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2025-11-06um: Always set up AT_HWCAP and AT_PLATFORMThomas Weißschuh
Historically the code to set up AT_HWCAP and AT_PLATFORM was only built for 32bit x86 as it was intermingled with the vDSO passthrough code. Now that vDSO passthrough has been removed, always pass through AT_HWCAP and AT_PLATFORM. Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Link: https://patch.msgid.link/20251028-uml-remove-32bit-pseudo-vdso-v1-10-e930063eff5f@weissschuh.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-11-06x86/um: Remove FIXADDR_USER_START and FIXADDR_USE_ENDThomas Weißschuh
There are no users left. Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Link: https://patch.msgid.link/20251028-uml-remove-32bit-pseudo-vdso-v1-9-e930063eff5f@weissschuh.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-11-06x86/um: Drop gate area handlingThomas Weißschuh
With the removal of the vDSO passthrough from the host, FIXADDR_USER_START is always 0 and the gate area setup code is dead. Remove it. Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Link: https://patch.msgid.link/20251028-uml-remove-32bit-pseudo-vdso-v1-5-e930063eff5f@weissschuh.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-11-06x86/um: Do not inherit vDSO from hostThomas Weißschuh
Inheriting the vDSO from the host is problematic. The values read from the time functions will not be correct for the UML kernel. Furthermore the start and end of the vDSO are not stable or detectable by userspace. Specifically the vDSO datapages start before AT_SYSINFO_EHDR and the vDSO itself is larger than a single page. This codepath is only used on 32bit x86 UML. In my testing with both 32bit and 64bit hosts the passthrough functionality has always been disabled anyways due to the checks against envp in scan_elf_aux(). Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Link: https://patch.msgid.link/20251028-uml-remove-32bit-pseudo-vdso-v1-4-e930063eff5f@weissschuh.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-11-06x86/um: Move ELF_PLATFORM fallback to x86-specific codeThomas Weißschuh
The generic UM code should not have references to x86-specific value. Move the fallback into the x86-specific header. Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Link: https://patch.msgid.link/20251028-uml-remove-32bit-pseudo-vdso-v1-2-e930063eff5f@weissschuh.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-10-27um: Enable SMP support on x86Tiwei Bie
Implement spinlock support for SMP on UML/x86, leveraging x86's spinlock implementation. In addition, to support SMP on CPUs that do not support CX8, some additional work is required. However, considering that such CPUs are already very outdated, and x86 is also removing support for them [1], let's enable SMP support only on CPUs that support CX8. [1] https://lore.kernel.org/lkml/20250515085708.2510123-1-mingo@kernel.org/ Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com> Link: https://patch.msgid.link/20251027001815.1666872-9-tiwei.bie@linux.dev Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-10-27um: vdso: Remove getcpu support on x86Tiwei Bie
We are going to support SMP on UML/x86, so we can't hard code the CPU and NUMA node in __vdso_getcpu() anymore. Let's just remove it and let applications fall back to the syscall. Suggested-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com> Link: https://patch.msgid.link/20251027001815.1666872-7-tiwei.bie@linux.dev Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-10-27x86/um/vdso: Drop VDSO64-y from MakefileThomas Weißschuh
This symbol is unnecessary, remove it. Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Link: https://patch.msgid.link/20251013-uml-vdso-cleanup-v1-4-a079c7adcc69@weissschuh.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-10-27x86/um/vdso: Panic when vDSO can not be allocatedThomas Weißschuh
The vDSO address is added to the userspace auxiliary vectors even if the vDSO was not allocated. When accessing the page, userspace processes will crash. Enforce that the allocation works. Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Link: https://patch.msgid.link/20251013-uml-vdso-cleanup-v1-3-a079c7adcc69@weissschuh.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-10-27x86/um/vdso: Use prototypes from generic vDSO headersThomas Weißschuh
The generic vDSO library provides a convenient header for the vDSO function prototypes, use it. Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Link: https://patch.msgid.link/20251013-uml-vdso-cleanup-v1-2-a079c7adcc69@weissschuh.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-10-27x86/um/vdso: Fix prototype of clock_gettime()Thomas Weißschuh
