user/sven/linux.git/include/linux/compiler-gcc.h, branch v5.4.38

bpf: Disable GCC -fgcse optimization for ___bpf_prog_run()

2019-07-18T19:01:06Z

On x86-64, with CONFIG_RETPOLINE=n, GCC's "global common subexpression elimination" optimization results in ___bpf_prog_run()'s jumptable code changing from this: select_insn: jmp *jumptable(, %rax, 8) ... ALU64_ADD_X: ... jmp *jumptable(, %rax, 8) ALU_ADD_X: ... jmp *jumptable(, %rax, 8) to this: select_insn: mov jumptable, %r12 jmp *(%r12, %rax, 8) ... ALU64_ADD_X: ... jmp *(%r12, %rax, 8) ALU_ADD_X: ... jmp *(%r12, %rax, 8) The jumptable address is placed in a register once, at the beginning of the function. The function execution can then go through multiple indirect jumps which rely on that same register value. This has a few issues: 1) Objtool isn't smart enough to be able to track such a register value across multiple recursive indirect jumps through the jump table. 2) With CONFIG_RETPOLINE enabled, this optimization actually results in a small slowdown. I measured a ~4.7% slowdown in the test_bpf "tcpdump port 22" selftest. This slowdown is actually predicted by the GCC manual: Note: When compiling a program using computed gotos, a GCC extension, you may get better run-time performance if you disable the global common subexpression elimination pass by adding -fno-gcse to the command line. So just disable the optimization for this function. Fixes: e55a73251da3 ("bpf: Fix ORC unwinding in non-JIT BPF code") Reported-by: Randy Dunlap Signed-off-by: Josh Poimboeuf Signed-off-by: Thomas Gleixner Acked-by: Alexei Starovoitov Acked-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/30c3ca29ba037afcbd860a8672eef0021addf9fe.1563413318.git.jpoimboe@redhat.com

Merge tags 'compiler-attributes-for-linus-v5.0-rc3' and 'clang-format-for-linus-v5.0-rc3' of git://github.com/ojeda/linux

2019-01-20T18:23:42Z

Pull misc clang fixes from Miguel Ojeda: - A fix for OPTIMIZER_HIDE_VAR from Michael S Tsirkin - Update clang-format with the latest for_each macro list from Jason Gunthorpe * tag 'compiler-attributes-for-linus-v5.0-rc3' of git://github.com/ojeda/linux: include/linux/compiler*.h: fix OPTIMIZER_HIDE_VAR * tag 'clang-format-for-linus-v5.0-rc3' of git://github.com/ojeda/linux: clang-format: Update .clang-format with the latest for_each macro list

include/linux/compiler*.h: fix OPTIMIZER_HIDE_VAR

2019-01-09T10:36:41Z

Since commit 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive") clang no longer reuses the OPTIMIZER_HIDE_VAR macro from compiler-gcc - instead it gets the version in include/linux/compiler.h. Unfortunately that version doesn't actually prevent compiler from optimizing out the variable. Fix up by moving the macro out from compiler-gcc.h to compiler.h. Compilers without incline asm support will keep working since it's protected by an ifdef. Also fix up comments to match reality since we are no longer overriding any macros. Build-tested with gcc and clang. Fixes: 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive") Cc: Eli Friedman Cc: Joe Perches Cc: Linus Torvalds Reviewed-by: Nick Desaulniers Signed-off-by: Michael S. Tsirkin Signed-off-by: Miguel Ojeda

