user/sven/linux.git/include/linux/compiler-gcc.h, branch v4.4.193

bug.h: work around GCC PR82365 in BUG()

2019-07-10T07:56:42Z

[ Upstream commit 173a3efd3edb2ef6ef07471397c5f542a360e9c1 ] 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 Acked-by: Vineet Gupta [arch/arc] Tested-by: Vineet Gupta [arch/arc] Cc: Mikael Starvik Cc: Jesper Nilsson Cc: Tony Luck Cc: Fenghua Yu Cc: Geert Uytterhoeven Cc: "David S. Miller" Cc: Christopher Li Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: Kees Cook Cc: Ingo Molnar Cc: Josh Poimboeuf Cc: Will Deacon Cc: "Steven Rostedt (VMware)" Cc: Mark Rutland Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin [ removed cris changes - gregkh] Signed-off-by: Greg Kroah-Hartman

compiler-gcc.h: Add attribute((gnu_inline)) to all inline declarations

2018-07-22T12:25:51Z

commit d03db2bc26f0e4a6849ad649a09c9c73fccdc656 upstream. Functions marked extern inline do not emit an externally visible function when the gnu89 C standard is used. Some KBUILD Makefiles overwrite KBUILD_CFLAGS. This is an issue for GCC 5.1+ users as without an explicit C standard specified, the default is gnu11. Since c99, the semantics of extern inline have changed such that an externally visible function is always emitted. This can lead to multiple definition errors of extern inline functions at link time of compilation units whose build files have removed an explicit C standard compiler flag for users of GCC 5.1+ or Clang. Suggested-by: Arnd Bergmann Suggested-by: H. Peter Anvin Suggested-by: Joe Perches Signed-off-by: Nick Desaulniers Acked-by: Juergen Gross Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: acme@redhat.com Cc: akataria@vmware.com Cc: akpm@linux-foundation.org Cc: andrea.parri@amarulasolutions.com Cc: ard.biesheuvel@linaro.org Cc: aryabinin@virtuozzo.com Cc: astrachan@google.com Cc: boris.ostrovsky@oracle.com Cc: brijesh.singh@amd.com Cc: caoj.fnst@cn.fujitsu.com Cc: geert@linux-m68k.org Cc: ghackmann@google.com Cc: gregkh@linuxfoundation.org Cc: jan.kiszka@siemens.com Cc: jarkko.sakkinen@linux.intel.com Cc: jpoimboe@redhat.com Cc: keescook@google.com Cc: kirill.shutemov@linux.intel.com Cc: kstewart@linuxfoundation.org Cc: linux-efi@vger.kernel.org Cc: linux-kbuild@vger.kernel.org Cc: manojgupta@google.com Cc: mawilcox@microsoft.com Cc: michal.lkml@markovi.net Cc: mjg59@google.com Cc: mka@chromium.org Cc: pombredanne@nexb.com Cc: rientjes@google.com Cc: rostedt@goodmis.org Cc: sedat.dilek@gmail.com Cc: thomas.lendacky@amd.com Cc: tstellar@redhat.com Cc: tweek@google.com Cc: virtualization@lists.linux-foundation.org Cc: will.deacon@arm.com Cc: yamada.masahiro@socionext.com Link: http://lkml.kernel.org/r/20180621162324.36656-2-ndesaulniers@google.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

compiler, clang: always inline when CONFIG_OPTIMIZE_INLINING is disabled

2018-07-22T12:25:51Z

commit 9a04dbcfb33b4012d0ce8c0282f1e3ca694675b1 upstream. The motivation for commit abb2ea7dfd82 ("compiler, clang: suppress warning for unused static inline functions") was to suppress clang's warnings about unused static inline functions. For configs without CONFIG_OPTIMIZE_INLINING enabled, such as any non-x86 architecture, `inline' in the kernel implies that __attribute__((always_inline)) is used. Some code depends on that behavior, see https://lkml.org/lkml/2017/6/13/918: net/built-in.o: In function `__xchg_mb': arch/arm64/include/asm/cmpxchg.h:99: undefined reference to `__compiletime_assert_99' arch/arm64/include/asm/cmpxchg.h:99: undefined reference to `__compiletime_assert_99 The full fix would be to identify these breakages and annotate the functions with __always_inline instead of `inline'. But since we are late in the 4.12-rc cycle, simply carry forward the forced inlining behavior and work toward moving arm64, and other architectures, toward CONFIG_OPTIMIZE_INLINING behavior. Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1706261552200.1075@chino.kir.corp.google.com Signed-off-by: David Rientjes Reported-by: Sodagudi Prasad Tested-by: Sodagudi Prasad Tested-by: Matthias Kaehlcke Cc: Mark Rutland Cc: Will Deacon Cc: Catalin Marinas Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