The clock_gettime() system call takes a pointer to 'struct __kernel_timespec', not 'struct __kernel_old_timespec'. Right now this is not an issue as the vDSO never works with the actual struct but only passes it through to the kernel. Fix the prototype for consistency with the system call. Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Link: https://patch.msgid.link/20251013-uml-vdso-cleanup-v1-1-a079c7adcc69@weissschuh.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-10-27um: move asm-offsets generation into a single fileJohannes Berg
There's nothing subarch dependent here, and it's odd that includes need to be done in the subarch, and then entries defined in the common file. Simplify the whole thing from three files into one. Link: https://patch.msgid.link/20251007071452.367989-4-johannes@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-10-27um/hostfs: define HOSTFS_ATTR_* via asm-offsetsJohannes Berg
The HOSTFS_ATTR_* values were meant to be standalone for communication between hostfs's kernel and user code parts. However, it's easy to forget that HOSTFS_ATTR_* should be used even on the kernel side, and that wasn't consistently done. As a result, the values need to match ATTR_* values, which is not useful to maintain by hand. Instead, generate them via asm-offsets like other constants that UML needs in user-side code that aren't otherwise available in any header files that can be included there. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Reviewed-by: Hongbo Li <lihongbo22@huawei.com> Link: https://patch.msgid.link/20251007071452.367989-3-johannes@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-09-10um: Centralize stub size calculationsTiwei Bie
Currently, the stub size is calculated in multiple places. Define a macro that performs the calculation so that the code is easier to read and maintain. Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com> Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-07-29Merge tag 'uml-for-linux-6.17-rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux Pull uml updates from Johannes Berg: "Mostly cleanups, except: - dynamic addition of vfio passthrough devices - implementation of HAVE_SYSCALL_TRACEPOINTS" * tag 'uml-for-linux-6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux: um: Replace __ASSEMBLY__ with __ASSEMBLER__ in the usermode headers um: Stop tracking stub's PID via userspace_pid[] um: Remove the pid parameter of handle_trap() um: Use err consistently in userspace() um: vfio: Support adding devices via mconsole um: rtc: Avoid shadowing err in uml_rtc_start() um: Avoid redefining ARCH_HAS_CACHE_LINE_SIZE um: Make mm_list and mm_list_lock static um: Make unscheduled_userspace_iterations static um: Re-evaluate thread flags repeatedly um: simplify syscall header files um/ptrace: Implement HAVE_SYSCALL_TRACEPOINTS um/x86: Add system call table to header file um: virt-pci: Switch to msi_create_parent_irq_domain() um: virtio_pcidev: Rename UM_PCI_STAT_WAITING
2025-07-28Merge tag 'execve-v6.17' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux Pull execve updates from Kees Cook: - Introduce regular REGSET note macros arch-wide (Dave Martin) - Remove arbitrary 4K limitation of program header size (Yin Fengwei) - Reorder function qualifiers for copy_clone_args_from_user() (Dishank Jogi) * tag 'execve-v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (25 commits) fork: reorder function qualifiers for copy_clone_args_from_user binfmt_elf: remove the 4k limitation of program header size binfmt_elf: Warn on missing or suspicious regset note names xtensa: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names um: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names x86/ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names sparc: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names sh: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names s390/ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names riscv: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names powerpc/ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names parisc: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names openrisc: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names nios2: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names MIPS: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names m68k: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names LoongArch: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names hexagon: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names csky: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names arm64: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note names ...
