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2024-05-19Merge tag 'x86-urgent-2024-05-18' of ↵Linus Torvalds1-0/+1
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 fixes from Ingo Molnar: - Fix a NOP-patching bug that resulted in valid but suboptimal NOP sequences in certain cases - Fix build warnings related to fall-through control flow * tag 'x86-urgent-2024-05-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/alternatives: Use the correct length when optimizing NOPs x86/boot: Address clang -Wimplicit-fallthrough in vsprintf() x86/boot: Add a fallthrough annotation
2024-05-16x86/boot: Add a fallthrough annotationBorislav Petkov1-0/+1
Add implicit fallthrough checking to the decompressor code and fix this warning: arch/x86/boot/printf.c: In function ‘vsprintf’: arch/x86/boot/printf.c:248:10: warning: this statement may fall through [-Wimplicit-fallthrough=] 248 | flags |= SMALL; | ^ arch/x86/boot/printf.c:249:3: note: here 249 | case 'X': | ^~~~ This is a patch from three years ago which I found in my trees, thus the SUSE authorship still. Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20240516102240.16270-1-bp@kernel.org
2024-05-14Makefile: remove redundant tool coverage variablesMasahiro Yamada1-15/+0
Now Kbuild provides reasonable defaults for objtool, sanitizers, and profilers. Remove redundant variables. Note: This commit changes the coverage for some objects: - include arch/mips/vdso/vdso-image.o into UBSAN, GCOV, KCOV - include arch/sparc/vdso/vdso-image-*.o into UBSAN - include arch/sparc/vdso/vma.o into UBSAN - include arch/x86/entry/vdso/extable.o into KASAN, KCSAN, UBSAN, GCOV, KCOV - include arch/x86/entry/vdso/vdso-image-*.o into KASAN, KCSAN, UBSAN, GCOV, KCOV - include arch/x86/entry/vdso/vdso32-setup.o into KASAN, KCSAN, UBSAN, GCOV, KCOV - include arch/x86/entry/vdso/vma.o into GCOV, KCOV - include arch/x86/um/vdso/vma.o into KASAN, GCOV, KCOV I believe these are positive effects because all of them are kernel space objects. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> Tested-by: Roberto Sassu <roberto.sassu@huawei.com>
2024-05-10kbuild: use $(src) instead of $(srctree)/$(src) for source directoryMasahiro Yamada1-1/+1
Kbuild conventionally uses $(obj)/ for generated files, and $(src)/ for checked-in source files. It is merely a convention without any functional difference. In fact, $(obj) and $(src) are exactly the same, as defined in scripts/Makefile.build: src := $(obj) When the kernel is built in a separate output directory, $(src) does not accurately reflect the source directory location. While Kbuild resolves this discrepancy by specifying VPATH=$(srctree) to search for source files, it does not cover all cases. For example, when adding a header search path for local headers, -I$(srctree)/$(src) is typically passed to the compiler. This introduces inconsistency between upstream and downstream Makefiles because $(src) is used instead of $(srctree)/$(src) for the latter. To address this inconsistency, this commit changes the semantics of $(src) so that it always points to the directory in the source tree. Going forward, the variables used in Makefiles will have the following meanings: $(obj) - directory in the object tree $(src) - directory in the source tree (changed by this commit) $(objtree) - the top of the kernel object tree $(srctree) - the top of the kernel source tree Consequently, $(srctree)/$(src) in upstream Makefiles need to be replaced with $(src). Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
2023-09-17x86/boot: Split off PE/COFF .data sectionArd Biesheuvel1-1/+1
Describe the code and data of the decompressor binary using separate .text and .data PE/COFF sections, so that we will be able to map them using restricted permissions once we increase the section and file alignment sufficiently. This avoids the need for memory mappings that are writable and executable at the same time, which is something that is best avoided for security reasons. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20230915171623.655440-17-ardb@google.com
2023-09-17x86/boot: Derive file size from _edata symbolArd Biesheuvel1-1/+1
Tweak the linker script so that the value of _edata represents the decompressor binary's file size rounded up to the appropriate alignment. This removes the need to calculate it in the build tool, and will make it easier to refer to the file size from the header directly in subsequent changes to the PE header layout. While adding _edata to the sed regex that parses the compressed vmlinux's symbol list, tweak the regex a bit for conciseness. This change has no impact on the resulting bzImage binary when configured with CONFIG_EFI_STUB=y. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20230915171623.655440-14-ardb@google.com
2023-09-15x86/boot: Drop references to startup_64Ard Biesheuvel1-1/+1
The x86 boot image generation tool assign a default value to startup_64 and subsequently parses the actual value from zoffset.h but it never actually uses the value anywhere. So remove this code. This change has no impact on the resulting bzImage binary. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20230912090051.4014114-25-ardb@google.com
2023-05-15x86/cpu: Remove X86_FEATURE_NAMESLukas Bulwahn1-2/+0
While discussing to change the visibility of X86_FEATURE_NAMES (see Link) in order to remove CONFIG_EMBEDDED, Boris suggested to simply make the X86_FEATURE_NAMES functionality unconditional. As the need for really tiny kernel images has gone away and kernel images with !X86_FEATURE_NAMES are hardly tested, remove this config and the whole ifdeffery in the source code. Suggested-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/all/20230509084007.24373-1-lukas.bulwahn@gmail.com/ Link: https://lore.kernel.org/r/20230510065713.10996-3-lukas.bulwahn@gmail.com
2022-11-24kbuild: fix "cat: .version: No such file or directory"Masahiro Yamada1-1/+1
Since commit 2df8220cc511 ("kbuild: build init/built-in.a just once"), the .version file is not touched at all when KBUILD_BUILD_VERSION is given. If KBUILD_BUILD_VERSION is specified and the .version file is missing (for example right after 'make mrproper'), "No such file or director" is shown. Even if the .version exists, it is irrelevant to the version of the current build. $ make -j$(nproc) KBUILD_BUILD_VERSION=100 mrproper defconfig all [ snip ] BUILD arch/x86/boot/bzImage cat: .version: No such file or directory Kernel: arch/x86/boot/bzImage is ready (#) Show KBUILD_BUILD_VERSION if it is given. Fixes: 2df8220cc511 ("kbuild: build init/built-in.a just once") Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
2022-10-03x86: kmsan: disable instrumentation of unsupported codeAlexander Potapenko1-0/+1
Instrumenting some files with KMSAN will result in kernel being unable to link, boot or crashing at runtime for various reasons (e.g. infinite recursion caused by instrumentation hooks calling instrumented code again). Completely omit KMSAN instrumentation in the following places: - arch/x86/boot and arch/x86/realmode/rm, as KMSAN doesn't work for i386; - arch/x86/entry/vdso, which isn't linked with KMSAN runtime; - three files in arch/x86/kernel - boot problems; - arch/x86/mm/cpu_entry_area.c - recursion. Link: https://lkml.kernel.org/r/20220915150417.722975-33-glider@google.com Signed-off-by: Alexander Potapenko <glider@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Eric Biggers <ebiggers@google.com> Cc: Eric Biggers <ebiggers@kernel.org> Cc: Eric Dumazet <edumazet@google.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Ilya Leoshkevich <iii@linux.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kees Cook <keescook@chromium.org> Cc: Marco Elver <elver@google.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-08-10x86: link vdso and boot with -z noexecstack --no-warn-rwx-segmentsNick Desaulniers1-1/+1
Users of GNU ld (BFD) from binutils 2.39+ will observe multiple instances of a new warning when linking kernels in the form: ld: warning: arch/x86/boot/pmjump.o: missing .note.GNU-stack section implies executable stack ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker ld: warning: arch/x86/boot/compressed/vmlinux has a LOAD segment with RWX permissions Generally, we would like to avoid the stack being executable. Because there could be a need for the stack to be executable, assembler sources have to opt-in to this security feature via explicit creation of the .note.GNU-stack feature (which compilers create by default) or command line flag --noexecstack. Or we can simply tell the linker the production of such sections is irrelevant and to link the stack as --noexecstack. LLVM's LLD linker defaults to -z noexecstack, so this flag isn't strictly necessary when linking with LLD, only BFD, but it doesn't hurt to be explicit here for all linkers IMO. --no-warn-rwx-segments is currently BFD specific and only available in the current latest release, so it's wrapped in an ld-option check. While the kernel makes extensive usage of ELF sections, it doesn't use permissions from ELF segments. Link: https://lore.kernel.org/linux-block/3af4127a-f453-4cf7-f133-a181cce06f73@kernel.dk/ Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=ba951afb99912da01a6e8434126b8fac7aa75107 Link: https://github.com/llvm/llvm-project/issues/57009 Reported-and-tested-by: Jens Axboe <axboe@kernel.dk> Suggested-by: Fangrui Song <maskray@google.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-08-25x86/build: Move the install rule to arch/x86/MakefileMasahiro Yamada1-6/+1
Currently, the install target in arch/x86/Makefile descends into arch/x86/boot/Makefile to invoke the shell script, but there is no good reason to do so. arch/x86/Makefile can run the shell script directly. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20210729140023.442101-2-masahiroy@kernel.org
2021-05-10x86/boot: Modernize genimage script; hdimage+EFI supportH. Peter Anvin (Intel)1-21/+23
The image generation scripts in arch/x86/boot are pretty out of date, except for the isoimage target. Update and clean up the genimage.sh script, and make it support an arbitrary number of initramfs files in the image. Add a "hdimage" target, which can be booted by either BIOS or EFI (if the kernel is compiled with the EFI stub.) For EFI to be able to pass the command line to the kernel, we need the EFI shell, but the firmware builtin EFI shell, if it even exists, is pretty much always the last resort boot option, so search for OVMF or EDK2 and explicitly include a copy of the EFI shell. To make this all work, use bash features in the script. Furthermore, this version of the script makes use of some mtools features, especially mpartition, that might not exist in very old version of mtools, but given all the other dependencies on this script this doesn't seem such a big deal. Finally, put a volume label ("LINUX_BOOT") on all generated images. Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20210510082840.628372-1-hpa@zytor.com
2020-06-11Rebase locking/kcsan to locking/urgentThomas Gleixner1-0/+2
Merge the state of the locking kcsan branch before the read/write_once() and the atomics modifications got merged. Squash the fallout of the rebase on top of the read/write once and atomic fallback work into the merge. The history of the original branch is preserved in tag locking-kcsan-2020-06-02. Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2020-04-21x86/boot/build: Add phony targets in arch/x86/boot/Makefile to PHONYMasahiro Yamada1-0/+2
These targets are correctly added to PHONY in arch/x86/Makefile, but not in arch/x86/boot/Makefile. Thus, with a file 'install' in the top directory, 'make install' does nothing: $ touch install $ make install make[1]: 'install' is up to date. Add them to the PHONY targets in the boot Makefile too. [ bp: Massage. ] Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20200215063852.8298-2-masahiroy@kernel.org
2020-04-21x86/boot/build: Make 'make bzlilo' not depend on vmlinux or $(obj)/bzImageMasahiro Yamada1-1/+1
bzlilo is an installation target because it copies files to $(INSTALL_PATH)/, then runs 'lilo'. However, arch/x86/Makefile and arch/x86/boot/Makefile have it depend on vmlinux and $(obj)/bzImage, respectively. 'make bzlilo' may update some build artifacts in the source tree. As commit 19514fc665ff ("arm, kbuild: make "make install" not depend on vmlinux") explained, this should not happen. Make 'bzlilo' not depend on any build artifact. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20200215063852.8298-1-masahiroy@kernel.org
2020-04-21x86/boot/build: Add cpustr.h to targets and remove clean-filesMasahiro Yamada1-2/+1
Files in $(targets) are always cleaned up. Move the 'targets' assignment out of the ifdef and remove 'clean-files'. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20200215063241.7437-1-masahiroy@kernel.org
2020-04-13Merge tag 'v5.7-rc1' into locking/kcsan, to resolve conflicts and refreshIngo Molnar1-1/+2
Resolve these conflicts: arch/x86/Kconfig arch/x86/kernel/Makefile Do a minor "evil merge" to move the KCSAN entry up a bit by a few lines in the Kconfig to reduce the probability of future conflicts. Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-03-31Merge branch 'x86-boot-for-linus' of ↵Linus Torvalds1-0/+1
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 boot updates from Ingo Molnar: "Misc cleanups and small enhancements all around the map" * 'x86-boot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/boot/compressed: Fix debug_puthex() parameter type x86/setup: Fix static memory detection x86/vmlinux: Drop unneeded linker script discard of .eh_frame x86/*/Makefile: Use -fno-asynchronous-unwind-tables to suppress .eh_frame sections x86/boot/compressed: Remove .eh_frame section from bzImage x86/boot/compressed/64: Remove .bss/.pgtable from bzImage x86/boot/compressed/64: Use 32-bit (zero-extended) MOV for z_output_len x86/boot/compressed/64: Use LEA to initialize boot stack pointer
2020-03-21Merge branch 'x86/kdump' into locking/kcsan, to resolve conflictsIngo Molnar1-3/+3
Conflicts: arch/x86/purgatory/Makefile Signed-off-by: Ingo Molnar <mingo@kernel.org>
2020-02-25x86/*/Makefile: Use -fno-asynchronous-unwind-tables to suppress .eh_frame ↵Arvind Sankar1-0/+1
sections While discussing a patch to discard .eh_frame from the compressed vmlinux using the linker script, Fangrui Song pointed out [1] that these sections shouldn't exist in the first place because arch/x86/Makefile uses -fno-asynchronous-unwind-tables. It turns out this is because the Makefiles used to build the compressed kernel redefine KBUILD_CFLAGS, dropping this flag. Add the flag to the Makefile for the compressed kernel, as well as the EFI stub Makefile to fix this. Also add the flag to boot/Makefile and realmode/rm/Makefile so that the kernel's boot code (boot/setup.elf) and realmode trampoline (realmode/rm/realmode.elf) won't be compiled with .eh_frame sections, since their linker scripts also just discard them. [1] https://lore.kernel.org/lkml/20200222185806.ywnqhfqmy67akfsa@google.com/ Suggested-by: Fangrui Song <maskray@google.com> Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Tested-by: Nathan Chancellor <natechancellor@gmail.com> Link: https://lkml.kernel.org/r/20200224232129.597160-2-nivedita@alum.mit.edu
2020-02-23efi/x86: Add true mixed mode entry point into .compat sectionArd Biesheuvel1-1/+1
Currently, mixed mode is closely tied to the EFI handover protocol and relies on intimate knowledge of the bootparams structure, setup header etc, all of which are rather byzantine and entirely specific to x86. Even though no other EFI supported architectures are currently known that could support something like mixed mode, it still makes sense to abstract a bit from this, and make it part of a generic Linux on EFI boot protocol. To that end, add a .compat section to the mixed mode binary, and populate it with the PE machine type and entry point address, allowing firmware implementations to match it to their native machine type, and invoke non-native binaries using a secondary entry point. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-02-04kbuild: rename hostprogs-y/always to hostprogs/always-yMasahiro Yamada1-2/+2
In old days, the "host-progs" syntax was used for specifying host programs. It was renamed to the current "hostprogs-y" in 2004. It is typically useful in scripts/Makefile because it allows Kbuild to selectively compile host programs based on the kernel configuration. This commit renames like follows: always -> always-y hostprogs-y -> hostprogs So, scripts/Makefile will look like this: always-$(CONFIG_BUILD_BIN2C) += ... always-$(CONFIG_KALLSYMS) += ... ... hostprogs := $(always-y) $(always-m) I think this makes more sense because a host program is always a host program, irrespective of the kernel configuration. We want to specify which ones to compile by CONFIG options, so always-y will be handier. The "always", "hostprogs-y", "hostprogs-m" will be kept for backward compatibility for a while. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-01-20x86/boot/compressed: Relax sed symbol type regex for LLVM ld.lldArd Biesheuvel1-1/+1
The final build stage of the x86 kernel captures some symbol addresses from the decompressor binary and copies them into zoffset.h. It uses sed with a regular expression that matches the address, symbol type and symbol name, and mangles the captured addresses and the names of symbols of interest into #define directives that are added to zoffset.h The symbol type is indicated by a single letter, which we match strictly: only letters in the set 'ABCDGRSTVW' are matched, even though the actual symbol type is relevant and therefore ignored. Commit bc7c9d620 ("efi/libstub/x86: Force 'hidden' visibility for extern declarations") made a change to the way external symbol references are classified, resulting in 'startup_32' now being emitted as a hidden symbol. This prevents the use of GOT entries to refer to this symbol via its absolute address, which recent toolchains (including Clang based ones) already avoid by default, making this change a no-op in the majority of cases. However, as it turns out, the LLVM linker classifies such hidden symbols as symbols with static linkage in fully linked ELF binaries, causing tools such as NM to output a lowercase 't' rather than an upper case 'T' for the type of such symbols. Since our sed expression only matches upper case letters for the symbol type, the line describing startup_32 is disregarded, resulting in a build error like the following arch/x86/boot/header.S:568:18: error: symbol 'ZO_startup_32' can not be undefined in a subtraction expression init_size: .long (0x00000000008fd000 - ZO_startup_32 + (((0x0000000001f6361c + ((0x0000000001f6361c >> 8) + 65536) - 0x00000000008c32e5) + 4095) & ~4095)) # kernel initialization size Given that we are only interested in the value of the symbol, let's match any character in the set 'a-zA-Z' instead. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Nathan Chancellor <natechancellor@gmail.com>
2019-12-30Merge tag 'v5.5-rc4' into locking/kcsan, to resolve conflictsIngo Molnar1-1/+2
Conflicts: init/main.c lib/Kconfig.debug Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-11-26Merge branch 'x86-asm-for-linus' of ↵Linus Torvalds1-0/+1
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 asm updates from Ingo Molnar: "The main changes in this cycle were: - Cross-arch changes to move the linker sections for NOTES and EXCEPTION_TABLE into the RO_DATA area, where they belong on most architectures. (Kees Cook) - Switch the x86 linker fill byte from x90 (NOP) to 0xcc (INT3), to trap jumps into the middle of those padding areas instead of sliding execution. (Kees Cook) - A thorough cleanup of symbol definitions within x86 assembler code. The rather randomly named macros got streamlined around a (hopefully) straightforward naming scheme: SYM_START(name, linkage, align...) SYM_END(name, sym_type) SYM_FUNC_START(name) SYM_FUNC_END(name) SYM_CODE_START(name) SYM_CODE_END(name) SYM_DATA_START(name) SYM_DATA_END(name) etc - with about three times of these basic primitives with some label, local symbol or attribute variant, expressed via postfixes. No change in functionality intended. (Jiri Slaby) - Misc other changes, cleanups and smaller fixes" * 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (67 commits) x86/entry/64: Remove pointless jump in paranoid_exit x86/entry/32: Remove unused resume_userspace label x86/build/vdso: Remove meaningless CFLAGS_REMOVE_*.o m68k: Convert missed RODATA to RO_DATA x86/vmlinux: Use INT3 instead of NOP for linker fill bytes x86/mm: Report actual image regions in /proc/iomem x86/mm: Report which part of kernel image is freed x86/mm: Remove redundant address-of operators on addresses xtensa: Move EXCEPTION_TABLE to RO_DATA segment powerpc: Move EXCEPTION_TABLE to RO_DATA segment parisc: Move EXCEPTION_TABLE to RO_DATA segment microblaze: Move EXCEPTION_TABLE to RO_DATA segment ia64: Move EXCEPTION_TABLE to RO_DATA segment h8300: Move EXCEPTION_TABLE to RO_DATA segment c6x: Move EXCEPTION_TABLE to RO_DATA segment arm64: Move EXCEPTION_TABLE to RO_DATA segment alpha: Move EXCEPTION_TABLE to RO_DATA segment x86/vmlinux: Move EXCEPTION_TABLE to RO_DATA segment x86/vmlinux: Actually use _etext for the end of the text segment vmlinux.lds.h: Allow EXCEPTION_TABLE to live in RO_DATA ...
