From 48dbb6dc86ca5d1b2224937d774c7ba98bc3a485 Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Tue, 3 May 2011 15:26:43 +0200 Subject: hw breakpoints: Move to kernel/events/ As part of the events sybsystem unification, relocate hw_breakpoint.c into its new destination. Cc: Frederic Weisbecker Signed-off-by: Borislav Petkov --- kernel/Makefile | 1 - kernel/events/Makefile | 3 +- kernel/events/hw_breakpoint.c | 659 ++++++++++++++++++++++++++++++++++++++++++ kernel/hw_breakpoint.c | 659 ------------------------------------------ 4 files changed, 661 insertions(+), 661 deletions(-) create mode 100644 kernel/events/hw_breakpoint.c delete mode 100644 kernel/hw_breakpoint.c diff --git a/kernel/Makefile b/kernel/Makefile index 79815306474..e9cf19155b4 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -105,7 +105,6 @@ obj-$(CONFIG_IRQ_WORK) += irq_work.o obj-$(CONFIG_PERF_EVENTS) += events/ -obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o obj-$(CONFIG_USER_RETURN_NOTIFIER) += user-return-notifier.o obj-$(CONFIG_PADATA) += padata.o obj-$(CONFIG_CRASH_DUMP) += crash_dump.o diff --git a/kernel/events/Makefile b/kernel/events/Makefile index 26c00e4570e..1ce23d3d839 100644 --- a/kernel/events/Makefile +++ b/kernel/events/Makefile @@ -2,4 +2,5 @@ ifdef CONFIG_FUNCTION_TRACER CFLAGS_REMOVE_core.o = -pg endif -obj-y += core.o +obj-y := core.o +obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c new file mode 100644 index 00000000000..086adf25a55 --- /dev/null +++ b/kernel/events/hw_breakpoint.c @@ -0,0 +1,659 @@ +/* + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Copyright (C) 2007 Alan Stern + * Copyright (C) IBM Corporation, 2009 + * Copyright (C) 2009, Frederic Weisbecker + * + * Thanks to Ingo Molnar for his many suggestions. + * + * Authors: Alan Stern + * K.Prasad + * Frederic Weisbecker + */ + +/* + * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility, + * using the CPU's debug registers. + * This file contains the arch-independent routines. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include + + +/* + * Constraints data + */ + +/* Number of pinned cpu breakpoints in a cpu */ +static DEFINE_PER_CPU(unsigned int, nr_cpu_bp_pinned[TYPE_MAX]); + +/* Number of pinned task breakpoints in a cpu */ +static DEFINE_PER_CPU(unsigned int *, nr_task_bp_pinned[TYPE_MAX]); + +/* Number of non-pinned cpu/task breakpoints in a cpu */ +static DEFINE_PER_CPU(unsigned int, nr_bp_flexible[TYPE_MAX]); + +static int nr_slots[TYPE_MAX]; + +/* Keep track of the breakpoints attached to tasks */ +static LIST_HEAD(bp_task_head); + +static int constraints_initialized; + +/* Gather the number of total pinned and un-pinned bp in a cpuset */ +struct bp_busy_slots { + unsigned int pinned; + unsigned int flexible; +}; + +/* Serialize accesses to the above constraints */ +static DEFINE_MUTEX(nr_bp_mutex); + +__weak int hw_breakpoint_weight(struct perf_event *bp) +{ + return 1; +} + +static inline enum bp_type_idx find_slot_idx(struct perf_event *bp) +{ + if (bp->attr.bp_type & HW_BREAKPOINT_RW) + return TYPE_DATA; + + return TYPE_INST; +} + +/* + * Report the maximum number of pinned breakpoints a task + * have in this cpu + */ +static unsigned int max_task_bp_pinned(int cpu, enum bp_type_idx type) +{ + int i; + unsigned int *tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu); + + for (i = nr_slots[type] - 1; i >= 0; i--) { + if (tsk_pinned[i] > 0) + return i + 1; + } + + return 0; +} + +/* + * Count the number of breakpoints of the same type and same task. + * The given event must be not on the list. + */ +static int task_bp_pinned(struct perf_event *bp, enum bp_type_idx type) +{ + struct task_struct *tsk = bp->hw.bp_target; + struct perf_event *iter; + int count = 0; + + list_for_each_entry(iter, &bp_task_head, hw.bp_list) { + if (iter->hw.bp_target == tsk && find_slot_idx(iter) == type) + count += hw_breakpoint_weight(iter); + } + + return count; +} + +/* + * Report the number of pinned/un-pinned breakpoints we have in + * a given cpu (cpu > -1) or in all of them (cpu = -1). + */ +static void +fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp, + enum bp_type_idx type) +{ + int cpu = bp->cpu; + struct task_struct *tsk = bp->hw.bp_target; + + if (cpu >= 0) { + slots->pinned = per_cpu(nr_cpu_bp_pinned[type], cpu); + if (!tsk) + slots->pinned += max_task_bp_pinned(cpu, type); + else + slots->pinned += task_bp_pinned(bp, type); + slots->flexible = per_cpu(nr_bp_flexible[type], cpu); + + return; + } + + for_each_online_cpu(cpu) { + unsigned int nr; + + nr = per_cpu(nr_cpu_bp_pinned[type], cpu); + if (!tsk) + nr += max_task_bp_pinned(cpu, type); + else + nr += task_bp_pinned(bp, type); + + if (nr > slots->pinned) + slots->pinned = nr; + + nr = per_cpu(nr_bp_flexible[type], cpu); + + if (nr > slots->flexible) + slots->flexible = nr; + } +} + +/* + * For now, continue to consider flexible as pinned, until we can + * ensure no flexible event can ever be scheduled before a pinned event + * in a same cpu. + */ +static void +fetch_this_slot(struct bp_busy_slots *slots, int weight) +{ + slots->pinned += weight; +} + +/* + * Add a pinned breakpoint for the given task in our constraint table + */ +static void toggle_bp_task_slot(struct perf_event *bp, int cpu, bool enable, + enum bp_type_idx type, int weight) +{ + unsigned int *tsk_pinned; + int old_count = 0; + int old_idx = 0; + int idx = 0; + + old_count = task_bp_pinned(bp, type); + old_idx = old_count - 1; + idx = old_idx + weight; + + /* tsk_pinned[n] is the number of tasks having n breakpoints */ + tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu); + if (enable) { + tsk_pinned[idx]++; + if (old_count > 0) + tsk_pinned[old_idx]--; + } else { + tsk_pinned[idx]--; + if (old_count > 0) + tsk_pinned[old_idx]++; + } +} + +/* + * Add/remove the given breakpoint in our constraint table + */ +static void +toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type, + int weight) +{ + int cpu = bp->cpu; + struct task_struct *tsk = bp->hw.bp_target; + + /* Pinned counter cpu profiling */ + if (!tsk) { + + if (enable) + per_cpu(nr_cpu_bp_pinned[type], bp->cpu) += weight; + else + per_cpu(nr_cpu_bp_pinned[type], bp->cpu) -= weight; + return; + } + + /* Pinned counter task profiling */ + + if (!enable) + list_del(&bp->hw.bp_list); + + if (cpu >= 0) { + toggle_bp_task_slot(bp, cpu, enable, type, weight); + } else { + for_each_online_cpu(cpu) + toggle_bp_task_slot(bp, cpu, enable, type, weight); + } + + if (enable) + list_add_tail(&bp->hw.bp_list, &bp_task_head); +} + +/* + * Function to perform processor-specific cleanup during unregistration + */ +__weak void arch_unregister_hw_breakpoint(struct perf_event *bp) +{ + /* + * A weak stub function here for those archs that don't define + * it inside arch/.../kernel/hw_breakpoint.c + */ +} + +/* + * Contraints to check before allowing this new breakpoint counter: + * + * == Non-pinned counter == (Considered as pinned for now) + * + * - If attached to a single cpu, check: + * + * (per_cpu(nr_bp_flexible, cpu) || (per_cpu(nr_cpu_bp_pinned, cpu) + * + max(per_cpu(nr_task_bp_pinned, cpu)))) < HBP_NUM + * + * -> If there are already non-pinned counters in this cpu, it means + * there is already a free slot for them. + * Otherwise, we check that the maximum number of per task + * breakpoints (for this cpu) plus the number of per cpu breakpoint + * (for this cpu) doesn't cover every registers. + * + * - If attached to every cpus, check: + * + * (per_cpu(nr_bp_flexible, *) || (max(per_cpu(nr_cpu_bp_pinned, *)) + * + max(per_cpu(nr_task_bp_pinned, *)))) < HBP_NUM + * + * -> This is roughly the same, except we check the number of per cpu + * bp for every cpu and we keep the max one. Same for the per tasks + * breakpoints. + * + * + * == Pinned counter == + * + * - If attached to a single cpu, check: + * + * ((per_cpu(nr_bp_flexible, cpu) > 1) + per_cpu(nr_cpu_bp_pinned, cpu) + * + max(per_cpu(nr_task_bp_pinned, cpu))) < HBP_NUM + * + * -> Same checks as before. But now the nr_bp_flexible, if any, must keep + * one register at least (or they will never be fed). + * + * - If attached to every cpus, check: + * + * ((per_cpu(nr_bp_flexible, *) > 1) + max(per_cpu(nr_cpu_bp_pinned, *)) + * + max(per_cpu(nr_task_bp_pinned, *))) < HBP_NUM + */ +static int __reserve_bp_slot(struct perf_event *bp) +{ + struct bp_busy_slots slots = {0}; + enum bp_type_idx type; + int weight; + + /* We couldn't initialize breakpoint constraints on boot */ + if (!constraints_initialized) + return -ENOMEM; + + /* Basic checks */ + if (bp->attr.bp_type == HW_BREAKPOINT_EMPTY || + bp->attr.bp_type == HW_BREAKPOINT_INVALID) + return -EINVAL; + + type = find_slot_idx(bp); + weight = hw_breakpoint_weight(bp); + + fetch_bp_busy_slots(&slots, bp, type); + /* + * Simulate the addition of this breakpoint to the constraints + * and see the result. + */ + fetch_this_slot(&slots, weight); + + /* Flexible counters need to keep at least one slot */ + if (slots.pinned + (!!slots.flexible) > nr_slots[type]) + return -ENOSPC; + + toggle_bp_slot(bp, true, type, weight); + + return 0; +} + +int reserve_bp_slot(struct perf_event *bp) +{ + int ret; + + mutex_lock(&nr_bp_mutex); + + ret = __reserve_bp_slot(bp); + + mutex_unlock(&nr_bp_mutex); + + return ret; +} + +static void __release_bp_slot(struct perf_event *bp) +{ + enum bp_type_idx type; + int weight; + + type = find_slot_idx(bp); + weight = hw_breakpoint_weight(bp); + toggle_bp_slot(bp, false, type, weight); +} + +void release_bp_slot(struct perf_event *bp) +{ + mutex_lock(&nr_bp_mutex); + + arch_unregister_hw_breakpoint(bp); + __release_bp_slot(bp); + + mutex_unlock(&nr_bp_mutex); +} + +/* + * Allow the kernel debugger to reserve breakpoint slots without + * taking a lock using the dbg_* variant of for the reserve and + * release breakpoint slots. + */ +int dbg_reserve_bp_slot(struct perf_event *bp) +{ + if (mutex_is_locked(&nr_bp_mutex)) + return -1; + + return __reserve_bp_slot(bp); +} + +int dbg_release_bp_slot(struct perf_event *bp) +{ + if (mutex_is_locked(&nr_bp_mutex)) + return -1; + + __release_bp_slot(bp); + + return 0; +} + +static int validate_hw_breakpoint(struct perf_event *bp) +{ + int ret; + + ret = arch_validate_hwbkpt_settings(bp); + if (ret) + return ret; + + if (arch_check_bp_in_kernelspace(bp)) { + if (bp->attr.exclude_kernel) + return -EINVAL; + /* + * Don't let unprivileged users set a breakpoint in the trap + * path to avoid trap recursion attacks. + */ + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + } + + return 0; +} + +int register_perf_hw_breakpoint(struct perf_event *bp) +{ + int ret; + + ret = reserve_bp_slot(bp); + if (ret) + return ret; + + ret = validate_hw_breakpoint(bp); + + /* if arch_validate_hwbkpt_settings() fails then release bp slot */ + if (ret) + release_bp_slot(bp); + + return ret; +} + +/** + * register_user_hw_breakpoint - register a hardware breakpoint for user space + * @attr: breakpoint attributes + * @triggered: callback to trigger when we hit the breakpoint + * @tsk: pointer to 'task_struct' of the process to which the address belongs + */ +struct perf_event * +register_user_hw_breakpoint(struct perf_event_attr *attr, + perf_overflow_handler_t triggered, + struct task_struct *tsk) +{ + return perf_event_create_kernel_counter(attr, -1, tsk, triggered); +} +EXPORT_SYMBOL_GPL(register_user_hw_breakpoint); + +/** + * modify_user_hw_breakpoint - modify a user-space hardware breakpoint + * @bp: the breakpoint structure to modify + * @attr: new breakpoint attributes + * @triggered: callback to trigger when we hit the breakpoint + * @tsk: pointer to 'task_struct' of the process to which the address belongs + */ +int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr) +{ + u64 old_addr = bp->attr.bp_addr; + u64 old_len = bp->attr.bp_len; + int old_type = bp->attr.bp_type; + int err = 0; + + perf_event_disable(bp); + + bp->attr.bp_addr = attr->bp_addr; + bp->attr.bp_type = attr->bp_type; + bp->attr.bp_len = attr->bp_len; + + if (attr->disabled) + goto end; + + err = validate_hw_breakpoint(bp); + if (!err) + perf_event_enable(bp); + + if (err) { + bp->attr.bp_addr = old_addr; + bp->attr.bp_type = old_type; + bp->attr.bp_len = old_len; + if (!bp->attr.disabled) + perf_event_enable(bp); + + return err; + } + +end: + bp->attr.disabled = attr->disabled; + + return 0; +} +EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint); + +/** + * unregister_hw_breakpoint - unregister a user-space hardware breakpoint + * @bp: the breakpoint structure to unregister + */ +void unregister_hw_breakpoint(struct perf_event *bp) +{ + if (!bp) + return; + perf_event_release_kernel(bp); +} +EXPORT_SYMBOL_GPL(unregister_hw_breakpoint); + +/** + * register_wide_hw_breakpoint - register a wide breakpoint in the kernel + * @attr: breakpoint attributes + * @triggered: callback to trigger when we hit the breakpoint + * + * @return a set of per_cpu pointers to perf events + */ +struct perf_event * __percpu * +register_wide_hw_breakpoint(struct perf_event_attr *attr, + perf_overflow_handler_t triggered) +{ + struct perf_event * __percpu *cpu_events, **pevent, *bp; + long err; + int cpu; + + cpu_events = alloc_percpu(typeof(*cpu_events)); + if (!cpu_events) + return (void __percpu __force *)ERR_PTR(-ENOMEM); + + get_online_cpus(); + for_each_online_cpu(cpu) { + pevent = per_cpu_ptr(cpu_events, cpu); + bp = perf_event_create_kernel_counter(attr, cpu, NULL, triggered); + + *pevent = bp; + + if (IS_ERR(bp)) { + err = PTR_ERR(bp); + goto fail; + } + } + put_online_cpus(); + + return cpu_events; + +fail: + for_each_online_cpu(cpu) { + pevent = per_cpu_ptr(cpu_events, cpu); + if (IS_ERR(*pevent)) + break; + unregister_hw_breakpoint(*pevent); + } + put_online_cpus(); + + free_percpu(cpu_events); + return (void __percpu __force *)ERR_PTR(err); +} +EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint); + +/** + * unregister_wide_hw_breakpoint - unregister a wide breakpoint in the kernel + * @cpu_events: the per cpu set of events to unregister + */ +void unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events) +{ + int cpu; + struct perf_event **pevent; + + for_each_possible_cpu(cpu) { + pevent = per_cpu_ptr(cpu_events, cpu); + unregister_hw_breakpoint(*pevent); + } + free_percpu(cpu_events); +} +EXPORT_SYMBOL_GPL(unregister_wide_hw_breakpoint); + +static struct notifier_block hw_breakpoint_exceptions_nb = { + .notifier_call = hw_breakpoint_exceptions_notify, + /* we need to be notified first */ + .priority = 0x7fffffff +}; + +static void bp_perf_event_destroy(struct perf_event *event) +{ + release_bp_slot(event); +} + +static int hw_breakpoint_event_init(struct perf_event *bp) +{ + int err; + + if (bp->attr.type != PERF_TYPE_BREAKPOINT) + return -ENOENT; + + err = register_perf_hw_breakpoint(bp); + if (err) + return err; + + bp->destroy = bp_perf_event_destroy; + + return 0; +} + +static int hw_breakpoint_add(struct perf_event *bp, int flags) +{ + if (!(flags & PERF_EF_START)) + bp->hw.state = PERF_HES_STOPPED; + + return arch_install_hw_breakpoint(bp); +} + +static void hw_breakpoint_del(struct perf_event *bp, int flags) +{ + arch_uninstall_hw_breakpoint(bp); +} + +static void hw_breakpoint_start(struct perf_event *bp, int flags) +{ + bp->hw.state = 0; +} + +static void hw_breakpoint_stop(struct perf_event *bp, int flags) +{ + bp->hw.state = PERF_HES_STOPPED; +} + +static struct pmu perf_breakpoint = { + .task_ctx_nr = perf_sw_context, /* could eventually get its own */ + + .event_init = hw_breakpoint_event_init, + .add = hw_breakpoint_add, + .del = hw_breakpoint_del, + .start = hw_breakpoint_start, + .stop = hw_breakpoint_stop, + .read = hw_breakpoint_pmu_read, +}; + +int __init init_hw_breakpoint(void) +{ + unsigned int **task_bp_pinned; + int cpu, err_cpu; + int i; + + for (i = 0; i < TYPE_MAX; i++) + nr_slots[i] = hw_breakpoint_slots(i); + + for_each_possible_cpu(cpu) { + for (i = 0; i < TYPE_MAX; i++) { + task_bp_pinned = &per_cpu(nr_task_bp_pinned[i], cpu); + *task_bp_pinned = kzalloc(sizeof(int) * nr_slots[i], + GFP_KERNEL); + if (!*task_bp_pinned) + goto err_alloc; + } + } + + constraints_initialized = 1; + + perf_pmu_register(&perf_breakpoint, "breakpoint", PERF_TYPE_BREAKPOINT); + + return register_die_notifier(&hw_breakpoint_exceptions_nb); + + err_alloc: + for_each_possible_cpu(err_cpu) { + if (err_cpu == cpu) + break; + for (i = 0; i < TYPE_MAX; i++) + kfree(per_cpu(nr_task_bp_pinned[i], cpu)); + } + + return -ENOMEM; +} + + diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c deleted file mode 100644 index 086adf25a55..00000000000 --- a/kernel/hw_breakpoint.c +++ /dev/null @@ -1,659 +0,0 @@ -/* - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; either version 2 of the License, or - * (at your option) any later version. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. - * - * Copyright (C) 2007 Alan Stern - * Copyright (C) IBM Corporation, 2009 - * Copyright (C) 2009, Frederic Weisbecker - * - * Thanks to Ingo Molnar for his many suggestions. - * - * Authors: Alan Stern - * K.Prasad - * Frederic Weisbecker - */ - -/* - * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility, - * using the CPU's debug registers. - * This file contains the arch-independent routines. - */ - -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include - -#include - - -/* - * Constraints data - */ - -/* Number of pinned cpu breakpoints in a cpu */ -static DEFINE_PER_CPU(unsigned int, nr_cpu_bp_pinned[TYPE_MAX]); - -/* Number of pinned task breakpoints in a cpu */ -static DEFINE_PER_CPU(unsigned int *, nr_task_bp_pinned[TYPE_MAX]); - -/* Number of non-pinned cpu/task breakpoints in a cpu */ -static DEFINE_PER_CPU(unsigned int, nr_bp_flexible[TYPE_MAX]); - -static int nr_slots[TYPE_MAX]; - -/* Keep track of the breakpoints attached to tasks */ -static LIST_HEAD(bp_task_head); - -static int constraints_initialized; - -/* Gather the number of total pinned and un-pinned bp in a cpuset */ -struct bp_busy_slots { - unsigned int pinned; - unsigned int flexible; -}; - -/* Serialize accesses to the above constraints */ -static DEFINE_MUTEX(nr_bp_mutex); - -__weak int hw_breakpoint_weight(struct perf_event *bp) -{ - return 1; -} - -static inline enum bp_type_idx find_slot_idx(struct perf_event *bp) -{ - if (bp->attr.bp_type & HW_BREAKPOINT_RW) - return TYPE_DATA; - - return TYPE_INST; -} - -/* - * Report the maximum number of pinned breakpoints a task - * have in this cpu - */ -static unsigned int max_task_bp_pinned(int cpu, enum bp_type_idx type) -{ - int i; - unsigned int *tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu); - - for (i = nr_slots[type] - 1; i >= 0; i--) { - if (tsk_pinned[i] > 0) - return i + 1; - } - - return 0; -} - -/* - * Count the number of breakpoints of the same type and same task. - * The given event must be not on the list. - */ -static int task_bp_pinned(struct perf_event *bp, enum bp_type_idx type) -{ - struct task_struct *tsk = bp->hw.bp_target; - struct perf_event *iter; - int count = 0; - - list_for_each_entry(iter, &bp_task_head, hw.bp_list) { - if (iter->hw.bp_target == tsk && find_slot_idx(iter) == type) - count += hw_breakpoint_weight(iter); - } - - return count; -} - -/* - * Report the number of pinned/un-pinned breakpoints we have in - * a given cpu (cpu > -1) or in all of them (cpu = -1). - */ -static void -fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp, - enum bp_type_idx type) -{ - int cpu = bp->cpu; - struct task_struct *tsk = bp->hw.bp_target; - - if (cpu >= 0) { - slots->pinned = per_cpu(nr_cpu_bp_pinned[type], cpu); - if (!tsk) - slots->pinned += max_task_bp_pinned(cpu, type); - else - slots->pinned += task_bp_pinned(bp, type); - slots->flexible = per_cpu(nr_bp_flexible[type], cpu); - - return; - } - - for_each_online_cpu(cpu) { - unsigned int nr; - - nr = per_cpu(nr_cpu_bp_pinned[type], cpu); - if (!tsk) - nr += max_task_bp_pinned(cpu, type); - else - nr += task_bp_pinned(bp, type); - - if (nr > slots->pinned) - slots->pinned = nr; - - nr = per_cpu(nr_bp_flexible[type], cpu); - - if (nr > slots->flexible) - slots->flexible = nr; - } -} - -/* - * For now, continue to consider flexible as pinned, until we can - * ensure no flexible event can ever be scheduled before a pinned event - * in a same cpu. - */ -static void -fetch_this_slot(struct bp_busy_slots *slots, int weight) -{ - slots->pinned += weight; -} - -/* - * Add a pinned breakpoint for the given task in our constraint table - */ -static void toggle_bp_task_slot(struct perf_event *bp, int cpu, bool enable, - enum bp_type_idx type, int weight) -{ - unsigned int *tsk_pinned; - int old_count = 0; - int old_idx = 0; - int idx = 0; - - old_count = task_bp_pinned(bp, type); - old_idx = old_count - 1; - idx = old_idx + weight; - - /* tsk_pinned[n] is the number of tasks having n breakpoints */ - tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu); - if (enable) { - tsk_pinned[idx]++; - if (old_count > 0) - tsk_pinned[old_idx]--; - } else { - tsk_pinned[idx]--; - if (old_count > 0) - tsk_pinned[old_idx]++; - } -} - -/* - * Add/remove the given breakpoint in our constraint table - */ -static void -toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type, - int weight) -{ - int cpu = bp->cpu; - struct task_struct *tsk = bp->hw.bp_target; - - /* Pinned counter cpu profiling */ - if (!tsk) { - - if (enable) - per_cpu(nr_cpu_bp_pinned[type], bp->cpu) += weight; - else - per_cpu(nr_cpu_bp_pinned[type], bp->cpu) -= weight; - return; - } - - /* Pinned counter task profiling */ - - if (!enable) - list_del(&bp->hw.bp_list); - - if (cpu >= 0) { - toggle_bp_task_slot(bp, cpu, enable, type, weight); - } else { - for_each_online_cpu(cpu) - toggle_bp_task_slot(bp, cpu, enable, type, weight); - } - - if (enable) - list_add_tail(&bp->hw.bp_list, &bp_task_head); -} - -/* - * Function to perform processor-specific cleanup during unregistration - */ -__weak void arch_unregister_hw_breakpoint(struct perf_event *bp) -{ - /* - * A weak stub function here for those archs that don't define - * it inside arch/.../kernel/hw_breakpoint.c - */ -} - -/* - * Contraints to check before allowing this new breakpoint counter: - * - * == Non-pinned counter == (Considered as pinned for now) - * - * - If attached to a single cpu, check: - * - * (per_cpu(nr_bp_flexible, cpu) || (per_cpu(nr_cpu_bp_pinned, cpu) - * + max(per_cpu(nr_task_bp_pinned, cpu)))) < HBP_NUM - * - * -> If there are already non-pinned counters in this cpu, it means - * there is already a free slot for them. - * Otherwise, we check that the maximum number of per task - * breakpoints (for this cpu) plus the number of per cpu breakpoint - * (for this cpu) doesn't cover every registers. - * - * - If attached to every cpus, check: - * - * (per_cpu(nr_bp_flexible, *) || (max(per_cpu(nr_cpu_bp_pinned, *)) - * + max(per_cpu(nr_task_bp_pinned, *)))) < HBP_NUM - * - * -> This is roughly the same, except we check the number of per cpu - * bp for every cpu and we keep the max one. Same for the per tasks - * breakpoints. - * - * - * == Pinned counter == - * - * - If attached to a single cpu, check: - * - * ((per_cpu(nr_bp_flexible, cpu) > 1) + per_cpu(nr_cpu_bp_pinned, cpu) - * + max(per_cpu(nr_task_bp_pinned, cpu))) < HBP_NUM - * - * -> Same checks as before. But now the nr_bp_flexible, if any, must keep - * one register at least (or they will never be fed). - * - * - If attached to every cpus, check: - * - * ((per_cpu(nr_bp_flexible, *) > 1) + max(per_cpu(nr_cpu_bp_pinned, *)) - * + max(per_cpu(nr_task_bp_pinned, *))) < HBP_NUM - */ -static int __reserve_bp_slot(struct perf_event *bp) -{ - struct bp_busy_slots slots = {0}; - enum bp_type_idx type; - int weight; - - /* We couldn't initialize breakpoint constraints on boot */ - if (!constraints_initialized) - return -ENOMEM; - - /* Basic checks */ - if (bp->attr.bp_type == HW_BREAKPOINT_EMPTY || - bp->attr.bp_type == HW_BREAKPOINT_INVALID) - return -EINVAL; - - type = find_slot_idx(bp); - weight = hw_breakpoint_weight(bp); - - fetch_bp_busy_slots(&slots, bp, type); - /* - * Simulate the addition of this breakpoint to the constraints - * and see the result. - */ - fetch_this_slot(&slots, weight); - - /* Flexible counters need to keep at least one slot */ - if (slots.pinned + (!!slots.flexible) > nr_slots[type]) - return -ENOSPC; - - toggle_bp_slot(bp, true, type, weight); - - return 0; -} - -int reserve_bp_slot(struct perf_event *bp) -{ - int ret; - - mutex_lock(&nr_bp_mutex); - - ret = __reserve_bp_slot(bp); - - mutex_unlock(&nr_bp_mutex); - - return ret; -} - -static void __release_bp_slot(struct perf_event *bp) -{ - enum bp_type_idx type; - int weight; - - type = find_slot_idx(bp); - weight = hw_breakpoint_weight(bp); - toggle_bp_slot(bp, false, type, weight); -} - -void release_bp_slot(struct perf_event *bp) -{ - mutex_lock(&nr_bp_mutex); - - arch_unregister_hw_breakpoint(bp); - __release_bp_slot(bp); - - mutex_unlock(&nr_bp_mutex); -} - -/* - * Allow the kernel debugger to reserve breakpoint slots without - * taking a lock using the dbg_* variant of for the reserve and - * release breakpoint slots. - */ -int dbg_reserve_bp_slot(struct perf_event *bp) -{ - if (mutex_is_locked(&nr_bp_mutex)) - return -1; - - return __reserve_bp_slot(bp); -} - -int dbg_release_bp_slot(struct perf_event *bp) -{ - if (mutex_is_locked(&nr_bp_mutex)) - return -1; - - __release_bp_slot(bp); - - return 0; -} - -static int validate_hw_breakpoint(struct perf_event *bp) -{ - int ret; - - ret = arch_validate_hwbkpt_settings(bp); - if (ret) - return ret; - - if (arch_check_bp_in_kernelspace(bp)) { - if (bp->attr.exclude_kernel) - return -EINVAL; - /* - * Don't let unprivileged users set a breakpoint in the trap - * path to avoid trap recursion attacks. - */ - if (!capable(CAP_SYS_ADMIN)) - return -EPERM; - } - - return 0; -} - -int register_perf_hw_breakpoint(struct perf_event *bp) -{ - int ret; - - ret = reserve_bp_slot(bp); - if (ret) - return ret; - - ret = validate_hw_breakpoint(bp); - - /* if arch_validate_hwbkpt_settings() fails then release bp slot */ - if (ret) - release_bp_slot(bp); - - return ret; -} - -/** - * register_user_hw_breakpoint - register a hardware breakpoint for user space - * @attr: breakpoint attributes - * @triggered: callback to trigger when we hit the breakpoint - * @tsk: pointer to 'task_struct' of the process to which the address belongs - */ -struct perf_event * -register_user_hw_breakpoint(struct perf_event_attr *attr, - perf_overflow_handler_t triggered, - struct task_struct *tsk) -{ - return perf_event_create_kernel_counter(attr, -1, tsk, triggered); -} -EXPORT_SYMBOL_GPL(register_user_hw_breakpoint); - -/** - * modify_user_hw_breakpoint - modify a user-space hardware breakpoint - * @bp: the breakpoint structure to modify - * @attr: new breakpoint attributes - * @triggered: callback to trigger when we hit the breakpoint - * @tsk: pointer to 'task_struct' of the process to which the address belongs - */ -int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr) -{ - u64 old_addr = bp->attr.bp_addr; - u64 old_len = bp->attr.bp_len; - int old_type = bp->attr.bp_type; - int err = 0; - - perf_event_disable(bp); - - bp->attr.bp_addr = attr->bp_addr; - bp->attr.bp_type = attr->bp_type; - bp->attr.bp_len = attr->bp_len; - - if (attr->disabled) - goto end; - - err = validate_hw_breakpoint(bp); - if (!err) - perf_event_enable(bp); - - if (err) { - bp->attr.bp_addr = old_addr; - bp->attr.bp_type = old_type; - bp->attr.bp_len = old_len; - if (!bp->attr.disabled) - perf_event_enable(bp); - - return err; - } - -end: - bp->attr.disabled = attr->disabled; - - return 0; -} -EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint); - -/** - * unregister_hw_breakpoint - unregister a user-space hardware breakpoint - * @bp: the breakpoint structure to unregister - */ -void unregister_hw_breakpoint(struct perf_event *bp) -{ - if (!bp) - return; - perf_event_release_kernel(bp); -} -EXPORT_SYMBOL_GPL(unregister_hw_breakpoint); - -/** - * register_wide_hw_breakpoint - register a wide breakpoint in the kernel - * @attr: breakpoint attributes - * @triggered: callback to trigger when we hit the breakpoint - * - * @return a set of per_cpu pointers to perf events - */ -struct perf_event * __percpu * -register_wide_hw_breakpoint(struct perf_event_attr *attr, - perf_overflow_handler_t triggered) -{ - struct perf_event * __percpu *cpu_events, **pevent, *bp; - long err; - int cpu; - - cpu_events = alloc_percpu(typeof(*cpu_events)); - if (!cpu_events) - return (void __percpu __force *)ERR_PTR(-ENOMEM); - - get_online_cpus(); - for_each_online_cpu(cpu) { - pevent = per_cpu_ptr(cpu_events, cpu); - bp = perf_event_create_kernel_counter(attr, cpu, NULL, triggered); - - *pevent = bp; - - if (IS_ERR(bp)) { - err = PTR_ERR(bp); - goto fail; - } - } - put_online_cpus(); - - return cpu_events; - -fail: - for_each_online_cpu(cpu) { - pevent = per_cpu_ptr(cpu_events, cpu); - if (IS_ERR(*pevent)) - break; - unregister_hw_breakpoint(*pevent); - } - put_online_cpus(); - - free_percpu(cpu_events); - return (void __percpu __force *)ERR_PTR(err); -} -EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint); - -/** - * unregister_wide_hw_breakpoint - unregister a wide breakpoint in the kernel - * @cpu_events: the per cpu set of events to unregister - */ -void unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events) -{ - int cpu; - struct perf_event **pevent; - - for_each_possible_cpu(cpu) { - pevent = per_cpu_ptr(cpu_events, cpu); - unregister_hw_breakpoint(*pevent); - } - free_percpu(cpu_events); -} -EXPORT_SYMBOL_GPL(unregister_wide_hw_breakpoint); - -static struct notifier_block hw_breakpoint_exceptions_nb = { - .notifier_call = hw_breakpoint_exceptions_notify, - /* we need to be notified first */ - .priority = 0x7fffffff -}; - -static void bp_perf_event_destroy(struct perf_event *event) -{ - release_bp_slot(event); -} - -static int hw_breakpoint_event_init(struct perf_event *bp) -{ - int err; - - if (bp->attr.type != PERF_TYPE_BREAKPOINT) - return -ENOENT; - - err = register_perf_hw_breakpoint(bp); - if (err) - return err; - - bp->destroy = bp_perf_event_destroy; - - return 0; -} - -static int hw_breakpoint_add(struct perf_event *bp, int flags) -{ - if (!(flags & PERF_EF_START)) - bp->hw.state = PERF_HES_STOPPED; - - return arch_install_hw_breakpoint(bp); -} - -static void hw_breakpoint_del(struct perf_event *bp, int flags) -{ - arch_uninstall_hw_breakpoint(bp); -} - -static void hw_breakpoint_start(struct perf_event *bp, int flags) -{ - bp->hw.state = 0; -} - -static void hw_breakpoint_stop(struct perf_event *bp, int flags) -{ - bp->hw.state = PERF_HES_STOPPED; -} - -static struct pmu perf_breakpoint = { - .task_ctx_nr = perf_sw_context, /* could eventually get its own */ - - .event_init = hw_breakpoint_event_init, - .add = hw_breakpoint_add, - .del = hw_breakpoint_del, - .start = hw_breakpoint_start, - .stop = hw_breakpoint_stop, - .read = hw_breakpoint_pmu_read, -}; - -int __init init_hw_breakpoint(void) -{ - unsigned int **task_bp_pinned; - int cpu, err_cpu; - int i; - - for (i = 0; i < TYPE_MAX; i++) - nr_slots[i] = hw_breakpoint_slots(i); - - for_each_possible_cpu(cpu) { - for (i = 0; i < TYPE_MAX; i++) { - task_bp_pinned = &per_cpu(nr_task_bp_pinned[i], cpu); - *task_bp_pinned = kzalloc(sizeof(int) * nr_slots[i], - GFP_KERNEL); - if (!*task_bp_pinned) - goto err_alloc; - } - } - - constraints_initialized = 1; - - perf_pmu_register(&perf_breakpoint, "breakpoint", PERF_TYPE_BREAKPOINT); - - return register_die_notifier(&hw_breakpoint_exceptions_nb); - - err_alloc: - for_each_possible_cpu(err_cpu) { - if (err_cpu == cpu) - break; - for (i = 0; i < TYPE_MAX; i++) - kfree(per_cpu(nr_task_bp_pinned[i], cpu)); - } - - return -ENOMEM; -} - - -- cgit v1.2.3