kernel/arch/um/include/shared/kern_util.h, branch linux-rolling-stable

um: Determine sleep based on need_resched()

2025-10-27T15:41:15Z

With SMP and NO_HZ enabled, the CPU may still need to sleep even if the timer is disarmed. Switch to deciding whether to sleep based on pending resched. Additionally, because disabling IRQs does not block SIGALRM, it is also necessary to check for any pending timer alarms. This is a preparation for adding SMP support. Signed-off-by: Tiwei Bie Link: https://patch.msgid.link/20251027001815.1666872-4-tiwei.bie@linux.dev Signed-off-by: Johannes Berg

um: Remove file-based iomem emulation support

2025-10-27T15:37:12Z

The file-based iomem emulation was introduced to support writing paravirtualized drivers based on emulated iomem regions. However, the only driver that makes use of it is an example driver called mmapper, which was written over two decades ago. We now have several modern device emulation mechanisms, such as vhost-user-based virtio-uml. Remove the file-based iomem emulation support to reduce the maintenance burden. Signed-off-by: Tiwei Bie Link: https://patch.msgid.link/20251027054519.1996090-5-tiwei.bie@linux.dev Signed-off-by: Johannes Berg

um: Replace UML_ROUND_UP() with PAGE_ALIGN()

2025-10-27T15:37:12Z

Although UML_ROUND_UP() is defined in a shared header file, it depends on the PAGE_SIZE and PAGE_MASK macros, so it can only be used in kernel code. Considering its name is not very clear and its functionality is the same as PAGE_ALIGN(), replace its usages with a direct call to PAGE_ALIGN() and remove it. Signed-off-by: Tiwei Bie Link: https://patch.msgid.link/20251027054519.1996090-4-tiwei.bie@linux.dev Signed-off-by: Johannes Berg

um: mark rodata read-only and implement _nofault accesses

2025-03-18T10:03:14Z

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 Co-developed-by: Benjamin Berg Signed-off-by: Benjamin Berg Link: https://patch.msgid.link/20250210160926.420133-2-benjamin@sipsolutions.net Signed-off-by: Johannes Berg

um: remove fault_catcher infrastructure

2024-10-23T07:52:46Z

This was perhaps intended to do _nofault copies, but the real reason is lost to history. Remove this, it's not needed, and using longjmp() out of the middle of the signal handler with all the state it has modified is not going to be a good idea anyway. Link: https://patch.msgid.link/20241010224513.901c4d390b3e.Ia74742668b44603c1ca23dd36f90e964e6e7ee55@changeid Signed-off-by: Johannes Berg

um: Remove unused ncpus variable

2024-07-03T10:21:57Z

It's no longer used. And uml_ncpus_setup doesn't exist anymore. Signed-off-by: Tiwei Bie Link: https://patch.msgid.link/20240527134024.1539848-2-tiwei.btw@antgroup.com Signed-off-by: Johannes Berg

um: Fix the declaration of kasan_map_memory

2024-04-30T12:15:42Z

Make it match its definition (size_t vs unsigned long). And declare it in a shared header to fix the -Wmissing-prototypes warning, as it is defined in the user code and called in the kernel code. Fixes: 5b301409e8bc ("UML: add support for KASAN under x86_64") Signed-off-by: Tiwei Bie Signed-off-by: Richard Weinberger

um: Move declarations to proper headers

2024-04-22T19:58:48Z

This will address below -Wmissing-prototypes warnings: arch/um/kernel/initrd.c:18:12: warning: no previous prototype for ‘read_initrd’ [-Wmissing-prototypes] arch/um/kernel/um_arch.c:408:19: warning: no previous prototype for ‘read_initrd’ [-Wmissing-prototypes] arch/um/os-Linux/start_up.c:301:12: warning: no previous prototype for ‘parse_iomem’ [-Wmissing-prototypes] arch/x86/um/ptrace_32.c:15:6: warning: no previous prototype for ‘arch_switch_to’ [-Wmissing-prototypes] arch/x86/um/ptrace_32.c:101:5: warning: no previous prototype for ‘poke_user’ [-Wmissing-prototypes] arch/x86/um/ptrace_32.c:153:5: warning: no previous prototype for ‘peek_user’ [-Wmissing-prototypes] arch/x86/um/ptrace_64.c:111:5: warning: no previous prototype for ‘poke_user’ [-Wmissing-prototypes] arch/x86/um/ptrace_64.c:171:5: warning: no previous prototype for ‘peek_user’ [-Wmissing-prototypes] arch/x86/um/syscalls_64.c:48:6: warning: no previous prototype for ‘arch_switch_to’ [-Wmissing-prototypes] arch/x86/um/tls_32.c:184:5: warning: no previous prototype for ‘arch_switch_tls’ [-Wmissing-prototypes] Signed-off-by: Tiwei Bie Signed-off-by: Richard Weinberger

um: Drop support for hosts without SYSEMU_SINGLESTEP support

2024-01-04T22:29:11Z

These features have existed since Linux 2.6.14 and can be considered widely available at this point. Also drop the backward compatibility code for PTRACE_SETOPTIONS. Signed-off-by: Benjamin Berg ---- v2: * Continue to define PTRACE_SYSEMU_SINGLESTEP as glibc only added it in version 2.27. Signed-off-by: Richard Weinberger

um: Fix naming clash between UML and scheduler

2024-01-04T20:22:27Z

__cant_sleep was already used and exported by the scheduler. The name had to be changed to a UML specific one. Signed-off-by: Anton Ivanov Reviewed-by: Peter Lafreniere Signed-off-by: Richard Weinberger