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2022-09-26treewide: Drop WARN_ON_FUNCTION_MISMATCHSami Tolvanen1-16/+0
CONFIG_CFI_CLANG no longer breaks cross-module function address equality, which makes WARN_ON_FUNCTION_MISMATCH unnecessary. Remove the definition and switch back to WARN_ON_ONCE. 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/20220908215504.3686827-15-samitolvanen@google.com
2022-04-26bug: Have __warn() prototype defined unconditionallyShida Zhang1-5/+6
The __warn() prototype is declared in CONFIG_BUG scope but the function definition in panic.c is unconditional. The IBT enablement started using it unconditionally but a CONFIG_X86_KERNEL_IBT=y, CONFIG_BUG=n .config will trigger a arch/x86/kernel/traps.c: In function ‘__exc_control_protection’: arch/x86/kernel/traps.c:249:17: error: implicit declaration of function \ ‘__warn’; did you mean ‘pr_warn’? [-Werror=implicit-function-declaration] Pull up the declarations so that they're unconditionally visible too. [ bp: Rewrite commit message. ] Fixes: 991625f3dd2c ("x86/ibt: Add IBT feature, MSR and #CP handling") Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Shida Zhang <zhangshida@kylinos.cn> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20220426032007.510245-1-starzhangzsd@gmail.com
2021-07-02Merge branch 'akpm' (patches from Andrew)Linus Torvalds1-1/+2
Merge more updates from Andrew Morton: "190 patches. Subsystems affected by this patch series: mm (hugetlb, userfaultfd, vmscan, kconfig, proc, z3fold, zbud, ras, mempolicy, memblock, migration, thp, nommu, kconfig, madvise, memory-hotplug, zswap, zsmalloc, zram, cleanups, kfence, and hmm), procfs, sysctl, misc, core-kernel, lib, lz4, checkpatch, init, kprobes, nilfs2, hfs, signals, exec, kcov, selftests, compress/decompress, and ipc" * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (190 commits) ipc/util.c: use binary search for max_idx ipc/sem.c: use READ_ONCE()/WRITE_ONCE() for use_global_lock ipc: use kmalloc for msg_queue and shmid_kernel ipc sem: use kvmalloc for sem_undo allocation lib/decompressors: remove set but not used variabled 'level' selftests/vm/pkeys: exercise x86 XSAVE init state selftests/vm/pkeys: refill shadow register after implicit kernel write selftests/vm/pkeys: handle negative sys_pkey_alloc() return code selftests/vm/pkeys: fix alloc_random_pkey() to make it really, really random kcov: add __no_sanitize_coverage to fix noinstr for all architectures exec: remove checks in __register_bimfmt() x86: signal: don't do sas_ss_reset() until we are certain that sigframe won't be abandoned hfsplus: report create_date to kstat.btime hfsplus: remove unnecessary oom message nilfs2: remove redundant continue statement in a while-loop kprobes: remove duplicated strong free_insn_page in x86 and s390 init: print out unknown kernel parameters checkpatch: do not complain about positive return values starting with EPOLL checkpatch: improve the indented label test checkpatch: scripts/spdxcheck.py now requires python3 ...
2021-07-01kernel.h: split out panic and oops helpersAndy Shevchenko1-1/+2
kernel.h is being used as a dump for all kinds of stuff for a long time. Here is the attempt to start cleaning it up by splitting out panic and oops helpers. There are several purposes of doing this: - dropping dependency in bug.h - dropping a loop by moving out panic_notifier.h - unload kernel.h from something which has its own domain At the same time convert users tree-wide to use new headers, although for the time being include new header back to kernel.h to avoid twisted indirected includes for existing users. [akpm@linux-foundation.org: thread_info.h needs limits.h] [andriy.shevchenko@linux.intel.com: ia64 fix] Link: https://lkml.kernel.org/r/20210520130557.55277-1-andriy.shevchenko@linux.intel.com Link: https://lkml.kernel.org/r/20210511074137.33666-1-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Co-developed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: Corey Minyard <cminyard@mvista.com> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Wei Liu <wei.liu@kernel.org> Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Sebastian Reichel <sre@kernel.org> Acked-by: Luis Chamberlain <mcgrof@kernel.org> Acked-by: Stephen Boyd <sboyd@kernel.org> Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Acked-by: Helge Deller <deller@gmx.de> # parisc Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-28once: implement DO_ONCE_LITE for non-fast-path "do once" functionalityTanner Love1-30/+7
Certain uses of "do once" functionality reside outside of fast path, and so do not require jump label patching via static keys, making existing DO_ONCE undesirable in such cases. Replace uses of __section(".data.once") with DO_ONCE_LITE(_IF)? This patch changes the return values of xfs_printk_once, printk_once, and printk_deferred_once. Before, they returned whether the print was performed, but now, they always return true. This is okay because the return values of the following macros are entirely ignored throughout the kernel: - xfs_printk_once - xfs_warn_once - xfs_notice_once - xfs_info_once - printk_once - pr_emerg_once - pr_alert_once - pr_crit_once - pr_err_once - pr_warn_once - pr_notice_once - pr_info_once - pr_devel_once - pr_debug_once - printk_deferred_once - orc_warn Changes v3: - Expand commit message to explain why changing return values of xfs_printk_once, printk_once, printk_deferred_once is benign v2: - Fix i386 build warnings Signed-off-by: Tanner Love <tannerlove@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Acked-by: Mahesh Bandewar <maheshb@google.com> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2021-04-08add support for Clang CFISami Tolvanen1-0/+16