2025-07-14um: ptrace: Use USER_REGSET_NOTE_TYPE() to specify regset note namesDave Martin
Instead of having the core code guess the note name for each regset, use USER_REGSET_NOTE_TYPE() to pick the correct name from elf.h. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Cc: Richard Weinberger <richard@nod.at> Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> Cc: Johannes Berg <johannes@sipsolutions.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kees Cook <kees@kernel.org> Cc: Akihiko Odaki <akihiko.odaki@daynix.com> Cc: linux-um@lists.infradead.org Cc: x86@kernel.org Acked-by: Johannes Berg <johannes@sipsolutions.net> Tested-by: Johannes Berg <johannes@sipsolutions.net> Reviewed-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp> Link: https://lore.kernel.org/r/20250701135616.29630-22-Dave.Martin@arm.com Signed-off-by: Kees Cook <kees@kernel.org>
2025-07-13um: Stop tracking stub's PID via userspace_pid[]Tiwei Bie
The PID of the stub process can be obtained from current_mm_id(). There is no need to track it via userspace_pid[]. Stop doing that to simplify the code. Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com> Link: https://patch.msgid.link/20250711065021.2535362-4-tiwei.bie@linux.dev Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-07-11um: simplify syscall header filesJohannes Berg
Since Thomas's recent commit 2af10530639b ("um/x86: Add system call table to header file") , we now have two extern declarations of the syscall table, one internal and one external, and they don't even match on 32-bit. Clean this up and remove all the extra code. Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de> Link: https://patch.msgid.link/20250704141243.a68366f6acc3.If8587a4aafdb90644fc6d0b2f5e31a2d1887915f@changeid Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-07-11um/x86: Add system call table to header fileThomas Weißschuh
The generic system call tracing infrastructure requires access to the system call table. The symbol is already visible to the linker but is lacking a public declaration. Add a public declaration. Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de> Reviewed-by: Nam Cao <namcao@linutronix.de> Link: https://patch.msgid.link/20250703-uml-have_syscall_tracepoints-v1-1-23c1d3808578@linutronix.de Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-06-25um: Use correct data source in fpregs_legacy_set()Tiwei Bie
Read from the buffer pointed to by 'from' instead of '&buf', as 'buf' contains no valid data when 'ubuf' is NULL. Fixes: b1e1bd2e6943 ("um: Add helper functions to get/set state for SECCOMP") Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com> Link: https://patch.msgid.link/20250606124428.148164-5-tiwei.btw@antgroup.com Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-06-05Merge tag 'uml-for-linux-6.16-rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux Pull UML updates from Johannes Berg: "The only really new thing is the long-standing seccomp work (originally from 2021!). Wven if it still isn't enabled by default due to security concerns it can still be used e.g. for tests. - remove obsolete network transports - remove PCI IO port support - start adding seccomp-based process handling instead of ptrace" * tag 'uml-for-linux-6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux: (29 commits) um: remove "extern" from implementation of sigchld_handler um: fix unused variable warning um: fix SECCOMP 32bit xstate register restore um: pass FD for memory operations when needed um: Add SECCOMP support detection and initialization um: Implement kernel side of SECCOMP based process handling um: Track userspace children dying in SECCOMP mode um: Add helper functions to get/set state for SECCOMP um: Add stub side of SECCOMP/futex based process handling um: Move faultinfo extraction into userspace routine um: vector: Use mac_pton() for MAC address parsing um: vector: Clean up and modernize log messages um: chan_kern: use raw spinlock for irqs_to_free_lock MAINTAINERS: remove obsolete file entry in TUN/TAP DRIVER um: Fix tgkill compile error on old host OSes um: stop using PCI port I/O um: Remove legacy network transport infrastructure um: vector: Eliminate the dependency on uml_net um: Remove obsolete legacy network transports um/asm: Replace "REP; NOP" with PAUSE mnemonic ...