x86, modpost: Replace last remnants of RETPOLINE with CONFIG_RETPOLINE

2019-01-09T09:35:56Z

Commit 4cd24de3a098 ("x86/retpoline: Make CONFIG_RETPOLINE depend on compiler support") replaced the RETPOLINE define with CONFIG_RETPOLINE checks. Remove the remaining pieces. [ bp: Massage commit message. ] Fixes: 4cd24de3a098 ("x86/retpoline: Make CONFIG_RETPOLINE depend on compiler support") Signed-off-by: WANG Chao Signed-off-by: Borislav Petkov Reviewed-by: Zhenzhong Duan Reviewed-by: Masahiro Yamada Cc: "H. Peter Anvin" Cc: Andi Kleen Cc: Andrew Morton Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Daniel Borkmann Cc: David Woodhouse Cc: Geert Uytterhoeven Cc: Jessica Yu Cc: Jiri Kosina Cc: Kees Cook Cc: Konrad Rzeszutek Wilk Cc: Luc Van Oostenryck Cc: Michal Marek Cc: Miguel Ojeda Cc: Peter Zijlstra Cc: Tim Chen Cc: Vasily Gorbik Cc: linux-kbuild@vger.kernel.org Cc: srinivas.eeda@oracle.com Cc: stable Cc: x86-ml Link: https://lkml.kernel.org/r/20181210163725.95977-1-chao.wang@ucloud.cn

kasan: add CONFIG_KASAN_GENERIC and CONFIG_KASAN_SW_TAGS

2018-12-28T20:11:43Z

This commit splits the current CONFIG_KASAN config option into two: 1. CONFIG_KASAN_GENERIC, that enables the generic KASAN mode (the one that exists now); 2. CONFIG_KASAN_SW_TAGS, that enables the software tag-based KASAN mode. The name CONFIG_KASAN_SW_TAGS is chosen as in the future we will have another hardware tag-based KASAN mode, that will rely on hardware memory tagging support in arm64. With CONFIG_KASAN_SW_TAGS enabled, compiler options are changed to instrument kernel files with -fsantize=kernel-hwaddress (except the ones for which KASAN_SANITIZE := n is set). Both CONFIG_KASAN_GENERIC and CONFIG_KASAN_SW_TAGS support both CONFIG_KASAN_INLINE and CONFIG_KASAN_OUTLINE instrumentation modes. This commit also adds empty placeholder (for now) implementation of tag-based KASAN specific hooks inserted by the compiler and adjusts common hooks implementation. While this commit adds the CONFIG_KASAN_SW_TAGS config option, this option is not selectable, as it depends on HAVE_ARCH_KASAN_SW_TAGS, which we will enable once all the infrastracture code has been added. Link: http://lkml.kernel.org/r/b2550106eb8a68b10fefbabce820910b115aa853.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Andrey Ryabinin Reviewed-by: Dmitry Vyukov Cc: Christoph Lameter Cc: Mark Rutland Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

compiler: remove __no_sanitize_address_or_inline again

2018-11-05T16:14:18Z

The __no_sanitize_address_or_inline and __no_kasan_or_inline defines are almost identical. The only difference is that __no_kasan_or_inline does not have the 'notrace' attribute. To be able to replace __no_sanitize_address_or_inline with the older definition, add 'notrace' to __no_kasan_or_inline and change to two users of __no_sanitize_address_or_inline in the s390 code. The 'notrace' option is necessary for e.g. the __load_psw_mask function in arch/s390/include/asm/processor.h. Without the option it is possible to trace __load_psw_mask which leads to kernel stack overflow. Signed-off-by: Martin Schwidefsky Pointed-out-by: Andrey Ryabinin Acked-by: Steven Rostedt (VMware) Signed-off-by: Linus Torvalds

Merge tag 'compiler-attributes-for-linus-4.20-rc1' of https://github.com/ojeda/linux

