*
* Copyright (C) 2007 Alan Stern
* Copyright (C) IBM Corporation, 2009
+ * Copyright (C) 2009, Frederic Weisbecker <fweisbec@gmail.com>
*/
/*
#include <linux/init.h>
#include <linux/smp.h>
-#include <asm/hw_breakpoint.h>
+#include <linux/hw_breakpoint.h>
+
#include <asm/processor.h>
#ifdef CONFIG_X86
#include <asm/debugreg.h>
#endif
-/*
- * Spinlock that protects all (un)register operations over kernel/user-space
- * breakpoint requests
- */
-static DEFINE_SPINLOCK(hw_breakpoint_lock);
-
-/* Array of kernel-space breakpoint structures */
-struct hw_breakpoint *hbp_kernel[HBP_NUM];
-
-/*
- * Per-processor copy of hbp_kernel[]. Used only when hbp_kernel is being
- * modified but we need the older copy to handle any hbp exceptions. It will
- * sync with hbp_kernel[] value after updation is done through IPIs.
- */
-DEFINE_PER_CPU(struct hw_breakpoint*, this_hbp_kernel[HBP_NUM]);
-
-/*
- * Kernel breakpoints grow downwards, starting from HBP_NUM
- * 'hbp_kernel_pos' denotes lowest numbered breakpoint register occupied for
- * kernel-space request. We will initialise it here and not in an __init
- * routine because load_debug_registers(), which uses this variable can be
- * called very early during CPU initialisation.
- */
-unsigned int hbp_kernel_pos = HBP_NUM;
-/*
- * An array containing refcount of threads using a given bkpt register
- * Accesses are synchronised by acquiring hw_breakpoint_lock
- */
-unsigned int hbp_user_refcount[HBP_NUM];
+static atomic_t bp_slot;
-/*
- * Load the debug registers during startup of a CPU.
- */
-void load_debug_registers(void)
+int reserve_bp_slot(struct perf_event *bp)
{
- unsigned long flags;
- struct task_struct *tsk = current;
-
- spin_lock_bh(&hw_breakpoint_lock);
-
- /* Prevent IPIs for new kernel breakpoint updates */
- local_irq_save(flags);
- arch_update_kernel_hw_breakpoint(NULL);
- local_irq_restore(flags);
-
- if (test_tsk_thread_flag(tsk, TIF_DEBUG))
- arch_install_thread_hw_breakpoint(tsk);
-
- spin_unlock_bh(&hw_breakpoint_lock);
-}
+ if (atomic_inc_return(&bp_slot) == HBP_NUM) {
+ atomic_dec(&bp_slot);
-/*
- * Erase all the hardware breakpoint info associated with a thread.
- *
- * If tsk != current then tsk must not be usable (for example, a
- * child being cleaned up from a failed fork).
- */
-void flush_thread_hw_breakpoint(struct task_struct *tsk)
-{
- int i;
- struct thread_struct *thread = &(tsk->thread);
-
- spin_lock_bh(&hw_breakpoint_lock);
-
- /* The thread no longer has any breakpoints associated with it */
- clear_tsk_thread_flag(tsk, TIF_DEBUG);
- for (i = 0; i < HBP_NUM; i++) {
- if (thread->hbp[i]) {
- hbp_user_refcount[i]--;
- kfree(thread->hbp[i]);
- thread->hbp[i] = NULL;
- }
+ return -ENOSPC;
}
- arch_flush_thread_hw_breakpoint(tsk);
-
- /* Actually uninstall the breakpoints if necessary */
- if (tsk == current)
- arch_uninstall_thread_hw_breakpoint();
- spin_unlock_bh(&hw_breakpoint_lock);
+ return 0;
}
-/*
- * Copy the hardware breakpoint info from a thread to its cloned child.
- */
-int copy_thread_hw_breakpoint(struct task_struct *tsk,
- struct task_struct *child, unsigned long clone_flags)
+void release_bp_slot(struct perf_event *bp)
{
- /*
- * We will assume that breakpoint settings are not inherited
- * and the child starts out with no debug registers set.
- * But what about CLONE_PTRACE?
- */
- clear_tsk_thread_flag(child, TIF_DEBUG);
-
- /* We will call flush routine since the debugregs are not inherited */
- arch_flush_thread_hw_breakpoint(child);
-
- return 0;
+ atomic_dec(&bp_slot);
}
-static int __register_user_hw_breakpoint(int pos, struct task_struct *tsk,
- struct hw_breakpoint *bp)
+int __register_perf_hw_breakpoint(struct perf_event *bp)
{
- struct thread_struct *thread = &(tsk->thread);
- int rc;
+ int ret;
- /* Do not overcommit. Fail if kernel has used the hbp registers */
- if (pos >= hbp_kernel_pos)
- return -ENOSPC;
+ ret = reserve_bp_slot(bp);
+ if (ret)
+ return ret;
- rc = arch_validate_hwbkpt_settings(bp, tsk);
- if (rc)
- return rc;
+ if (!bp->attr.disabled)
+ ret = arch_validate_hwbkpt_settings(bp, bp->ctx->task);
- thread->hbp[pos] = bp;
- hbp_user_refcount[pos]++;
+ return ret;
+}
- arch_update_user_hw_breakpoint(pos, tsk);
- /*
- * Does it need to be installed right now?
