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2012-01-10kernel.h: add BUILD_BUG() macroDavid Daney
We can place this in definitions that we expect the compiler to remove by dead code elimination. If this assertion fails, we get a nice error message at build time. The GCC function attribute error("message") was added in version 4.3, so we define a new macro __linktime_error(message) to expand to this for GCC-4.3 and later. This will give us an error diagnostic from the compiler on the line that fails. For other compilers __linktime_error(message) expands to nothing, and we have to be content with a link time error, but at least we will still get a build error. BUILD_BUG() expands to the undefined function __build_bug_failed() and will fail at link time if the compiler ever emits code for it. On GCC-4.3 and later, attribute((error())) is used so that the failure will be noted at compile time instead. Signed-off-by: David Daney <david.daney@cavium.com> Acked-by: David Rientjes <rientjes@google.com> Cc: DM <dm.n9107@gmail.com> Cc: Ralf Baechle <ralf@linux-mips.org> Acked-by: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-25sparse: Undef __compiletime_{warning,error} if __CHECKER__ is definedKOSAKI Motohiro
sparse can't parse warning and error attribute. then they should be hidden from sparse. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-03-22include/linux/compiler-gcc*.h: unify macro definitionsBorislav Petkov
Unify identical gcc3.x and gcc4.x macros. Signed-off-by: Borislav Petkov <borislav.petkov@amd.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-06-29compiler-gcc.h: gcc-4.5 needs noclone and noinline on __naked functionsMikael Pettersson
A __naked function is defined in C but with a body completely implemented by asm(), including any prologue and epilogue. These asm() bodies expect standard calling conventions for parameter passing. Older GCCs implement that correctly, but 4.[56] currently do not, see GCC PR44290. In the Linux kernel this breaks ARM, causing most arch/arm/mm/copypage-*.c modules to get miscompiled, resulting in kernel crashes during bootup. Part of the kernel fix is to augment the __naked function attribute to also imply noinline and noclone. This patch implements that, and has been verified to fix boot failures with gcc-4.5 compiled 2.6.34 and 2.6.35-rc1 kernels. The patch is a no-op with older GCCs. Signed-off-by: Mikael Pettersson <mikpe@it.uu.se> Signed-off-by: Khem Raj <raj.khem@gmail.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-05Merge branch 'x86-asm-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: include/linux/compiler-gcc4.h: Fix build bug - gcc-4.0.2 doesn't understand __builtin_object_size x86/alternatives: No need for alternatives-asm.h to re-invent stuff already in asm.h x86/alternatives: Check replacementlen <= instrlen at build time x86, 64-bit: Set data segments to null after switching to 64-bit mode x86: Clean up the loadsegment() macro x86: Optimize loadsegment() x86: Add missing might_fault() checks to copy_{to,from}_user() x86-64: __copy_from_user_inatomic() adjustments x86: Remove unused thread_return label from switch_to() x86, 64-bit: Fix bstep_iret jump x86: Don't use the strict copy checks when branch profiling is in use x86, 64-bit: Move K8 B step iret fixup to fault entry asm x86: Generate cmpxchg build failures x86: Add a Kconfig option to turn the copy_from_user warnings into errors x86: Turn the copy_from_user check into an (optional) compile time warning x86: Use __builtin_memset and __builtin_memcpy for memset/memcpy x86: Use __builtin_object_size() to validate the buffer size for copy_from_user()
2009-12-05Add support for GCC-4.5's __builtin_unreachable() to compiler.h (v2)David Daney
Starting with version 4.5, GCC has a new built-in function __builtin_unreachable() that can be used in places like the kernel's BUG() where inline assembly is used to transfer control flow. This eliminated the need for an endless loop in these places. The patch adds a new macro 'unreachable()' that will expand to either __builtin_unreachable() or an endless loop depending on the compiler version. Change from v1: Simplify unreachable() for non-GCC 4.5 case. Signed-off-by: David Daney <ddaney@caviumnetworks.com> Acked-by: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-03include/linux/compiler-gcc4.h: Fix build bug - gcc-4.0.2 doesn't understand ↵Andrew Morton
