linux-toradex.git/include/linux/ptrace.h, branch v3.0.16

ptrace: Prepare to fix racy accesses on task breakpoints

2011-04-25T15:28:24+00:00

When a task is traced and is in a stopped state, the tracer
may execute a ptrace request to examine the tracee state and
get its task struct. Right after, the tracee can be killed
and thus its breakpoints released.
This can happen concurrently when the tracer is in the middle
of reading or modifying these breakpoints, leading to dereferencing
a freed pointer.

Hence, to prepare the fix, create a generic breakpoint reference
holding API. When a reference on the breakpoints of a task is
held, the breakpoints won't be released until the last reference
is dropped. After that, no more ptrace request on the task's
breakpoints can be serviced for the tracer.

Reported-by: Oleg Nesterov 
Signed-off-by: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Cc: Will Deacon 
Cc: Prasad 
Cc: Paul Mundt 
Cc: v2.6.33.. 
Link: http://lkml.kernel.org/r/1302284067-7860-2-git-send-email-fweisbec@gmail.com

Mark ptrace_{traceme,attach,detach} static

2011-03-04T17:23:30+00:00

They are only used inside kernel/ptrace.c, and have been for a long
time.  We don't want to go back to the bad-old-days when architectures
did things on their own, so make them static and private.

Signed-off-by: Linus Torvalds

ptrace: change signature of arch_ptrace()

2010-10-28T01:03:10+00:00

Fix up the arguments to arch_ptrace() to take account of the fact that
@addr and @data are now unsigned long rather than long as of a preceding
patch in this series.

Signed-off-by: Namhyung Kim 
Cc: 
Acked-by: Roland McGrath 
Acked-by: David Howells 
Acked-by: Geert Uytterhoeven 
Acked-by: David S. Miller 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ptrace: change signature of sys_ptrace() and friends

2010-10-28T01:03:10+00:00

Since userspace API of ptrace syscall defines @addr and @data as void
pointers, it would be more appropriate to define them as unsigned long in
kernel.  Therefore related functions are changed also.

'unsigned long' is typically used in other places in kernel as an opaque
data type and that using this helps cleaning up a lot of warnings from
sparse.

Suggested-by: Arnd Bergmann 
Signed-off-by: Namhyung Kim 
Acked-by: Arnd Bergmann 
Acked-by: Roland McGrath 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

x86, perf, bts, mm: Delete the never used BTS-ptrace code

2010-03-26T10:33:55+00:00

Support for the PMU's BTS features has been upstreamed in
v2.6.32, but we still have the old and disabled ptrace-BTS,
as Linus noticed it not so long ago.

It's buggy: TIF_DEBUGCTLMSR is trampling all over that MSR without
regard for other uses (perf) and doesn't provide the flexibility
needed for perf either.

Its users are ptrace-block-step and ptrace-bts, since ptrace-bts
was never used and ptrace-block-step can be implemented using a
much simpler approach.

So axe all 3000 lines of it. That includes the *locked_memory*()
APIs in mm/mlock.c as well.

Reported-by: Linus Torvalds 
Signed-off-by: Peter Zijlstra 
Cc: Roland McGrath 
Cc: Oleg Nesterov 
Cc: Markus Metzger 
Cc: Steven Rostedt 
Cc: Andrew Morton 
LKML-Reference: <20100325135413.938004390@chello.nl>
Signed-off-by: Ingo Molnar

ptrace: move user_enable_single_step & co prototypes to linux/ptrace.h

2010-03-12T23:52:38+00:00

While in theory user_enable_single_step/user_disable_single_step/
user_enable_blockstep could also be provided as an inline or macro there's
no good reason to do so, and having the prototype in one places keeps code
size and confusion down.

Roland said:

  The original thought there was that user_enable_single_step() et al
  might well be only an instruction or three on a sane machine (as if we
  have any of those!), and since there is only one call site inlining
  would be beneficial.  But I agree that there is no strong reason to care
  about inlining it.

