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kprobes test cases need to have a stack that is aligned to an 8-byte
boundary because they call other functions (and the ARM ABI mandates
that alignment) and because test cases include 64-bit accesses to the
stack. Unfortunately, GCC doesn't ensure this alignment for inline
assembler and for the code in question seems to always misalign it by
pushing just the LR register onto the stack. We therefore need to
explicitly perform stack alignment at the start of each test case.
Without this fix, some test cases will generate alignment faults on
systems where alignment is enforced. Even if the kernel is configured to
handle these faults in software, triggering them is ugly. It also
exposes limitations in the fault handling code which doesn't cope with
writes to the stack. E.g. when handling this instruction
strd r6, [sp, #-64]!
the fault handling code will write to a stack location below the SP
value at the point the fault occurred, which coincides with where the
exception handler has pushed the saved register context. This results in
corruption of those registers.
Signed-off-by: Jon Medhurst <tixy@linaro.org>
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This is arm port of commit 737480a0d525 ("kprobes/x86:
Fix the return address of multiple kretprobes").
Fix the return address of subsequent kretprobes when multiple
kretprobes are set on the same function.
For example:
# cd /sys/kernel/debug/tracing
# echo "r:event1 sys_symlink" > kprobe_events
# echo "r:event2 sys_symlink" >> kprobe_events
# echo 1 > events/kprobes/enable
# ln -s /tmp/foo /tmp/bar
(without this patch)
# cat trace | grep -v ^#
ln-82 [000] dn.2 68.446525: event1: (kretprobe_trampoline+0x0/0x18 <- SyS_symlink)
ln-82 [000] dn.2 68.447831: event2: (ret_fast_syscall+0x0/0x1c <- SyS_symlink)
(with this patch)
# cat trace | grep -v ^#
ln-81 [000] dn.1 39.463469: event1: (ret_fast_syscall+0x0/0x1c <- SyS_symlink)
ln-81 [000] dn.1 39.464701: event2: (ret_fast_syscall+0x0/0x1c <- SyS_symlink)
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: KUMANO Syuhei <kumano.prog@gmail.com>
Signed-off-by: Jon Medhurst <tixy@linaro.org>
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Kprobes/arm skips single-stepping (moreover handling the event)
if the conditional instruction must not be executed. This
also apply the rule when we hit the recursing kprobe, so
that kprobe does not count nmissed up in that case.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Jon Medhurst <tixy@linaro.org>
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This is arm port of commit 6a5022a56ac3 ("kprobes/x86: Allow to
handle reentered kprobe on single-stepping")
Since the FIQ handlers can interrupt in the single stepping
(or preparing the single stepping, do_debug etc.), we should
consider a kprobe is hit in the NMI handler. Even in that
case, the kprobe is allowed to be reentered as same as the
kprobes hit in kprobe handlers
(KPROBE_HIT_ACTIVE or KPROBE_HIT_SSDONE).
The real issue will happen when a kprobe hit while another
reentered kprobe is processing (KPROBE_REENTER), because
we already consumed a saved-area for the previous kprobe.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Jon Medhurst <tixy@linaro.org>
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<linux/sched/debug.h>
We are going to split <linux/sched/debug.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/debug.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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<linux/sched/clock.h>
We are going to split <linux/sched/clock.h> out of <linux/sched.h>, which
will have to be picked up from other headers and .c files.
Create a trivial placeholder <linux/sched/clock.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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There is a superfluous '*' in the definition of kprobe_decode_insn_t
which on older versions of GCC (4.2.4) causes the compilation error:
In file included from arch/arm/probes/kprobes/core.c:37:
arch/arm/probes/kprobes/core.h:43: error: '[*]' not allowed in other than a declaration
Fix this by removing the unneeded character.
Reported-by: Janusz Użycki <j.uzycki@elproma.com.pl>
Signed-off-by: Jon Medhurst <tixy@linaro.org>
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Non-T variants of ARMv4 CPUs don't support the BX instruction so
eliminate its use.
Signed-off-by: Jon Medhurst <tixy@linaro.org>
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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>
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This patch utilizes the previously introduced checker to check
register usage for probed ARM instruction and saves it in a mask.
A further patch will use such information to avoid simulation or
emulation.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Reviewed-by: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Jon Medhurst <tixy@linaro.org>
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For the instruction 'mrs Rn, cpsr' the resulting value of Rn can vary due to
external factors we can't control. So get the test code to mask out these
indeterminate bits.
Signed-off-by: Jon Medhurst <tixy@linaro.org>
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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>
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These have extra 'checker' functions associated with them so lets make
sure those get covered by testing. As they may create uninitialised
space on the stack we also update the test code to ensure such space is
consistent between test runs. This is done by disabling interrupts in
setup_test_context().
Signed-off-by: Jon Medhurst <tixy@linaro.org>
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This patch prohibits probing instructions for which the stack
requirements are unable to be determined statically. Some test cases
are found not work again after the modification, this patch also
removes them.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Reviewed-by: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Jon Medhurst <tixy@linaro.org>
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This patch uses the previously introduced checker functionality on
store instructions to record their stack consumption information to
arch_probes_insn.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Reviewed-by: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Jon Medhurst <tixy@linaro.org>
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This patch introdces 'checker' to decoding phase, and calls checkers
when instruction decoding. This allows further decoding for specific
instructions. This patch introduces a stub call of checkers in kprobe
arch_prepare_kprobe() as an example and for further expansion.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Reviewed-by: Jon Medhurst <tixy@linaro.org>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Jon Medhurst <tixy@linaro.org>
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This doesn't correct any bugs when probing these instructions but makes
MOVW slightly faster and makes everything more symmetric with the Thumb
instruction cases.
We can also remove the now redundant PROBES_EMULATE_NONE and
PROBES_SIMULATE_NOP actions.
Signed-off-by: Jon Medhurst <tixy@linaro.org>
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In discussion on LKML (https://lkml.org/lkml/2014/11/28/158), Russell
King suggests to move all probe related code to arch/arm/probes. This
patch does the work. Due to dependency on 'arch/arm/kernel/patch.h', this
patch also moves patch.h to 'arch/arm/include/asm/patch.h', and related
'#include' directives are also midified to '#include <asm/patch.h>'.
Following is an overview of this patch:
./arch/arm/kernel/ ./arch/arm/probes/
|-- Makefile |-- Makefile
|-- probes-arm.c ==> |-- decode-arm.c
|-- probes-arm.h ==> |-- decode-arm.h
|-- probes-thumb.c ==> |-- decode-thumb.c
|-- probes-thumb.h ==> |-- decode-thumb.h
|-- probes.c ==> |-- decode.c
|-- probes.h ==> |-- decode.h
| |-- kprobes
| | |-- Makefile
|-- kprobes-arm.c ==> | |-- actions-arm.c
|-- kprobes-common.c ==> | |-- actions-common.c
|-- kprobes-thumb.c ==> | |-- actions-thumb.c
|-- kprobes.c ==> | |-- core.c
|-- kprobes.h ==> | |-- core.h
|-- kprobes-test-arm.c ==> | |-- test-arm.c
|-- kprobes-test.c ==> | |-- test-core.c
|-- kprobes-test.h ==> | |-- test-core.h
|-- kprobes-test-thumb.c ==> | `-- test-thumb.c
| `-- uprobes
| |-- Makefile
|-- uprobes-arm.c ==> |-- actions-arm.c
|-- uprobes.c ==> |-- core.c
|-- uprobes.h ==> `-- core.h
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`-- patch.h ==> arch/arm/include/asm/patch.h
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Jon Medhurst <tixy@linaro.org>
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