__builtin_object_size Maybe 4.1.0 doesn't too, but this fixed it for me. Caused by: 4a31276: x86: Turn the copy_from_user check into an (optional) compile time warning 9f0cf4a: x86: Use __builtin_object_size() to validate the buffer size for copy_from_user() Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Arjan van de Ven <arjan@linux.intel.com> LKML-Reference: <200910090724.n997OQl6013538@imap1.linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-10-02x86: Add a Kconfig option to turn the copy_from_user warnings into errorsArjan van de Ven
For automated testing it is useful to have the option to turn the warnings on copy_from_user() etc checks into errors: In function ‘copy_from_user’, inlined from ‘fd_copyin’ at drivers/block/floppy.c:3080, inlined from ‘fd_ioctl’ at drivers/block/floppy.c:3503: linux/arch/x86/include/asm/uaccess_32.h:213: error: call to ‘copy_from_user_overflow’ declared with attribute error: copy_from_user buffer size is not provably correct Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> LKML-Reference: <20091002075050.4e9f7641@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-10-01x86: Turn the copy_from_user check into an (optional) compile time warningArjan van de Ven
A previous patch added the buffer size check to copy_from_user(). One of the things learned from analyzing the result of the previous patch is that in general, gcc is really good at proving that the code contains sufficient security checks to not need to do a runtime check. But that for those cases where gcc could not prove this, there was a relatively high percentage of real security issues. This patch turns the case of "gcc cannot prove" into a compile time warning, as long as a sufficiently new gcc is in use that supports this. The objective is that these warnings will trigger developers checking new cases out before a security hole enters a linux kernel release. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: James Morris <jmorris@namei.org> Cc: Jan Beulich <jbeulich@novell.com> LKML-Reference: <20090930130523.348ae6c4@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-09-26x86: Use __builtin_object_size() to validate the buffer size for ↵Arjan van de Ven
copy_from_user() gcc (4.x) supports the __builtin_object_size() builtin, which reports the size of an object that a pointer point to, when known at compile time. If the buffer size is not known at compile time, a constant -1 is returned. This patch uses this feature to add a sanity check to copy_from_user(); if the target buffer is known to be smaller than the copy size, the copy is aborted and a WARNing is emitted in memory debug mode. These extra checks compile away when the object size is not known, or if both the buffer size and the copy length are constants. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> LKML-Reference: <20090926143301.2c396b94@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-26compiler-gcc4: conditionalize #error on __KERNEL__H. Peter Anvin
Impact: Fix for exported headers We only want to error out on specific gcc versions if we are actually building the kernel, so conditionalize the #if...#error on __KERNEL__. Based on a patchset by Arnd Bergmann <arnd@arndb.de>. Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-02Disallow gcc versions 4.1.{0,1}Linus Torvalds
These compiler versions are known to miscompile __weak functions and thus generate kernels that don't necessarily work correctly. If a weak function is int he same compilation unit as a caller, gcc may end up inlining it, and thus binding the weak function too early. See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27781 for details. Cc: Adrian Bunk <bunk@kernel.org> Cc: Helge Deller <deller@gmx.de> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-02Sanitize gcc version header includesLinus Torvalds
- include the gcc version-dependent header files from the generic gcc header file, rather than the other way around (iow: don't make the non-gcc header file have to know about gcc versions) - don't include compiler-gcc4.h for gcc 5 (for whenever it gets released). That's just confusing and made us do odd things in the gcc4 header file (testing that we really had version 4!) - generate the name from the __GNUC__ version directly, rather than having a mess of #if conditionals. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-09x86, core: remove CONFIG_FORCED_INLININGHarvey Harrison
Other than the defconfigs, remove the entry in compiler-gcc4.h, Kconfig.debug and feature-removal-schedule.txt. Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-28remove __attribute_used__Adrian Bunk
Remove the deprecated __attribute_used__. [Introduce __section in a few places to silence checkpatch /sam] Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
2007-10-17Force erroneous inclusions of compiler-*.h files to be errorsRobert P. J. Day
Replace worthless comments with actual preprocessor errors when including the wrong versions of the compiler.h files. [akpm@linux-foundation.org: make it work] Signed-off-by: Robert P. J. Day <rpjday@mindspring.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-21x86: Support __attribute__((__cold__)) in gcc 4.3Andi Kleen
