branch 'rc-fixes' of ↵Linus Torvalds1-2/+3
git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild Pull kbuild fixes from Michal Marek: "Here are some regression fixes for kbuild: - modversion support for exported asm symbols (Nick Piggin). The affected architectures need separate patches adding asm-prototypes.h. - fix rebuilds of lib-ksyms.o (Nick Piggin) - -fno-PIE builds (Sebastian Siewior and Borislav Petkov). This is not a kernel regression, but one of the Debian gcc package. Nevertheless, it's quite annoying, so I think it should go into mainline and stable now" * 'rc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild: kbuild: Steal gcc's pie from the very beginning kbuild: be more careful about matching preprocessed asm ___EXPORT_SYMBOL x86/kexec: add -fno-PIE scripts/has-stack-protector: add -fno-PIE kbuild: add -fno-PIE kbuild: modversions for EXPORT_SYMBOL() for asm kbuild: prevent lib-ksyms.o rebuilds
2016-11-15kbuild: Steal gcc's pie from the very beginningBorislav Petkov1-4/+3
So Sebastian turned off the PIE for kernel builds but that was too late - Kbuild.include already uses KBUILD_CFLAGS and trying to disable gcc options with, say cc-disable-warning, fails: gcc -D__KERNEL__ -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs ... -Wno-sign-compare -fno-asynchronous-unwind-tables -Wframe-address -c -x c /dev/null -o .31392.tmp /dev/null:1:0: error: code model kernel does not support PIC mode because that returns an error and we can't disable the warning. For example in this case: KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,) which leads to gcc issuing all those warnings again. So let's turn off PIE/PIC at the earliest possible moment, when we declare KBUILD_CFLAGS so that cc-disable-warning picks it up too. Also, we need the $(call cc-option ...) because -fno-PIE is supported since gcc v3.4 and our lowest supported gcc version is 3.2 right now. Signed-off-by: Borislav Petkov <bp@suse.de> Cc: stable@vger.kernel.org Cc: Ben Hutchings <ben@decadent.org.uk> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Michal Marek <mmarek@suse.com>
2016-11-13Linux 4.9-rc5v4.9-rc5Linus Torvalds1-1/+1
2016-11-11Kbuild: enable -Wmaybe-uninitialized warning for "make W=1"Arnd Bergmann1-4/+6
Traditionally, we have always had warnings about uninitialized variables enabled, as this is part of -Wall, and generally a good idea [1], but it also always produced false positives, mainly because this is a variation of the halting problem and provably impossible to get right in all cases [2]. Various people have identified cases that are particularly bad for false positives, and in commit e74fc973b6e5 ("Turn off -Wmaybe-uninitialized when building with -Os"), I turned off the warning for any build that was done with CC_OPTIMIZE_FOR_SIZE. This drastically reduced the number of false positive warnings in the default build but unfortunately had the side effect of turning the warning off completely in 'allmodconfig' builds, which in turn led to a lot of warnings (both actual bugs, and remaining false positives) to go in unnoticed. With commit 877417e6ffb9 ("Kbuild: change CC_OPTIMIZE_FOR_SIZE definition") enabled the warning again for allmodconfig builds in v4.7 and in v4.8-rc1, I had finally managed to address all warnings I get in an ARM allmodconfig build and most other maybe-uninitialized warnings for ARM randconfig builds. However, commit 6e8d666e9253 ("Disable "maybe-uninitialized" warning globally") was merged at the same time and disabled it completely for all configurations, because of false-positive warnings on x86 that I had not addressed until then. This caused a lot of actual bugs to get merged into mainline, and I sent several dozen patches for these during the v4.9 development cycle. Most of these are actual bugs, some are for correct code that is safe because it is only called under external constraints that make it impossible to run into the case that gcc sees, and in a few cases gcc is just stupid and finds something that can obviously never happen. I have now done a few thousand randconfig builds on x86 and collected all patches that I needed to address every single warning I got (I can provide the combined patch for the other warnings if anyone is interested), so I hope we can get the warning back and let people catch the actual bugs earlier. This reverts the change to disable the warning completely and for now brings it back at the "make W=1" level, so we can get it merged into mainline without introducing false positives. A follow-up patch enables it on all levels unless some configuration option turns it off because of false-positives. Link: https://rusty.ozlabs.org/?p=232 [1] Link: https://gcc.gnu.org/wiki/Better_Uninitialized_Warnings [2] Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-11-09kbuild: add -fno-PIESebastian Andrzej Siewior1-0/+2
