commit 70948c05fdde0aac32f9667856a88725c192fa40 upstream.
Prohibit probing on optimized_callback() because
it is called from kprobes itself. If we put a kprobes
on it, that will cause a recursive call loop.
Mark it NOKPROBE_SYMBOL.
Fixes: 0dc016dbd8 ("ARM: kprobes: enable OPTPROBES for ARM 32")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This patch removes software emulation or simulation for most of probed
instructions. If the instruction doesn't use PC relative addressing,
it will be translated into following instructions in the restore code
in code template:
ldmia {r0 - r14} // restore all instruction except PC
<instruction> // direct execute the probed instruction
b next_insn // branch to next instruction.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Jon Medhurst <tixy@linaro.org>
This patch introduce kprobeopt for ARM 32.
Limitations:
- Currently only kernel compiled with ARM ISA is supported.
- Offset between probe point and optinsn slot must not larger than
32MiB. Masami Hiramatsu suggests replacing 2 words, it will make
things complex. Futher patch can make such optimization.
Kprobe opt on ARM is relatively simpler than kprobe opt on x86 because
ARM instruction is always 4 bytes aligned and 4 bytes long. This patch
replace probed instruction by a 'b', branch to trampoline code and then
calls optimized_callback(). optimized_callback() calls opt_pre_handler()
to execute kprobe handler. It also emulate/simulate replaced instruction.
When unregistering kprobe, the deferred manner of unoptimizer may leave
branch instruction before optimizer is called. Different from x86_64,
which only copy the probed insn after optprobe_template_end and
reexecute them, this patch call singlestep to emulate/simulate the insn
directly. Futher patch can optimize this behavior.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Will Deacon <will.deacon@arm.com>
Reviewed-by: Jon Medhurst (Tixy) <tixy@linaro.org>
Signed-off-by: Jon Medhurst <tixy@linaro.org>