gcc 4.3 supports a new __attribute__((__cold__)) to mark functions cold. Any path directly leading to a call of this function will be unlikely. And gcc will try to generate smaller code for the function itself. Please use with care. The code generation advantage isn't large and in most cases it is not worth uglifying code with this. This patch marks some common error functions like panic(), printk() as cold. This will longer term make many unlikely()s unnecessary, although we can keep them for now for older compilers. BUG is not marked cold because there is currently no way to tell gcc to mark a inline function told. Also all __init and __exit functions are marked cold. With a non -Os build this will tell the compiler to generate slightly smaller code for them. I think it currently only uses less alignments for labels, but that might change in the future. One disadvantage over *likely() is that they cannot be easily instrumented to verify them. Another drawback is that only the latest gcc 4.3 snapshots support this. Unfortunately we cannot detect this using the preprocessor. This means older snapshots will fail now. I don't think that's a problem because they are unreleased compilers that nobody should be using. gcc also has a __hot__ attribute, but I don't see any sense in using this in the kernel right now. But someday I hope gcc will be able to use more aggressive optimizing for hot functions even in -Os, if that happens it should be added. Includes compile fix from Thomas Gleixner. Cc: Jan Hubicka <jh@suse.cz> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-09compiler: introduce __used and __maybe_unusedDavid Rientjes
__used is defined to be __attribute__((unused)) for all pre-3.3 gcc compilers to suppress warnings for unused functions because perhaps they are referenced only in inline assembly. It is defined to be __attribute__((used)) for gcc 3.3 and later so that the code is still emitted for such functions. __maybe_unused is defined to be __attribute__((unused)) for both function and variable use if it could possibly be unreferenced due to the evaluation of preprocessor macros. Function prototypes shall be marked with __maybe_unused if the actual definition of the function is dependant on preprocessor macros. No update to compiler-intel.h is necessary because ICC supports both __attribute__((used)) and __attribute__((unused)) as specified by the gcc manual. __attribute_used__ is deprecated and will be removed once all current code is converted to using __used. Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Adrian Bunk <bunk@stusta.de> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-07Add unitialized_var() macro for suppressing gcc warningsBorislav Petkov
Introduce a macro for suppressing gcc from generating a warning about a probable uninitialized state of a variable. Example: - spinlock_t *ptl; + spinlock_t *uninitialized_var(ptl); Not a happy solution, but those warnings are obnoxious. - Using the usual pointlessly-set-it-to-zero approach wastes several bytes of text. - Using a macro means we can (hopefully) do something else if gcc changes cause the `x = x' hack to stop working - Using a macro means that people who are worried about hiding true bugs can easily turn it off. Signed-off-by: Borislav Petkov <bbpetkov@yahoo.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2006-01-14[PATCH] When CONFIG_CC_OPTIMIZE_FOR_SIZE, allow gcc4 to control inliningIngo Molnar
If optimizing for size (CONFIG_CC_OPTIMIZE_FOR_SIZE), allow gcc4 compilers to decide what to inline and what not - instead of the kernel forcing gcc to inline all the time. This requires several places that require to be inlined to be marked as such, previous patches in this series do that. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@infradead.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-14[PATCH] Make __always_inline actually force always inliningIngo Molnar
This patch is the first in a series that tries to optimize the kernel in terms of size (and thus cache behavior, both cpu and pagecache). This first patch changes __always_inline to be a forced inline instead of the "regular" inline it was on everything except alpha. This forced inline matches the intention of the define better as a matter of documentation. There is no change in behavior by this patch, since "inline" currently is mapped to a forced inline anyway. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@infradead.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08[PATCH] remove gcc-2 checksAndrew Morton
Remove various things which were checking for gcc-1.x and gcc-2.x compilers. From: Adrian Bunk <bunk@stusta.de> Some documentation updates and removes some code paths for gcc < 3.2. Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-16Linux-2.6.12-rc2v2.6.12-rc2Linus Torvalds
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!