Re: [PATCH v6 0/8] powerpc/watchpoint: Bug fixes plus new feature flag

Rogerio Alves [off-list ref] writes:

On 9/2/20 1:29 AM, Ravi Bangoria wrote:

quoted

Patch #1 fixes issue for quardword instruction on p10 predecessors.
Patch #2 fixes issue for vector instructions.
Patch #3 fixes a bug about watchpoint not firing when created with
          ptrace PPC_PTRACE_SETHWDEBUG and CONFIG_HAVE_HW_BREAKPOINT=N.
          The fix uses HW_BRK_TYPE_PRIV_ALL for ptrace user which, I
          guess, should be fine because we don't leak any kernel
          addresses and PRIV_ALL will also help to cover scenarios when
          kernel accesses user memory.
Patch #4,#5 fixes infinite exception bug, again the bug happens only
          with CONFIG_HAVE_HW_BREAKPOINT=N.
Patch #6 fixes two places where we are missing to set hw_len.
Patch #7 introduce new feature bit PPC_DEBUG_FEATURE_DATA_BP_ARCH_31
          which will be set when running on ISA 3.1 compliant machine.
Patch #8 finally adds selftest to test scenarios fixed by patch#2,#3
          and also moves MODE_EXACT tests outside of BP_RANGE condition.

Christophe, let me know if this series breaks something for 8xx.

v5: https://lore.kernel.org/r/20200825043617.1073634-1-ravi.bangoria@linux.ibm.com (local)

v5->v6:
  - Fix build faulure reported by kernel test robot
  - patch #5. Use more compact if condition, suggested by Christophe


Ravi Bangoria (8):
   powerpc/watchpoint: Fix quarword instruction handling on p10
     predecessors
   powerpc/watchpoint: Fix handling of vector instructions
   powerpc/watchpoint/ptrace: Fix SETHWDEBUG when
     CONFIG_HAVE_HW_BREAKPOINT=N
   powerpc/watchpoint: Move DAWR detection logic outside of
     hw_breakpoint.c
   powerpc/watchpoint: Fix exception handling for
     CONFIG_HAVE_HW_BREAKPOINT=N
   powerpc/watchpoint: Add hw_len wherever missing
   powerpc/watchpoint/ptrace: Introduce PPC_DEBUG_FEATURE_DATA_BP_ARCH_31
   powerpc/watchpoint/selftests: Tests for kernel accessing user memory

  Documentation/powerpc/ptrace.rst              |   1 +
  arch/powerpc/include/asm/hw_breakpoint.h      |  12 ++
  arch/powerpc/include/uapi/asm/ptrace.h        |   1 +
  arch/powerpc/kernel/Makefile                  |   3 +-
  arch/powerpc/kernel/hw_breakpoint.c           | 149 +---------------
  .../kernel/hw_breakpoint_constraints.c        | 162 ++++++++++++++++++
  arch/powerpc/kernel/process.c                 |  48 ++++++
  arch/powerpc/kernel/ptrace/ptrace-noadv.c     |   9 +-
  arch/powerpc/xmon/xmon.c                      |   1 +
  .../selftests/powerpc/ptrace/ptrace-hwbreak.c |  48 +++++-
  10 files changed, 282 insertions(+), 152 deletions(-)
  create mode 100644 arch/powerpc/kernel/hw_breakpoint_constraints.c

Tested this patch set for:
- SETHWDEBUG when CONFIG_HAVE_HW_BREAKPOINT=N = OK
- Fix exception handling for CONFIG_HAVE_HW_BREAKPOINT=N = OK
- Check for PPC_DEBUG_FEATURE_DATA_BP_ARCH_31 = OK
- Fix quarword instruction handling on p10 predecessors = OK
- Fix handling of vector instructions = OK

Also tested for:
- Set second watchpoint (P10 Mambo) = OK
- Infinity loop on sc instruction = OK

Thanks.

I wasn't able to pick up your Tested-by tags as I'd already applied the
patches, but thanks for sending them anyway, they will live on in the
mailing list archives for eternity.

cheers