This change adds support for Clang’s forward-edge Control Flow Integrity (CFI) checking. With CONFIG_CFI_CLANG, the compiler injects a runtime check before each indirect function call to ensure the target is a valid function with the correct static type. This restricts possible call targets and makes it more difficult for an attacker to exploit bugs that allow the modification of stored function pointers. For more details, see: https://clang.llvm.org/docs/ControlFlowIntegrity.html Clang requires CONFIG_LTO_CLANG to be enabled with CFI to gain visibility to possible call targets. Kernel modules are supported with Clang’s cross-DSO CFI mode, which allows checking between independently compiled components. With CFI enabled, the compiler injects a __cfi_check() function into the kernel and each module for validating local call targets. For cross-module calls that cannot be validated locally, the compiler calls the global __cfi_slowpath_diag() function, which determines the target module and calls the correct __cfi_check() function. This patch includes a slowpath implementation that uses __module_address() to resolve call targets, and with CONFIG_CFI_CLANG_SHADOW enabled, a shadow map that speeds up module look-ups by ~3x. Clang implements indirect call checking using jump tables and offers two methods of generating them. With canonical jump tables, the compiler renames each address-taken function to <function>.cfi and points the original symbol to a jump table entry, which passes __cfi_check() validation. This isn’t compatible with stand-alone assembly code, which the compiler doesn’t instrument, and would result in indirect calls to assembly code to fail. Therefore, we default to using non-canonical jump tables instead, where the compiler generates a local jump table entry <function>.cfi_jt for each address-taken function, and replaces all references to the function with the address of the jump table entry. Note that because non-canonical jump table addresses are local to each component, they break cross-module function address equality. Specifically, the address of a global function will be different in each module, as it's replaced with the address of a local jump table entry. If this address is passed to a different module, it won’t match the address of the same function taken there. This may break code that relies on comparing addresses passed from other components. CFI checking can be disabled in a function with the __nocfi attribute. Additionally, CFI can be disabled for an entire compilation unit by filtering out CC_FLAGS_CFI. By default, CFI failures result in a kernel panic to stop a potential exploit. CONFIG_CFI_PERMISSIVE enables a permissive mode, where the kernel prints out a rate-limited warning instead, and allows execution to continue. This option is helpful for locating type mismatches, but should only be enabled during development. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20210408182843.1754385-2-samitolvanen@google.com
2020-10-25treewide: Convert macro and uses of __section(foo) to __section("foo")Joe Perches1-3/+3
Use a more generic form for __section that requires quotes to avoid complications with clang and gcc differences. Remove the quote operator # from compiler_attributes.h __section macro. Convert all unquoted __section(foo) uses to quoted __section("foo"). Also convert __attribute__((section("foo"))) uses to __section("foo") even if the __attribute__ has multiple list entry forms. Conversion done using the script at: https://lore.kernel.org/lkml/75393e5ddc272dc7403de74d645e6c6e0f4e70eb.camel@perches.com/2-convert_section.pl Signed-off-by: Joe Perches <joe@perches.com> Reviewed-by: Nick Desaulniers <ndesaulniers@gooogle.com> Reviewed-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-07-24compiler.h: Move instrumentation_begin()/end() to new ↵Ingo Molnar1-0/+1
<linux/instrumentation.h> header Linus pointed out that compiler.h - which is a key header that gets included in every single one of the 28,000+ kernel files during a kernel build - was bloated in: 655389666643: ("vmlinux.lds.h: Create section for protection against instrumentation") Linus noted: > I have pulled this, but do we really want to add this to a header file > that is _so_ core that it gets included for basically every single > file built? > > I don't even see those instrumentation_begin/end() things used > anywhere right now. > > It seems excessive. That 53 lines is maybe not a lot, but it pushed > that header file to over 12kB, and while it's mostly comments, it's > extra IO and parsing basically for _every_ single file compiled in the > kernel. > > For what appears to be absolutely zero upside right now, and I really > don't see why this should be in such a core header file! Move these primitives into a new header: <linux/instrumentation.h>, and include that header in the headers that make use of it. Unfortunately one of these headers is asm-generic/bug.h, which does get included in a lot of places, similarly to compiler.h. So the de-bloating effect isn't as good as we'd like it to be - but at least the interfaces are defined separately. No change to functionality intended. Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20200604071921.GA1361070@gmail.com Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Peter Zijlstra <peterz@infradead.org>
2020-06-11bug: Annotate WARN/BUG/stackfail as noinstr safeThomas Gleixner1-2/+7
Warnings, bugs and stack protection fails from noinstr sections, e.g. low level and early entry code, are likely to be fatal. Mark them as "safe" to be invoked from noinstr protected code to avoid annotating all usage sites. Getting the information out is important. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200505134100.376598577@linutronix.de
2019-09-25bug: move WARN_ON() "cut here" into exception handlerKees Cook1-5/+3
The original clean up of "cut here" missed the WARN_ON() case (that does not have a printk message), which was fixed recently by adding an explicit printk of "cut here". This had the downside of adding a printk() to every WARN_ON() caller, which reduces the utility of using an instruction exception to streamline the resulting code. By making this a new BUGFLAG, all of these can be removed and "cut here" can be handled by the exception handler. This was very pronounced on PowerPC, but the effect can be seen on x86 as well. The resulting text size of a defconfig build shows some small savings from this patch: text data bss dec hex filename 19691167 5134320 1646664 26472151 193eed7 vmlinux.before 19676362 5134260 1663048 26473670 193f4c6 vmlinux.after This change also opens the door for creating something like BUG_MSG(), where a custom printk() before issuing BUG(), without confusing the "cut here" line. Link: http://lkml.kernel.org/r/201908200943.601DD59DCE@keescook Fixes: 6b15f678fb7d ("include/asm-generic/bug.h: fix "cut here" for WARN_ON for __WARN_TAINT architectures") Signed-off-by: Kees Cook <keescook@chromium.org> Reported-by: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Drew Davenport <ddavenport@chromium.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org> Cc: Feng Tang <feng.tang@intel.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Cc: Borislav Petkov <bp@suse.de> Cc: YueHaibing <yuehaibing@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-09-25bug: consolidate __WARN_FLAGS usageKees Cook1-11/+7
Instead of having separate tests for __WARN_FLAGS, merge the two #ifdef blocks and replace the synonym WANT_WARN_ON_SLOWPATH macro. Link: http://lkml.kernel.org/r/20190819234111.9019-7-keescook@chromium.org Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@suse.de> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Drew Davenport <ddavenport@chromium.org> Cc: Feng Tang <feng.tang@intel.com> Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org> Cc: YueHaibing <yuehaibing@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-09-25bug: clean up helper macros to remove __WARN_TAINT()Kees Cook1-10/+11
In preparation for cleaning up "cut here" even more, this removes the __WARN_*TAINT() helpers, as they limit the ability to add new BUGFLAG_* flags to call sites. They are removed by expanding them into full __WARN_FLAGS() calls. Link: http://lkml.kernel.org/r/20190819234111.9019-6-keescook@chromium.org Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@suse.de> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Drew Davenport <ddavenport@chromium.org> Cc: Feng Tang <feng.tang@intel.com> Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org> Cc: YueHaibing <yuehaibing@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-09-25bug: consolidate warn_slowpath_fmt() usageKees Cook1-2/+1
Instead of having a separate helper for no printk output, just consolidate the logic into warn_slowpath_fmt(). Link: http://lkml.kernel.org/r/20190819234111.9019-4-keescook@chromium.org Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@suse.de> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Drew Davenport <ddavenport@chromium.org> Cc: Feng Tang <feng.tang@intel.com> Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org> Cc: YueHaibing <yuehaibing@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-09-25bug: rename __WARN_printf_taint() to __WARN_printf()Kees Cook1-4/+4
This just renames the helper to improve readability. Link: http://lkml.kernel.org/r/20190819234111.9019-3-keescook@chromium.org Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@suse.de> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Drew Davenport <ddavenport@chromium.org> Cc: Feng Tang <feng.tang@intel.com> Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org> Cc: YueHaibing <yuehaibing@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-09-25bug: refactor away warn_slowpath_fmt_taint()Kees Cook1-9/+4
Patch series "Clean up WARN() "cut here" handling", v2. Christophe Leroy noticed that the fix for missing "cut here" in the WARN() case was adding explicit printk() calls instead of teaching the exception handler to add it. This refactors the bug/warn infrastructure to pass this information as a new BUGFLAG. Longer details repeated from the last patch in the series: bug: move WARN_ON() "cut here" into exception handler The original cleanup of "cut here" missed the WARN_ON() case (that does not have a printk message), which was fixed recently by adding an explicit printk of "cut here". This had the downside of adding a printk() to every WARN_ON() caller, which reduces the utility of using an instruction exception to streamline the resulting code. By making this a new BUGFLAG, all of these can be removed and "cut here" can be handled by the exception handler. This was very pronounced on PowerPC, but the effect can be seen on x86 as well. The resulting text size of a defconfig build shows some small savings from this patch: text data bss dec hex filename 19691167 5134320 1646664 26472151 193eed7 vmlinux.before 19676362 5134260 1663048 26473670 193f4c6 vmlinux.after This change also opens the door for creating something like BUG_MSG(), where a custom printk() before issuing BUG(), without confusing the "cut here" line. This patch (of 7): There's no reason to have specialized helpers for passing the warn taint down to __warn(). Consolidate and refactor helper macros, removing __WARN_printf() and warn_slowpath_fmt_taint(). Link: http://lkml.kernel.org/r/20190819234111.9019-2-keescook@chromium.org Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Drew Davenport <ddavenport@chromium.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org> Cc: Feng Tang <feng.tang@intel.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Cc: Borislav Petkov <bp@suse.de> Cc: YueHaibing <yuehaibing@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-09-01asm-generic: add unlikely to default BUG_ON(x)Denis Efremov1-1/+1
Add unlikely to default BUG_ON(x) in !CONFIG_BUG. It makes the define consistent with BUG_ON(x) in CONFIG_BUG. Signed-off-by: Denis Efremov <efremov@linux.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2019-07-16include/asm-generic/bug.h: fix "cut here" for WARN_ON for __WARN_TAINT ↵Drew Davenport1-2/+4
architectures For architectures using __WARN_TAINT, the WARN_ON macro did not print out the "cut here" string. The other WARN_XXX macros would print "cut here" inside __warn_printk, which is not called for WARN_ON since it doesn't have a message to print. Link: http://lkml.kernel.org/r/20190624154831.163888-1-ddavenport@chromium.org Fixes: a7bed27af194 ("bug: fix "cut here" location for __WARN_TAINT architectures") Signed-off-by: Drew Davenport <ddavenport@chromium.org> Acked-by: Kees Cook <keescook@chromium.org> Tested-by: Kees Cook <keescook@chromium.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-01-25include/asm-generic: Remove spin_is_locked() commentPaul E. McKenney1-3/+0
The WARN_ON_SMP() comment header suggests using spin_is_locked() to check for locks being held. But these days we prefer lockdep_assert_held(), so this commit removes that suggestion. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: <linux-arch@vger.kernel.org>
2018-12-19Revert "x86/bug: Macrofy the BUG table section handling, to work around GCC ↵Ingo Molnar1-4/+4
inlining bugs" This reverts commit f81f8ad56fd1c7b99b2ed1c314527f7d9ac447c6. See this commit for details about the revert: e769742d3584 ("Revert "x86/jump-labels: Macrofy inline assembly code to work around GCC inlining bugs"") Reported-by: Masahiro Yamada <yamada.masahiro@socionext.com> Reviewed-by: Borislav Petkov <bp@alien8.de> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Juergen Gross <jgross@suse.com> Cc: Richard Biener <rguenther@suse.de> Cc: Kees Cook <keescook@chromium.org> Cc: Segher Boessenkool <segher@kernel.crashing.org> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Nadav Amit <namit@vmware.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-10-04x86/bug: Macrofy the BUG table section handling, to work around GCC inlining ↵Nadav Amit1-4/+4
bugs As described in: 77b0bf55bc67: ("kbuild/Makefile: Prepare for using macros in inline assembly code to work around asm() related GCC inlining bugs") GCC's inlining heuristics are broken with common asm() patterns used in kernel code, resulting in the effective disabling of inlining. The workaround is to set an assembly macro and call it from the inline assembly block. As a result GCC considers the inline assembly block as a single instruction. (Which it isn't, but that's the best we can get.) This patch increases the kernel size: text data bss dec hex filename 18146889 10225380 2957312 31329581 1de0d2d ./vmlinux before 18147336 10226688 2957312 31331336 1de1408 ./vmlinux after (+1755) But enables more aggressive inlining (and probably better branch decisions). The number of static text symbols in vmlinux is much lower: Before: 40218 After: 40053 (-165) The assembly code gets harder to read due to the extra macro layer. [ mingo: Rewrote the changelog. ] Tested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Nadav Amit <namit@vmware.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.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: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20181003213100.189959-7-namit@vmware.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-08-22include/asm-generic/bug.h: clarify valid uses of WARN()Dmitry Vyukov1-3/+13
Explicitly state that WARN*() should be used only for recoverable kernel issues/bugs and that it should not be used for any kind of invalid external inputs or transient conditions. Motivation: it's a very useful capability to be able to understand if a particular kernel splat means a kernel bug or simply an invalid user-space program. For the former one wants to notify kernel developers, while notifying kernel developers for the latter is annoying. Even a kernel developer may not know what to do with a WARNING in an unfamiliar subsystem. This is especially critical for any automated testing systems that may use panic_on_warn and mail kernel developers. The clear separation also serves as an additional documentation: is it a condition that must never occur because of additional checks/logic elsewhere? or is it simply a check for invalid inputs or unfortunate conditions? Use of pr_err() for user messages also leads to better error messages. "Something is wrong in file foo on line X" is not particularly useful message for end user. pr_err() forces developers to write more meaningful error messages for user. As of now we are almost there. We are doing systematic kernel testing with panic_on_warn and are not seeing massive amounts of false positives. But every now and then another WARN on ENOMEM or invalid inputs pops up and leads to a lengthy argument each time. The goal of this change is to officially document the rules. Link: http://lkml.kernel.org/r/20180620103716.61636-1-dvyukov@gmail.com Signed-off-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-21bug.h: work around GCC PR82365 in BUG()Arnd Bergmann1-0/+1
Looking at functions with large stack frames across all architectures led me discovering that BUG() suffers from the same problem as fortify_panic(), which I've added a workaround for already. In short, variables that go out of scope by calling a noreturn function or __builtin_unreachable() keep using stack space in functions afterwards. A workaround that was identified is to insert an empty assembler statement just before calling the function that doesn't return. I'm adding a macro "barrier_before_unreachable()" to document this, and insert calls to that in all instances of BUG() that currently suffer from this problem. The files that saw the largest change from this had these frame sizes before, and much less with my patch: fs/ext4/inode.c:82:1: warning: the frame size of 1672 bytes is larger than 800 bytes [-Wframe-larger-than=] fs/ext4/namei.c:434:1: warning: the frame size of 904 bytes is larger than 800 bytes [-Wframe-larger-than=] fs/ext4/super.c:2279:1: warning: the frame size of 1160 bytes is larger than 800 bytes [-Wframe-larger-than=] fs/ext4/xattr.c:146:1: warning: the frame size of 1168 bytes is larger than 800 bytes [-Wframe-larger-than=] fs/f2fs/inode.c:152:1: warning: the frame size of 1424 bytes is larger than 800 bytes [-Wframe-larger-than=] net/netfilter/ipvs/ip_vs_core.c:1195:1: warning: the frame size of 1068 bytes is larger than 800 bytes [-Wframe-larger-than=] net/netfilter/ipvs/ip_vs_core.c:395:1: warning: the frame size of 1084 bytes is larger than 800 bytes [-Wframe-larger-than=] net/netfilter/ipvs/ip_vs_ftp.c:298:1: warning: the frame size of 928 bytes is larger than 800 bytes [-Wframe-larger-than=] net/netfilter/ipvs/ip_vs_ftp.c:418:1: warning: the frame size of 908 bytes is larger than 800 bytes [-Wframe-larger-than=] net/netfilter/ipvs/ip_vs_lblcr.c:718:1: warning: the frame size of 960 bytes is larger than 800 bytes [-Wframe-larger-than=] drivers/net/xen-netback/netback.c:1500:1: warning: the frame size of 1088 bytes is larger than 800 bytes [-Wframe-larger-than=] In case of ARC and CRIS, it turns out that the BUG() implementation actually does return (or at least the compiler thinks it does), resulting in lots of warnings about uninitialized variable use and leaving noreturn functions, such as: block/cfq-iosched.c: In function 'cfq_async_queue_prio': block/cfq-iosched.c:3804:1: error: control reaches end of non-void function [-Werror=return-type] include/linux/dmaengine.h: In function 'dma_maxpq': include/linux/dmaengine.h:1123:1: error: control reaches end of non-void function [-Werror=return-type] This makes them call __builtin_trap() instead, which should normally dump the stack and kill the current process, like some of the other architectures already do. I tried adding barrier_before_unreachable() to panic() and fortify_panic() as well, but that had very little effect, so I'm not submitting that patch. Vineet said: : For ARC, it is double win. : : 1. Fixes 3 -Wreturn-type warnings : : | ../net/core/ethtool.c:311:1: warning: control reaches end of non-void function : [-Wreturn-type] : | ../kernel/sched/core.c:3246:1: warning: control reaches end of non-void function : [-Wreturn-type] : | ../include/linux/sunrpc/svc_xprt.h:180:1: warning: control reaches end of : non-void function [-Wreturn-type] : : 2. bloat-o-meter reports code size improvements as gcc elides the : generated code for stack return. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365 Link: http://lkml.kernel.org/r/20171219114112.939391-1-arnd@arndb.de Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Vineet Gupta <vgupta@synopsys.com> [arch/arc] Tested-by: Vineet Gupta <vgupta@synopsys.com> [arch/arc] Cc: Mikael Starvik <starvik@axis.com> Cc: Jesper Nilsson <jesper.nilsson@axis.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Christopher Li <sparse@chrisli.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Kees Cook <keescook@chromium.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Will Deacon <will.deacon@arm.com> Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-17bug: fix "cut here" location for __WARN_TAINT architecturesKees Cook1-2/+3
Prior to v4.11, x86 used warn_slowpath_fmt() for handling WARN()s. After WARN() was moved to using UD0 on x86, the warning text started appearing _before_ the "cut here" line. This appears to have been a long-standing bug on architectures that used __WARN_TAINT, but it didn't get fixed. v4.11 and earlier on x86: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 2956 at drivers/misc/lkdtm_bugs.c:65 lkdtm_WARNING+0x21/0x30 This is a warning message Modules linked in: v4.12 and later on x86: This is a warning message ------------[ cut here ]------------ WARNING: CPU: 1 PID: 2982 at drivers/misc/lkdtm_bugs.c:68 lkdtm_WARNING+0x15/0x20 Modules linked in: With this fix: ------------[ cut here ]------------ This is a warning message WARNING: CPU: 3 PID: 3009 at drivers/misc/lkdtm_bugs.c:67 lkdtm_WARNING+0x15/0x20 Since the __FILE__ reporting happens as part of the UD0 handler, it isn't trivial to move the message to after the WARNING line, but at least we can fix the position of the "cut here" line so all the various logging tools will start including the actual runtime warning message again, when they follow the instruction and "cut here". Link: http://lkml.kernel.org/r/1510100869-73751-4-git-send-email-keescook@chromium.org Fixes: 9a93848fe787 ("x86/debug: Implement __WARN() using UD0") Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-17bug: define the "cut here" string in a single placeKees Cook1-0/+2
The "cut here" string is used in a few paths. Define it in a single place. Link: http://lkml.kernel.org/r/1510100869-73751-3-git-send-email-keescook@chromium.org Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-17kernel debug: support resetting WARN*_ONCEAndi Kleen1-3/+3
I like _ONCE warnings because it's guaranteed that they don't flood the log. During testing I find it useful to reset the state of the once warnings, so that I can rerun tests and see if they trigger again, or can guarantee that a test run always hits the same warnings. This patch adds a debugfs interface to reset all the _ONCE warnings so that they appear again: echo 1 > /sys/kernel/debug/clear_warn_once This is implemented by putting all the warning booleans into a special section, and clearing it. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/20171017221455.6740-1-andi@firstfloor.org Signed-off-by: Andi Kleen <ak@linux.intel.com> Tested-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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>
2017-07-10asm-generic/bug.h: declare struct pt_regs; before function prototypeIan Abbott1-0/+1
This series of patches splits BUILD_BUG related macros out of "include/linux/bug.h" into new file "include/linux/build_bug.h" (patch 5), and changes the pointer type checking in the `container_of()` macro to deal with pointers of array type better (patch 6). Patches 1 to 4 are prerequisites. Patches 2, 3, 4, and 5 have been inserted since the previous version of this patch series. Patch 6 here corresponds to v3 and v4's patch 2. Patch 1 was a prerequisite in v3 of this series to avoid a lot of warnings when <linux/bug.h> was included by <linux/kernel.h>. That is no longer relevant for v5 of the series, but I left it in because it was acked by a Arnd Bergmann and Michal Nazarewicz. Patches 2, 3, and 4 are some checkpatch clean-ups on "include/linux/bug.h" before splitting out the BUILD_BUG stuff in patch 5. Patch 5 splits the BUILD_BUG related macros out of "include/linux/bug.h" into new file "include/linux/build_bug.h" because including <linux/bug.h> in "include/linux/kernel.h" would result in build failures due to circular dependencies. Patch 6 changes the pointer type checking by `container_of()` to avoid some incompatible pointer warnings when the dereferenced pointer has array type. 1) asm-generic/bug.h: declare struct pt_regs; before function prototype 2) linux/bug.h: correct formatting of block comment 3) linux/bug.h: correct "(foo*)" should be "(foo *)" 4) linux/bug.h: correct "space required before that '-'" 5) bug: split BUILD_BUG stuff out into <linux/build_bug.h> 6) kernel.h: handle pointers to arrays better in container_of() This patch (of 6): The declaration of `__warn()` has `struct pt_regs *regs` as one of its parameters. This can result in compiler warnings if `struct regs` is not already declared. Add an empty declaration of `struct pt_regs` to avoid the warnings. Link: http://lkml.kernel.org/r/20170525120316.24473-2-abbotti@mev.co.uk Signed-off-by: Ian Abbott <abbotti@mev.co.uk> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Michal Nazarewicz <mina86@mina86.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-04-14debug: Avoid setting BUGFLAG_WARNING twicePeter Zijlstra1-1/+1