kasan: update kasan_global for gcc 7

2016-12-08T06:15:24Z

commit 045d599a286bc01daa3510d59272440a17b23c2e upstream. kasan_global struct is part of compiler/runtime ABI. gcc revision 241983 has added a new field to kasan_global struct. Update kernel definition of kasan_global struct to include the new field. Without this patch KASAN is broken with gcc 7. Link: http://lkml.kernel.org/r/1479219743-28682-1-git-send-email-dvyukov@google.com Signed-off-by: Dmitry Vyukov Acked-by: Andrey Ryabinin Cc: Alexander Potapenko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

compiler-gcc: disable -ftracer for __noclone functions

2016-04-20T06:41:54Z

commit 95272c29378ee7dc15f43fa2758cb28a5913a06d upstream. -ftracer can duplicate asm blocks causing compilation to fail in noclone functions. For example, KVM declares a global variable in an asm like asm("2: ... \n .pushsection data \n .global vmx_return \n vmx_return: .long 2b"); and -ftracer causes a double declaration. Cc: Andrew Morton Cc: Michal Marek Cc: kvm@vger.kernel.org Reported-by: Linda Walsh Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman

include/linux/compiler-gcc.h: improve __visible documentation

2015-11-07T01:50:42Z

Cc: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

include/linux/compiler-gcc.h: hide assume_aligned attribute from sparse

2015-11-06T03:34:48Z

The patch "slab.h: sprinkle __assume_aligned attributes" causes *tons* of whinges if you do 'make C=2' with sparse 0.5.0: CHECK drivers/media/usb/pwc/pwc-if.c include/linux/slab.h:307:43: error: attribute '__assume_aligned__': unknown attribute include/linux/slab.h:308:58: error: attribute '__assume_aligned__': unknown attribute include/linux/slab.h:337:73: error: attribute '__assume_aligned__': unknown attribute include/linux/slab.h:375:74: error: attribute '__assume_aligned__': unknown attribute include/linux/slab.h:378:80: error: attribute '__assume_aligned__': unknown attribute sparse apparently pretends to be gcc >= 4.9, yet isn't prepared to handle all the function attributes supported by those gccs and complains loudly. So hide the definition of __assume_aligned from it (so that the generic one in compiler.h gets used). Signed-off-by: Rasmus Villemoes Reported-by: Valdis Kletnieks Tested-By: Valdis Kletnieks Cc: Christopher Li Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

compiler.h: add support for function attribute assume_aligned

2015-11-06T03:34:48Z

gcc 4.9 added the function attribute assume_aligned, indicating to the caller that the returned pointer may be assumed to have a certain minimal alignment. This is useful if, for example, the return value is passed to memset(). Add a shorthand macro for that. Signed-off-by: Rasmus Villemoes Cc: Christoph Lameter Cc: David Rientjes Cc: Pekka Enberg Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

compiler, atomics, kasan: Provide READ_ONCE_NOCHECK()

2015-10-20T09:04:19Z

Some code may perform racy by design memory reads. This could be harmless, yet such code may produce KASAN warnings. To hide such accesses from KASAN this patch introduces READ_ONCE_NOCHECK() macro. KASAN will not check the memory accessed by READ_ONCE_NOCHECK(). The KernelThreadSanitizer (KTSAN) is going to ignore it as well. This patch creates __read_once_size_nocheck() a clone of __read_once_size(). The only difference between them is 'no_sanitized_address' attribute appended to '*_nocheck' function. This attribute tells the compiler that instrumentation of memory accesses should not be applied to that function. We declare it as static '__maybe_unsed' because GCC is not capable to inline such function: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 With KASAN=n READ_ONCE_NOCHECK() is just a clone of READ_ONCE(). Signed-off-by: Andrey Ryabinin Cc: Alexander Potapenko Cc: Andrew Morton Cc: Andrey Konovalov Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Denys Vlasenko Cc: Dmitry Vyukov Cc: Kostya Serebryany Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Sasha Levin Cc: Thomas Gleixner Cc: Wolfram Gloger Cc: kasan-dev Link: http://lkml.kernel.org/r/1445243838-17763-2-git-send-email-aryabinin@virtuozzo.com Signed-off-by: Ingo Molnar

compiler-gcc: integrate the various compiler-gcc[345].h files

2015-06-26T00:00:38Z

As gcc major version numbers are going to advance rather rapidly in the future, there's no real value in separate files for each compiler version. Deduplicate some of the macros #defined in each file too. Neaten comments using normal kernel commenting style. Signed-off-by: Joe Perches Cc: Andi Kleen Cc: Michal Marek Cc: Segher Boessenkool Cc: Sasha Levin Cc: Anton Blanchard Cc: Alan Modra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds