[PATCH 2/2] powerpc/ptrace: Fix setting 512B aligned breakpoints with PTRACE_SET_DEBUGREG

[Michael Neuling <mikey@neuling.org>]

In this change:
  e2a800beac powerpc/hw_brk: Fix off by one error when validating DAWR region end

We fixed setting the DAWR end point to its max value via
PPC_PTRACE_SETHWDEBUG. Unfortunately we broke PTRACE_SET_DEBUGREG when
setting a 512 byte aligned breakpoint.

PTRACE_SET_DEBUGREG currently sets the length of the breakpoint to
zero (memset() in hw_breakpoint_init()).  This worked with
arch_validate_hwbkpt_settings() before the above patch was applied but
is now broken if the breakpoint is 512byte aligned.

This sets the length of the breakpoint to 8 bytes when using
PTRACE_SET_DEBUGREG.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Cc: stable@vger.kernel.org # 3.10+
---
 arch/powerpc/kernel/ptrace.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index d23cf632ed..0f63dd5972 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -2443,6 +2443,7 @@ static int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
 	/* Create a new breakpoint request if one doesn't exist already */
 	hw_breakpoint_init(&attr);
 	attr.bp_addr = hw_brk.address;
+	attr.bp_len = 8;
 	arch_bp_generic_fields(hw_brk.type,
 			       &attr.bp_type);
 
-- 
2.14.1