Dan reported that his static checking complains about BUGFLAG_WARNING being set on both sides of the bitwise-or, it figures that that might've been an unintentional mistake. Since there are no architectures that implement __WARN_TAINT() (I converted them all to implement __WARN_FLAGS()), and all __WARN_FLAGS() implementations already set BUGFLAG_WARNING, we can remove the bit from BUGFLAG_TAINT() and make Dan's checker happy. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> 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/20170410084939.4bwhrvpmauwfzauq@hirez.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-30debug: Add _ONCE() logic to report_bug()Peter Zijlstra1-1/+17
Josh suggested moving the _ONCE logic inside the trap handler, using a bit in the bug_entry::flags field, avoiding the need for the extra variable. Sadly this only works for WARN_ON_ONCE(), since the others have printk() statements prior to triggering the trap. Still, this saves a fair amount of text and some data: text data filename 10682460 4530992 defconfig-build/vmlinux.orig 10665111 4530096 defconfig-build/vmlinux.patched Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> 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> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-24Merge tag 'asm-generic-4.6' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic Pull asm-generic updates from Arnd Bergmann: "There are only three patches this time, most other changes to files in include/asm-generic tend to go through the tree of whoever depends on the change. Two patches are cleanups for stuff that is no longer needed, the main change is to adapt the generic version of BUG_ON() for CONFIG_BUG=n to make it behave consistently with BUG(). This avoids undefined behavior along with a number of warnings about that undefined behavior in randconfig builds when we keep going on after hitting a BUG_ON()" * tag 'asm-generic-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic: asm-generic: remove old nonatomic-io wrapper files asm-generic: default BUG_ON(x) to if(x)BUG() asm-generic: page.h: Remove useless get_user_page and free_user_page
2016-03-17lib/bug.c: use common WARN helperJosh Poimboeuf1-0/+6
The traceoff_on_warning option doesn't have any effect on s390, powerpc, arm64, parisc, and sh because there are two different types of WARN implementations: 1) The above mentioned architectures treat WARN() as a special case of a BUG() exception. They handle warnings in report_bug() in lib/bug.c. 2) All other architectures just call warn_slowpath_*() directly. Their warnings are handled in warn_slowpath_common() in kernel/panic.c. Support traceoff_on_warning on all architectures and prevent any future divergence by using a single common function to emit the warning. Also remove the '()' from '%pS()', because the parentheses look funky: [ 45.607629] WARNING: at /root/warn_mod/warn_mod.c:17 .init_dummy+0x20/0x40 [warn_mod]() Reported-by: Chunyu Hu <chuhu@redhat.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> Tested-by: Prarit Bhargava <prarit@redhat.com> Acked-by: Prarit Bhargava <prarit@redhat.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-17bug: set warn variable before calling WARN()Steven Rostedt1-9/+12
This has hit me a couple of times already. I would be debugging code and the system would simply hang and then reboot. Finally, I found that the problem was caused by WARN_ON_ONCE() and friends. The macro WARN_ON_ONCE(condition) is defined as: static bool __section(.data.unlikely) __warned; int __ret_warn_once = !!(condition); if (unlikely(__ret_warn_once)) if (WARN_ON(!__warned)) __warned = true; unlikely(__ret_warn_once); Which looks great and all. But what I have hit, is an issue when WARN_ON() itself hits the same WARN_ON_ONCE() code. Because, the variable __warned is not yet set. Then it too calls WARN_ON() and that triggers the warning again. It keeps doing this until the stack is overflowed and the system crashes. By setting __warned first before calling WARN_ON() makes the original WARN_ON_ONCE() really only warn once, and not an infinite amount of times if the WARN_ON() also triggers the warning. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-01asm-generic: default BUG_ON(x) to if(x)BUG()Arnd Bergmann1-1/+1
When CONFIG_BUG is disabled, BUG_ON() will only evaluate the condition, but will not actually stop the current thread. GCC warns about a couple of BUG_ON() users where this actually leads to further undefined behavior: include/linux/ceph/osdmap.h: In function 'ceph_can_shift_osds': include/linux/ceph/osdmap.h:54:1: warning: control reaches end of non-void function fs/ext4/inode.c: In function 'ext4_map_blocks': fs/ext4/inode.c:548:5: warning: 'retval' may be used uninitialized in this function drivers/mfd/db8500-prcmu.c: In function 'prcmu_config_clkout': drivers/mfd/db8500-prcmu.c:762:10: warning: 'div_mask' may be used uninitialized in this function drivers/mfd/db8500-prcmu.c:769:13: warning: 'mask' may be used uninitialized in this function drivers/mfd/db8500-prcmu.c:757:7: warning: 'bits' may be used uninitialized in this function drivers/tty/serial/8250/8250_core.c: In function 'univ8250_release_irq': drivers/tty/serial/8250/8250_core.c:252:18: warning: 'i' may be used uninitialized in this function drivers/tty/serial/8250/8250_core.c:235:19: note: 'i' was declared here There is an obvious conflict of interest here: on the one hand, someone who disables CONFIG_BUG() will want the kernel to be as small as possible and doesn't care about printing error messages to a console that nobody looks at. On the other hand, running into a BUG_ON() condition means that something has gone wrong, and we probably want to also stop doing things that might cause data corruption. This patch picks the second choice, and changes the NOP to BUG(), which normally stops the execution of the current thread in some form (endless loop or a trap). This follows the logic we applied in a4b5d580e078 ("bug: Make BUG() always stop the machine"). For ARM multi_v7_defconfig, the size slightly increases: section CONFIG_BUG=y CONFIG_BUG=n CONFIG_BUG=n+patch .text 8320248 | 8180944 | 8207688 .rodata 3633720 | 3567144 | 3570648 __bug_table 32508 | --- | --- __modver 692 | 1584 | 2176 .init.text 558132 | 548300 | 550088 .exit.text 12380 | 12256 | 12380 .data 1016672 | 1016064 | 1016128 Total 14622556 | 14374510 | 14407326 So instead of saving 1.70% of the total image size, we only save 1.48% by turning off CONFIG_BUG, but in return we can ensure that we don't run into cases of uninitialized variable or return code uses when something bad happens. Aside from that, we significantly reduce the number of warnings in randconfig builds, which makes it easier to fix the warnings about other problems. Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2014-04-07bug: Make BUG() always stop the machineJosh Triplett1-1/+1
When !CONFIG_BUG and !HAVE_ARCH_BUG, define the generic BUG() as an infinite loop rather than a no-op. This avoids undefined behavior if execution ever actually reaches BUG(), and avoids warnings about code after BUG() (such as on non-void functions calling BUG() and then not returning). bloat-o-meter results: add/remove: 0/0 grow/shrink: 43/10 up/down: 235/-98 (137) function old new delta umount_collect 119 138 +19 notify_change 306 324 +18 xstate_enable_boot_cpu 252 269 +17 kunmap 54 70 +16 balloon_page_dequeue 112 126 +14 mm_take_all_locks 223 233 +10 list_lru_walk_node 143 152 +9 vma_adjust 1059 1067 +8 pcpu_setup_first_chunk 1130 1138 +8 mm_drop_all_locks 143 151 +8 ns_capable 55 62 +7 anon_transport_class_unregister 8 15 +7 srcu_init_notifier_head 35 41 +6 shrink_dcache_for_umount 174 180 +6 kunmap_high 99 105 +6 end_page_writeback 43 49 +6 do_exit 1339 1345 +6 __kfifo_dma_out_prepare_r 86 92 +6 __kfifo_dma_in_prepare_r 90 96 +6 fixup_user_fault 120 125 +5 repair_env_string 73 77 +4 read_cache_pages_invalidate_page 56 60 +4 isolate_lru_pages.isra 142 146 +4 do_notify_parent_cldstop 255 259 +4 cpu_init 370 374 +4 utimes_common 270 272 +2 tasklet_hi_action 91 93 +2 tasklet_action 91 93 +2 set_pte_vaddr 46 48 +2 find_get_pages_tag 202 204 +2 early_iounmap 185 187 +2 __native_set_fixmap 36 38 +2 __get_user_pages 822 824 +2 __early_ioremap 299 301 +2 yield_task_stop 1 2 +1 tick_resume 37 38 +1 switched_to_stop 1 2 +1 switched_to_idle 1 2 +1 prio_changed_stop 1 2 +1 prio_changed_idle 1 2 +1 pm_qos_power_read 111 112 +1 arch_cpu_idle_dead 1 2 +1 __insert_vmap_area 140 141 +1 sys_renameat 614 612 -2 mm_fault_error 297 295 -2 SyS_renameat 614 612 -2 sys_linkat 416 413 -3 SyS_linkat 416 413 -3 chmod_common 129 122 -7 proc_cap_handler 240 225 -15 __schedule 849 831 -18 sys_madvise 1077 1054 -23 SyS_madvise 1077 1054 -23 Signed-off-by: Josh Triplett <josh@joshtriplett.org> Reported-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07bug: when !CONFIG_BUG, make WARN call no_printk to check format and argsJosh Triplett1-0/+1
The stub version of WARN for !CONFIG_BUG completely ignored its format string and subsequent arguments; make it check them instead, using no_printk. Signed-off-by: Josh Triplett <josh@joshtriplett.org> Reported-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07include/asm-generic/bug.h: style fix: s/while(0)/while (0)/Josh Triplett1-3/+3
Signed-off-by: Josh Triplett <josh@joshtriplett.org> Reported-by: Randy Dunlap <rdunlap@infradead.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07bug: when !CONFIG_BUG, simplify WARN_ON_ONCE and familyJosh Triplett1-27/+30
When !CONFIG_BUG, WARN_ON and family become simple passthroughs of their condition argument; however, WARN_ON_ONCE and family still have conditions and a boolean to detect one-time invocation, even though the warning they'd emit doesn't exist. Make the existing definitions conditional on CONFIG_BUG, and add definitions for !CONFIG_BUG that map to the passthrough versions of WARN and WARN_ON. This saves 4.4k on a minimized configuration (smaller than allnoconfig), and 20.6k with defconfig plus CONFIG_BUG=n. Signed-off-by: Josh Triplett <josh@joshtriplett.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-06-25bug.h: Fix up CONFIG_BUG=n implicit function declarations.Paul Mundt1-10/+9
Commit 2603efa31a03 ("bug.h: Fix up powerpc build regression") corrected the powerpc build case and extended the __ASSEMBLY__ guards, but it also got caught in pre-processor hell accidentally matching the else case of CONFIG_BUG resulting in the BUG disabled case tripping up on -Werror=implicit-function-declaration. It's not possible to __ASSEMBLY__ guard the entire file as architecture code needs to get at the BUGFLAG_WARNING definition in the GENERIC_BUG case, but the rest of the CONFIG_BUG=y/n case needs to be guarded. Rather than littering endless __ASSEMBLY__ checks in each of the if/else cases we just move the BUGFLAG definitions up under their own GENERIC_BUG test and then shove everything else under one big __ASSEMBLY__ guard. Build tested on all of x86 CONFIG_BUG=y, CONFIG_BUG=n, powerpc (due to it's dependence on BUGFLAG definitions in assembly code), and sh (due to not bringing in linux/kernel.h to satisfy the taint flag definitions used by the generic bug code). Hopefully that's the end of the corner cases and I can abstain from ever having to touch this infernal header ever again. Reported-by: Fengguang Wu <fengguang.wu@intel.com> Tested-by: Fengguang Wu <wfg@linux.intel.com> Acked-by: Randy Dunlap <rdunlap@xenotime.net> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Paul Mundt <lethal@linux-sh.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-06-18bug.h: Fix up powerpc build regression.Paul Mundt1-3/+5
The asm-generic/bug.h __ASSEMBLY__ guarding is completely bogus, which tripped up the powerpc build when the kernel.h include was added: In file included from include/asm-generic/bug.h:5:0, from arch/powerpc/include/asm/bug.h:127, from arch/powerpc/kernel/head_64.S:31: include/linux/kernel.h:44:0: warning: "ALIGN" redefined [enabled by default] include/linux/linkage.h:57:0: note: this is the location of the previous definition include/linux/sysinfo.h: Assembler messages: include/linux/sysinfo.h:7: Error: Unrecognized opcode: `struct' include/linux/sysinfo.h:8: Error: Unrecognized opcode: `__kernel_long_t' Moving the __ASSEMBLY__ guard up and stashing the kernel.h include under it fixes this up, as well as covering the case the original fix was attempting to handle. Tested-by: Stephen Rothwell <sfr@canb.auug.org.au> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Paul Mundt <lethal@linux-sh.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-06-11bug.h: need linux/kernel.h for TAINT_WARN.Paul Mundt1-0/+1
