We need linux/threads.h for that variable.

Fixes: 8bba077066d6d0 ("um: Set number of CPUs")
Signed-off-by: Richard Weinberger <richard@nod.at>

Define NR_CPUS required by the timer subsystem.

Fixes this make warning:

    scripts/kconfig/conf  --oldconfig arch/x86/um/Kconfig
    kernel/time/Kconfig:155:warning: range is invalid

Signed-off-by: Nikola Kotur <kotnick@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

This adds support for kcov to UML.

There is a small problem where UML will randomly segfault during boot;
this is because current_thread_info() occasionally returns an invalid
(non-NULL) pointer and we try to dereference it in
__sanitizer_cov_trace_pc(). I consider this a bug in UML itself and this
patch merely exposes it.

[v2: disable instrumentation in UML-specific code]

Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Thomas Meyer <thomas@m3y3r.de>
Cc: user-mode-linux-devel <user-mode-linux-devel@lists.sourceforge.net>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

We are in atomic context and must not sleep.
Sleeping here is possible since malloc() maps
to kmalloc() with GFP_KERNEL.

Cc: stable@vger.kernel.org
Fixes: b6024b21 ("um: extend fpstate to _xstate to support YMM registers")
Signed-off-by: Richard Weinberger <richard@nod.at>

Extends fpstate to _xstate, in order to hold AVX/YMM registers.

To avoid oversized stack frame, the following functions have been
refactored by using malloc.
 - sig_handler_common
 - timer_real_alarm_handler

Signed-off-by: Eli Cooper <elicooper@gmx.com>

Open the memory mapped file with the O_TMPFILE flag when available.

Signed-off-by: Mickaël Salaün <mic@digikod.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Acked-by: Tristan Schmelcher <tschmelcher@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

Remove the insecure 0777 mode for temporary file to prohibit other users
to change the executable mapped code.

An attacker could gain access to the mapped file descriptor from the
temporary file (before it is unlinked) in a read-only mode but it should
not be accessible in write mode to avoid arbitrary code execution.

To not change the hostfs behavior, the temporary file creation
permission now depends on the current umask(2) and the implementation of
mkstemp(3).

Signed-off-by: Mickaël Salaün <mic@digikod.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Acked-by: Tristan Schmelcher <tschmelcher@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

This fix two related bugs:
* PTRACE_GETREGS doesn't get the right orig_ax (syscall) value
* PTRACE_SETREGS can't set the orig_ax value (erased by initial value)

Get rid of the now useless and error-prone get_syscall().

Fix inconsistent behavior in the ptrace implementation for i386 when
updating orig_eax automatically update the syscall number as well. This
is now updated in handle_syscall().

Signed-off-by: Mickaël Salaün <mic@digikod.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Will Drewry <wad@chromium.org>
Cc: Thomas Meyer <thomas@m3y3r.de>
Cc: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Cc: Anton Ivanov <aivanov@brocade.com>
Cc: Meredydd Luff <meredydd@senatehouse.org>
Cc: David Drysdale <drysdale@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Acked-by: Kees Cook <keescook@chromium.org>

This decreases the number of syscalls per read/write by half.

Signed-off-by: Anton Ivanov <aivanov@brocade.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

The existing IRQ handler design in UML does not prevent reentrancy

This is mitigated by fd-enable/fd-disable semantics for the IO
portion of the UML subsystem. The timer, however, can and is
re-entered resulting in very deep stack usage and occasional
stack exhaustion.

This patch prevents this by checking if there is a timer
interrupt in-flight before processing any pending timer interrupts.

Signed-off-by: Anton Ivanov <aivanov@brocade.com>
Signed-off-by: Richard Weinberger <richard@nod.at>