2018-11-02T01:34:46Z

Pull compiler attribute updates from Miguel Ojeda: "This is an effort to disentangle the include/linux/compiler*.h headers and bring them up to date. The main idea behind the series is to use feature checking macros (i.e. __has_attribute) instead of compiler version checks (e.g. GCC_VERSION), which are compiler-agnostic (so they can be shared, reducing the size of compiler-specific headers) and version-agnostic. Other related improvements have been performed in the headers as well, which on top of the use of __has_attribute it has amounted to a significant simplification of these headers (e.g. GCC_VERSION is now only guarding a few non-attribute macros). This series should also help the efforts to support compiling the kernel with clang and icc. A fair amount of documentation and comments have also been added, clarified or removed; and the headers are now more readable, which should help kernel developers in general. The series was triggered due to the move to gcc >= 4.6. In turn, this series has also triggered Sparse to gain the ability to recognize __has_attribute on its own. Finally, the __nonstring variable attribute series has been also applied on top; plus two related patches from Nick Desaulniers for unreachable() that came a bit afterwards" * tag 'compiler-attributes-for-linus-4.20-rc1' of https://github.com/ojeda/linux: compiler-gcc: remove comment about gcc 4.5 from unreachable() compiler.h: update definition of unreachable() Compiler Attributes: ext4: remove local __nonstring definition Compiler Attributes: auxdisplay: panel: use __nonstring Compiler Attributes: enable -Wstringop-truncation on W=1 (gcc >= 8) Compiler Attributes: add support for __nonstring (gcc >= 8) Compiler Attributes: add MAINTAINERS entry Compiler Attributes: add Doc/process/programming-language.rst Compiler Attributes: remove uses of __attribute__ from compiler.h Compiler Attributes: KENTRY used twice the "used" attribute Compiler Attributes: use feature checks instead of version checks Compiler Attributes: add missing SPDX ID in compiler_types.h Compiler Attributes: remove unneeded sparse (__CHECKER__) tests Compiler Attributes: homogenize __must_be_array Compiler Attributes: remove unneeded tests Compiler Attributes: always use the extra-underscores syntax Compiler Attributes: remove unused attributes

Merge tag 's390-4.20-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2018-10-23T10:14:47Z

Pull s390 updates from Martin Schwidefsky: - Improved access control for the zcrypt driver, multiple device nodes can now be created with different access control lists - Extend the pkey API to provide random protected keys, this is useful for encrypted swap device with ephemeral protected keys - Add support for virtually mapped kernel stacks - Rework the early boot code, this moves the memory detection into the boot code that runs prior to decompression. - Add KASAN support - Bug fixes and cleanups * tag 's390-4.20-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (83 commits) s390/pkey: move pckmo subfunction available checks away from module init s390/kasan: support preemptible kernel build s390/pkey: Load pkey kernel module automatically s390/perf: Return error when debug_register fails s390/sthyi: Fix machine name validity indication s390/zcrypt: fix broken zcrypt_send_cprb in-kernel api function s390/vmalloc: fix VMALLOC_START calculation s390/mem_detect: add missing include s390/dumpstack: print psw mask and address again s390/crypto: Enhance paes cipher to accept variable length key material s390/pkey: Introduce new API for transforming key blobs s390/pkey: Introduce new API for random protected key verification s390/pkey: Add sysfs attributes to emit secure key blobs s390/pkey: Add sysfs attributes to emit protected key blobs s390/pkey: Define protected key blob format s390/pkey: Introduce new API for random protected key generation s390/zcrypt: add ap_adapter_mask sysfs attribute s390/zcrypt: provide apfs failure code on type 86 error reply s390/zcrypt: zcrypt device driver cleanup s390/kasan: add support for mem= kernel parameter ...

compiler-gcc: remove comment about gcc 4.5 from unreachable()

2018-10-19T06:47:30Z

Remove the comment about being unable to detect __builtin_unreachable. __builtin_unreachable was implemented in the GCC 4.5 timeframe. The kernel's minimum supported version of GCC is 4.6 since commit cafa0010cd51 ("Raise the minimum required gcc version to 4.6"). Commit cb984d101b30 ("compiler-gcc: integrate the various compiler-gcc[345].h files") shows that unreachable() had different guards based on GCC version. Suggested-by: Miguel Ojeda Signed-off-by: Nick Desaulniers Signed-off-by: Miguel Ojeda

compiler: introduce __no_sanitize_address_or_inline

2018-10-09T09:21:25Z

Due to conflict between kasan instrumentation and inlining https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 functions which are defined as inline could not be called from functions defined with __no_sanitize_address. Introduce __no_sanitize_address_or_inline which would expand to __no_sanitize_address when the kernel is built with kasan support and to inline otherwise. This helps to avoid disabling kasan instrumentation for entire files. Reviewed-by: Martin Schwidefsky Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky