[PATCH v3 0/2] powerpc: Emulation support for load/store instructions on LE

Ravi Bangoria ravi.bangoria at linux.vnet.ibm.com
Tue Feb 14 20:16:41 AEDT 2017

emulate_step is the basic infrastructure which is used by number of other
kernel infrastructures like kprobe, hw-breakpoint(data breakpoint) etc.
In case of kprobe, enabling emulation of load/store instructions will
speedup the execution of probed instruction. In case of kernel-space
breakpoint, causative instruction is first get emulated before executing
user registered handler. If emulation fails, hw-breakpoint is disabled
with error. As emulate_step does not support load/store instructions on
LE, kernel-space hw-breakpoint infrastructure is broken on LE.

emulate_step() uses a number of underlying kernel functions that were
initially not enabled for LE. This has been rectified since. So, fix
emulate_step() for LE for the corresponding instructions.

Also add selftest which will run at boot if CONFIG_KPROBES_SANITY_TEST
and CONFIG_PPC64 is set.

Changes in v3:
  - Rebased to powerpc/next. No functionality changes.

v2 link: https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1332638.html

Ravi Bangoria (2):
  powerpc: Emulation support for load/store instructions on LE
  powerpc: emulate_step tests for load/store instructions

 arch/powerpc/include/asm/ppc-opcode.h |   7 +
 arch/powerpc/include/asm/sstep.h      |   8 +
 arch/powerpc/kernel/kprobes.c         |   2 +
 arch/powerpc/lib/Makefile             |   4 +
 arch/powerpc/lib/sstep.c              |  20 --
 arch/powerpc/lib/test_emulate_step.c  | 439 ++++++++++++++++++++++++++++++++++
 6 files changed, 460 insertions(+), 20 deletions(-)
 create mode 100644 arch/powerpc/lib/test_emulate_step.c


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