linux-toradex.git/include/linux/uprobes.h, branch v3.14.3

uprobes: Cleanup !CONFIG_UPROBES decls, unexport xol_area

2013-11-20T15:31:01+00:00

1. Don't include asm/uprobes.h unconditionally, we only need
   it if CONFIG_UPROBES.

2. Move the definition of "struct xol_area" into uprobes.c.

   Perhaps we should simply kill struct uprobes_state, it buys
   nothing.

3. Kill the dummy definition of uprobe_get_swbp_addr(), nobody
   except handle_swbp() needs it.

4. Purely cosmetic, but move the decl of uprobe_get_swbp_addr()
   up, close to other __weak helpers.

Signed-off-by: Oleg Nesterov 
Acked-by: Srikar Dronamraju

uprobes: Add uprobe_task->dup_xol_work/dup_xol_addr

2013-11-20T15:30:57+00:00

uprobe_task->vaddr is a bit strange. The generic code uses it only
to pass the additional argument to arch_uprobe_pre_xol(), and since
it is always equal to instruction_pointer() this looks even more
strange.

And both utask->vaddr and and utask->autask have the same scope,
they only have the meaning when the task executes the probed insn
out-of-line, so it is safe to reuse both in UTASK_RUNNING state.

This all means that logically ->vaddr belongs to arch_uprobe_task
and we should probably move it there, arch_uprobe_pre_xol() can
record instruction_pointer() itself.

OTOH, it is also used by uprobe_copy_process() and dup_xol_work()
for another purpose, this doesn't look clean and doesn't allow to
move this member into arch_uprobe_task.

This patch adds the union with 2 anonymous structs into uprobe_task.

The first struct is autask + vaddr, this way we "almost" move vaddr
into autask.

The second struct has 2 new members for uprobe_copy_process() paths:
->dup_xol_addr which can be used instead ->vaddr, and ->dup_xol_work
which can be used to avoid kmalloc() and simplify the code.

Note that this union will likely have another member(s), we need
something like "private_data_for_handlers" so that the tracing
handlers could use it to communicate with call_fetch() methods.

Signed-off-by: Oleg Nesterov 
Reviewed-by: Masami Hiramatsu 
Acked-by: Srikar Dronamraju

uprobes: Export write_opcode() as uprobe_write_opcode()

2013-11-06T19:00:09+00:00

set_swbp() and set_orig_insn() are __weak, but this is pointless
because write_opcode() is static.

Export write_opcode() as uprobe_write_opcode() for the upcoming
arm port, this way it can actually override set_swbp() and use
__opcode_to_mem_arm(bpinsn) instead if UPROBE_SWBP_INSN.

Signed-off-by: Oleg Nesterov

uprobes: Move function declarations out of arch

2013-11-06T18:59:37+00:00

Move the function declarations from the arch headers to the common
header, since only the function bodies are architecture-specific.
These changes are from Vincent Rabin's uprobes patch.

[ oleg: update arch/powerpc/include/asm/uprobes.h ]

Signed-off-by: Rabin Vincent 
Signed-off-by: David A. Long 
Signed-off-by: Oleg Nesterov

uprobes: Teach uprobe_copy_process() to handle CLONE_VFORK

2013-10-29T17:02:55+00:00

uprobe_copy_process() does nothing if the child shares ->mm with
the forking process, but there is a special case: CLONE_VFORK.
In this case it would be more correct to do dup_utask() but avoid
dup_xol(). This is not that important, the child should not unwind
its stack too much, this can corrupt the parent's stack, but at
least we need this to allow to ret-probe __vfork() itself.

Note: in theory, it would be better to check task_pt_regs(p)->sp
instead of CLONE_VFORK, we need to dup_utask() if and only if the
child can return from the function called by the parent. But this
needs the arch-dependant helper, and I think that nobody actually
does clone(same_stack, CLONE_VM).

Reported-by: Martin Cermak 
Reported-by: David Smith 
Signed-off-by: Oleg Nesterov

uprobes: Remove the wrong __weak attribute

2013-10-29T17:02:47+00:00

linux/uprobes.h declares arch_uprobe_skip_sstep() as a weak function.
But as there is no definition of generic version so when trying to build
uprobes for an architecture that doesn't yet have a arch_uprobe_skip_sstep()
implementation, the vmlinux will try to call arch_uprobe_skip_sstep()
somehwere in Stupidhistan leading to a system crash.  We rather want a
proper link error so remove arch_uprobe_skip_sstep().

Signed-off-by: Ralf Baechle 
Signed-off-by: Oleg Nesterov

uretprobes: Limit the depth of return probe nestedness

2013-04-13T13:31:58+00:00

Unlike the kretprobes we can't trust userspace, thus must have
protection from user space attacks. User-space have  "unlimited"
stack, and this patch limits the return probes nestedness as a
simple remedy for it.

Note that this implementation leaks return_instance on siglongjmp
until exit()/exec().

The intention is to have KISS and bare minimum solution for the
initial implementation in order to not complicate the uretprobes
code.

In the future we may come up with more sophisticated solution that
remove this depth limitation. It is not easy task and lays beyond
this patchset.

Signed-off-by: Anton Arapov 
Acked-by: Srikar Dronamraju 
Signed-off-by: Oleg Nesterov

uretprobes: Return probe entry, prepare_uretprobe()

2013-04-13T13:31:57+00:00

When a uprobe with return probe consumer is hit, prepare_uretprobe()
function is invoked. It creates return_instance, hijacks return address
and replaces it with the trampoline.

* Return instances are kept as stack per uprobed task.
* Return instance is chained, when the original return address is
  trampoline's page vaddr (e.g. recursive call of the probed function).

Signed-off-by: Anton Arapov 
Acked-by: Srikar Dronamraju 
Signed-off-by: Oleg Nesterov

uretprobes: Introduce uprobe_consumer->ret_handler()

2013-04-13T13:31:53+00:00

Enclose return probes implementation, introduce ->ret_handler() and update
existing code to rely on ->handler() *and* ->ret_handler() for uprobe and
uretprobe respectively.

Signed-off-by: Anton Arapov 
Acked-by: Srikar Dronamraju 
Signed-off-by: Oleg Nesterov

uprobes: Add trap variant helper

2013-04-04T11:57:04+00:00

Some architectures like powerpc have multiple variants of the trap
instruction. Introduce an additional helper is_trap_insn() for run-time
handling of non-uprobe traps on such architectures.

While there, change is_swbp_at_addr() to is_trap_at_addr() for reading
clarity.

With this change, the uprobe registration path will supercede any trap
instruction inserted at the requested location, while taking care of
delivering the SIGTRAP for cases where the trap notification came in
for an address without a uprobe. See [1] for a more detailed explanation.

[1] https://lists.ozlabs.org/pipermail/linuxppc-dev/2013-March/104771.html

This change was suggested by Oleg Nesterov.

Signed-off-by: Ananth N Mavinakayanahalli 
Acked-by: Srikar Dronamraju 
Signed-off-by: Oleg Nesterov