um: remove copy_from_kernel_nofault_allowed

There is no need to override the default version of this function
anymore as UML now has proper _nofault memory access functions.

Doing this also fixes t

um: remove copy_from_kernel_nofault_allowed

There is no need to override the default version of this function
anymore as UML now has proper _nofault memory access functions.

Doing this also fixes the fact that the implementation was incorrect as
using mincore() will incorrectly flag pages as inaccessible if they were
swapped out by the host.

Fixes: f75b1b1bedfb ("um: Implement probe_kernel_read()")
Signed-off-by: Benjamin Berg <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Johannes Berg <[email protected]>

show more ...

um: Add os_set_pdeathsig helper function

This helper can be used to set the parent-death signal of the calling
process to SIGKILL to ensure that the process will be killed if the
UML kernel dies une

um: Add os_set_pdeathsig helper function

This helper can be used to set the parent-death signal of the calling
process to SIGKILL to ensure that the process will be killed if the
UML kernel dies unexpectedly without proper cleanup. This helper will
be used in the follow-up patches.

Signed-off-by: Tiwei Bie <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Johannes Berg <[email protected]>

show more ...

um: Remove unused os_getpgrp function

The function is not used anywhere.

Signed-off-by: Benjamin Berg <[email protected]>
Link: https://patch.msgid.link/20240913134442.967599-5-benjamin@sipso

um: Remove unused os_getpgrp function

The function is not used anywhere.

Signed-off-by: Benjamin Berg <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Johannes Berg <[email protected]>

show more ...

um: Remove unused os_stop_process

The function is not used anywhere.

Signed-off-by: Benjamin Berg <[email protected]>
Link: https://patch.msgid.link/20240913134442.967599-4-benjamin@sipsoluti

um: Remove unused os_stop_process

The function is not used anywhere.

Signed-off-by: Benjamin Berg <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Johannes Berg <[email protected]>

show more ...

um: Remove unused os_process_parent

The function is not used anywhere.

Signed-off-by: Benjamin Berg <[email protected]>
Link: https://patch.msgid.link/20240913134442.967599-3-benjamin@sipsolu

um: Remove unused os_process_parent

The function is not used anywhere.

Signed-off-by: Benjamin Berg <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Johannes Berg <[email protected]>

show more ...

um: Remove unused os_process_pc

The function is not used anywhere in the codebase.

Signed-off-by: Benjamin Berg <[email protected]>
Link: https://patch.msgid.link/20240913134442.967599-2-benj

um: Remove unused os_process_pc

The function is not used anywhere in the codebase.

Signed-off-by: Benjamin Berg <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Johannes Berg <[email protected]>

show more ...

um: Add SPDX headers for files in arch/um/os-Linux

Convert files to use SPDX header. All files are licensed under the GPLv2.

Signed-off-by: Alex Dewar <[email protected]>
Signed-off-by: Richard

um: Add SPDX headers for files in arch/um/os-Linux

Convert files to use SPDX header. All files are licensed under the GPLv2.

Signed-off-by: Alex Dewar <[email protected]>
Signed-off-by: Richard Weinberger <[email protected]>

show more ...

um: Switch clocksource to hrtimers

UML is using an obsolete itimer call for
all timers and "polls" for kernel space timer firing
in its userspace portion resulting in a long list
of bugs and incorre

um: Switch clocksource to hrtimers

UML is using an obsolete itimer call for
all timers and "polls" for kernel space timer firing
in its userspace portion resulting in a long list
of bugs and incorrect behaviour(s). It also uses
ITIMER_VIRTUAL for its timer which results in the
timer being dependent on it running and the cpu
load.

This patch fixes this by moving to posix high resolution
timers firing off CLOCK_MONOTONIC and relaying the timer
correctly to the UML userspace.

Fixes:
- crashes when hosts suspends/resumes
- broken userspace timers - effecive ~40Hz instead
of what they should be. Note - this modifies skas behavior
by no longer setting an itimer per clone(). Timer events
are relayed instead.
- kernel network packet scheduling disciplines
- tcp behaviour especially under load
- various timer related corner cases

Finally, overall responsiveness of userspace is better.

Signed-off-by: Thomas Meyer <[email protected]>
Signed-off-by: Anton Ivanov <[email protected]>
[rw: massaged commit message]
Signed-off-by: Richard Weinberger <[email protected]>

show more ...

um: Remove SKAS3/4 support

Before we had SKAS0 UML had two modes of operation
TT (tracing thread) and SKAS3/4 (separated kernel address space).
TT was known to be insecure and got removed a long tim

um: Remove SKAS3/4 support

Before we had SKAS0 UML had two modes of operation
TT (tracing thread) and SKAS3/4 (separated kernel address space).
TT was known to be insecure and got removed a long time ago.
SKAS3/4 required a few (3 or 4) patches on the host side which never went
mainline. The last host patch is 10 years old.

With SKAS0 mode (separated kernel address space using 0 host patches),
default since 2005, SKAS3/4 is obsolete and can be removed.

Signed-off-by: Richard Weinberger <[email protected]>

show more ...

um: Cleanup SIGTERM handling

Richard reported that some UML processes survive if the UML
main process receives a SIGTERM.
This issue was caused by a wrongly placed signal(SIGTERM, SIG_DFL)
in init_n

um: Cleanup SIGTERM handling

Richard reported that some UML processes survive if the UML
main process receives a SIGTERM.
This issue was caused by a wrongly placed signal(SIGTERM, SIG_DFL)
in init_new_thread_signals().
It disabled the UML exit handler accidently for some processes.
The correct solution is to disable the fatal handler for all
UML helper threads/processes.
Such that last_ditch_exit() does not get called multiple times
and all processes can exit due to SIGTERM.

Reported-and-tested-by: Richard W.M. Jones <[email protected]>
Signed-off-by: Richard Weinberger <[email protected]>

show more ...

um: Implement probe_kernel_read()

UML needs it's own probe_kernel_read() to handle kernel
mode faults correctly.
The implementation uses mincore() on the host side to detect
whether a page is owned

um: Implement probe_kernel_read()

UML needs it's own probe_kernel_read() to handle kernel
mode faults correctly.
The implementation uses mincore() on the host side to detect
whether a page is owned by the UML kernel process.

This fixes also a possible crash when sysrq-t is used.
Starting with 3.10 sysrq-t calls probe_kernel_read() to
read details from the kernel workers. As kernel worker are
completely async pointers may turn NULL while reading them.

Cc: <[email protected]>
Cc: <[email protected]>
Cc: <[email protected]> # 3.10.x
Signed-off-by: Richard Weinberger <[email protected]>

show more ...

x86, um: convert to saner kernel_execve() semantics

Signed-off-by: Al Viro <[email protected]>

um: get rid of pointless include "..." where include <...> will do

Signed-off-by: Al Viro <[email protected]>
Signed-off-by: Richard Weinberger <[email protected]>

um: shared/process.h is empty now; kill it

Signed-off-by: Al Viro <[email protected]>
Signed-off-by: Richard Weinberger <[email protected]>

um: fill the handlers array at build time

Signed-off-by: Al Viro <[email protected]>
Signed-off-by: Richard Weinberger <[email protected]>

um: simplify set_handler()

For one thing, we always block the same signals (IRQ ones - IO, WINCH, VTALRM),
so there's no need to pass sa_mask elements in arguments. For another, the
flags depend on

um: simplify set_handler()

For one thing, we always block the same signals (IRQ ones - IO, WINCH, VTALRM),
so there's no need to pass sa_mask elements in arguments. For another, the
flags depend only on whether it's an IRQ signal or not (we add SA_RESTART
for them).

Signed-off-by: Al Viro <[email protected]>
Signed-off-by: Richard Weinberger <[email protected]>

show more ...

um: don't bother blocking SIGARLM and SIGUSR1

We used to generate those, but we hadn't done that for a long
time. No need to bother blocking them for signal handlers.

Signed-off-by: Al Viro <viro@

um: don't bother blocking SIGARLM and SIGUSR1

We used to generate those, but we hadn't done that for a long
time. No need to bother blocking them for signal handlers.

Signed-off-by: Al Viro <[email protected]>
Signed-off-by: Richard Weinberger <[email protected]>

show more ...

um: -include user.h for USER_OBJ, trim includes

Signed-off-by: Al Viro <[email protected]>
Signed-off-by: Richard Weinberger <[email protected]>

um: fix crash while os_dump_core()

os_dump_core() emits SIGTERM to terminate all UML processes. Kernel
threads have to exit on SIGTERM instead of calling last_ditch_exit().
Multiple calls to last_d

um: fix crash while os_dump_core()

os_dump_core() emits SIGTERM to terminate all UML processes. Kernel
threads have to exit on SIGTERM instead of calling last_ditch_exit().
Multiple calls to last_ditch_exit() can cause a crash.

Signed-off-by: Richard Weinberger <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

uml: style fixes in arch/um/os-Linux

Style changes under arch/um/os-Linux:
include trimming
CodingStyle fixes
some printks needed severity indicators

make_tempfile turns out not to be used outsi

uml: style fixes in arch/um/os-Linux

Style changes under arch/um/os-Linux:
include trimming
CodingStyle fixes
some printks needed severity indicators

make_tempfile turns out not to be used outside of mem.c, so it is now static.
Its declaration in tempfile.h is no longer needed, and tempfile.h itself is no
longer needed.

create_tmp_file was also made static.

checkpatch moans about an EXPORT_SYMBOL in user_syms.c which is part of a
macro definition - this is copying a bit of kernel infrastructure into the
libc side of UML because the kernel headers can't be included there.

Signed-off-by: Jeff Dike <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

uml: remove init_irq_signals

init_irq_signals doesn't need to be called from the context of a new process.
It initializes handlers, which are useless in process context. With that call
gone, init_i

uml: remove init_irq_signals

init_irq_signals doesn't need to be called from the context of a new process.
It initializes handlers, which are useless in process context. With that call
gone, init_irq_signals has only one caller, so it can be inlined into
init_new_thread_signals.

Signed-off-by: Jeff Dike <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

uml: stop gdb from deleting breakpoints when running UML

Sometimes when UML is debugged gdb miss breakpoints.

When process traced by gdb do fork, debugger remove breakpoints from
child address spac

uml: stop gdb from deleting breakpoints when running UML

Sometimes when UML is debugged gdb miss breakpoints.

When process traced by gdb do fork, debugger remove breakpoints from
child address space. There is possibility to trace more than one fork,
but this not work with UML, I guess (only guess) there is a deadlock -
gdb waits for UML and UML waits for gdb.

When clone() is called with SIGCHLD and CLONE_VM flags, gdb see this
as PTRACE_EVENT_FORK not as PTRACE_EVENT_CLONE and remove breakpoints
from child and at the same time from traced process, because either
have the same address space.

Maybe it is possible to do fix in gdb, but I'm not sure if there is
easy way to find out if traced and child processes share memory. So I
do fix for UML, it simply do not call clone() with both SIGCHLD and
CLONE_VM flags together. Additionally __WALL flag is used for
waitpid() to assure not miss clone and normal process events.

[ jdike - checkpatch fixes ]

Signed-off-by: Stanislaw Gruszka <[email protected]>
Signed-off-by: Jeff Dike <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

uml: eliminate SIGALRM

Now that ITIMER_REAL is no longer used, there is no need for any use of
SIGALRM whatsoever. This patch removes all mention of it.

In addition, real_alarm_handler took a sign

uml: eliminate SIGALRM

Now that ITIMER_REAL is no longer used, there is no need for any use of
SIGALRM whatsoever. This patch removes all mention of it.

In addition, real_alarm_handler took a signal argument which is now always
SIGVTALRM. So, that is gone.

Signed-off-by: Jeff Dike <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

uml: userspace files should call libc directly

A number of files that were changed in the recent removal of tt mode
are userspace files which call the os_* wrappers instead of calling
libc directly.

uml: userspace files should call libc directly

A number of files that were changed in the recent removal of tt mode
are userspace files which call the os_* wrappers instead of calling
libc directly. A few other files were affected by this, through

This patch makes these call glibc directly.

There are also style fixes in the affected areas.

os_print_error has no remaining callers, so it is deleted.

There is a interface change to os_set_exec_close, eliminating a
parameter which was always the same. The callers are fixed as well.

os_process_pc got its error path cleaned up.

Signed-off-by: Jeff Dike <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

uml: get rid of do_longjmp

do_longjmp used to be needed when UML didn't have its own implementation of
setjmp and longjmp. They came from libc, and couldn't be called directly from
kernel code, as

uml: get rid of do_longjmp

do_longjmp used to be needed when UML didn't have its own implementation of
setjmp and longjmp. They came from libc, and couldn't be called directly from
kernel code, as the libc jmp_buf couldn't be imported there. do_longjmp was a
userspace function which served to provide longjmp access to kernel code.

This is gone, and a number of void * pointers can now be jmp_buf *.

Signed-off-by: Jeff Dike <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...