When compiling kprobes-test-arm.c the following error has been observed
/tmp/ccoT403o.s:21439: Error: bad immediate value for offset (4168)
This is caused by the compiler spilling it's literal pool too far away
from the site which is trying to reference it with a PC relative load.
This arises because the compiler is underestimating the size of the
inline assembler code present, which apparently it approximates as 4
bytes per line or instruction.
We fix this problem by moving the operations which generate more than
4 bytes out of the text section. Specifically, moving the .ascii
directives to the .rodata section.
Signed-off-by: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Due to a long-standing issue with Thumb symbol lookup [1] the jprobes
tests fail when built into a kernel compiled as Thumb mode. (They work
fine for ARM mode kernels or for Thumb when built as a loadable module.)
Rather than have this problem terminate testing prematurely lets instead
emit an error message and carry on with the main kprobes tests, delaying
the final failure report until the end.
[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2011-August/063026.html
Signed-off-by: Jon Medhurst <tixy@linaro.org>
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>
