linux-toradex.git/arch/arm/probes, branch v4.9.83 Linux kernel for Apalis and Colibri modules arm: kprobes: Align stack to 8-bytes in test code 2017-12-25T13:23:37+00:00 Jon Medhurst tixy@linaro.org 2017-03-02T13:04:09+00:00 c9bbd2727d1e02584ee98efe075e3483c287adb0 [ Upstream commit 974310d047f3c7788a51d10c8d255eebdb1fa857 ] 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> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit 974310d047f3c7788a51d10c8d255eebdb1fa857 ]

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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arm: kprobes: Fix the return address of multiple kretprobes 2017-12-25T13:23:37+00:00 Masami Hiramatsu mhiramat@kernel.org 2017-02-13T15:05:59+00:00 d0ee8d5b86b81d5e1cd282efb9b6e3cde221cc0d [ Upstream commit 06553175f585b52509c7df37d6f4a50aacb7b211 ] 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> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ Upstream commit 06553175f585b52509c7df37d6f4a50aacb7b211 ]

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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ARM: kprobes: Fix compilation error caused by superfluous '*' 2015-02-10T07:05:30+00:00 Jon Medhurst tixy@linaro.org 2015-02-10T07:03:22+00:00 4e1c0664de11e4b5861957ab4ddff2aeeffd042f 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> 
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>
ARM: kprobes: Eliminate test code's use of BX instruction on ARMv4 CPUs 2015-01-20T09:06:04+00:00 Jon Medhurst tixy@linaro.org 2015-01-19T15:15:36+00:00 fb892bd0fdcb2e5eac9c105cf68def90396ed8cc Non-T variants of ARMv4 CPUs don't support the BX instruction so eliminate its use. Signed-off-by: Jon Medhurst <tixy@linaro.org> 
Non-T variants of ARMv4 CPUs don't support the BX instruction so
eliminate its use.

Signed-off-by: Jon Medhurst <tixy@linaro.org>
ARM: optprobes: execute instruction during restoring if possible. 2015-01-14T12:24:52+00:00 Wang Nan wangnan0@huawei.com 2015-01-05T11:34:47+00:00 bfc9657d752c47d59dc0bab85ebdc19cf60100dd 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 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>
ARM: kprobes: check register usage for probed instruction. 2015-01-13T16:10:48+00:00 Wang Nan wangnan0@huawei.com 2015-01-05T11:29:44+00:00 28a1899db30a9325498aef114055506286dc8010 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> 
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>
ARM: kprobes: Fix unreliable MRS instruction tests 2015-01-13T16:10:17+00:00 Jon Medhurst (Tixy) tixy@linaro.org 2015-01-05T11:29:40+00:00 4cd872d973c7e1ce6a41e36db9d9352152da32d4 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> 
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>
ARM: kprobes: enable OPTPROBES for ARM 32 2015-01-13T16:10:17+00:00 Wang Nan wangnan0@huawei.com 2015-01-09T06:37:36+00:00 0dc016dbd820260b8ea74337980735b8c88d4ef2 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> 
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>
ARM: kprobes: Add test cases for stack consuming instructions 2015-01-13T16:10:16+00:00 Jon Medhurst (Tixy) tixy@linaro.org 2015-01-05T11:29:29+00:00 8d257e95a9e643518e72232bf852b054a3d06c95 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> 
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>
ARM: kprobes: disallow probing stack consuming instructions 2015-01-13T16:10:15+00:00 Wang Nan wangnan0@huawei.com 2015-01-05T11:29:25+00:00 a0266c214fab21371a499e6ab1c9385cc6589189 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> 
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>