2019-11-16x86, kcsan: Enable KCSAN for x86Marco Elver1-0/+2
This patch enables KCSAN for x86, with updates to build rules to not use KCSAN for several incompatible compilation units. Signed-off-by: Marco Elver <elver@google.com> Acked-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-11-12x86/boot: Introduce kernel_infoDaniel Kiper1-1/+1
The relationships between the headers are analogous to the various data sections: setup_header = .data boot_params/setup_data = .bss What is missing from the above list? That's right: kernel_info = .rodata We have been (ab)using .data for things that could go into .rodata or .bss for a long time, for lack of alternatives and -- especially early on -- inertia. Also, the BIOS stub is responsible for creating boot_params, so it isn't available to a BIOS-based loader (setup_data is, though). setup_header is permanently limited to 144 bytes due to the reach of the 2-byte jump field, which doubles as a length field for the structure, combined with the size of the "hole" in struct boot_params that a protected-mode loader or the BIOS stub has to copy it into. It is currently 119 bytes long, which leaves us with 25 very precious bytes. This isn't something that can be fixed without revising the boot protocol entirely, breaking backwards compatibility. boot_params proper is limited to 4096 bytes, but can be arbitrarily extended by adding setup_data entries. It cannot be used to communicate properties of the kernel image, because it is .bss and has no image-provided content. kernel_info solves this by providing an extensible place for information about the kernel image. It is readonly, because the kernel cannot rely on a bootloader copying its contents anywhere, but that is OK; if it becomes necessary it can still contain data items that an enabled bootloader would be expected to copy into a setup_data chunk. Do not bump setup_header version in arch/x86/boot/header.S because it will be followed by additional changes coming into the Linux/x86 boot protocol. Suggested-by: H. Peter Anvin (Intel) <hpa@zytor.com> Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Reviewed-by: Ross Philipson <ross.philipson@oracle.com> Reviewed-by: H. Peter Anvin (Intel) <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: ard.biesheuvel@linaro.org Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: dave.hansen@linux.intel.com Cc: eric.snowberg@oracle.com Cc: Ingo Molnar <mingo@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Juergen Gross <jgross@suse.com> Cc: kanth.ghatraju@oracle.com Cc: linux-doc@vger.kernel.org Cc: linux-efi <linux-efi@vger.kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: rdunlap@infradead.org Cc: ross.philipson@oracle.com Cc: Thomas Gleixner <tglx@linutronix.de> Cc: x86-ml <x86@kernel.org> Cc: xen-devel@lists.xenproject.org Link: https://lkml.kernel.org/r/20191112134640.16035-2-daniel.kiper@oracle.com
2019-10-01arch/x86/boot: Use prefix map to avoid embedded pathsBruce Ashfield1-0/+1
It was observed that the kernel embeds the absolute build path in the x86 boot image when the __FILE__ macro is expanded. > From https://bugzilla.yoctoproject.org/show_bug.cgi?id=13458: If you turn on the buildpaths QA test, or try a reproducible build, you discover that the kernel image contains build paths. $ strings bzImage-5.0.19-yocto-standard |grep tmp/ out of pgt_buf in /data/poky-tmp/reproducible/tmp/work-shared/qemux86-64/kernel-source/arch/x86/boot/compressed/kaslr_64.c!? But what's this in the top-level Makefile: $ git grep prefix-map Makefile:KBUILD_CFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=) So the __FILE__ shouldn't be using the full path. However arch/x86/boot/compressed/Makefile has this: KBUILD_CFLAGS := -m$(BITS) -O2 So that clears KBUILD_FLAGS, removing the -fmacro-prefix-map option. Use -fmacro-prefix-map to have relative paths in the boot image too. [ bp: Massage commit message and put the KBUILD_CFLAGS addition in ..boot/Makefile after the KBUILD_AFLAGS assignment because gas doesn't support -fmacro-prefix-map. ] Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com> Signed-off-by: Ross Burton <ross.burton@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: George Rimar <grimar@accesssoftek.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Nathan Chancellor <natechancellor@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/20190926093226.8568-1-ross.burton@intel.com Link: https://bugzilla.kernel.org/show_bug.cgi?id=204333
2019-01-12x86/build: Specify elf_i386 linker emulation explicitly for i386 objectsGeorge Rimar1-1/+1
The kernel uses the OUTPUT_FORMAT linker script command in it's linker scripts. Most of the time, the -m option is passed to the linker with correct architecture, but sometimes (at least for x86_64) the -m option contradicts the OUTPUT_FORMAT directive. Specifically, arch/x86/boot and arch/x86/realmode/rm produce i386 object files, but are linked with the -m elf_x86_64 linker flag when building for x86_64. The GNU linker manpage doesn't explicitly state any tie-breakers between -m and OUTPUT_FORMAT. But with BFD and Gold linkers, OUTPUT_FORMAT overrides the emulation value specified with the -m option. LLVM lld has a different behavior, however. When supplied with contradicting -m and OUTPUT_FORMAT values it fails with the following error message: ld.lld: error: arch/x86/realmode/rm/header.o is incompatible with elf_x86_64 Therefore, just add the correct -m after the incorrect one (it overrides it), so the linker invocation looks like this: ld -m elf_x86_64 -z max-page-size=0x200000 -m elf_i386 --emit-relocs -T \ realmode.lds header.o trampoline_64.o stack.o reboot.o -o realmode.elf This is not a functional change for GNU ld, because (although not explicitly documented) OUTPUT_FORMAT overrides -m EMULATION. Tested by building x86_64 kernel with GNU gcc/ld toolchain and booting it in QEMU. [ bp: massage and clarify text. ] Suggested-by: Dmitry Golovin <dima@golovin.in> Signed-off-by: George Rimar <grimar@accesssoftek.com> Signed-off-by: Tri Vo <trong@android.com> Signed-off-by: Borislav Petkov <bp@suse.de> Tested-by: Tri Vo <trong@android.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Michael Matz <matz@suse.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: morbo@google.com Cc: ndesaulniers@google.com Cc: ruiu@google.com Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/20190111201012.71210-1-trong@android.com
2017-11-07x86/build: Factor out fdimage/isoimage generation commands to standalone scriptChangbin Du1-48/+11
The build messages for fdimage/isoimage generation are pretty unstructured, just the raw shell command blocks are printed. Emit shortened messages similar to existing kbuild messages, and move the Makefile commands into a separate shell script - which is much easier to handle. This patch factors out the commands used for fdimage/isoimage generation from arch/x86/boot/Makefile to a new script arch/x86/boot/genimage.sh. Then it adds the new kbuild command 'genimage' which invokes the new script. All fdimages/isoimage files are now generated by a call to 'genimage' with different parameters. Now 'make isoimage' becomes: ... Kernel: arch/x86/boot/bzImage is ready (#30) GENIMAGE arch/x86/boot/image.iso Size of boot image is 4 sectors -> No emulation 15.37% done, estimate finish Sun Nov 5 23:36:57 2017 30.68% done, estimate finish Sun Nov 5 23:36:57 2017 46.04% done, estimate finish Sun Nov 5 23:36:57 2017 61.35% done, estimate finish Sun Nov 5 23:36:57 2017 76.69% done, estimate finish Sun Nov 5 23:36:57 2017 92.00% done, estimate finish Sun Nov 5 23:36:57 2017 Total translation table size: 2048 Total rockridge attributes bytes: 659 Total directory bytes: 0 Path table size(bytes): 10 Max brk space used 0 32608 extents written (63 MB) Kernel: arch/x86/boot/image.iso is ready Before: Kernel: arch/x86/boot/bzImage is ready (#63) rm -rf arch/x86/boot/isoimage mkdir arch/x86/boot/isoimage for i in lib lib64 share end ; do \ if [ -f /usr/$i/syslinux/isolinux.bin ] ; then \ cp /usr/$i/syslinux/isolinux.bin arch/x86/boot/isoimage ; \ if [ -f /usr/$i/syslinux/ldlinux.c32 ]; then \ cp /usr/$i/syslinux/ldlinux.c32 arch/x86/boot/isoimage ; \ fi ; \ break ; \ fi ; \ if [ $i = end ] ; then exit 1 ; fi ; \ done ... Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Changbin Du <changbin.du@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1509939179-7556-2-git-send-email-changbin.du@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-20x86/build: Silence the build with "make -s"Arnd Bergmann1-2/+3
Every kernel build on x86 will result in some output: Setup is 13084 bytes (padded to 13312 bytes). System is 4833 kB CRC 6d35fa35 Kernel: arch/x86/boot/bzImage is ready (#2) This shuts it up, so that 'make -s' is truely silent as long as everything works. Building without '-s' should produce unchanged output. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20170719125310.2487451-6-arnd@arndb.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-11-07x86/boot/build: Remove always empty $(USERINCLUDE)Paul Bolle1-1/+1
Commmit b6eea87fc685: ("x86, boot: Explicitly include autoconf.h for hostprogs") correctly noted: [...] that because $(USERINCLUDE) isn't exported by the top-level Makefile it's actually empty in arch/x86/boot/Makefile. So let's do the sane thing and remove the reference to that make variable. Signed-off-by: Paul Bolle <pebolle@tiscali.nl> Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk> Cc: David Howells <dhowells@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/1478166468-9760-1-git-send-email-pebolle@tiscali.nl Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-08-02Merge branch 'kbuild' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild Pull kbuild updates from Michal Marek: - GCC plugin support by Emese Revfy from grsecurity, with a fixup from Kees Cook. The plugins are meant to be used for static analysis of the kernel code. Two plugins are provided already. - reduction of the gcc commandline by Arnd Bergmann. - IS_ENABLED / IS_REACHABLE macro enhancements by Masahiro Yamada - bin2c fix by Michael Tautschnig - setlocalversion fix by Wolfram Sang * 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild: gcc-plugins: disable under COMPILE_TEST kbuild: Abort build on bad stack protector flag scripts: Fix size mismatch of kexec_purgatory_size kbuild: make samples depend on headers_install Kbuild: don't add obj tree in additional includes Kbuild: arch: look for generated headers in obtree Kbuild: always prefix objtree in LINUXINCLUDE Kbuild: avoid duplicate include path Kbuild: don't add ../../ to include path vmlinux.lds.h: replace config_enabled() with IS_ENABLED() kconfig.h: allow to use IS_{ENABLE,REACHABLE} in macro expansion kconfig.h: use already defined macros for IS_REACHABLE() define export.h: use __is_defined() to check if __KSYM_* is defined kconfig.h: use __is_defined() to check if MODULE is defined kbuild: setlocalversion: print error to STDERR Add sancov plugin Add Cyclomatic complexity GCC plugin GCC plugin infrastructure Shared library support
2016-07-18Kbuild: arch: look for generated headers in obtreeArnd Bergmann1-1/+1
There are very few files that need add an -I$(obj) gcc for the preprocessor or the assembler. For C files, we add always these for both the objtree and srctree, but for the other ones we require the Makefile to add them, and Kbuild then adds it for both trees. As a preparation for changing the meaning of the -I$(obj) directive to only refer to the srctree, this changes the two instances in arch/x86 to use an explictit $(objtree) prefix where needed, otherwise we won't find the headers any more, as reported by the kbuild 0day builder. arch/x86/realmode/rm/realmode.lds.S:75:20: fatal error: pasyms.h: No such file or directory Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Michal Marek <mmarek@suse.com>
2016-06-07x86, build: copy ldlinux.c32 to image.isoH. Peter Anvin1-0/+3
For newer versions of Syslinux, we need ldlinux.c32 in addition to isolinux.bin to reside on the boot disk, so if the latter is found, copy it, too, to the isoimage tree. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: Linux Stable Tree <stable@vger.kernel.org>
2016-04-29x86/boot: Fix "run_size" calculationYinghai Lu1-10/+1
Currently, the "run_size" variable holds the total kernel size (size of code plus brk and bss) and is calculated via the shell script arch/x86/tools/calc_run_size.sh. It gets the file offset and mem size of the .bss and .brk sections from the vmlinux, and adds them as follows: run_size = $(( $offsetA + $sizeA + $sizeB )) However, this is not correct (it is too large). To illustrate, here's a walk-through of the script's calculation, compared to the correct way to find it. First, offsetA is found as the starting address of the first .bss or .brk section seen in the ELF file. The sizeA and sizeB values are the respective section sizes. [bhe@x1 linux]$ objdump -h vmlinux vmlinux: file format elf64-x86-64 Sections: Idx Name Size VMA LMA File off Algn 27 .bss 00170000 ffffffff81ec8000 0000000001ec8000 012c8000 2**12 ALLOC 28 .brk 00027000 ffffffff82038000 0000000002038000 012c8000 2**0 ALLOC Here, offsetA is 0x012c8000, with sizeA at 0x00170000 and sizeB at 0x00027000. The resulting run_size is 0x145f000: 0x012c8000 + 0x00170000 + 0x00027000 = 0x145f000 However, if we instead examine the ELF LOAD program headers, we see a different picture. [bhe@x1 linux]$ readelf -l vmlinux Elf file type is EXEC (Executable file) Entry point 0x1000000 There are 5 program headers, starting at offset 64 Program Headers: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flags Align LOAD 0x0000000000200000 0xffffffff81000000 0x0000000001000000 0x0000000000b5e000 0x0000000000b5e000 R E 200000 LOAD 0x0000000000e00000 0xffffffff81c00000 0x0000000001c00000 0x0000000000145000 0x0000000000145000 RW 200000 LOAD 0x0000000001000000 0x0000000000000000 0x0000000001d45000 0x0000000000018158 0x0000000000018158 RW 200000 LOAD 0x000000000115e000 0xffffffff81d5e000 0x0000000001d5e000 0x000000000016a000 0x0000000000301000 RWE 200000 NOTE 0x000000000099bcac 0xffffffff8179bcac 0x000000000179bcac 0x00000000000001bc 0x00000000000001bc 4 Section to Segment mapping: Segment Sections... 00 .text .notes __ex_table .rodata __bug_table .pci_fixup .tracedata __ksymtab __ksymtab_gpl __ksymtab_strings __init_rodata __param __modver 01 .data .vvar 02 .data..percpu 03 .init.text .init.data .x86_cpu_dev.init .parainstructions .altinstructions .altinstr_replacement .iommu_table .apicdrivers .exit.text .smp_locks .bss .brk 04 .notes As mentioned, run_size needs to be the size of the running kernel including .bss and .brk. We can see from the Section/Segment mapping above that .bss and .brk are included in segment 03 (which corresponds to the final LOAD program header). To find the run_size, we calculate the end of the LOAD segment from its PhysAddr start (0x0000000001d5e000) and its MemSiz (0x0000000000301000), minus the physical load address of the kernel (the first LOAD segment's PhysAddr: 0x0000000001000000). The resulting run_size is 0x105f000: 0x0000000001d5e000 + 0x0000000000301000 - 0x0000000001000000 = 0x105f000 So, from this we can see that the existing run_size calculation is 0x400000 too high. And, as it turns out, the correct run_size is actually equal to VO_end - VO_text, which is certainly easier to calculate. _end: 0xffffffff8205f000 _text:0xffffffff81000000 0xffffffff8205f000 - 0xffffffff81000000 = 0x105f000 As a result, run_size is a simple constant, so we don't need to pass it around; we already have voffset.h for such things. We can share voffset.h between misc.c and header.S instead of getting run_size in other ways. This patch moves voffset.h creation code to boot/compressed/Makefile, and switches misc.c to use the VO_end - VO_text calculation for run_size. Dependence before: boot/header.S ==> boot/voffset.h ==> vmlinux boot/header.S ==> compressed/vmlinux ==> compressed/misc.c Dependence after: boot/header.S ==> compressed/vmlinux ==> compressed/misc.c ==> boot/voffset.h ==> vmlinux Signed-off-by: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Baoquan He <bhe@redhat.com> [ Rewrote the changelog. ] Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Young <dyoung@redhat.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Junjie Mao <eternal.n08@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: lasse.collin@tukaani.org Fixes: e6023367d779 ("x86, kaslr: Prevent .bss from overlaping initrd") Link: http://lkml.kernel.org/r/1461888548-32439-5-git-send-email-keescook@chromium.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-04-29x86/boot: Calculate decompression size during boot not buildYinghai Lu1-1/+1
Currently z_extract_offset is calculated in boot/compressed/mkpiggy.c. This doesn't work well because mkpiggy.c doesn't know the details of the decompressor in use. As a result, it can only make an estimation, which has risks: - output + output_len (VO) could be much bigger than input + input_len (ZO). In this case, the decompressed kernel plus relocs could overwrite the decompression code while it is running. - The head code of ZO could be bigger than z_extract_offset. In this case an overwrite could happen when the head code is running to move ZO to the end of buffer. Though currently the size of the head code is very small it's still a potential risk. Since there is no rule to limit the size of the head code of ZO, it runs the risk of suddenly becoming a (hard to find) bug. Instead, this moves the z_extract_offset calculation into header.S, and makes adjustments to be sure that the above two cases can never happen, and further corrects the comments describing the calculations. Since we have (in the previous patch) made ZO always be located against the end of decompression buffer, z_extract_offset is only used here to calculate an appropriate buffer size (INIT_SIZE), and is not longer used elsewhere. As such, it can be removed from voffset.h. Additionally clean up #if/#else #define to improve readability. Signed-off-by: Yinghai Lu <yinghai@kernel.org> Signed-off-by: Baoquan He <bhe@redhat.com> [ Rewrote the changelog and comments. ] Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Young <dyoung@redhat.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> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: lasse.collin@tukaani.org Link: http://lkml.kernel.org/r/1461888548-32439-4-git-send-email-keescook@chromium.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-03-22kernel: add kcov code coverageDmitry Vyukov1-0/+7
kcov provides code coverage collection for coverage-guided fuzzing (randomized testing). Coverage-guided fuzzing is a testing technique that uses coverage feedback to determine new interesting inputs to a system. A notable user-space example is AFL (http://lcamtuf.coredump.cx/afl/). However, this technique is not widely used for kernel testing due to missing compiler and kernel support. kcov does not aim to collect as much coverage as possible. It aims to collect more or less stable coverage that is function of syscall inputs. To achieve this goal it does not collect coverage in soft/hard interrupts and instrumentation of some inherently non-deterministic or non-interesting parts of kernel is disbled (e.g. scheduler, locking). Currently there is a single coverage collection mode (tracing), but the API anticipates additional collection modes. Initially I also implemented a second mode which exposes coverage in a fixed-size hash table of counters (what Quentin used in his original patch). I've dropped the second mode for simplicity. This patch adds the necessary support on kernel side. The complimentary compiler support was added in gcc revision 231296. We've used this support to build syzkaller system call fuzzer, which has found 90 kernel bugs in just 2 months: https://github.com/google/syzkaller/wiki/Found-Bugs We've also found 30+ bugs in our internal systems with syzkaller. Another (yet unexplored) direction where kcov coverage would greatly help is more traditional "blob mutation". For example, mounting a random blob as a filesystem, or receiving a random blob over wire. Why not gcov. Typical fuzzing loop looks as follows: (1) reset coverage, (2) execute a bit of code, (3) collect coverage, repeat. A typical coverage can be just a dozen of basic blocks (e.g. an invalid input). In such context gcov becomes prohibitively expensive as reset/collect coverage steps depend on total number of basic blocks/edges in program (in case of kernel it is about 2M). Cost of kcov depends only on number of executed basic blocks/edges. On top of that, kernel requires per-thread coverage because there are always background threads and unrelated processes that also produce coverage. With inlined gcov instrumentation per-thread coverage is not possible. kcov exposes kernel PCs and control flow to user-space which is insecure. But debugfs should not be mapped as user accessible. Based on a patch by Quentin Casasnovas. [akpm@linux-foundation.org: make task_struct.kcov_mode have type `enum kcov_mode'] [akpm@linux-foundation.org: unbreak allmodconfig] [akpm@linux-foundation.org: follow x86 Makefile layout standards] Signed-off-by: Dmitry Vyukov <dvyukov@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: syzkaller <syzkaller@googlegroups.com> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Tavis Ormandy <taviso@google.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Kees Cook <keescook@google.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: David Drysdale <drysdale@google.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-02-29objtool: Mark non-standard object files and directoriesJosh Poimboeuf1-1/+2
Code which runs outside the kernel's normal mode of operation often does unusual things which can cause a static analysis tool like objtool to emit false positive warnings: - boot image - vdso image - relocation - realmode - efi - head - purgatory - modpost Set OBJECT_FILES_NON_STANDARD for their related files and directories, which will tell objtool to skip checking them. It's ok to skip them because they don't affect runtime stack traces. Also skip the following code which does the right thing with respect to frame pointers, but is too "special" to be validated by a tool: - entry - mcount Also skip the test_nx module because it modifies its exception handling table at runtime, which objtool can't understand. Fortunately it's just a test module so it doesn't matter much. Currently objtool is the only user of OBJECT_FILES_NON_STANDARD, but it might eventually be useful for other tools. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris J Arges <chris.j.arges@canonical.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Marek <mmarek@suse.cz> Cc: Namhyung Kim <namhyung@gmail.com> Cc: Pedro Alves <palves@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/366c080e3844e8a5b6a0327dc7e8c2b90ca3baeb.1456719558.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-20UBSAN: run-time undefined behavior sanity checkerAndrey Ryabinin1-0/+1
UBSAN uses compile-time instrumentation to catch undefined behavior (UB). Compiler inserts code that perform certain kinds of checks before operations that could cause UB. If check fails (i.e. UB detected) __ubsan_handle_* function called to print error message. So the most of the work is done by compiler. This patch just implements ubsan handlers printing errors. GCC has this capability since 4.9.x [1] (see -fsanitize=undefined option and its suboptions). However GCC 5.x has more checkers implemented [2]. Article [3] has a bit more details about UBSAN in the GCC. [1] - https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Debugging-Options.html [2] - https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html [3] - http://developerblog.redhat.com/2014/10/16/gcc-undefined-behavior-sanitizer-ubsan/ Issues which UBSAN has found thus far are: Found bugs: * out-of-bounds access - 97840cb67ff5 ("netfilter: nfnetlink: fix insufficient validation in nfnetlink_bind") undefined shifts: * d48458d4a768 ("jbd2: use a better hash function for the revoke table") * 10632008b9e1 ("clockevents: Prevent shift out of bounds") * 'x << -1' shift in ext4 - http://lkml.kernel.org/r/<5444EF21.8020501@samsung.com> * undefined rol32(0) - http://lkml.kernel.org/r/<1449198241-20654-1-git-send-email-sasha.levin@oracle.com> * undefined dirty_ratelimit calculation - http://lkml.kernel.org/r/<566594E2.3050306@odin.com> * undefined roundown_pow_of_two(0) - http://lkml.kernel.org/r/<1449156616-11474-1-git-send-email-sasha.levin@oracle.com> * [WONTFIX] undefined shift in __bpf_prog_run - http://lkml.kernel.org/r/<CACT4Y+ZxoR3UjLgcNdUm4fECLMx2VdtfrENMtRRCdgHB2n0bJA@mail.gmail.com> WONTFIX here because it should be fixed in bpf program, not in kernel. signed overflows: * 32a8df4e0b33f ("sched: Fix odd values in effective_load() calculations") * mul overflow in ntp - http://lkml.kernel.org/r/<1449175608-1146-1-git-send-email-sasha.levin@oracle.com> * incorrect conversion into rtc_time in rtc_time64_to_tm() - http://lkml.kernel.org/r/<1449187944-11730-1-git-send-email-sasha.levin@oracle.com> * unvalidated timespec in io_getevents() - http://lkml.kernel.org/r/<CACT4Y+bBxVYLQ6LtOKrKtnLthqLHcw-BMp3aqP3mjdAvr9FULQ@mail.gmail.com> * [NOTABUG] signed overflow in ktime_add_safe() - http://lkml.kernel.org/r/<CACT4Y+aJ4muRnWxsUe1CMnA6P8nooO33kwG-c8YZg=0Xc8rJqw@mail.gmail.com> [akpm@linux-foundation.org: fix unused local warning] [akpm@linux-foundation.org: fix __int128 build woes] Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Marek <mmarek@suse.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Yury Gribov <y.gribov@samsung.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-05kasan: move KASAN_SANITIZE in arch/x86/boot/MakefileAndrey Konovalov1-2/+2
