Commit 8f34a1da authored Oct 18, 2012 by Will Deacon Committed by Catalin Marinas Oct 18, 2012

arm64: ptrace: use HW_BREAKPOINT_EMPTY type for disabled breakpoints



If a debugger tries to zero a hardware debug control register, the
kernel will try to infer both the type and length of the breakpoint
in order to sanity-check against the requested regset type. This will
fail because the encoding will appear as a zero-length breakpoint.

This patch changes the control register setting so that disabled
breakpoints are treated as HW_BREAKPOINT_EMPTY and no further
sanity-checking is required.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

parent 7797d17c

arch/arm64/kernel/ptrace.c

+21 −16

Original line number	Diff line number	Diff line
		@@ -234,8 +234,12 @@ static int ptrace_hbp_fill_attr_ctrl(unsigned int note_type,
		struct arch_hw_breakpoint_ctrl ctrl,
		struct perf_event_attr *attr)
		{
		int err, len, type;
		int err, len, type, disabled = !ctrl.enabled;

		if (disabled) {
		len = 0;
		type = HW_BREAKPOINT_EMPTY;
		} else {
		err = arch_bp_generic_fields(ctrl, &len, &type);
		if (err)
		return err;
		@@ -252,10 +256,11 @@ static int ptrace_hbp_fill_attr_ctrl(unsigned int note_type,
		default:
		return -EINVAL;
		}
		}

		attr->bp_len = len;
		attr->bp_type = type;
		attr->disabled = !ctrl.enabled;
		attr->disabled = disabled;

		return 0;
		}