kernel/linux.git/arch/x86/include/asm/elf.h, branch v7.1

x86/elf: Use savesegment() for segment register reads in ELF core dump

2026-03-31T07:50:10+00:00

ELF_CORE_COPY_REGS() currently reads %ds, %es, %fs, and %gs using inline assembly and manual zero-extension. This results in redundant instructions like `mov %eax,%eax`. Replace the inline assembly with the `savesegment()` helper, which automatically zero-extends the value to the full register width, eliminating unnecessary instructions. For example, the %ds load sequence changes from: d03: 8c d8 mov %ds,%eax d05: 89 c0 mov %eax,%eax d07: 48 89 84 24 38 01 00 mov %rax,0x138(%rsp) d0e: 00 to: ce8: 8c d8 mov %ds,%eax cea: 48 89 84 24 38 01 00 mov %rax,0x138(%rsp) cf1: 00 thus eliminating the unnecessary zero-extending `mov %eax,%eax`. No functional change intended. Signed-off-by: Uros Bizjak Signed-off-by: Ingo Molnar Cc: H. Peter Anvin Cc: Linus Torvalds Link: https://patch.msgid.link/20260330085938.67985-1-ubizjak@gmail.com

x86/entry/vdso: Rename vdso_image_* to vdso*_image

2026-01-13T23:33:20+00:00

The vdso .so files are named vdso*.so. These structures are binary images and descriptions of these files, so it is more consistent for them to have a naming that more directly mirrors the filenames. It is also very slightly more compact (by one character...) and simplifies the Makefile just a little bit. Signed-off-by: H. Peter Anvin (Intel) Signed-off-by: Dave Hansen Link: https://patch.msgid.link/20251216212606.1325678-2-hpa@zytor.com

x86/vdso: Remove #ifdeffery around page setup variants

2025-04-22T12:24:07+00:00

Replace the open-coded ifdefs in C sources files with IS_ENABLED(). This makes the code easier to read and enables the compiler to typecheck also the disabled parts, before optimizing them away. To make this work, also remove the ifdefs from declarations of used variables. Signed-off-by: Thomas Weißschuh Signed-off-by: Ingo Molnar Cc: Andrew Cooper Cc: Andy Lutomirski Cc: Brian Gerst Cc: Eric Biederman Cc: H. Peter Anvin Cc: Juergen Gross Cc: Kees Cook Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Rik van Riel Link: https://lore.kernel.org/r/20240910-x86-vdso-ifdef-v1-1-877c9df9b081@linutronix.de

x86/module: Deal with GOT based stack cookie load on Clang < 17

2025-02-18T09:15:05+00:00

Clang versions before 17 will not honour -fdirect-access-external-data for the load of the stack cookie emitted into each function's prologue and epilogue. This is not an issue for the core kernel, as the linker will relax these loads into LEA instructions that take the address of __stack_chk_guard directly. For modules, however, we need to work around this, by dealing with R_X86_64_REX_GOTPCRELX relocations that refer to __stack_chk_guard. In this case, given that this is a GOT load, the reference should not refer to __stack_chk_guard directly, but to a memory location that holds its address. So take the address of __stack_chk_guard into a static variable, and fix up the relocations to refer to that. [ mingo: Fix broken R_X86_64_GOTPCRELX definition. ] Signed-off-by: Ard Biesheuvel Signed-off-by: Brian Gerst Signed-off-by: Ingo Molnar Cc: Linus Torvalds Link: https://lore.kernel.org/r/20250123190747.745588-7-brgerst@gmail.com

x86/vdso: Move vDSO to mmap region

2024-02-26T23:23:55+00:00

The vDSO (and its initial randomization) was introduced in commit 2aae950b21e4 ("x86_64: Add vDSO for x86-64 with gettimeofday/clock_gettime/getcpu"), but had very low entropy. The entropy was improved in commit 394f56fe4801 ("x86_64, vdso: Fix the vdso address randomization algorithm"), but there is still improvement to be made. In principle there should not be executable code at a low entropy offset from the stack, since the stack and executable code having separate randomization is part of what makes ASLR stronger. Remove the only executable code near the stack region and give the vDSO the same randomized base as other mmap mappings including the linker and other shared objects. This results in higher entropy being provided and there's little to no advantage in separating this from the existing executable code there. This is already how other architectures like arm64 handle the vDSO. As an side, while it's sensible for userspace to reserve the initial mmap base as a region for executable code with a random gap for other mmap allocations, along with providing randomization within that region, there isn't much the kernel can do to help due to how dynamic linkers load the shared objects. This was extracted from the PaX RANDMMAP feature. [kees: updated commit log with historical details and other tweaks] Signed-off-by: Daniel Micay Signed-off-by: Kees Cook Signed-off-by: Thomas Gleixner Closes: https://github.com/KSPP/linux/issues/280 Link: https://lore.kernel.org/r/20240210091827.work.233-kees@kernel.org

x86/ia32: State that IA32 emulation is disabled

2023-12-11T09:14:28+00:00

Issue a short message once, on the first try to load a 32-bit process to save people time when wondering why it won't load and trying to execute it, would say: -bash: ./strsep32: cannot execute binary file: Exec format error Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Nikolay Borisov Link: https://lore.kernel.org/r/20231130155213.1407-1-bp@alien8.de

x86/elf: Make loading of 32bit processes depend on ia32_enabled()

2023-09-14T11:19:53+00:00

Major aspect of ia32 emulation is the ability to load 32bit processes. That's currently decided (among others) by compat_elf_check_arch(). Make the macro use ia32_enabled() to decide if IA32 compat is enabled before loading a 32bit process. Signed-off-by: Nikolay Borisov Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20230623111409.3047467-5-nik.borisov@suse.com

Merge tag 'pull-elfcore' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2022-12-13T02:18:34+00:00

Pull elf coredumping updates from Al Viro: "Unification of regset and non-regset sides of ELF coredump handling. Collecting per-thread register values is the only thing that needs to be ifdefed there..." * tag 'pull-elfcore' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: [elf] get rid of get_note_info_size() [elf] unify regset and non-regset cases [elf][non-regset] use elf_core_copy_task_regs() for dumper as well [elf][non-regset] uninline elf_core_copy_task_fpregs() (and lose pt_regs argument) elf_core_copy_task_regs(): task_pt_regs is defined everywhere [elf][regset] simplify thread list handling in fill_note_info() [elf][regset] clean fill_note_info() a bit kill extern of vsyscall32_sysctl kill coredump_params->regs kill signal_pt_regs()

kill extern of vsyscall32_sysctl

2022-10-23T22:06:55+00:00

it's been dead for years. Signed-off-by: Al Viro

x86: Remove __USER32_DS

2022-10-19T07:58:49+00:00

Replace all users with the equivalent __USER_DS, which will make merging native and compat code simpler. Signed-off-by: Brian Gerst Signed-off-by: Borislav Petkov Acked-by: "Eric W. Biederman" Link: https://lore.kernel.org/r/20220606203802.158958-5-brgerst@gmail.com Signed-off-by: Borislav Petkov