By default if no fill symbol is given to .align directive in a code
section it fills gap with NOPs. If previous fragment is not
instruction-aligned, additional pre-alignment is done by zero bytes
before NOPs. These zero bytes are marked as data by special symbol $d in
symbol table. Unfortunately GAS assumes that there is only code in the
code section so it "puts back" code symbol $a at the end of this
pre-alignment. So if there is some data after alignment it will be
interpreted as code and will be swapped back to LE for BE8 system during
a final linking.
If explicit fill value is given to .align, the NOP-padding code is
skipped and symbol table does not get messed-up.
So the workaround for this issue:
Use explicit fill value if data should be aligned in the code section.
Acked-by: Ben Dooks <ben.dooks@codethink.co.uk>
Acked-by: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Taras Kondratiuk <taras.kondratiuk@linaro.org>
Ensure we read instructions in the correct endian-ness by using
the <asm/opcodes.h> helper to transform them as necessary.
Acked-by: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
[taras.kondratiuk@linaro.org: fix next_instruction() function]
Signed-off-by: Taras Kondratiuk <taras.kondratiuk@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: David A. Long <dave.long@linaro.org>
Acked-by: Jon 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: David A. Long <dave.long@linaro.org>
Acked-by: Jon Medhurst <tixy@linaro.org>
This patch changes the kprobes implementation to use the generic ARM
instruction set condition code checks, rather than a dedicated
implementation.
Signed-off-by: Leif Lindholm <leif.lindholm@arm.com>
Acked-by: Jon Medhurst <tixy@yxit.co.uk>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
These benchmarks show the basic speed of kprobes and verify the success
of optimisations done to the emulation of typical function entry
instructions (i.e. push/stmdb).
Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
This is used to verify that all combinations of CPU instructions
described by the kprobes decoding tables have a test case.
Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
These check that the bitmask and match value used in the decoding tables
are self consistent.
Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
On ARM we have to simulate/emulate CPU instructions in order to
singlestep them. This patch adds a framework which can be used to
construct test cases for different instruction forms. It is described in
detail in the in-source comments of kprobes-test.c
Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
These test that the different kinds of probes can be successfully placed
into ARM and Thumb code and that the handlers are called correctly when
this code is executed.
Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
