Since we've already stepped away from ENABLE is a JMP and DISABLE is a
NOP with the branch_default bits, and are going to make it even worse,
rename it to make it all clearer.
This way we don't mix multiple levels of logic attributes, but have a
plain 'physical' name for what the current instruction patching status
of a jump label is.
This is a first step in removing the naming confusion that has led to
a stream of avoidable bugs such as:
a833581e37 ("x86, perf: Fix static_key bug in load_mm_cr4()")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
[ Beefed up the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.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>
Use fixmaps for text patching when the kernel text is read-only,
inspired by x86. This makes jump labels and kprobes work with the
currently available CONFIG_DEBUG_SET_MODULE_RONX and the upcoming
CONFIG_DEBUG_RODATA options.
Signed-off-by: Rabin Vincent <rabin@rab.in>
[kees: fixed up for merge with "arm: use generic fixmap.h"]
[kees: added parse acquire/release annotations to pass C=1 builds]
[kees: always use stop_machine to keep TLB flushing local]
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Add the arch-specific code to support jump labels for ARM and Thumb-2.
This code will only be activated on compilers that are capable of
building it. It has been tested with GCC 4.6 patched with the patch
from GCC bug 48637.
Cc: Jason Baron <jbaron@redhat.com>
Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Peter Zijlstra
Wang Nan
Rabin Vincent