'sub pc, pc, #1b-2b+8-2' results in address<1:0> == '10'.
sub pc, pc, #const (== ADR pc, #const) performs an interworking branch
(BXWritePC()) on ARMv7+ and a simple branch (BranchWritePC()) on earlier
versions.
In ARM state, BXWritePC() is UNPREDICTABLE when address<1:0> == '10'.
In ARM state on ARMv6+, BranchWritePC() ignores address<1:0>. Before
ARMv6, BranchWritePC() is UNPREDICTABLE if address<1:0> != '00'
So the instruction is UNPREDICTABLE both before and after v6.
Acked-by: Jon Medhurst <tixy@yxit.co.uk>
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The SWP instruction is deprecated on ARMv6 and with ARMv7 it will be
UNDEFINED when CONFIG_SWP_EMULATE is selected. In this case, probing a
SWP instruction will cause an oops when the kprobes emulation code
executes an undefined instruction.
As the SWP instruction should be rare or non-existent in kernels for
ARMv6 and later, we can simply avoid these problems by not allowing
probing of these.
Reported-by: Leif Lindholm <leif.lindholm@arm.com>
Tested-by: Leif Lindholm <leif.lindholm@arm.com>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
There is a kprobes testcase for the instruction "strd r2, [r3], r4".
This has unpredictable behaviour as it uses r3 for register writeback
addressing and also stores it to memory.
On a cortex A9, this testcase would fail because the instruction writes
the updated value of r3 to memory, whereas the kprobes emulation code
writes the original value.
Fix this by changing testcase to used r5 instead of r3.
Reported-by: Leif Lindholm <leif.lindholm@arm.com>
Tested-by: Leif Lindholm <leif.lindholm@arm.com>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Rabin Vincent