This patch prohibits probing instructions for which the stack
requirements are unable to be determined statically. Some test cases
are found not work again after the modification, this patch also
removes them.
Signed-off-by: NWang Nan <wangnan0@huawei.com>
Reviewed-by: NJon Medhurst <tixy@linaro.org>
Signed-off-by: NJon Medhurst <tixy@linaro.org>

This patch uses the previously introduced checker functionality on
store instructions to record their stack consumption information to
arch_probes_insn.
Signed-off-by: NWang Nan <wangnan0@huawei.com>
Reviewed-by: NJon Medhurst <tixy@linaro.org>
Signed-off-by: NJon Medhurst <tixy@linaro.org>

Because the common underlying code for ARM kprobes and uprobes needs
to share a common architecrure-specific context structure, and because
the generic kprobes include file insists on defining this to a dummy
structure when kprobes is not configured, a new common structure is
required which can exist when uprobes is configured without kprobes.
In this case kprobes will define a dummy structure, but without the
define aliasing the two structure tags it will not affect uprobes and
the shared probes code.
Signed-off-by: NDavid A. Long <dave.long@linaro.org>
Acked-by: NJon Medhurst <tixy@linaro.org>

Any more ARM kprobes/uprobes symbols which have "kprobe" in the name must be
changed to the more generic "probes" or other non-kprobes specific symbol.
Signed-off-by: NDavid A. Long <dave.long@linaro.org>
Acked-by: NJon Medhurst <tixy@linaro.org>

In preparation for sharing the ARM kprobes instruction interpreting
code with uprobes, make the symbols names less kprobes-specific.
Signed-off-by: NDavid A. Long <dave.long@linaro.org>
Acked-by: NJon Medhurst <tixy@linaro.org>

Change the generic ARM probes code to pass in the opcode and architecture-specific
structure separately instead of using struct kprobe, so we do not pollute
code being used only for uprobes or other non-kprobes instruction
interpretation.
Signed-off-by: NDavid A. Long <dave.long@linaro.org>
Acked-by: NJon Medhurst <tixy@linaro.org>

Move the arm version of the kprobes instruction parsing code into more generic
files from where it can be used by uprobes and possibly other subsystems. The
symbol names will be made more generic in a subsequent part of this patchset.
Signed-off-by: NDavid A. Long <dave.long@linaro.org>
Acked-by: NJon Medhurst <tixy@linaro.org>

Separate the kprobe-only definitions from the definitions needed by
both kprobes and uprobes.
Signed-off-by: NDavid A. Long <dave.long@linaro.org>
Acked-by: NJon Medhurst <tixy@linaro.org>

Make sure includes in ARM kprobes sources are done explicitly. Do not
rely on includes from other includes.
Signed-off-by: NDavid A. Long <dave.long@linaro.org>
Acked-by: NJon Medhurst <tixy@linaro.org>

This patch provides functionality to audit system call events on the
ARM platform. The implementation was based off the structure of the
MIPS platform and information in this
(http://lists.fedoraproject.org/pipermail/arm/2009-October/000382.html)
mailing list thread. The required audit_syscall_exit and
audit_syscall_entry checks were added to ptrace using the standard
registers for system call values (r0 through r3). A thread information
flag was added for auditing (TIF_SYSCALL_AUDIT) and a meta-flag was
added (_TIF_SYSCALL_WORK) to simplify modifications to the syscall
entry/exit. Now, if either the TRACE flag is set or the AUDIT flag is
set, the syscall_trace function will be executed. The prober changes
were made to Kconfig to allow CONFIG_AUDITSYSCALL to be enabled.

Due to platform availability limitations, this patch was only tested
on the Android platform running the modified "android-goldfish-2.6.29"
kernel. A test compile was performed using Code Sourcery's
cross-compilation toolset and the current linux-3.0 stable kernel. The
changes compile without error. I'm hoping, due to the simple modifications,
the patch is "obviously correct".
Signed-off-by: NNathaniel Husted <nhusted@gmail.com>
Signed-off-by: NEric Paris <eparis@redhat.com>

When we come to emulating Thumb instructions then, to interwork
correctly, the code on in the instruction slot must be invoked with a
function pointer which has the least significant bit set. Rather that
set this by hand in every Thumb emulation function we will add a new
field for this purpose to arch_specific_insn, called insn_fn.

This also enables us to seamlessly share emulation functions between ARM
and Thumb code.
Signed-off-by: NJon Medhurst <tixy@yxit.co.uk>
Acked-by: NNicolas Pitre <nicolas.pitre@linaro.org>

When a probe fires we must single-step the instruction which was
replaced by a breakpoint. As the steps to do this vary between ARM and
Thumb instructions we need a way to customise single-stepping.

This is done by adding a new hook called insn_singlestep to
arch_specific_insn which is initialised by the instruction decoding
functions.

These single-step hooks must update PC and call the instruction handler.
For Thumb instructions an additional step of updating ITSTATE is needed.
We do this after calling the handler because some handlers will need to
test if they are running in an IT block.
Signed-off-by: NJon Medhurst <tixy@yxit.co.uk>
Acked-by: NNicolas Pitre <nicolas.pitre@linaro.org>

Later, we will be adding a considerable amount of internal
implementation definitions to kprobe header files and it would be good
to have these in local header file along side the source code, rather
than pollute the existing header which is include by all users of
kprobes.

To this end, we add arch/arm/kernel/kprobes.h and move into this the
existing internal defintions from arch/arm/include/asm/kprobes.h
Signed-off-by: NJon Medhurst <tixy@yxit.co.uk>
Acked-by: NNicolas Pitre <nicolas.pitre@linaro.org>

When a kprobe is placed onto conditionally executed ARM instructions,
many of the emulation routines used to single step them produce corrupt
register results. Rather than fix all of these cases we modify the
framework which calls them to test the relevant condition flags and, if
the test fails, skip calling the emulation code.
Signed-off-by: NJon Medhurst <tixy@yxit.co.uk>
Signed-off-by: NNicolas Pitre <nicolas.pitre@linaro.org>

As mentioned in commit 79696910,
and because of commit b03a5b75,
the direct calling of kprobe_trap_handler() can be removed.
Signed-off-by: NNicolas Pitre <nico@marvell.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Move platform independent header files to arch/arm/include/asm, leaving
those in asm/arch* and asm/plat* alone.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Follow suit from kprobe implementations on other archs and make kretprobe_trampoline non-static. Ftrace implmentation (more specifically, kernel/trace/trace.c) requires access to it (see-> http://kerneltrap.org/mailarchive/linux-kernel/2008/5/27/1955234).
Signed-off-by: NAbhishek Sagar <sagar.abhishek@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Add CONFIG_HAVE_KRETPROBES to the arch/<arch>/Kconfig file for relevant
architectures with kprobes support.  This facilitates easy handling of
in-kernel modules (like samples/kprobes/kretprobe_example.c) that depend on
kretprobes being present in the kernel.

Thanks to Sam Ravnborg for helping make the patch more lean.

Per Mathieu's suggestion, added CONFIG_KRETPROBES and fixed up dependencies.
Signed-off-by: NAnanth N Mavinakayanahalli <ananth@in.ibm.com>
Acked-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The kprobes code is already able to cope with reentrant probes, so its
handler must be called outside of the region protected by undef_lock.

If ever this lock is released when handlers are called then this commit
could be reverted.
Signed-off-by: NNicolas Pitre <nico@marvell.com>

This is a full implementation of Kprobes including Jprobes and
Kretprobes support.

This ARM implementation does not follow the usual kprobes double-
exception model. The traditional model is where the initial kprobes
breakpoint calls kprobe_handler(), which returns from exception to
execute the instruction in its original context, then immediately
re-enters after a second breakpoint (or single-stepping exception)
into post_kprobe_handler(), each time the probe is hit..  The ARM
implementation only executes one kprobes exception per hit, so no
post_kprobe_handler() phase. All side-effects from the kprobe'd
instruction are resolved before returning from the initial exception.
As a result, all instructions are _always_ effectively boosted
regardless of the type of instruction, and even regardless of whether
or not there is a post-handler for the probe.
Signed-off-by: NAbhishek Sagar <sagar.abhishek@gmail.com>
Signed-off-by: NQuentin Barnes <qbarnes@gmail.com>
Signed-off-by: NNicolas Pitre <nico@marvell.com>

This is the code implementing instruction single-stepping for kprobes
on ARM.

To get around the limitation of no Next-PC and no hardware single-
stepping, all kprobe'd instructions are split into three camps:
simulation, emulation, and rejected. "Simulated" instructions are
those instructions which behavior is reproduced by straight C code.
"Emulated" instructions are ones that are copied, slightly altered
and executed directly in the instruction slot to reproduce their
behavior.  "Rejected" instructions are ones that could be simulated,
but work hasn't been put into simulating them. These instructions
should be very rare, if not unencountered, in the kernel. If ever
needed, code could be added to simulate them.

One might wonder why this and the ptrace singlestep facility are not
sharing some code.  Both approaches are fundamentally different because
the ptrace code regains control after the stepped instruction by installing
a breakpoint after the instruction itself, and possibly at the location
where the instruction might be branching to, instead of simulating or
emulating the target instruction.

The ptrace approach isn't suitable for kprobes because the breakpoints
would have to be moved back, and the icache flushed, everytime the
probe is hit to let normal code execution resume, which would have a
significant performance impact. It is also racy on SMP since another
CPU could, with the right timing, sail through the probe point without
being caught.  Because ptrace single-stepping always result in a
different process to be scheduled, the concern for performance is much
less significant.

On the other hand, the kprobes approach isn't (currently) suitable for
ptrace because it has no provision for proper user space memory
protection and translation, and even if that was implemented, the gain
wouldn't be worth the added complexity in the ptrace path compared to
the current approach.

So, until kprobes does support user space, both kprobes and ptrace are
best kept independent and separate.
Signed-off-by: NQuentin Barnes <qbarnes@gmail.com>
Signed-off-by: NAbhishek Sagar <sagar.abhishek@gmail.com>
Signed-off-by: NNicolas Pitre <nico@marvell.com>