Debian started to build the gcc with -fPIE by default so the kernel build ends before it starts properly with: |kernel/bounds.c:1:0: error: code model kernel does not support PIC mode Also add to KBUILD_AFLAGS due to: |gcc -Wp,-MD,arch/x86/entry/vdso/vdso32/.note.o.d … -mfentry -DCC_USING_FENTRY … vdso/vdso32/note.S |arch/x86/entry/vdso/vdso32/note.S:1:0: sorry, unimplemented: -mfentry isn’t supported for 32-bit in combination with -fpic Tagging it stable so it is possible to compile recent stable kernels as well. Cc: stable@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Michal Marek <mmarek@suse.com>
2016-11-06Linux 4.9-rc4v4.9-rc4Linus Torvalds1-1/+1
2016-10-29Linux 4.9-rc3v4.9-rc3Linus Torvalds1-1/+1
2016-10-24Linux 4.9-rc2v4.9-rc2Linus Torvalds1-1/+1
2016-10-15Linux 4.9-rc1v4.9-rc1Linus Torvalds1-2/+2
2016-10-15Merge tag 'linux-kselftest-4.9-rc1-update' of ↵Linus Torvalds1-3/+0
git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest Pull kselftest updates from Shuah Khan: "This update consists of: - Fixes and improvements to existing tests - Moving code from Documentation to selftests, samples, and tools: * Moves dnotify_test, prctl, ptp, vDSO, ia64, watchdog, and networking tests from Documentation to selftests. * Moves mic/mpssd, misc-devices/mei, timers, watchdog, auxdisplay, and blackfin examples from Documentation to samples. * Moves accounting, laptops/dslm, and pcmcia/crc32hash tools from Documentation to tools. * Deletes BUILD_DOCSRC and its dependencies" * tag 'linux-kselftest-4.9-rc1-update' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: (21 commits) selftests/futex: Check ANSI terminal color support Doc: update 00-INDEX files to reflect the runnable code move samples: move blackfin gptimers-example from Documentation tools: move pcmcia crc32hash tool from Documentation tools: move laptops dslm tool from Documentation tools: move accounting tool from Documentation samples: move auxdisplay example code from Documentation samples: move watchdog example code from Documentation samples: move timers example code from Documentation samples: move misc-devices/mei example code from Documentation samples: move mic/mpssd example code from Documentation selftests: Move networking/timestamping from Documentation selftests: move watchdog tests from Documentation/watchdog selftests: move ia64 tests from Documentation/ia64 selftests: move vDSO tests from Documentation/vDSO selftests: move ptp tests from Documentation/ptp selftests: move prctl tests from Documentation/prctl selftests: move dnotify_test from Documentation/filesystems selftests/timers: Add missing error code assignment before test selftests/zram: replace ZRAM_LZ4_COMPRESS ...
2016-10-15Merge branch 'kbuild' of ↵Linus Torvalds1-3/+16
git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild Pull kbuild updates from Michal Marek: - EXPORT_SYMBOL for asm source by Al Viro. This does bring a regression, because genksyms no longer generates checksums for these symbols (CONFIG_MODVERSIONS). Nick Piggin is working on a patch to fix this. Plus, we are talking about functions like strcpy(), which rarely change prototypes. - Fixes for PPC fallout of the above by Stephen Rothwell and Nick Piggin - fixdep speedup by Alexey Dobriyan. - preparatory work by Nick Piggin to allow architectures to build with -ffunction-sections, -fdata-sections and --gc-sections - CONFIG_THIN_ARCHIVES support by Stephen Rothwell - fix for filenames with colons in the initramfs source by me. * 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild: (22 commits) initramfs: Escape colons in depfile ppc: there is no clear_pages to export powerpc/64: whitelist unresolved modversions CRCs kbuild: -ffunction-sections fix for archs with conflicting sections kbuild: add arch specific post-link Makefile kbuild: allow archs to select link dead code/data elimination kbuild: allow architectures to use thin archives instead of ld -r kbuild: Regenerate genksyms lexer kbuild: genksyms fix for typeof handling fixdep: faster CONFIG_ search ia64: move exports to definitions sparc32: debride memcpy.S a bit [sparc] unify 32bit and 64bit string.h sparc: move exports to definitions ppc: move exports to definitions arm: move exports to definitions s390: move exports to definitions m68k: move exports to definitions alpha: move exports to actual definitions x86: move exports to actual definitions ...
2016-10-12Disable the __builtin_return_address() warning globally after allLinus Torvalds1-0/+1
This affectively reverts commit 377ccbb48373 ("Makefile: Mute warning for __builtin_return_address(>0) for tracing only") because it turns out that it really isn't tracing only - it's all over the tree. We already also had the warning disabled separately for mm/usercopy.c (which this commit also removes), and it turns out that we will also want to disable it for get_lock_parent_ip(), that is used for at least TRACE_IRQFLAGS. Which (when enabled) ends up being all over the tree. Steven Rostedt had a patch that tried to limit it to just the config options that actually triggered this, but quite frankly, the extra complexity and abstraction just isn't worth it. We have never actually had a case where the warning is actually useful, so let's just disable it globally and not worry about it. Acked-by: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Anvin <hpa@zytor.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-10samples: move blackfin gptimers-example from DocumentationShuah Khan1-3/+0
Move blackfin gptimers-example to samples and remove it from Documentation Makefile. Update samples Kconfig and Makefile to build gptimers-example. blackfin is the last CONFIG_BUILD_DOCSRC target in Documentation/Makefile. Hence this patch also includes changes to remove CONFIG_BUILD_DOCSRC from Makefile and lib/Kconfig.debug and updates VIDEO_PCI_SKELETON dependency on BUILD_DOCSRC. Documentation/Makefile is not deleted to avoid braking make htmldocs and make distclean. Acked-by: Michal Marek <mmarek@suse.com> Acked-by: Jonathan Corbet <corbet@lwn.net> Reviewed-by: Kees Cook <keescook@chromium.org> Reported-by: Valentin Rothberg <valentinrothberg@gmail.com> Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
2016-10-04Merge tag 'docs-4.9' of git://git.lwn.net/linuxLinus Torvalds1-1/+1
Pull documentation updates from Jonathan Corbet: "This is the documentation update pull for the 4.9 merge window. The Sphinx transition is still creating a fair amount of work. Here we have a number of fixes and, importantly, a proper PDF output solution, thanks to Jani Nikula, Mauro Carvalho Chehab and Markus Heiser. I've started a couple of new books: a driver API book (based on the old device-drivers.tmpl) and a development tools book. Both are meant to show how we can integrate together our existing documentation into a more coherent and accessible whole. It involves moving some stuff around and formatting changes, but, I think, the results are worth it. The good news is that most of our existing Documentation/*.txt files are *almost* in RST format already; the amount of messing around required is minimal. And, of course, there's the usual set of updates, typo fixes, and more" * tag 'docs-4.9' of git://git.lwn.net/linux: (120 commits) URL changed for Linux Foundation TAB dax : Fix documentation with respect to struct pages iio: Documentation: Correct the path used to create triggers. docs: Remove space-before-label guidance from CodingStyle docs-rst: add inter-document cross references Documentation/email-clients.txt: convert it to ReST markup Documentation/kernel-docs.txt: reorder based on timestamp Documentation/kernel-docs.txt: Add dates for online docs Documentation/kernel-docs.txt: get rid of broken docs Documentation/kernel-docs.txt: move in-kernel docs Documentation/kernel-docs.txt: remove more legacy references Documentation/kernel-docs.txt: add two published books Documentation/kernel-docs.txt: sort books per publication date Documentation/kernel-docs.txt: adjust LDD references Documentation/kernel-docs.txt: some improvements on the ReST output Documentation/kernel-docs.txt: Consistent indenting: 4 spaces Documentation/kernel-docs.txt: Add 4 paper/book references Documentation/kernel-docs.txt: Improve layouting of book list Documentation/kernel-docs.txt: Remove offline or outdated entries docs: Clean up bare :: lines ...
2016-10-03Linux 4.8v4.8Linus Torvalds1-1/+1
2016-09-26Linux 4.8-rc8v4.8-rc8Linus Torvalds1-1/+1
2016-09-19Linux 4.8-rc7v4.8-rc7Linus Torvalds1-1/+1
2016-09-12Linux 4.8-rc6v4.8-rc6Linus Torvalds1-1/+1
2016-09-09kbuild: add arch specific post-link MakefileNicholas Piggin1-3/+7
Allow architectures to create arch/xxx/Makefile.postlink with targets for vmlinux, modules.ko, and clean, which will be invoked after final linking of vmlinux and modules. powerpc will use this to check vmlinux linker relocations for sanity, and may use it to fix up alternate instruction patch branch addresses. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michal Marek <mmarek@suse.com>
2016-09-09kbuild: allow archs to select link dead code/data eliminationNicholas Piggin1-0/+9
Introduce LD_DEAD_CODE_DATA_ELIMINATION option for architectures to select to build with -ffunction-sections, -fdata-sections, and link with --gc-sections. It requires some work (documented) to ensure all unreferenced entrypoints are live, and requires toolchain and build verification, so it is made a per-arch option for now. On a random powerpc64le build, this yelds a significant size saving, it boots and runs fine, but there is a lot I haven't tested as yet, so these savings may be reduced if there are bugs in the link. text data bss dec filename 11169741 1180744 1923176 14273661 vmlinux 10445269 1004127 1919707 13369103 vmlinux.dce ~700K text, ~170K data, 6% removed from kernel image size. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michal Marek <mmarek@suse.com>
2016-09-05Linux 4.8-rc5v4.8-rc5Linus Torvalds1-1/+1
2016-08-29Linux 4.8-rc4v4.8-rc4Linus Torvalds1-1/+1
2016-08-23docs-rst: add support for LaTeX outputMauro Carvalho Chehab1-1/+1
Sphinx supports LaTeX output. Sometimes, it is interesting to call it directly, instead of also generating a PDF. As it comes for free, add a target for it. Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2016-08-22Linux 4.8-rc3v4.8-rc3Linus Torvalds1-1/+1
2016-08-15Linux 4.8-rc2v4.8-rc2Linus Torvalds1-1/+1
2016-08-09gcc-plugins: abort builds cleanly when not supportedKees Cook1-7/+0
When the compiler doesn't support gcc plugins (either due to missing headers or too old a version), report the problem and abort the build instead of emitting a warning and letting the build founder with arcane compiler errors. Signed-off-by: Kees Cook <keescook@chromium.org>
2016-08-08Linux 4.8-rc1v4.8-rc1Linus Torvalds1-2/+2
2016-08-04Merge tag 'media/v4.8-5' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media Pull media DocBook removal and some fixups from Mauro Carvalho Chehab: - removal of the media DocBook (since it's all in Sphinx now) - videobuf2: Fix an allocation regression - a few fixes related to the CEC drivers * tag 'media/v4.8-5' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: [media] cec: fix off-by-one memset [media] staging: add MEDIA_SUPPORT dependency [media] vivid: don't handle CEC_MSG_SET_STREAM_PATH [media] media: adv7180: Fix broken interrupt register access [media] vb2: Fix allocation size of dma_parms [media] vim2m: copy the other colorspace-related fields as well [media] adv7511: fix VIC autodetect doc-rst: Remove the media docbook
2016-08-03Merge tag 'trace-v4.8-1' of ↵Linus Torvalds1-1/+0
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing fixes from Steven Rostedt: "A few updates and fixes: - move the suppressing of the __builtin_return_address >0 warning to the tracing directory only. - metag recordmcount fix for newer glibc's - two tracing histogram fixes that were reported by KASAN" * tag 'trace-v4.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: tracing: Fix use-after-free in hist_register_trigger() tracing: Fix use-after-free in hist_unreg_all/hist_enable_unreg_all Makefile: Mute warning for __builtin_return_address(>0) for tracing only ftrace/recordmcount: Work around for addition of metag magic but not relocations
2016-08-02Merge branch 'kbuild' of ↵Linus Torvalds1-22/+23
