From 8f34a1da35aed7b438a2de8ac27723a5472e8399 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Thu, 18 Oct 2012 15:17:00 +0100 Subject: [PATCH] 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 Signed-off-by: Catalin Marinas --- arch/arm64/kernel/ptrace.c | 37 +++++++++++++++++++++---------------- 1 file changed, 21 insertions(+), 16 deletions(-) diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index c62d39d..6e1e77f 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -234,28 +234,33 @@ 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; - err = arch_bp_generic_fields(ctrl, &len, &type); - if (err) - return err; - - switch (note_type) { - case NT_ARM_HW_BREAK: - if ((type & HW_BREAKPOINT_X) != type) - return -EINVAL; - break; - case NT_ARM_HW_WATCH: - if ((type & HW_BREAKPOINT_RW) != type) + if (disabled) { + len = 0; + type = HW_BREAKPOINT_EMPTY; + } else { + err = arch_bp_generic_fields(ctrl, &len, &type); + if (err) + return err; + + switch (note_type) { + case NT_ARM_HW_BREAK: + if ((type & HW_BREAKPOINT_X) != type) + return -EINVAL; + break; + case NT_ARM_HW_WATCH: + if ((type & HW_BREAKPOINT_RW) != type) + return -EINVAL; + break; + default: return -EINVAL; - break; - default: - return -EINVAL; + } } attr->bp_len = len; attr->bp_type = type; - attr->disabled = !ctrl.enabled; + attr->disabled = disabled; return 0; } -- 2.7.4