diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c index ba386bd94107642d9819a7d8bafb7ba04e92b83f..18d39ea4c02f8d67a8d894714e102c79c9bebb81 100644 --- a/arch/arm/kernel/hw_breakpoint.c +++ b/arch/arm/kernel/hw_breakpoint.c @@ -159,6 +159,12 @@ static int debug_arch_supported(void) arch >= ARM_DEBUG_ARCH_V7_1; } +/* Can we determine the watchpoint access type from the fsr? */ +static int debug_exception_updates_fsr(void) +{ + return 0; +} + /* Determine number of WRP registers available. */ static int get_num_wrp_resources(void) { @@ -619,18 +625,35 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp) info->address &= ~alignment_mask; info->ctrl.len <<= offset; - /* - * Currently we rely on an overflow handler to take - * care of single-stepping the breakpoint when it fires. - * In the case of userspace breakpoints on a core with V7 debug, - * we can use the mismatch feature as a poor-man's hardware - * single-step, but this only works for per-task breakpoints. - */ - if (!bp->overflow_handler && (arch_check_bp_in_kernelspace(bp) || - !core_has_mismatch_brps() || !bp->hw.bp_target)) { - pr_warning("overflow handler required but none found\n"); - ret = -EINVAL; + if (!bp->overflow_handler) { + /* + * Mismatch breakpoints are required for single-stepping + * breakpoints. + */ + if (!core_has_mismatch_brps()) + return -EINVAL; + + /* We don't allow mismatch breakpoints in kernel space. */ + if (arch_check_bp_in_kernelspace(bp)) + return -EPERM; + + /* + * Per-cpu breakpoints are not supported by our stepping + * mechanism. + */ + if (!bp->hw.bp_target) + return -EINVAL; + + /* + * We only support specific access types if the fsr + * reports them. + */ + if (!debug_exception_updates_fsr() && + (info->ctrl.type == ARM_BREAKPOINT_LOAD || + info->ctrl.type == ARM_BREAKPOINT_STORE)) + return -EINVAL; } + out: return ret; } @@ -706,10 +729,12 @@ static void watchpoint_handler(unsigned long addr, unsigned int fsr, goto unlock; /* Check that the access type matches. */ - access = (fsr & ARM_FSR_ACCESS_MASK) ? HW_BREAKPOINT_W : - HW_BREAKPOINT_R; - if (!(access & hw_breakpoint_type(wp))) - goto unlock; + if (debug_exception_updates_fsr()) { + access = (fsr & ARM_FSR_ACCESS_MASK) ? + HW_BREAKPOINT_W : HW_BREAKPOINT_R; + if (!(access & hw_breakpoint_type(wp))) + goto unlock; + } /* We have a winner. */ info->trigger = addr;