Move KASAN_SANITIZE in arch/x86/boot/Makefile above the comment related to SVGA_MODE, since the comment refers to 'the next line'. Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Konstantin Serebryany <kcc@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-07-21x86/boot: Obsolete the MCA sys_desc_tablePaolo Pisati1-1/+1
The kernel does not support the MCA bus anymroe, so mark sys_desc_table as obsolete: remove any reference from the code together with the remaining of MCA logic. bloat-o-meter output: add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-55 (-55) function old new delta i386_start_kernel 128 119 -9 setup_arch 1421 1375 -46 Signed-off-by: Paolo Pisati <p.pisati@gmail.com> Cc: Josh Triplett <josh@joshtriplett.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/1437409430-8491-1-git-send-email-p.pisati@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-02-13x86_64: add KASan supportAndrey Ryabinin1-0/+2
This patch adds arch specific code for kernel address sanitizer. 16TB of virtual addressed used for shadow memory. It's located in range [ffffec0000000000 - fffffc0000000000] between vmemmap and %esp fixup stacks. At early stage we map whole shadow region with zero page. Latter, after pages mapped to direct mapping address range we unmap zero pages from corresponding shadow (see kasan_map_shadow()) and allocate and map a real shadow memory reusing vmemmap_populate() function. Also replace __pa with __pa_nodebug before shadow initialized. __pa with CONFIG_DEBUG_VIRTUAL=y make external function call (__phys_addr) __phys_addr is instrumented, so __asan_load could be called before shadow area initialized. Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Serebryany <kcc@google.com> Cc: Dmitry Chernenkov <dmitryc@google.com> Signed-off-by: Andrey Konovalov <adech.fo@gmail.com> Cc: Yuri Gribov <tetra2005@gmail.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Christoph Lameter <cl@linux.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Jim Davis <jim.epost@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-12-23x86/build: Clean auto-generated processor feature filesBjørn Mork1-0/+1
Commit 9def39be4e96 ("x86: Support compiling out human-friendly processor feature names") made two source file targets conditional. Such conditional targets will not be cleaned automatically by make mrproper. Fix by adding explicit clean-files targets for the two files. Fixes: 9def39be4e96 ("x86: Support compiling out human-friendly processor feature names") Signed-off-by: Bjørn Mork <bjorn@mork.no> Cc: Josh Triplett <josh@joshtriplett.org> Link: http://lkml.kernel.org/r/1419335863-10608-1-git-send-email-bjorn@mork.no Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-08-17x86: Support compiling out human-friendly processor feature namesJosh Triplett1-2/+5
The table mapping CPUID bits to human-readable strings takes up a non-trivial amount of space, and only exists to support /proc/cpuinfo and a couple of kernel messages. Since programs depend on the format of /proc/cpuinfo, force inclusion of the table when building with /proc support; otherwise, support omitting that table to save space, in which case the kernel messages will print features numerically instead. In addition to saving 1408 bytes out of vmlinux, this also saves 1373 bytes out of the uncompressed setup code, which contributes directly to the size of bzImage. Signed-off-by: Josh Triplett <josh@joshtriplett.org>
2014-05-05x86, build: Don't get confused by local symbolsH. Peter Anvin1-2/+2
arch/x86/crypto/sha1_avx2_x86_64_asm.S introduced _end as a local symbol, which broke the build under certain circumstances. Although the wisdom of _end as a local symbol can definitely be questioned, the build should not break for that reason. Thus, filter the output of nm to only get global symbols of appropriate type. Reported-by: Andy Lutomirski <luto@amacapital.net> Cc: Chandramouli Narayanan <mouli@linux.intel.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Link: http://lkml.kernel.org/n/tip-uxm3j3w3odglcwhafwq5tjqu@git.kernel.org
2014-03-04x86/efi: Firmware agnostic handover entry pointsMatt Fleming1-1/+1
The EFI handover code only works if the "bitness" of the firmware and the kernel match, i.e. 64-bit firmware and 64-bit kernel - it is not possible to mix the two. This goes against the tradition that a 32-bit kernel can be loaded on a 64-bit BIOS platform without having to do anything special in the boot loader. Linux distributions, for one thing, regularly run only 32-bit kernels on their live media. Despite having only one 'handover_offset' field in the kernel header, EFI boot loaders use two separate entry points to enter the kernel based on the architecture the boot loader was compiled for, (1) 32-bit loader: handover_offset (2) 64-bit loader: handover_offset + 512 Since we already have two entry points, we can leverage them to infer the bitness of the firmware we're running on, without requiring any boot loader modifications, by making (1) and (2) valid entry points for both CONFIG_X86_32 and CONFIG_X86_64 kernels. To be clear, a 32-bit boot loader will always use (1) and a 64-bit boot loader will always use (2). It's just that, if a single kernel image supports (1) and (2) that image can be used with both 32-bit and 64-bit boot loaders, and hence both 32-bit and 64-bit EFI. (1) and (2) must be 512 bytes apart at all times, but that is already part of the boot ABI and we could never change that delta without breaking existing boot loaders anyhow. Signed-off-by: Matt Fleming <matt.fleming@intel.com>
2014-01-29Merge commit 'f4bcd8ccddb02833340652e9f46f5127828eb79d' into x86/buildH. Peter Anvin1-1/+1
Bring in upstream merge of x86/kaslr for future patches. Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-01-22x86: Remove duplication of 16-bit CFLAGSDavid Woodhouse1-14/+1
Define them once in arch/x86/Makefile instead of twice. Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> Link: http://lkml.kernel.org/r/1389180083-23249-1-git-send-email-David.Woodhouse@intel.com Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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