X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=blobdiff_plain;f=arch%2Farm%2Fkernel%2Fhw_breakpoint.c;h=c9f3f046757046010ea1f95d13321f676f202d0a;hp=21e3a4ab3b8c58047304b694aa8161b9ebbf1c31;hb=e691d24e9c5007486bef59c589c2a2d784e0c30b;hpb=dda5f0a372873bca5f0b1d1866d7784dffd8b675 diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c index 21e3a4ab3b8c..c9f3f0467570 100644 --- a/arch/arm/kernel/hw_breakpoint.c +++ b/arch/arm/kernel/hw_breakpoint.c @@ -24,6 +24,7 @@ #define pr_fmt(fmt) "hw-breakpoint: " fmt #include +#include #include #include #include @@ -44,6 +45,7 @@ static DEFINE_PER_CPU(struct perf_event *, wp_on_reg[ARM_MAX_WRP]); /* Number of BRP/WRP registers on this CPU. */ static int core_num_brps; +static int core_num_reserved_brps; static int core_num_wrps; /* Debug architecture version. */ @@ -52,87 +54,6 @@ static u8 debug_arch; /* Maximum supported watchpoint length. */ static u8 max_watchpoint_len; -/* Determine number of BRP registers available. */ -static int get_num_brps(void) -{ - u32 didr; - ARM_DBG_READ(c0, 0, didr); - return ((didr >> 24) & 0xf) + 1; -} - -/* Determine number of WRP registers available. */ -static int get_num_wrps(void) -{ - /* - * FIXME: When a watchpoint fires, the only way to work out which - * watchpoint it was is by disassembling the faulting instruction - * and working out the address of the memory access. - * - * Furthermore, we can only do this if the watchpoint was precise - * since imprecise watchpoints prevent us from calculating register - * based addresses. - * - * For the time being, we only report 1 watchpoint register so we - * always know which watchpoint fired. In the future we can either - * add a disassembler and address generation emulator, or we can - * insert a check to see if the DFAR is set on watchpoint exception - * entry [the ARM ARM states that the DFAR is UNKNOWN, but - * experience shows that it is set on some implementations]. - */ - -#if 0 - u32 didr, wrps; - ARM_DBG_READ(c0, 0, didr); - return ((didr >> 28) & 0xf) + 1; -#endif - - return 1; -} - -int hw_breakpoint_slots(int type) -{ - /* - * We can be called early, so don't rely on - * our static variables being initialised. - */ - switch (type) { - case TYPE_INST: - return get_num_brps(); - case TYPE_DATA: - return get_num_wrps(); - default: - pr_warning("unknown slot type: %d\n", type); - return 0; - } -} - -/* Determine debug architecture. */ -static u8 get_debug_arch(void) -{ - u32 didr; - - /* Do we implement the extended CPUID interface? */ - if (((read_cpuid_id() >> 16) & 0xf) != 0xf) { - pr_warning("CPUID feature registers not supported. " - "Assuming v6 debug is present.\n"); - return ARM_DEBUG_ARCH_V6; - } - - ARM_DBG_READ(c0, 0, didr); - return (didr >> 16) & 0xf; -} - -/* Does this core support mismatch breakpoints? */ -static int core_has_mismatch_bps(void) -{ - return debug_arch >= ARM_DEBUG_ARCH_V7_ECP14 && core_num_brps > 1; -} - -u8 arch_get_debug_arch(void) -{ - return debug_arch; -} - #define READ_WB_REG_CASE(OP2, M, VAL) \ case ((OP2 << 4) + M): \ ARM_DBG_READ(c ## M, OP2, VAL); \ @@ -210,6 +131,94 @@ static void write_wb_reg(int n, u32 val) isb(); } +/* Determine debug architecture. */ +static u8 get_debug_arch(void) +{ + u32 didr; + + /* Do we implement the extended CPUID interface? */ + if (((read_cpuid_id() >> 16) & 0xf) != 0xf) { + pr_warning("CPUID feature registers not supported. " + "Assuming v6 debug is present.\n"); + return ARM_DEBUG_ARCH_V6; + } + + ARM_DBG_READ(c0, 0, didr); + return (didr >> 16) & 0xf; +} + +u8 arch_get_debug_arch(void) +{ + return debug_arch; +} + +/* Determine number of BRP register available. */ +static int get_num_brp_resources(void) +{ + u32 didr; + ARM_DBG_READ(c0, 0, didr); + return ((didr >> 24) & 0xf) + 1; +} + +/* Does this core support mismatch breakpoints? */ +static int core_has_mismatch_brps(void) +{ + return (get_debug_arch() >= ARM_DEBUG_ARCH_V7_ECP14 && + get_num_brp_resources() > 1); +} + +/* Determine number of usable WRPs available. */ +static int get_num_wrps(void) +{ + /* + * FIXME: When a watchpoint fires, the only way to work out which + * watchpoint it was is by disassembling the faulting instruction + * and working out the address of the memory access. + * + * Furthermore, we can only do this if the watchpoint was precise + * since imprecise watchpoints prevent us from calculating register + * based addresses. + * + * Providing we have more than 1 breakpoint register, we only report + * a single watchpoint register for the time being. This way, we always + * know which watchpoint fired. In the future we can either add a + * disassembler and address generation emulator, or we can insert a + * check to see if the DFAR is set on watchpoint exception entry + * [the ARM ARM states that the DFAR is UNKNOWN, but experience shows + * that it is set on some implementations]. + */ + +#if 0 + int wrps; + u32 didr; + ARM_DBG_READ(c0, 0, didr); + wrps = ((didr >> 28) & 0xf) + 1; +#endif + int wrps = 1; + + if (core_has_mismatch_brps() && wrps >= get_num_brp_resources()) + wrps = get_num_brp_resources() - 1; + + return wrps; +} + +/* We reserve one breakpoint for each watchpoint. */ +static int get_num_reserved_brps(void) +{ + if (core_has_mismatch_brps()) + return get_num_wrps(); + return 0; +} + +/* Determine number of usable BRPs available. */ +static int get_num_brps(void) +{ + int brps = get_num_brp_resources(); + if (core_has_mismatch_brps()) + brps -= get_num_reserved_brps(); + return brps; +} + /* * In order to access the breakpoint/watchpoint control registers, * we must be running in debug monitor mode. Unfortunately, we can @@ -230,8 +239,12 @@ static int enable_monitor_mode(void) goto out; } + /* If monitor mode is already enabled, just return. */ + if (dscr & ARM_DSCR_MDBGEN) + goto out; + /* Write to the corresponding DSCR. */ - switch (debug_arch) { + switch (get_debug_arch()) { case ARM_DEBUG_ARCH_V6: case ARM_DEBUG_ARCH_V6_1: ARM_DBG_WRITE(c1, 0, (dscr | ARM_DSCR_MDBGEN)); @@ -246,15 +259,30 @@ static int enable_monitor_mode(void) /* Check that the write made it through. */ ARM_DBG_READ(c1, 0, dscr); - if (WARN_ONCE(!(dscr & ARM_DSCR_MDBGEN), - "failed to enable monitor mode.")) { + if (!(dscr & ARM_DSCR_MDBGEN)) ret = -EPERM; - } out: return ret; } +int hw_breakpoint_slots(int type) +{ + /* + * We can be called early, so don't rely on + * our static variables being initialised. + */ + switch (type) { + case TYPE_INST: + return get_num_brps(); + case TYPE_DATA: + return get_num_wrps(); + default: + pr_warning("unknown slot type: %d\n", type); + return 0; + } +} + /* * Check if 8-bit byte-address select is available. * This clobbers WRP 0. @@ -268,9 +296,6 @@ static u8 get_max_wp_len(void) if (debug_arch < ARM_DEBUG_ARCH_V7_ECP14) goto out; - if (enable_monitor_mode()) - goto out; - memset(&ctrl, 0, sizeof(ctrl)); ctrl.len = ARM_BREAKPOINT_LEN_8; ctrl_reg = encode_ctrl_reg(ctrl); @@ -289,23 +314,6 @@ u8 arch_get_max_wp_len(void) return max_watchpoint_len; } -/* - * Handler for reactivating a suspended watchpoint when the single - * step `mismatch' breakpoint is triggered. - */ -static void wp_single_step_handler(struct perf_event *bp, int unused, - struct perf_sample_data *data, - struct pt_regs *regs) -{ - perf_event_enable(counter_arch_bp(bp)->suspended_wp); - unregister_hw_breakpoint(bp); -} - -static int bp_is_single_step(struct perf_event *bp) -{ - return bp->overflow_handler == wp_single_step_handler; -} - /* * Install a perf counter breakpoint. */ @@ -314,30 +322,41 @@ int arch_install_hw_breakpoint(struct perf_event *bp) struct arch_hw_breakpoint *info = counter_arch_bp(bp); struct perf_event **slot, **slots; int i, max_slots, ctrl_base, val_base, ret = 0; + u32 addr, ctrl; /* Ensure that we are in monitor mode and halting mode is disabled. */ ret = enable_monitor_mode(); if (ret) goto out; + addr = info->address; + ctrl = encode_ctrl_reg(info->ctrl) | 0x1; + if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) { /* Breakpoint */ ctrl_base = ARM_BASE_BCR; val_base = ARM_BASE_BVR; - slots = __get_cpu_var(bp_on_reg); - max_slots = core_num_brps - 1; - - if (bp_is_single_step(bp)) { - info->ctrl.mismatch = 1; - i = max_slots; - slots[i] = bp; - goto setup; + slots = (struct perf_event **)__get_cpu_var(bp_on_reg); + max_slots = core_num_brps; + if (info->step_ctrl.enabled) { + /* Override the breakpoint data with the step data. */ + addr = info->trigger & ~0x3; + ctrl = encode_ctrl_reg(info->step_ctrl); } } else { /* Watchpoint */ - ctrl_base = ARM_BASE_WCR; - val_base = ARM_BASE_WVR; - slots = __get_cpu_var(wp_on_reg); + if (info->step_ctrl.enabled) { + /* Install into the reserved breakpoint region. */ + ctrl_base = ARM_BASE_BCR + core_num_brps; + val_base = ARM_BASE_BVR + core_num_brps; + /* Override the watchpoint data with the step data. */ + addr = info->trigger & ~0x3; + ctrl = encode_ctrl_reg(info->step_ctrl); + } else { + ctrl_base = ARM_BASE_WCR; + val_base = ARM_BASE_WVR; + } + slots = (struct perf_event **)__get_cpu_var(wp_on_reg); max_slots = core_num_wrps; } @@ -355,12 +374,11 @@ int arch_install_hw_breakpoint(struct perf_event *bp) goto out; } -setup: /* Setup the address register. */ - write_wb_reg(val_base + i, info->address); + write_wb_reg(val_base + i, addr); /* Setup the control register. */ - write_wb_reg(ctrl_base + i, encode_ctrl_reg(info->ctrl) | 0x1); + write_wb_reg(ctrl_base + i, ctrl); out: return ret; @@ -375,18 +393,15 @@ void arch_uninstall_hw_breakpoint(struct perf_event *bp) if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) { /* Breakpoint */ base = ARM_BASE_BCR; - slots = __get_cpu_var(bp_on_reg); - max_slots = core_num_brps - 1; - - if (bp_is_single_step(bp)) { - i = max_slots; - slots[i] = NULL; - goto reset; - } + slots = (struct perf_event **)__get_cpu_var(bp_on_reg); + max_slots = core_num_brps; } else { /* Watchpoint */ - base = ARM_BASE_WCR; - slots = __get_cpu_var(wp_on_reg); + if (info->step_ctrl.enabled) + base = ARM_BASE_BCR + core_num_brps; + else + base = ARM_BASE_WCR; + slots = (struct perf_event **)__get_cpu_var(wp_on_reg); max_slots = core_num_wrps; } @@ -403,7 +418,6 @@ void arch_uninstall_hw_breakpoint(struct perf_event *bp) if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot")) return; -reset: /* Reset the control register. */ write_wb_reg(base + i, 0); } @@ -537,12 +551,23 @@ static int arch_build_bp_info(struct perf_event *bp) return -EINVAL; } + /* + * Breakpoints must be of length 2 (thumb) or 4 (ARM) bytes. + * Watchpoints can be of length 1, 2, 4 or 8 bytes if supported + * by the hardware and must be aligned to the appropriate number of + * bytes. + */ + if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE && + info->ctrl.len != ARM_BREAKPOINT_LEN_2 && + info->ctrl.len != ARM_BREAKPOINT_LEN_4) + return -EINVAL; + /* Address */ info->address = bp->attr.bp_addr; /* Privilege */ info->ctrl.privilege = ARM_BREAKPOINT_USER; - if (arch_check_bp_in_kernelspace(bp) && !bp_is_single_step(bp)) + if (arch_check_bp_in_kernelspace(bp)) info->ctrl.privilege |= ARM_BREAKPOINT_PRIV; /* Enabled? */ @@ -561,7 +586,7 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp) { struct arch_hw_breakpoint *info = counter_arch_bp(bp); int ret = 0; - u32 bytelen, max_len, offset, alignment_mask = 0x3; + u32 offset, alignment_mask = 0x3; /* Build the arch_hw_breakpoint. */ ret = arch_build_bp_info(bp); @@ -571,84 +596,85 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp) /* Check address alignment. */ if (info->ctrl.len == ARM_BREAKPOINT_LEN_8) alignment_mask = 0x7; - if (info->address & alignment_mask) { - /* - * Try to fix the alignment. This may result in a length - * that is too large, so we must check for that. - */ - bytelen = get_hbp_len(info->ctrl.len); - max_len = info->ctrl.type == ARM_BREAKPOINT_EXECUTE ? 4 : - max_watchpoint_len; - - if (max_len >= 8) - offset = info->address & 0x7; - else - offset = info->address & 0x3; - - if (bytelen > (1 << ((max_len - (offset + 1)) >> 1))) { - ret = -EFBIG; - goto out; - } - - info->ctrl.len <<= offset; - info->address &= ~offset; - - pr_debug("breakpoint alignment fixup: length = 0x%x, " - "address = 0x%x\n", info->ctrl.len, info->address); + offset = info->address & alignment_mask; + switch (offset) { + case 0: + /* Aligned */ + break; + case 1: + /* Allow single byte watchpoint. */ + if (info->ctrl.len == ARM_BREAKPOINT_LEN_1) + break; + case 2: + /* Allow halfword watchpoints and breakpoints. */ + if (info->ctrl.len == ARM_BREAKPOINT_LEN_2) + break; + default: + ret = -EINVAL; + goto out; } + 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. + * we can use the mismatch feature as a poor-man's hardware + * single-step, but this only works for per-task breakpoints. */ if (WARN_ONCE(!bp->overflow_handler && - (arch_check_bp_in_kernelspace(bp) || !core_has_mismatch_bps()), + (arch_check_bp_in_kernelspace(bp) || !core_has_mismatch_brps() + || !bp->hw.bp_target), "overflow handler required but none found")) { ret = -EINVAL; - goto out; } out: return ret; } -static void update_mismatch_flag(int idx, int flag) +/* + * Enable/disable single-stepping over the breakpoint bp at address addr. + */ +static void enable_single_step(struct perf_event *bp, u32 addr) { - struct perf_event *bp = __get_cpu_var(bp_on_reg[idx]); - struct arch_hw_breakpoint *info; - - if (bp == NULL) - return; + struct arch_hw_breakpoint *info = counter_arch_bp(bp); - info = counter_arch_bp(bp); + arch_uninstall_hw_breakpoint(bp); + info->step_ctrl.mismatch = 1; + info->step_ctrl.len = ARM_BREAKPOINT_LEN_4; + info->step_ctrl.type = ARM_BREAKPOINT_EXECUTE; + info->step_ctrl.privilege = info->ctrl.privilege; + info->step_ctrl.enabled = 1; + info->trigger = addr; + arch_install_hw_breakpoint(bp); +} - /* Update the mismatch field to enter/exit `single-step' mode */ - if (!bp->overflow_handler && info->ctrl.mismatch != flag) { - info->ctrl.mismatch = flag; - write_wb_reg(ARM_BASE_BCR + idx, encode_ctrl_reg(info->ctrl) | 0x1); - } +static void disable_single_step(struct perf_event *bp) +{ + arch_uninstall_hw_breakpoint(bp); + counter_arch_bp(bp)->step_ctrl.enabled = 0; + arch_install_hw_breakpoint(bp); } static void watchpoint_handler(unsigned long unknown, struct pt_regs *regs) { int i; - struct perf_event *bp, **slots = __get_cpu_var(wp_on_reg); + struct perf_event *wp, **slots; struct arch_hw_breakpoint *info; - struct perf_event_attr attr; + + slots = (struct perf_event **)__get_cpu_var(wp_on_reg); /* Without a disassembler, we can only handle 1 watchpoint. */ BUG_ON(core_num_wrps > 1); - hw_breakpoint_init(&attr); - attr.bp_addr = regs->ARM_pc & ~0x3; - attr.bp_len = HW_BREAKPOINT_LEN_4; - attr.bp_type = HW_BREAKPOINT_X; - for (i = 0; i < core_num_wrps; ++i) { rcu_read_lock(); - if (slots[i] == NULL) { + wp = slots[i]; + + if (wp == NULL) { rcu_read_unlock(); continue; } @@ -658,24 +684,51 @@ static void watchpoint_handler(unsigned long unknown, struct pt_regs *regs) * single watchpoint, we can set the trigger to the lowest * possible faulting address. */ - info = counter_arch_bp(slots[i]); - info->trigger = slots[i]->attr.bp_addr; + info = counter_arch_bp(wp); + info->trigger = wp->attr.bp_addr; pr_debug("watchpoint fired: address = 0x%x\n", info->trigger); - perf_bp_event(slots[i], regs); + perf_bp_event(wp, regs); /* * If no overflow handler is present, insert a temporary * mismatch breakpoint so we can single-step over the * watchpoint trigger. */ - if (!slots[i]->overflow_handler) { - bp = register_user_hw_breakpoint(&attr, - wp_single_step_handler, - current); - counter_arch_bp(bp)->suspended_wp = slots[i]; - perf_event_disable(slots[i]); - } + if (!wp->overflow_handler) + enable_single_step(wp, instruction_pointer(regs)); + + rcu_read_unlock(); + } +} +static void watchpoint_single_step_handler(unsigned long pc) +{ + int i; + struct perf_event *wp, **slots; + struct arch_hw_breakpoint *info; + + slots = (struct perf_event **)__get_cpu_var(wp_on_reg); + + for (i = 0; i < core_num_reserved_brps; ++i) { + rcu_read_lock(); + + wp = slots[i]; + + if (wp == NULL) + goto unlock; + + info = counter_arch_bp(wp); + if (!info->step_ctrl.enabled) + goto unlock; + + /* + * Restore the original watchpoint if we've completed the + * single-step. + */ + if (info->trigger != pc) + disable_single_step(wp); + +unlock: rcu_read_unlock(); } } @@ -683,62 +736,69 @@ static void watchpoint_handler(unsigned long unknown, struct pt_regs *regs) static void breakpoint_handler(unsigned long unknown, struct pt_regs *regs) { int i; - int mismatch; u32 ctrl_reg, val, addr; - struct perf_event *bp, **slots = __get_cpu_var(bp_on_reg); + struct perf_event *bp, **slots; struct arch_hw_breakpoint *info; struct arch_hw_breakpoint_ctrl ctrl; + slots = (struct perf_event **)__get_cpu_var(bp_on_reg); + /* The exception entry code places the amended lr in the PC. */ addr = regs->ARM_pc; + /* Check the currently installed breakpoints first. */ for (i = 0; i < core_num_brps; ++i) { rcu_read_lock(); bp = slots[i]; - if (bp == NULL) { - rcu_read_unlock(); - continue; - } + if (bp == NULL) + goto unlock; - mismatch = 0; + info = counter_arch_bp(bp); /* Check if the breakpoint value matches. */ val = read_wb_reg(ARM_BASE_BVR + i); if (val != (addr & ~0x3)) - goto unlock; + goto mismatch; /* Possible match, check the byte address select to confirm. */ ctrl_reg = read_wb_reg(ARM_BASE_BCR + i); decode_ctrl_reg(ctrl_reg, &ctrl); if ((1 << (addr & 0x3)) & ctrl.len) { - mismatch = 1; - info = counter_arch_bp(bp); info->trigger = addr; - } - -unlock: - if ((mismatch && !info->ctrl.mismatch) || bp_is_single_step(bp)) { pr_debug("breakpoint fired: address = 0x%x\n", addr); perf_bp_event(bp, regs); + if (!bp->overflow_handler) + enable_single_step(bp, addr); + goto unlock; } - update_mismatch_flag(i, mismatch); +mismatch: + /* If we're stepping a breakpoint, it can now be restored. */ + if (info->step_ctrl.enabled) + disable_single_step(bp); +unlock: rcu_read_unlock(); } + + /* Handle any pending watchpoint single-step breakpoints. */ + watchpoint_single_step_handler(addr); } /* * Called from either the Data Abort Handler [watchpoint] or the - * Prefetch Abort Handler [breakpoint]. + * Prefetch Abort Handler [breakpoint] with preemption disabled. */ static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr, struct pt_regs *regs) { - int ret = 1; /* Unhandled fault. */ + int ret = 0; u32 dscr; + /* We must be called with preemption disabled. */ + WARN_ON(preemptible()); + /* We