kernel.git/arch/powerpc/kernel/vdso/Makefile, branch linux-6.1.y

powerpc/vdso: Drop -mstack-protector-guard flags in 32-bit files with clang

2024-12-14T18:54:25Z

[ Upstream commit d677ce521334d8f1f327cafc8b1b7854b0833158 ] Under certain conditions, the 64-bit '-mstack-protector-guard' flags may end up in the 32-bit vDSO flags, resulting in build failures due to the structure of clang's argument parsing of the stack protector options, which validates the arguments of the stack protector guard flags unconditionally in the frontend, choking on the 64-bit values when targeting 32-bit: clang: error: invalid value 'r13' in 'mstack-protector-guard-reg=', expected one of: r2 clang: error: invalid value 'r13' in 'mstack-protector-guard-reg=', expected one of: r2 make[3]: *** [arch/powerpc/kernel/vdso/Makefile:85: arch/powerpc/kernel/vdso/vgettimeofday-32.o] Error 1 make[3]: *** [arch/powerpc/kernel/vdso/Makefile:87: arch/powerpc/kernel/vdso/vgetrandom-32.o] Error 1 Remove these flags by adding them to the CC32FLAGSREMOVE variable, which already handles situations similar to this. Additionally, reformat and align a comment better for the expanding CONFIG_CC_IS_CLANG block. Cc: stable@vger.kernel.org # v6.1+ Signed-off-by: Nathan Chancellor Signed-off-by: Michael Ellerman Link: https://patch.msgid.link/20241030-powerpc-vdso-drop-stackp-flags-clang-v1-1-d95e7376d29c@kernel.org Signed-off-by: Sasha Levin

powerpc/vdso: Refactor CFLAGS for CVDSO build

2024-12-14T18:54:25Z

[ Upstream commit a6b67eb09963af29991625862cbb4f56b85954ed ] In order to avoid two much duplication when we add new VDSO functionnalities in C like getrandom, refactor common CFLAGS. Signed-off-by: Christophe Leroy Acked-by: Michael Ellerman Signed-off-by: Jason A. Donenfeld Stable-dep-of: d677ce521334 ("powerpc/vdso: Drop -mstack-protector-guard flags in 32-bit files with clang") Signed-off-by: Sasha Levin

powerpc/vdso: Include CLANG_FLAGS explicitly in ldflags-y

2024-12-14T18:54:25Z

[ Upstream commit a7e5eb53bf9b800d086e2ebcfebd9a3bb16bd1b0 ] A future change will move CLANG_FLAGS from KBUILD_{A,C}FLAGS to KBUILD_CPPFLAGS so that '--target' is available while preprocessing. When that occurs, the following error appears when building the compat PowerPC vDSO: clang: error: unsupported option '-mbig-endian' for target 'x86_64-pc-linux-gnu' make[3]: *** [.../arch/powerpc/kernel/vdso/Makefile:76: arch/powerpc/kernel/vdso/vdso32.so.dbg] Error 1 Explicitly add CLANG_FLAGS to ldflags-y, so that '--target' will always be present. Signed-off-by: Nathan Chancellor Signed-off-by: Masahiro Yamada Stable-dep-of: d677ce521334 ("powerpc/vdso: Drop -mstack-protector-guard flags in 32-bit files with clang") Signed-off-by: Sasha Levin

powerpc/vdso: Remove an unsupported flag from vgettimeofday-32.o with clang

2024-12-14T18:54:25Z

[ Upstream commit 05e05bfc92d196669a3d087fc34d3998b6ddb758 ] When clang's -Qunused-arguments is dropped from KBUILD_CPPFLAGS, it warns: clang-16: error: argument unused during compilation: '-fno-stack-clash-protection' [-Werror,-Wunused-command-line-argument] This warning happens because vgettimeofday-32.c gets its base CFLAGS from the main kernel, which may contain flags that are only supported on a 64-bit target but not a 32-bit one, which is the case here. -fstack-clash-protection and its negation are only suppported by the 64-bit powerpc target but that flag is included in an invocation for a 32-bit powerpc target, so clang points out that while the flag is one that it recognizes, it is not actually used by this compiler job. To eliminate the warning, remove -fno-stack-clash-protection from vgettimeofday-32.c's CFLAGS when using clang, as has been done for other flags previously. Signed-off-by: Nathan Chancellor Reviewed-by: Nick Desaulniers Tested-by: Linux Kernel Functional Testing Tested-by: Anders Roxell Signed-off-by: Masahiro Yamada Stable-dep-of: d677ce521334 ("powerpc/vdso: Drop -mstack-protector-guard flags in 32-bit files with clang") Signed-off-by: Sasha Levin