asm-generic/bug.h uses taint flags that are only defined in linux/kernel.h, resulting in build failures on platforms that don't include linux/kernel.h some other way: arch/sh/include/asm/thread_info.h:172:2: error: 'TAINT_WARN' undeclared (first use in this function) Caused by commit edd63a2763bd ("set_restore_sigmask() is never called without SIGPENDING (and never should be)"). Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2012-03-23consolidate WARN_...ONCE() static variablesJan Beulich1-3/+3
Due to the alignment of following variables, these typically consume more than just the single byte that 'bool' requires, and as there are a few hundred instances, the cache pollution (not so much the waste of memory) sums up. Put these variables into their own section, outside of any half way frequently used memory range. Do the same also to the __warned variable of rcu_lockdep_assert(). (Don't, however, include the ones used by printk_once() and alike, as they can potentially be hot.) Signed-off-by: Jan Beulich <jbeulich@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31treewide: use __printf not __attribute__((format(printf,...)))Joe Perches1-5/+6
Standardize the style for compiler based printf format verification. Standardized the location of __printf too. Done via script and a little typing. $ grep -rPl --include=*.[ch] -w "__attribute__" * | \ grep -vP "^(tools|scripts|include/linux/compiler-gcc.h)" | \ xargs perl -n -i -e 'local $/; while (<>) { s/\b__attribute__\s*\(\s*\(\s*format\s*\(\s*printf\s*,\s*(.+)\s*,\s*(.+)\s*\)\s*\)\s*\)/__printf($1, $2)/g ; print; }' [akpm@linux-foundation.org: revert arch bits] Signed-off-by: Joe Perches <joe@perches.com> Cc: "Kirill A. Shutemov" <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-26bug.h: Move ratelimit warn interfaces to ratelimit.hDavid S. Miller1-40/+0
As reported by Ingo Molnar, we still have configuration combinations where use of the WARN_RATELIMIT interfaces break the build because dependencies don't get met. Instead of going down the long road of trying to make it so that ratelimit.h can get included by kernel.h or asm-generic/bug.h, just move the interface into ratelimit.h and make users have to include that. Reported-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: David S. Miller <davem@davemloft.net> Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
2011-05-24bug.h: Fix build with CONFIG_PRINTK disabled.David S. Miller1-0/+21
Based upon an email by Joe Perches. Reported-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net> Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
2011-05-23bug.h: Add WARN_RATELIMITJoe Perches1-0/+16
Add a generic mechanism to ratelimit WARN(foo, fmt, ...) messages using a hidden per call site static struct ratelimit_state. Also add an __WARN_RATELIMIT variant to be able to use a specific struct ratelimit_state. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2011-03-28WARN_ON_SMP(): Add comment to explain ({0;})Steven Rostedt1-0/+7
The define to use ({0;}) for the !CONFIG_SMP case of WARN_ON_SMP() can be confusing. As the WARN_ON_SMP() needs to be a nop when CONFIG_SMP is not set, including all its parameters must not be evaluated, and that it must work as both a stand alone statement and inside an if condition, we define it to a funky ({0;}). A simple "0" will not work as it causes gcc to give the warning that the statement has no effect. As this strange definition has raised a few eyebrows from some major kernel developers, it is wise to document why we create such a work of art. Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-03-25WARN_ON_SMP(): Allow use in if() statements on UPSteven Rostedt1-1/+27
Both WARN_ON() and WARN_ON_SMP() should be able to be used in an if statement. if (WARN_ON_SMP(foo)) { ... } Because WARN_ON_SMP() is defined as a do { } while (0) on UP, it can not be used this way. Convert it to the same form that WARN_ON() is, even when CONFIG_SMP is off. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Darren Hart <dvhart@linux.intel.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> LKML-Reference: <20110317192208.444147791@goodmis.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-05-19panic: Allow warnings to set different taint flagsBen Hutchings1-2/+32
WARN() is used in some places to report firmware or hardware bugs that are then worked-around. These bugs do not affect the stability of the kernel and should not set the flag for TAINT_WARN. To allow for this, add WARN_TAINT() and WARN_TAINT_ONCE() macros that take a taint number as argument. Architectures that implement warnings using trap instructions instead of calls to warn_slowpath_*() now implement __WARN_TAINT(taint) instead of __WARN(). Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Acked-by: Helge Deller <deller@gmx.de> Tested-by: Paul Mundt <lethal@linux-sh.org> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2009-12-15WARN_ONCE(): use bool for boolean flagCesar Eduardo Barros1-4/+4
Commit 70867453092297be9afb2249e712a1f960ec0a09 ("printk_once(): use bool for boolean flag") changed printk_once() to use bool instead of int for its guard variable. Do the same change to WARN_ONCE() and WARN_ON_ONCE(), for the same reasons. This resulted in a reduction of 1462 bytes on a x86-64 defconfig: text data bss dec hex filename 8101271 1207116 992764 10301151 9d2edf vmlinux.before 8100553 1207148 991988 10299689 9d2929 vmlinux.after Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net> Cc: Roland Dreier <rolandd@cisco.com> Cc: Daniel Walker <dwalker@fifo99.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-05-06Eliminate thousands of warnings with gcc 3.2 buildAndi Kleen1-3/+4
When building with gcc 3.2 I get thousands of warnings such as include/linux/gfp.h: In function `allocflags_to_migratetype': include/linux/gfp.h:105: warning: null format string due to passing a NULL format string to warn_slowpath() in #define __WARN() warn_slowpath(__FILE__, __LINE__, NULL) Split this case out into a separate call. This also shrinks the kernel slightly: text data bss dec hex filename 4802274 707668 712704 6222646 5ef336 vmlinux text data bss dec hex filename 4799027 703572 712704 6215303 5ed687 vmlinux due to removeing one argument from the commonly-called __WARN(). [akpm@linux-foundation.org: reduce scope of `empty'] Acked-by: Jesper Nilsson <jesper.nilsson@axis.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andi Kleen <ak@linux.intel.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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