git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild Pull kbuild updates from Michal Marek: - GCC plugin support by Emese Revfy from grsecurity, with a fixup from Kees Cook. The plugins are meant to be used for static analysis of the kernel code. Two plugins are provided already. - reduction of the gcc commandline by Arnd Bergmann. - IS_ENABLED / IS_REACHABLE macro enhancements by Masahiro Yamada - bin2c fix by Michael Tautschnig - setlocalversion fix by Wolfram Sang * 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild: gcc-plugins: disable under COMPILE_TEST kbuild: Abort build on bad stack protector flag scripts: Fix size mismatch of kexec_purgatory_size kbuild: make samples depend on headers_install Kbuild: don't add obj tree in additional includes Kbuild: arch: look for generated headers in obtree Kbuild: always prefix objtree in LINUXINCLUDE Kbuild: avoid duplicate include path Kbuild: don't add ../../ to include path vmlinux.lds.h: replace config_enabled() with IS_ENABLED() kconfig.h: allow to use IS_{ENABLE,REACHABLE} in macro expansion kconfig.h: use already defined macros for IS_REACHABLE() define export.h: use __is_defined() to check if __KSYM_* is defined kconfig.h: use __is_defined() to check if MODULE is defined kbuild: setlocalversion: print error to STDERR Add sancov plugin Add Cyclomatic complexity GCC plugin GCC plugin infrastructure Shared library support
2016-08-02Makefile: Mute warning for __builtin_return_address(>0) for tracing onlySteven Rostedt1-1/+0
With the latest gcc compilers, they give a warning if __builtin_return_address() parameter is greater than 0. That is because if it is used by a function called by a top level function (or in the case of the kernel, by assembly), it can try to access stack frames outside the stack and crash the system. The tracing system uses __builtin_return_address() of up to 2! But it is well aware of the dangers that it may have, and has even added precautions to protect against it (see the thunk code in arch/x86/entry/thunk*.S) Linus originally added KBUILD_CFLAGS that would suppress the warning for the entire kernel, as simply adding KBUILD_CFLAGS to the tracing directory wouldn't work. The tracing directory plays a bit with the CFLAGS and requires a little more logic. This adds that special logic to only suppress the warning for the tracing directory. If it is used anywhere else outside of tracing, the warning will still be triggered. Link: http://lkml.kernel.org/r/20160728223043.51996267@grimm.local.home Tested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2016-07-29doc-rst: Remove the media docbookMauro Carvalho Chehab1-1/+1
Now that all media documentation was converted to Sphinx, we should get rid of the old DocBook one, as we don't want people to submit patches against the old stuff. Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com> Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
2016-07-28Disable "frame-address" warningLinus Torvalds1-0/+1
Newer versions of gcc warn about the use of __builtin_return_address() with a non-zero argument when "-Wall" is specified: kernel/trace/trace_irqsoff.c: In function ‘stop_critical_timings’: kernel/trace/trace_irqsoff.c:433:86: warning: calling ‘__builtin_return_address’ with a nonzero argument is unsafe [-Wframe-address] stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1); [ .. repeats a few times for other similar cases .. ] It is true that a non-zero argument is somewhat dangerous, and we do not actually have very many uses of that in the kernel - but the ftrace code does use it, and as Stephen Rostedt says: "We are well aware of the danger of using __builtin_return_address() of > 0. In fact that's part of the reason for having the "thunk" code in x86 (See arch/x86/entry/thunk_{64,32}.S). [..] it adds extra frames when tracking irqs off sections, to prevent __builtin_return_address() from accessing bad areas. In fact the thunk_32.S states: 'Trampoline to trace irqs off. (otherwise CALLER_ADDR1 might crash)'." For now, __builtin_return_address() with a non-zero argument is the best we can do, and the warning is not helpful and can end up making people miss other warnings for real problems. So disable the frame-address warning on compilers that need it. Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-27Disable "maybe-uninitialized" warning globallyLinus Torvalds1-3/+4
Several build configurations had already disabled this warning because it generates a lot of false positives. But some had not, and it was still enabled for "allmodconfig" builds, for example. Looking at the warnings produced, every single one I looked at was a false positive, and the warnings are frequent enough (and big enough) that they can easily hide real problems that you don't notice in the noise generated by -Wmaybe-uninitialized. The warning is good in theory, but this is a classic case of a warning that causes more problems than the warning can solve. If gcc gets better at avoiding false positives, we may be able to re-enable this warning. But as is, we're better off without it, and I want to be able to see the *real* warnings. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>