[PATCH 3.16 070/366] powerpc/ptrace: Fix setting 512B aligned breakpoints with PTRACE_SET_DEBUGREG

Ben Hutchings
2018-11-12T05:53:29Z

From: Michael Neuling <mikey@neuling.org>

commit 4f7c06e26ec9cf7fe9f0c54dc90079b6a4f4b2c3 upstream.

In commit e2a800beaca1 ("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.

Fixes: e2a800beaca1 ("powerpc/hw_brk: Fix off by one error when validating DAWR region end")
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
arch/powerpc/kernel/ptrace.c | 1 +
1 file changed, 1 insertion(+)

--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -1011,6 +1011,7 @@ int ptrace_set_debugreg(struct task_stru
/* 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);