only handle watchpoints and hardware breakpoints. */ ARM_DBG_READ(c1, 0, dscr); @@ -753,25 +813,47 @@ static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr, watchpoint_handler(addr, regs); break; default: - goto out; + ret = 1; /* Unhandled fault. */ } - ret = 0; -out: + /* + * Re-enable preemption after it was disabled in the + * low-level exception handling code. + */ + preempt_enable(); + return ret; } /* * One-time initialisation. */ -static void __init reset_ctrl_regs(void *unused) +static void reset_ctrl_regs(void *unused) { int i; + /* + * v7 debug contains save and restore registers so that debug state + * can be maintained across low-power modes without leaving + * the debug logic powered up. It is IMPLEMENTATION DEFINED whether + * we can write to the debug registers out of reset, so we must + * unlock the OS Lock Access Register to avoid taking undefined + * instruction exceptions later on. + */ + if (debug_arch >= ARM_DEBUG_ARCH_V7_ECP14) { + /* + * Unconditionally clear the lock by writing a value + * other than 0xC5ACCE55 to the access register. + */ + asm volatile("mcr p14, 0, %0, c1, c0, 4" : : "r" (0)); + isb(); + } + if (enable_monitor_mode()) return; - for (i = 0; i < core_num_brps; ++i) { + /* We must also reset any reserved registers. */ + for (i = 0; i < core_num_brps + core_num_reserved_brps; ++i) { write_wb_reg(ARM_BASE_BCR + i, 0UL); write_wb_reg(ARM_BASE_BVR + i, 0UL); } @@ -782,45 +864,57 @@ static void __init reset_ctrl_regs(void *unused) } } +static int __cpuinit dbg_reset_notify(struct notifier_block *self, + unsigned long action, void *cpu) +{ + if (action == CPU_ONLINE) + smp_call_function_single((int)cpu, reset_ctrl_regs, NULL, 1); + return NOTIFY_OK; +} + +static struct notifier_block __cpuinitdata dbg_reset_nb = { + .notifier_call = dbg_reset_notify, +}; + static int __init arch_hw_breakpoint_init(void) { - int ret = 0; u32 dscr; debug_arch = get_debug_arch(); if (debug_arch > ARM_DEBUG_ARCH_V7_ECP14) { pr_info("debug architecture 0x%x unsupported.\n", debug_arch); - ret = -ENODEV; - goto out; + return 0; } /* Determine how many BRPs/WRPs are available. */ core_num_brps = get_num_brps(); + core_num_reserved_brps = get_num_reserved_brps(); core_num_wrps = get_num_wrps(); pr_info("found %d breakpoint and %d watchpoint registers.\n", - core_num_brps, core_num_wrps); + core_num_brps + core_num_reserved_brps, core_num_wrps); - if (core_has_mismatch_bps()) - pr_info("1 breakpoint reserved for watchpoint single-step.\n"); + if (core_num_reserved_brps) + pr_info("%d breakpoint(s) reserved for watchpoint " + "single-step.\n", core_num_reserved_brps); ARM_DBG_READ(c1, 0, dscr); if (dscr & ARM_DSCR_HDBGEN) { pr_warning("halting debug mode enabled. Assuming maximum " "watchpoint size of 4 bytes."); } else { - /* Work out the maximum supported watchpoint length. */ - max_watchpoint_len = get_max_wp_len(); - pr_info("maximum watchpoint size is %u bytes.\n", - max_watchpoint_len); - /* * Reset the breakpoint resources. We assume that a halting * debugger will leave the world in a nice state for us. */ smp_call_function(reset_ctrl_regs, NULL, 1); reset_ctrl_regs(NULL); + + /* Work out the maximum supported watchpoint length. */ + max_watchpoint_len = get_max_wp_len(); + pr_info("maximum watchpoint size is %u bytes.\n", + max_watchpoint_len); } /* Register debug fault handler. */ @@ -829,8 +923,9 @@ static int __init arch_hw_breakpoint_init(void) hook_ifault_code(2, hw_breakpoint_pending, SIGTRAP, TRAP_HWBKPT, "breakpoint debug exception"); -out: - return ret; + /* Register hotplug notifier. */ + register_cpu_notifier(&dbg_reset_nb); + return 0; } arch_initcall(arch_hw_breakpoint_init);