2025-06-05um: fix unused variable warningBenjamin Berg
The code was updated to access the PID of the userspace stub process in a different way, making the local cpu variable obsolete. Remove it. Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202506050008.AwXLNxQX-lkp@intel.com/ Fixes: 406d17c6c370 ("um: Implement kernel side of SECCOMP based process handling") Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20250605050325.1077208-1-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-06-04um: fix SECCOMP 32bit xstate register restoreBenjamin Berg
There was a typo that caused the extended FP state to be copied into the wrong location on 32 bit. On 32 bit we only store the xstate internally as that already contains everything. However, for compatibility, the mcontext on 32 bit first contains the legacy FP state and then the xstate. The code copied the xstate on top of the legacy FP state instead of using the correct offset. This offset was already calculated in the xstate_* variables, so simply switch to those to fix the problem. With this SECCOMP mode works on 32 bit, so lift the restriction. Fixes: b1e1bd2e6943 ("um: Add helper functions to get/set state for SECCOMP") Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20250604081705.934112-1-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-06-02um: Implement kernel side of SECCOMP based process handlingBenjamin Berg
This adds the kernel side of the seccomp based process handling. Co-authored-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net> Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20250602130052.545733-6-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-06-02um: Add helper functions to get/set state for SECCOMPBenjamin Berg
When not using ptrace, we need to both save and restore registers through the mcontext as provided by the host kernel to our signal handlers. Add corresponding functions to store the state to an mcontext and helpers to access the mcontext of the subprocess through the stub data. Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net> Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20250602130052.545733-4-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-06-02um: Add stub side of SECCOMP/futex based process handlingBenjamin Berg
This adds the stub side for the new seccomp process management code. In this case we do register save/restore through the signal handler mcontext. Add special code for handling TLS, which for x86_64 means setting the FS_BASE/GS_BASE registers while for i386 it means calling the set_thread_area syscall. Co-authored-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net> Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20250602130052.545733-3-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-05-05um/asm: Replace "REP; NOP" with PAUSE mnemonicUros Bizjak
Current minimum required version of binutils is 2.25, which supports PAUSE instruction mnemonic. Replace "REP; NOP" with this proper mnemonic. No functional change intended. Signed-off-by: Uros Bizjak <ubizjak@gmail.com> Cc: Richard Weinberger <richard@nod.at> Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> Cc: Johannes Berg <johannes@sipsolutions.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: David Laight <david.laight.linux@gmail.com> Link: https://patch.msgid.link/20250418083436.133148-2-ubizjak@gmail.com Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-05-05um/asm: Rename rep_nop() to native_pause()Uros Bizjak
Rename rep_nop() function to what it really does. No functional change intended. Signed-off-by: Uros Bizjak <ubizjak@gmail.com> Cc: Richard Weinberger <richard@nod.at> Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> Cc: Johannes Berg <johannes@sipsolutions.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: David Laight <david.laight.linux@gmail.com> Link: https://patch.msgid.link/20250418083436.133148-1-ubizjak@gmail.com Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-05-05um: Add cmpxchg8b_emu and checksum functions to asm-prototypes.hSami Tolvanen
With CONFIG_GENDWARFKSYMS, um builds fail due to missing prototypes in asm/asm-prototypes.h. Add declarations for cmpxchg8b_emu and the exported checksum functions, including csum_partial_copy_generic as it's also exported. Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: linux-kbuild@vger.kernel.org Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202503251216.lE4t9Ikj-lkp@intel.com/ Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Link: https://patch.msgid.link/20250326190500.847236-2-samitolvanen@google.com Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-05-05um: fix _nofault accessesJohannes Berg
Nathan reported [1] that when built with clang, the um kernel crashes pretty much immediately. This turned out to be an issue with the inline assembly I had added, when clang used %rax/%eax for both operands. Reorder it so current->thread.segv_continue is written first, and then the lifetime of _faulted won't have overlap with the lifetime of segv_continue. In the email thread Benjamin also pointed out that current->mm is only NULL for true kernel tasks, but we could do this for a userspace task, so the current->thread.segv_continue logic must be lifted out of the mm==NULL check. Finally, while looking at this, put a barrier() so the NULL assignment to thread.segv_continue cannot be reorder before the possibly faulting operation. Reported-by: Nathan Chancellor <nathan@kernel.org> Closes: https://lore.kernel.org/r/20250402221254.GA384@ax162 [1] Fixes: d1d7f01f7cd3 ("um: mark rodata read-only and implement _nofault accesses") Tested-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-03-18um: x86: clean up elf specific definitionsHajime Tazaki
