linux-stable.git/arch/um/kernel, branch linux-3.16.y

um: Use get_signal() signal_setup_done()

2019-05-02T20:41:47+00:00

commit 307627eebbb0bc41b21e74d78b932362a6c1b38d upstream.

Use the more generic functions get_signal() signal_setup_done()
for signal delivery.

Signed-off-by: Richard Weinberger 
[bwh: Backported to 3.16 as dependency of commit 35634ffa1751
 "signal: Always notice exiting tasks"]
Signed-off-by: Ben Hutchings

vm: add VM_FAULT_SIGSEGV handling support

2015-02-04T10:58:27+00:00

commit 33692f27597fcab536d7cbbcc8f52905133e4aa7 upstream.

The core VM already knows about VM_FAULT_SIGBUS, but cannot return a
"you should SIGSEGV" error, because the SIGSEGV case was generally
handled by the caller - usually the architecture fault handler.

That results in lots of duplication - all the architecture fault
handlers end up doing very similar "look up vma, check permissions, do
retries etc" - but it generally works.  However, there are cases where
the VM actually wants to SIGSEGV, and applications _expect_ SIGSEGV.

In particular, when accessing the stack guard page, libsigsegv expects a
SIGSEGV.  And it usually got one, because the stack growth is handled by
that duplicated architecture fault handler.

However, when the generic VM layer started propagating the error return
from the stack expansion in commit fee7e49d4514 ("mm: propagate error
from stack expansion even for guard page"), that now exposed the
existing VM_FAULT_SIGBUS result to user space.  And user space really
expected SIGSEGV, not SIGBUS.

To fix that case, we need to add a VM_FAULT_SIGSEGV, and teach all those
duplicate architecture fault handlers about it.  They all already have
the code to handle SIGSEGV, so it's about just tying that new return
value to the existing code, but it's all a bit annoying.

This is the mindless minimal patch to do this.  A more extensive patch
would be to try to gather up the mostly shared fault handling logic into
one generic helper routine, and long-term we really should do that
cleanup.

Just from this patch, you can generally see that most architectures just
copied (directly or indirectly) the old x86 way of doing things, but in
the meantime that original x86 model has been improved to hold the VM
semaphore for shorter times etc and to handle VM_FAULT_RETRY and other
"newer" things, so it would be a good idea to bring all those
improvements to the generic case and teach other architectures about
them too.

Reported-and-tested-by: Takashi Iwai 
Tested-by: Jan Engelhardt 
Acked-by: Heiko Carstens  # "s390 still compiles and boots"
Cc: linux-arch@vger.kernel.org
Signed-off-by: Linus Torvalds 
[ luis: backported to 3.16:
  - file renamed: arch/powerpc/mm/copro_fault.c ->
    arch/powerpc/platforms/cell/spu_fault.c
  - dropped changes to arch/nios2/mm/fault.c ]
Signed-off-by: Luis Henriques

um: segv: Save regs only in case of a kernel mode fault

2014-07-20T11:39:27+00:00

...otherwise me lose user mode regs and the resulting
stack trace is useless.

Signed-off-by: Richard Weinberger

um: Fix hung task in fix_range_common()

2014-07-20T11:16:20+00:00

If do_ops() fails we have to release current->mm->mmap_sem
otherwise the failing task will never terminate.

Reported-by: Toralf Förster 
Signed-off-by: Richard Weinberger

um: Ensure that a stub page cannot get unmapped

2014-07-20T11:09:15+00:00

Trinity discovered an execution path such that a task
can unmap his stub page.

Reported-by: Toralf Förster 
Signed-off-by: Richard Weinberger

um: Memory corruption on startup

2014-04-20T21:57:21+00:00

The reverse case of this race (you must msync before read) is
well known. This is the not so common one.

It can be triggered only on systems which do a lot of task
switching and only at UML startup. If you are starting 200+ UMLs
~ 0.5% will always die without this fix.

Signed-off-by: Anton Ivanov 
[rw: minor whitespace fixes]
Signed-off-by: Richard Weinberger

asm/system.h: um: arch_align_stack() moved to asm/exec.h

2014-04-07T23:36:12+00:00

arch_align_stack() moved to asm/exec.h, so change the comment referring to
asm/system.h which no longer exists.

Signed-off-by: David Howells 
Cc: Jeff Dike 
Cc: Richard Weinberger 
Cc: Arnd Bergmann 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

um: Rename print_stack_trace to do_stack_trace

2013-12-01T12:06:51+00:00

We cannot use print_stack_trace because the name conflicts
with linux/stacktrace.h.

Reported-by: Randy Dunlap 
Acked-by: Randy Dunlap 
Signed-off-by: Richard Weinberger

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml

2013-11-19T19:42:32+00:00

Pull UML changes from Richard Weinberger:
 "This pile contains a nice defconfig cleanup, a rewritten stack
  unwinder and various cleanups"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml:
  um: Remove unused declarations from 
  um: remove used STDIO_CONSOLE Kconfig param
  um/vdso: add .gitignore for a couple of targets
  arch/um: make it work with defconfig and x86_64
  um: Make kstack_depth_to_print conform to arch/x86
  um: Get rid of thread_struct->saved_task
  um: Make stack trace reliable against kernel mode faults
  um: Rewrite show_stack()

um: Remove unused declarations from

2013-11-17T10:39:22+00:00

_end is used, but it's already provided by , so use that.

Signed-off-by: Geert Uytterhoeven 
Cc: Richard Weinberger 
Cc: user-mode-linux-devel@lists.sourceforge.net
Signed-off-by: Richard Weinberger