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| author | Anju T | 2017-02-08 10:50:51 +0100 |
|---|---|---|
| committer | Michael Ellerman | 2017-02-10 03:28:04 +0100 |
| commit | 51c9c0843993528bffc920c54c2121d9e6f8b090 (patch) | |
| tree | 1ffd280d9ca0ce51faaa957d23c1e217ee0e2e20 /arch/powerpc/Kconfig | |
| parent | powerpc/kprobes: Fixes for kprobe_lookup_name() on BE (diff) | |
| download | kernel-qcow2-linux-51c9c0843993528bffc920c54c2121d9e6f8b090.tar.gz kernel-qcow2-linux-51c9c0843993528bffc920c54c2121d9e6f8b090.tar.xz kernel-qcow2-linux-51c9c0843993528bffc920c54c2121d9e6f8b090.zip | |
powerpc/kprobes: Implement Optprobes
Current infrastructure of kprobe uses the unconditional trap instruction
to probe a running kernel. Optprobe allows kprobe to replace the trap
with a branch instruction to a detour buffer. Detour buffer contains
instructions to create an in memory pt_regs. Detour buffer also has a
call to optimized_callback() which in turn call the pre_handler(). After
the execution of the pre-handler, a call is made for instruction
emulation. The NIP is determined in advanced through dummy instruction
emulation and a branch instruction is created to the NIP at the end of
the trampoline.
To address the limitation of branch instruction in POWER architecture,
detour buffer slot is allocated from a reserved area. For the time
being, 64KB is reserved in memory for this purpose.
Instructions which can be emulated using analyse_instr() are the
candidates for optimization. Before optimization ensure that the address
range between the detour buffer allocated and the instruction being
probed is within +/- 32MB.
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/Kconfig')
| -rw-r--r-- | arch/powerpc/Kconfig | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index bfdd80e7754c..f26c2253fdf2 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -100,6 +100,7 @@ config PPC select HAVE_IOREMAP_PROT select HAVE_EFFICIENT_UNALIGNED_ACCESS if !(CPU_LITTLE_ENDIAN && POWER7_CPU) select HAVE_KPROBES + select HAVE_OPTPROBES if PPC64 select HAVE_ARCH_KGDB select HAVE_KRETPROBES select HAVE_ARCH_TRACEHOOK |