powerpc/vdso: Improve linker flags

2024-12-14T18:54:25Z

[ Upstream commit f0a42fbab447ed9f55bbd99751183e71f3a1f6ec ] When clang's -Qunused-arguments is dropped from KBUILD_CPPFLAGS, there are several warnings in the PowerPC vDSO: clang-16: error: -Wl,-soname=linux-vdso32.so.1: 'linker' input unused [-Werror,-Wunused-command-line-argument] clang-16: error: -Wl,--hash-style=both: 'linker' input unused [-Werror,-Wunused-command-line-argument] clang-16: error: argument unused during compilation: '-shared' [-Werror,-Wunused-command-line-argument] clang-16: error: argument unused during compilation: '-nostdinc' [-Werror,-Wunused-command-line-argument] clang-16: error: argument unused during compilation: '-Wa,-maltivec' [-Werror,-Wunused-command-line-argument] The first group of warnings point out that linker flags were being added to all invocations of $(CC), even though they will only be used during the final vDSO link. Move those flags to ldflags-y. The second group of warnings are compiler or assembler flags that will be unused during linking. Filter them out from KBUILD_CFLAGS so that they are not used during linking. Additionally, '-z noexecstack' was added directly to the ld_and_check rule in commit 1d53c0192b15 ("powerpc/vdso: link with -z noexecstack") but now that there is a common ldflags variable, it can be moved there. Signed-off-by: Nathan Chancellor Reviewed-by: Nick Desaulniers Tested-by: Linux Kernel Functional Testing Tested-by: Anders Roxell Signed-off-by: Masahiro Yamada Stable-dep-of: d677ce521334 ("powerpc/vdso: Drop -mstack-protector-guard flags in 32-bit files with clang") Signed-off-by: Sasha Levin

powerpc/vdso: Remove unused '-s' flag from ASFLAGS

2024-12-14T18:54:25Z

[ Upstream commit 024734d132846dcb27f07deb1ec5be64d4cbfae9 ] When clang's -Qunused-arguments is dropped from KBUILD_CPPFLAGS, it warns: clang-16: error: argument unused during compilation: '-s' [-Werror,-Wunused-command-line-argument] The compiler's '-s' flag is a linking option (it is passed along to the linker directly), which means it does nothing when the linker is not invoked by the compiler. The kernel builds all .o files with '-c', which stops the compilation pipeline before linking, so '-s' can be safely dropped from ASFLAGS. Signed-off-by: Nathan Chancellor Reviewed-by: Nick Desaulniers Reviewed-by: Segher Boessenkool Tested-by: Linux Kernel Functional Testing Tested-by: Anders Roxell Acked-by: Michael Ellerman Signed-off-by: Masahiro Yamada Stable-dep-of: d677ce521334 ("powerpc/vdso: Drop -mstack-protector-guard flags in 32-bit files with clang") Signed-off-by: Sasha Levin

powerpc/vdso: Skip objtool from running on VDSO files

2024-12-14T18:54:25Z

[ Upstream commit d0160bd5d389da247fb5affb6a35ea393d22fedb ] Do not run objtool on VDSO files, by using OBJECT_FILES_NON_STANDARD. Suggested-by: Christophe Leroy Tested-by: Naveen N. Rao Reviewed-by: Naveen N. Rao Reviewed-by: Christophe Leroy Acked-by: Josh Poimboeuf Signed-off-by: Sathvika Vasireddy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221114175754.1131267-8-sv@linux.ibm.com Stable-dep-of: d677ce521334 ("powerpc/vdso: Drop -mstack-protector-guard flags in 32-bit files with clang") Signed-off-by: Sasha Levin