  As to the arch changes, there is only one thought I'd add to the
  record.  It was always my thinking that for an arch where
  PTRACE_SINGLESTEP does text-modifying breakpoint insertion,
  user_enable_single_step() should not be provided.  That is,
  arch_has_single_step()=>true means that there is an arch facility with
  "pure" semantics that does not have any unexpected side effects.
  Inserting a breakpoint might do very unexpected strange things in
  multi-threaded situations.  Aside from that, it is a peculiar side
  effect that user_{enable,disable}_single_step() should cause COW
  de-sharing of text pages and so forth.  For PTRACE_SINGLESTEP, all these
  peculiarities are the status quo ante for that arch, so having
  arch_ptrace() itself do those is one thing.  But for building other
  things in the future, it is nicer to have a uniform "pure" semantics
  that arch-independent code can expect.

  OTOH, all such arch issues are really up to the arch maintainer.  As
  of today, there is nothing but ptrace using user_enable_single_step() et
  al so it's a distinction without a practical difference.  If/when there
  are other facilities that use user_enable_single_step() and might care,
  the affected arch's can revisit the question when someone cares about
  the quality of the arch support for said new facility.

Signed-off-by: Christoph Hellwig 
Cc: Oleg Nesterov 
Cc: Roland McGrath 
Acked-by: David Howells 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ptrace: Fix ptrace_regset() comments and diagnose errors specifically

2010-02-23T21:45:26+00:00

Return -EINVAL for the bad size and for unrecognized NT_* type in
ptrace_regset() instead of -EIO.

Also update the comments for this ptrace interface with more clarifications.

Requested-by: Roland McGrath 
Requested-by: Oleg Nesterov 
Signed-off-by: Suresh Siddha 
LKML-Reference: <20100222225240.397523600@sbs-t61.sc.intel.com>
Acked-by: Roland McGrath 
Signed-off-by: H. Peter Anvin

ptrace: Add support for generic PTRACE_GETREGSET/PTRACE_SETREGSET

2010-02-11T23:08:33+00:00

Generic support for PTRACE_GETREGSET/PTRACE_SETREGSET commands which
export the regsets supported by each architecture using the correponding
NT_* types. These NT_* types are already part of the userland ABI, used
in representing the architecture specific register sets as different NOTES
in an ELF core file.

'addr' parameter for the ptrace system call encode the REGSET type (using
the corresppnding NT_* type) and the 'data' parameter points to the
struct iovec having the user buffer and the length of that buffer.

	struct iovec iov = { buf, len};
	ret = ptrace(PTRACE_GETREGSET/PTRACE_SETREGSET, pid, NT_XXX_TYPE, &iov);

On successful completion, iov.len will be updated by the kernel specifying
how much the kernel has written/read to/from the user's iov.buf.

x86 extended state registers are primarily exported using this interface.

Signed-off-by: Suresh Siddha 
LKML-Reference: <20100211195614.886724710@sbs-t61.sc.intel.com>
Acked-by: Hongjiu Lu 
Cc: Roland McGrath 
Signed-off-by: H. Peter Anvin

ptrace: introduce user_single_step_siginfo() helper

2009-12-16T15:20:08+00:00

Suggested by Roland.

Currently there is no way to synthesize a single-stepping trap in the
arch-independent manner.  This patch adds the default helper which fills
siginfo_t, arch/ can can override it.

Architetures which implement user_enable_single_step() should add
user_single_step_siginfo() also.

Signed-off-by: Oleg Nesterov 
Acked-by: Roland McGrath 
Cc: 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: "H. Peter Anvin" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ptrace: cleanup ptrace_init_task()->ptrace_link() path

2009-12-16T15:20:08+00:00

No functional changes.

ptrace_init_task() looks confusing, as if we always auto-attach when "bool
ptrace" argument is true, while in fact we attach only if current is
traced.

Make the code more explicit and kill now unused ptrace_link().

Signed-off-by: Oleg Nesterov 
Acked-by: Roland McGrath 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds