Re: [PATCH v4 00/24] vdso: Reject absolute relocations during build
From: Christophe Leroy <hidden>
Date: 2025-08-14 13:50:35
Also in:
linux-kbuild, linux-mips, linux-mm, linux-riscv, linux-s390, linux-um, lkml, llvm, loongarch, rust-for-linux
Le 12/08/2025 à 07:44, Thomas Weißschuh a écrit :
The compiler can emit absolute relocations in vDSO code, which are invalid in vDSO code. Detect them at compile-time.
I'm a bit puzzled with this series. If I understand correctly, the check will be done only when you have RUST available ? I wouldn't expect having RUST to build a C kernel. By the way, aren't relocations already detected by command cmd_vdso_check in lib/vdso/Makefile.include , using readelf ? Why is a new tool needed and why does it have to be written in RUST langage ? Thanks Christophe
libc elf.h is missing some of the relocation constants, so make user of the kernels own UAPI headers instead. Kbuild and Rust folks: This contains custom definitions of hostprog bindgen and rust library commands. These are currently only defined inside the subsystem directory. Let me know if they should go into scripts/Makefile.host. This will conflict with my SPARC64 generic vDSO patches [0]. If both end up being applied at the same time, please leave out commit 'vdso/vdsocheck: Drop the transitional kconfig option' from this series. [0] https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flkml%2F20250724-vdso-sparc64-generic-2-v1-0-e376a3bd24d1%40linutronix.de%2F&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C3f03f6747325451ee98808ddd9634f27%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638905742749561064%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=HacF%2FvlUoxA9P6fTiN1ytw49gwayX1wNE7IxfEkFutE%3D&reserved=0 Signed-off-by: Thomas Weißschuh <redacted> --- Changes in v4: - Replace the inline shell logic with a dedicated build-time tool - Link to v3: https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fr%2F20250611-vdso-absolute-reloc-v3-0-47897d73784b%40linutronix.de&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C3f03f6747325451ee98808ddd9634f27%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638905742749584369%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=7NxAhutk6IXl%2B3fe1kkZEzhZz6CWye%2FVAcFO%2BgtS4uo%3D&reserved=0 Changes in v3: - Drop already applied bugfix for arm64 - Disable LTO for the riscv vDSO, as it is incompatible - Link to v2: https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fr%2F20250430-vdso-absolute-reloc-v2-0-5efcc3bc4b26%40linutronix.de&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C3f03f6747325451ee98808ddd9634f27%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638905742749600546%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=uv0qMS5qq0DovLHtxfRvT42atbJEkztylpOS8zt6bJ4%3D&reserved=0 Changes in v2: - Link to openend (invalid) GCC bug containing more explanations - Refine commit messages - Don't fail on commit absolute relocations in debug info - Link to v1: https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fr%2F20250429-vdso-absolute-reloc-v1-0-987a0afd10b5%40linutronix.de&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C3f03f6747325451ee98808ddd9634f27%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638905742749616057%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=K5iwoz0Xqc8kheotWEc4M2KrZ7UVMDObOyFfCPj4N8Q%3D&reserved=0 --- Thomas Weißschuh (24): elf, uapi: Add a header for relocation constants x86/elf, um/x86/elf: Move relocation constants to UAPI ARM: elf: Move relocation constants to UAPI arm64: elf: Move relocation constants to UAPI powerpc/elf: Move relocation constants to UAPI riscv: elf: Move relocation constants to UAPI LoongArch: Move relocation constants to UAPI s390/elf: Move relocation constants to UAPI MIPS: ELF: Move relocation constants to UAPI tools headers UAPI: Sync ELF headers with the kernel sources vdso: Add the vdsocheck tool x86/vdso: Enable the vdsocheck tool ARM: vdso: Enable the vdsocheck tool arm64: vdso: Enable the vdsocheck tool powerpc/elf: Add 32-bit REL16 relocation definitions powerpc/vdso: Enable the vdsocheck tool riscv: vdso: Deduplicate CFLAGS_REMOVE_* variables riscv: vdso: Disable LTO for the vDSO riscv: vdso: Enable the vdsocheck tool LoongArch: vDSO: Enable the vdsocheck tool s390/vdso: Enable the vdsocheck tool MIPS: ELF: Add more PC-relative relocation definitions MIPS: vdso: Enable the vdsocheck tool vdso/vdsocheck: Drop the transitional kconfig option arch/arm/include/asm/elf.h | 24 -- arch/arm/vdso/Makefile | 4 +- arch/arm64/include/asm/elf.h | 55 ---- arch/arm64/kernel/vdso/Makefile | 4 +- arch/loongarch/include/asm/elf.h | 100 ------ arch/loongarch/vdso/Makefile | 4 +- arch/mips/include/asm/elf.h | 53 --- arch/mips/vdso/Makefile | 8 +- arch/powerpc/include/uapi/asm/elf.h | 201 ------------ arch/powerpc/kernel/vdso/Makefile | 4 +- arch/riscv/include/uapi/asm/elf.h | 66 ---- arch/riscv/kernel/vdso/Makefile | 11 +- arch/s390/include/asm/elf.h | 83 ----- arch/s390/kernel/vdso32/Makefile | 4 +- arch/s390/kernel/vdso64/Makefile | 4 +- arch/x86/entry/vdso/Makefile | 6 +- arch/x86/include/asm/elf.h | 34 -- arch/x86/um/asm/elf.h | 33 -- include/uapi/linux/elf-r.h | 631 ++++++++++++++++++++++++++++++++++++ include/uapi/linux/elf.h | 1 + lib/vdso/Makefile | 2 + lib/vdso/Makefile.include | 17 + lib/vdso/check/.gitignore | 3 + lib/vdso/check/Makefile | 28 ++ lib/vdso/check/elf.rs | 488 ++++++++++++++++++++++++++++ lib/vdso/check/vdsocheck.rs | 279 ++++++++++++++++ tools/include/uapi/linux/elf-em.h | 71 ++++ tools/include/uapi/linux/elf-r.h | 631 ++++++++++++++++++++++++++++++++++++ tools/include/uapi/linux/elf.h | 112 ++++++- 29 files changed, 2277 insertions(+), 684 deletions(-) --- base-commit: 5180c6526acc9f1cb58f8b11fba67583c22e0854 change-id: 20250428-vdso-absolute-reloc-a226293c1761 Best regards,