powerpc/vdso: link with -z noexecstack

2022-09-05T07:28:25Z

With recent binutils, the following warning appears: VDSO32L arch/powerpc/kernel/vdso/vdso32.so.dbg /opt/gcc-12.2.0-nolibc/powerpc64-linux/bin/../lib/gcc/powerpc64-linux/12.2.0/../../../../powerpc64-linux/bin/ld: warning: arch/powerpc/kernel/vdso/getcpu-32.o: missing .note.GNU-stack section implies executable stack /opt/gcc-12.2.0-nolibc/powerpc64-linux/bin/../lib/gcc/powerpc64-linux/12.2.0/../../../../powerpc64-linux/bin/ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker To avoid that, explicitly tell the linker we don't want executable stack. For more explanations, see commit ffcf9c5700e4 ("x86: link vdso and boot with -z noexecstack --no-warn-rwx-segments") Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/b95f2e3216a574837dd61208444e9515c3423da4.1662132312.git.christophe.leroy@csgroup.eu

powerpc/vdso: Link with ld.lld when requested

2022-05-19T13:11:26Z

The PowerPC vDSO uses $(CC) to link, which differs from the rest of the kernel, which uses $(LD) directly. As a result, the default linker of the compiler is used, which may differ from the linker requested by the builder. For example: $ make ARCH=powerpc LLVM=1 mrproper defconfig arch/powerpc/kernel/vdso/ ... $ llvm-readelf -p .comment arch/powerpc/kernel/vdso/vdso{32,64}.so.dbg File: arch/powerpc/kernel/vdso/vdso32.so.dbg String dump of section '.comment': [ 0] clang version 14.0.0 (Fedora 14.0.0-1.fc37) File: arch/powerpc/kernel/vdso/vdso64.so.dbg String dump of section '.comment': [ 0] clang version 14.0.0 (Fedora 14.0.0-1.fc37) LLVM=1 sets LD=ld.lld but ld.lld is not used to link the vDSO; GNU ld is because "ld" is the default linker for clang on most Linux platforms. This is a problem for Clang's Link Time Optimization as implemented in the kernel because use of GNU ld with LTO requires the LLVMgold plugin, which is not technically supported for ld.bfd per https://llvm.org/docs/GoldPlugin.html. Furthermore, if LLVMgold.so is missing from a user's system, the build will fail, even though LTO as it is implemented in the kernel requires ld.lld to avoid this dependency in the first place. Ultimately, the PowerPC vDSO should be converted to compiling and linking with $(CC) and $(LD) respectively but there were issues last time this was tried, potentially due to older but supported tool versions. To avoid regressing GCC + binutils, use the compiler option '-fuse-ld', which tells the compiler which linker to use when it is invoked as both the compiler and linker. Use '-fuse-ld=lld' when LD=ld.lld has been specified (CONFIG_LD_IS_LLD) so that the vDSO is linked with the same linker as the rest of the kernel. $ llvm-readelf -p .comment arch/powerpc/kernel/vdso/vdso{32,64}.so.dbg File: arch/powerpc/kernel/vdso/vdso32.so.dbg String dump of section '.comment': [ 0] Linker: LLD 14.0.0 [ 14] clang version 14.0.0 (Fedora 14.0.0-1.fc37) File: arch/powerpc/kernel/vdso/vdso64.so.dbg String dump of section '.comment': [ 0] Linker: LLD 14.0.0 [ 14] clang version 14.0.0 (Fedora 14.0.0-1.fc37) LD can be a full path to ld.lld, which will not be handled properly by '-fuse-ld=lld' if the full path to ld.lld is outside of the compiler's search path. '-fuse-ld' can take a path to the linker but it is deprecated in clang 12.0.0; '--ld-path' is preferred for this scenario. Use '--ld-path' if it is supported, as it will handle a full path or just 'ld.lld' properly. See the LLVM commit below for the full details of '--ld-path'. Signed-off-by: Nathan Chancellor Tested-by: Alexey Kardashevskiy Reviewed-by: Nick Desaulniers Reviewed-by: Alexey Kardashevskiy Signed-off-by: Michael Ellerman Link: https://github.com/ClangBuiltLinux/linux/issues/774 Link: https://github.com/llvm/llvm-project/commit/1bc5c84710a8c73ef21295e63c19d10a8c71f2f5 Link: https://lore.kernel.org/r/20220511185001.3269404-3-nathan@kernel.org

powerpc/vdso: Merge vdso64 and vdso32 into a single directory

2022-02-12T11:47:43Z

merge vdso64 into vdso32 and rename it vdso. Reported-by: kernel test robot Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/4dbe05cc130f6a0858d09ac72e436c373cb08b70.1642782130.git.christophe.leroy@csgroup.eu