linux/arch/arm64/kernel/vdso/Makefile, branch master

stackleak: Split KSTACK_ERASE_CFLAGS from GCC_PLUGINS_CFLAGS

2025-07-22T04:40:57Z

In preparation for Clang stack depth tracking for KSTACK_ERASE, split the stackleak-specific cflags out of GCC_PLUGINS_CFLAGS into KSTACK_ERASE_CFLAGS. Link: https://lore.kernel.org/r/20250717232519.2984886-3-kees@kernel.org Signed-off-by: Kees Cook

vdso: Rename included Makefile

2025-02-21T08:54:01Z

As the Makefile is included into other Makefiles it can not be used to define objects to be built from the current source directory. However the generic datastore will introduce such a local source file. Rename the included Makefile so it is clear how it is to be used and to make room for a regular Makefile in lib/vdso/. Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/20250204-vdso-store-rng-v3-4-13a4669dfc8c@linutronix.de

arm64: vDSO: Wire up getrandom() vDSO implementation

2024-09-13T15:28:36Z

Hook up the generic vDSO implementation to the aarch64 vDSO data page. The _vdso_rng_data required data is placed within the _vdso_data vvar page, by using a offset larger than the vdso_data. The vDSO function requires a ChaCha20 implementation that does not write to the stack, and that can do an entire ChaCha20 permutation. The one provided uses NEON on the permute operation, with a fallback to the syscall for chips that do not support AdvSIMD. This also passes the vdso_test_chacha test along with vdso_test_getrandom. The vdso_test_getrandom bench-single result on Neoverse-N1 shows: vdso: 25000000 times in 0.783884250 seconds libc: 25000000 times in 8.780275399 seconds syscall: 25000000 times in 8.786581518 seconds A small fixup to arch/arm64/include/asm/mman.h was required to avoid pulling kernel code into the vDSO, similar to what's already done in arch/arm64/include/asm/rwonce.h. Signed-off-by: Adhemerval Zanella Reviewed-by: Ard Biesheuvel Acked-by: Will Deacon Signed-off-by: Jason A. Donenfeld

arm64/vdso: Remove --hash-style=sysv

2024-07-23T14:28:23Z

glibc added support for .gnu.hash in 2006 and .hash has been obsoleted for more than one decade in many Linux distributions. Using --hash-style=sysv might imply unaddressed issues and confuse readers. Just drop the option and rely on the linker default, which is likely "both", or "gnu" when the distribution really wants to eliminate sysv hash overhead. Similar to commit 6b7e26547fad ("x86/vdso: Emit a GNU hash"). Signed-off-by: Fangrui Song Link: https://lore.kernel.org/r/20240718173423.1574395-1-maskray@google.com Signed-off-by: Will Deacon

Makefile: remove redundant tool coverage variables

2024-05-14T14:35:48Z

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 Reviewed-by: Kees Cook Tested-by: Roberto Sassu

kbuild: use $(src) instead of $(srctree)/$(src) for source directory

2024-05-09T19:34:52Z

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 Reviewed-by: Nicolas Schier

kbuild: unify vdso_install rules

2023-10-28T12:09:02Z

Currently, there is no standard implementation for vdso_install, leading to various issues: 1. Code duplication Many architectures duplicate similar code just for copying files to the install destination. Some architectures (arm, sparc, x86) create build-id symlinks, introducing more code duplication. 2. Unintended updates of in-tree build artifacts The vdso_install rule depends on the vdso files to install. It may update in-tree build artifacts. This can be problematic, as explained in commit 19514fc665ff ("arm, kbuild: make "make install" not depend on vmlinux"). 3. Broken code in some architectures Makefile code is often copied from one architecture to another without proper adaptation. 'make vdso_install' for parisc does not work. 'make vdso_install' for s390 installs vdso64, but not vdso32. To address these problems, this commit introduces a generic vdso_install rule. Architectures that support vdso_install need to define vdso-install-y in arch/*/Makefile. vdso-install-y lists the files to install. For example, arch/x86/Makefile looks like this: vdso-install-$(CONFIG_X86_64) += arch/x86/entry/vdso/vdso64.so.dbg vdso-install-$(CONFIG_X86_X32_ABI) += arch/x86/entry/vdso/vdsox32.so.dbg vdso-install-$(CONFIG_X86_32) += arch/x86/entry/vdso/vdso32.so.dbg vdso-install-$(CONFIG_IA32_EMULATION) += arch/x86/entry/vdso/vdso32.so.dbg These files will be installed to $(MODLIB)/vdso/ with the .dbg suffix, if exists, stripped away. vdso-install-y can optionally take the second field after the colon separator. This is needed because some architectures install a vdso file as a different base name. The following is a snippet from arch/arm64/Makefile. vdso-install-$(CONFIG_COMPAT_VDSO) += arch/arm64/kernel/vdso32/vdso.so.dbg:vdso32.so This will rename vdso.so.dbg to vdso32.so during installation. If such architectures change their implementation so that the base names match, this workaround will go away. Signed-off-by: Masahiro Yamada Acked-by: Sven Schnelle # s390 Reviewed-by: Nicolas Schier Reviewed-by: Guo Ren Acked-by: Helge Deller # parisc Acked-by: Catalin Marinas Acked-by: Russell King (Oracle)

vdso: Improve cmd_vdso_check to check all dynamic relocations

2023-03-21T20:15:34Z

The actual intention is that no dynamic relocation exists in the VDSO. For this the VDSO build validates that the resulting .so file does not have any relocations which are specified via $(ARCH_REL_TYPE_ABS) per architecture, which is fragile as e.g. ARM64 lacks an entry for R_AARCH64_RELATIVE. Aside of that ARCH_REL_TYPE_ABS is a misnomer as it checks for relative relocations too. However, some GNU ld ports produce unneeded R_*_NONE relocation entries. If a port fails to determine the exact .rel[a].dyn size, the trailing zeros become R_*_NONE relocations. E.g. ld's powerpc port recently fixed https://sourceware.org/bugzilla/show_bug.cgi?id=29540). R_*_NONE are generally a no-op in the dynamic loaders. So just ignore them. Remove the ARCH_REL_TYPE_ABS defines and just validate that the resulting .so file does not contain any R_* relocation entries except R_*_NONE. Signed-off-by: Fangrui Song Signed-off-by: Thomas Gleixner Tested-by: Vincenzo Frascino # for aarch64 Reviewed-by: Christophe Leroy Reviewed-by: Vincenzo Frascino # for vDSO, aarch64 Acked-by: Michael Ellerman (powerpc) Link: https://lore.kernel.org/r/20230310190750.3323802-1-maskray@google.com

kbuild: upgrade the orphan section warning to an error if CONFIG_WERROR is set

2022-11-01T17:04:52Z

Andrew Cooper suggested upgrading the orphan section warning to a hard link error. However Nathan Chancellor said outright turning the warning into an error with no escape hatch might be too aggressive, as we have had these warnings triggered by new compiler generated sections, and suggested turning orphan sections into an error only if CONFIG_WERROR is set. Kees Cook echoed and emphasized that the mandate from Linus is that we should avoid breaking builds. It wrecks bisection, it causes problems across compiler versions, etc. Thus upgrade the orphan section warning to a hard link error only if CONFIG_WERROR is set. Suggested-by: Andrew Cooper Suggested-by: Nathan Chancellor Signed-off-by: Xin Li Reviewed-by: Nathan Chancellor Tested-by: Nathan Chancellor Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20221025073023.16137-2-xin3.li@intel.com

treewide: Filter out CC_FLAGS_CFI

2022-09-26T17:13:12Z

In preparation for removing CC_FLAGS_CFI from CC_FLAGS_LTO, explicitly filter out CC_FLAGS_CFI in all the makefiles where we currently filter out CC_FLAGS_LTO. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor Acked-by: Peter Zijlstra (Intel) Tested-by: Peter Zijlstra (Intel) Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20220908215504.3686827-2-samitolvanen@google.com