Commit b0b0aa9c authored Jun 24, 2013 by Michael Neuling Committed by Benjamin Herrenschmidt Jun 25, 2013

powerpc/hw_brk: Fix setting of length for exact mode breakpoints



The smallest match region for both the DABR and DAWR is 8 bytes, so the
kernel needs to filter matches when users want to look at regions smaller than
this.

Currently we set the length of PPC_BREAKPOINT_MODE_EXACT breakpoints to 8.
This is wrong as in exact mode we should only match on 1 address, hence the
length should be 1.

This ensures that the kernel will filter out any exact mode hardware breakpoint
matches on any addresses other than the requested one.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Reported-by: Edjunior Barbosa Machado <emachado@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

parent e7f345a2

arch/powerpc/kernel/ptrace.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -1449,7 +1449,9 @@ static long ppc_set_hwdebug(struct task_struct *child,
		*/
		if (bp_info->addr_mode == PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE) {
		len = bp_info->addr2 - bp_info->addr;
		} else if (bp_info->addr_mode != PPC_BREAKPOINT_MODE_EXACT) {
		} else if (bp_info->addr_mode == PPC_BREAKPOINT_MODE_EXACT)
		len = 1;
		else {
		ptrace_put_breakpoints(child);
		return -EINVAL;
		}