The file arch/x86/um/asm/module.h is equivalent to the definition of asm-generic. Thus this commit cleans up to use it. Signed-off-by: Hajime Tazaki <thehajime@gmail.com> Link: https://patch.msgid.link/2d70a0ed79ee0a0bef80ad4790063f4833dd9bed.1737348399.git.thehajime@gmail.com Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-03-18um: Store full CSGSFS and SS register from mcontextBenjamin Berg
Doing this allows using registers as retrieved from an mcontext to be pushed to a process using PTRACE_SETREGS. It is not entirely clear to me why CSGSFS was masked. Doing so creates issues when using the mcontext as process state in seccomp and simply copying the register appears to work perfectly fine for ptrace. Signed-off-by: Benjamin Berg <benjamin@sipsolutions.net> Link: https://patch.msgid.link/20250224181827.647129-2-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-03-18um/locking: Remove semicolon from "lock" prefixUros Bizjak
Minimum version of binutils required to compile the kernel is 2.25. This version correctly handles the "lock" prefix, so it is possible to remove the semicolon, which was used to support ancient versions of GNU as. Due to the semicolon, the compiler considers "lock; insn" as two separate instructions. Removing the semicolon makes asm length calculations more accurate, consequently making scheduling and inlining decisions of the compiler more accurate. Removing the semicolon also enables assembler checks involving lock prefix. Trying to assemble e.g. "lock andl %eax, %ebx" results in: Error: expecting lockable instruction after `lock' Signed-off-by: Uros Bizjak <ubizjak@gmail.com> Cc: Richard Weinberger <richard@nod.at> Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> Cc: Johannes Berg <johannes@sipsolutions.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Link: https://patch.msgid.link/20250228090058.2499163-1-ubizjak@gmail.com Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-03-18um: Allocate vdso page pointer staticallyTiwei Bie
Instead of dynamically allocating the pointer to the vdso page during boot, we can just allocate it statically. Doing so will reduce error handling and make the code slightly more readable. Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com> Link: https://patch.msgid.link/20250212045756.164977-1-tiwei.btw@antgroup.com Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-03-18um: mark rodata read-only and implement _nofault accessesJohannes Berg
Mark read-only data actually read-only (simple mprotect), and to be able to test it also implement _nofault accesses. This works by setting up a new "segv_continue" pointer in current, and then when we hit a segfault we change the signal return context so that we continue at that address. The code using this sets it up so that it jumps to a label and then aborts the access that way, returning -EFAULT. It's possible to optimize the ___backtrack_faulted() thing by using asm goto (compiler version dependent) and/or gcc's (not sure if clang has it) &&label extension, but at least in one attempt I made the && caused the compiler to not load -EFAULT into the register in case of jumping to the &&label from the fault handler. So leave it like this for now. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Co-developed-by: Benjamin Berg <benjamin.berg@intel.com> Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20250210160926.420133-2-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-02-12um: properly align signal stack on x86_64Benjamin Berg
The stack needs to be properly aligned so 16 byte memory accesses on the stack are correct. This was broken when introducing the dynamic math register sizing as the rounding was not moved appropriately. Fixes: 3f17fed21491 ("um: switch to regset API and depend on XSTATE") Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20250107133509.265576-1-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Richard Weinberger <richard@nod.at>
2025-02-12um: add back support for FXSAVE registersBenjamin Berg
It was reported that qemu may not enable the XSTATE CPU extension, which is a requirement after commit 3f17fed21491 ("um: switch to regset API and depend on XSTATE"). Add a fallback to use FXSAVE (FP registers on x86_64 and XFP on i386) which is just a shorter version of the same data. The only difference is that the XSTATE magic should not be set in the signal frame. Note that this still drops support for the older i386 FP register layout as supporting this would require more backward compatibility to build a correct signal frame. Fixes: 3f17fed21491 ("um: switch to regset API and depend on XSTATE") Reported-by: SeongJae Park <sj@kernel.org> Closes: https://lore.kernel.org/r/20241203070218.240797-1-sj@kernel.org Tested-by: SeongJae Park <sj@kernel.org> Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20241204074827.1582917-1-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Richard Weinberger <richard@nod.at>
2025-01-13um: Remove unused asm/archparam.h headerTiwei Bie
This header is no longer used after the removal of fixmap support in commit 5bfc4a3a0af3 ("um: Remove obsolete fixmap support"). Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com> Link: https://patch.msgid.link/20250113153218.3331321-3-tiwei.btw@antgroup.com Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2025-01-10um: Remove unused user_context functionTiwei Bie
It's no longer used since commit 6aa802ce6acc ("uml: throw out CHOOSE_MODE"). Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com> Link: https://patch.msgid.link/20241128083137.2219830-10-tiwei.btw@antgroup.com Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-11-07um: fix sparse warnings in signal codeBenjamin Berg
sparse reports that various places were missing the __user tag in casts. In addition, one location was using 0 instead of NULL. Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20241031142017.430420-2-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-11-07um: fix sparse warnings from regset refactorBenjamin Berg
Some variables were not tagged with __user and another was not marked as static even though it should be. Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202410280655.gOlEFwdG-lkp@intel.com/ Closes: https://lore.kernel.org/oe-kbuild-all/202410281821.WSPsAwq7-lkp@intel.com/ Fixes: 3f17fed21491 ("um: switch to regset API and depend on XSTATE") Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20241031142017.430420-1-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-23um: switch to regset API and depend on XSTATEBenjamin Berg
The PTRACE_GETREGSET API has now existed since Linux 2.6.33. The XSAVE CPU feature should also be sufficiently common to be able to rely on it. With this, define our internal FP state to be the hosts XSAVE data. Add discovery for the hosts XSAVE size and place the FP registers at the end of task_struct so that we can adjust the size at runtime. Next we can implement the regset API on top and update the signal handling as well as ptrace APIs to use them. Also switch coredump creation to use the regset API and finally set HAVE_ARCH_TRACEHOOK. This considerably improves the signal frames. Previously they might not have contained all the registers (i386) and also did not have the sizes and magic values set to the correct values to permit userspace to decode the frame. As a side effect, this will permit UML to run on hosts with newer CPU extensions (such as AMX) that need even more register state. Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20241023094120.4083426-1-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-23um: vdso: Always reject undefined references in during linkingThomas Weißschuh
Instead of using a custom script to detect and fail on undefined references, use --no-undefined for all VDSO linker invocations. Drop the now unused checkundef.sh script. Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de> Link: https://patch.msgid.link/20241011-vdso-checkundef-v1-2-1a46e0352d20@linutronix.de Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-23um: make stub_exe _start() pure inline asmJohannes Berg
Since __attribute__((naked)) cannot be used with functions containing C statements, just generate the few instructions it needs in assembly directly. While at it, fix the stack usage ("1 + 2*x - 1" is odd) and document what it must do, and why it must adjust the stack. Fixes: 8508a5e0e9db ("um: Fix misaligned stack in stub_exe") Link: https://lore.kernel.org/linux-um/CABVgOSntH-uoOFMP5HwMXjx_f1osMnVdhgKRKm4uz6DFm2Lb8Q@mail.gmail.com/ Reviewed-by: David Gow <davidgow@google.com> Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-10um: Switch to 4 level page tables on 64 bitBenjamin Berg
The larger memory space is useful to support more applications inside UML. One example for this is ASAN instrumentation of userspace applications which requires addresses that would otherwise not be available. Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20240919124511.282088-11-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-10um: Discover host_task_size from envpBenjamin Berg
When loading the UML binary, the host kernel will place the stack at the highest possible address. It will then map the program name and environment variables onto the start of the stack. As such, an easy way to figure out the host_task_size is to use the highest pointer to an environment variable as a reference. Ensure that this works by disabling address layout randomization and re-executing UML in case it was enabled. This increases the available TASK_SIZE for 64 bit UML considerably. Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20240919124511.282088-9-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-10um: Calculate stub data address relative to stub codeBenjamin Berg
Instead of using the current stack pointer, we can also use the current instruction to calculate where the stub data is. With this the stub data only needs to be aligned to a full page boundary. Changing this has the advantage that we do not have a hole in the memory space above the stub data (which would need to be explicitly cleared). Another motivation to do this is that with the planned addition of a SECCOMP based userspace the stack pointer may not be fully trustworthy. Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20240919124511.282088-7-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-10um: Add generic stub_syscall1 functionBenjamin Berg
The 64bit version did not have a stub_syscall1 function yet. Add it as it will be useful to implement a static binary for stub loading. Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20240919124511.282088-2-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2024-10-10um: Remove 3-level page table support on i386Tiwei Bie
The highmem support has been removed by commit a98a6d864d3b ("um: Remove broken highmem support"). The 2-level page table is sufficient on UML/i386 now. Remove the 3-level page table support on UML/i386 which is still marked as experimental. Suggested-by: Benjamin Berg <benjamin@sipsolutions.net> Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com> Link: https://patch.msgid.link/20240918061702.614837-1-tiwei.btw@antgroup.com Signed-off-by: Johannes Berg <johannes.berg@intel.com>
generated by cgit v1.2.3 (git 2.46.0) at 2025-12-11 10:21:17 +0000