- * Otherwise it will get installed the next time tsk runs
- */
- if (tsk == current)
- arch_install_thread_hw_breakpoint(tsk);
+int register_perf_hw_breakpoint(struct perf_event *bp)
+{
+ bp->callback = perf_bp_event;
- return rc;
+ return __register_perf_hw_breakpoint(bp);
}
/*
- * Modify the address of a hbp register already in use by the task
- * Do not invoke this in-lieu of a __unregister_user_hw_breakpoint()
+ * Register a breakpoint bound to a task and a given cpu.
+ * If cpu is -1, the breakpoint is active for the task in every cpu
+ * If the task is -1, the breakpoint is active for every tasks in the given
+ * cpu.
*/
-static int __modify_user_hw_breakpoint(int pos, struct task_struct *tsk,
- struct hw_breakpoint *bp)
+static struct perf_event *
+register_user_hw_breakpoint_cpu(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ pid_t pid,
+ int cpu,
+ bool active)
{
- struct thread_struct *thread = &(tsk->thread);
-
- if ((pos >= hbp_kernel_pos) || (arch_validate_hwbkpt_settings(bp, tsk)))
- return -EINVAL;
-
- if (thread->hbp[pos] == NULL)
- return -EINVAL;
-
- thread->hbp[pos] = bp;
+ struct perf_event_attr *attr;
+ struct perf_event *bp;
+
+ attr = kzalloc(sizeof(*attr), GFP_KERNEL);
+ if (!attr)
+ return ERR_PTR(-ENOMEM);
+
+ attr->type = PERF_TYPE_BREAKPOINT;
+ attr->size = sizeof(*attr);
+ attr->bp_addr = addr;
+ attr->bp_len = len;
+ attr->bp_type = type;
/*
- * 'pos' must be that of a hbp register already used by 'tsk'
- * Otherwise arch_modify_user_hw_breakpoint() will fail
+ * Such breakpoints are used by debuggers to trigger signals when
+ * we hit the excepted memory op. We can't miss such events, they
+ * must be pinned.
*/
- arch_update_user_hw_breakpoint(pos, tsk);
+ attr->pinned = 1;
- if (tsk == current)
- arch_install_thread_hw_breakpoint(tsk);
+ if (!active)
+ attr->disabled = 1;
- return 0;
-}
-
-static void __unregister_user_hw_breakpoint(int pos, struct task_struct *tsk)
-{
- hbp_user_refcount[pos]--;
- tsk->thread.hbp[pos] = NULL;
+ bp = perf_event_create_kernel_counter(attr, cpu, pid, triggered);
+ kfree(attr);
- arch_update_user_hw_breakpoint(pos, tsk);
-
- if (tsk == current)
- arch_install_thread_hw_breakpoint(tsk);
+ return bp;
}
/**
* register_user_hw_breakpoint - register a hardware breakpoint for user space
+ * @addr: is the memory address that triggers the breakpoint
+ * @len: the length of the access to the memory (1 byte, 2 bytes etc...)
+ * @type: the type of the access to the memory (read/write/exec)
+ * @triggered: callback to trigger when we hit the breakpoint
* @tsk: pointer to 'task_struct' of the process to which the address belongs
- * @bp: the breakpoint structure to register
- *
- * @bp.info->name or @bp.info->address, @bp.info->len, @bp.info->type and
- * @bp->triggered must be set properly before invocation
+ * @active: should we activate it while registering it
*
*/
-int register_user_hw_breakpoint(struct task_struct *tsk,
- struct hw_breakpoint *bp)
+struct perf_event *
+register_user_hw_breakpoint(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ struct task_struct *tsk,
+ bool active)
{
- struct thread_struct *thread = &(tsk->thread);
- int i, rc = -ENOSPC;
-
- spin_lock_bh(&hw_breakpoint_lock);
-
- for (i = 0; i < hbp_kernel_pos; i++) {
- if (!thread->hbp[i]) {
- rc = __register_user_hw_breakpoint(i, tsk, bp);
- break;
- }
- }
- if (!rc)
- set_tsk_thread_flag(tsk, TIF_DEBUG);
-
- spin_unlock_bh(&hw_breakpoint_lock);
- return rc;
+ return register_user_hw_breakpoint_cpu(addr, len, type, triggered,
+ tsk->pid, -1, active);
}
EXPORT_SYMBOL_GPL(register_user_hw_breakpoint);
/**
* modify_user_hw_breakpoint - modify a user-space hardware breakpoint
+ * @bp: the breakpoint structure to modify
+ * @addr: is the memory address that triggers the breakpoint
+ * @len: the length of the access to the memory (1 byte, 2 bytes etc...)
+ * @type: the type of the access to the memory (read/write/exec)
+ * @triggered: callback to trigger when we hit the breakpoint
* @tsk: pointer to 'task_struct' of the process to which the address belongs
- * @bp: the breakpoint structure to unregister
- *
+ * @active: should we activate it while registering it
*/
-int modify_user_hw_breakpoint(struct task_struct *tsk, struct hw_breakpoint *bp)
+struct perf_event *
+modify_user_hw_breakpoint(struct perf_event *bp,
+ unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ struct task_struct *tsk,
+ bool active)
{
- struct thread_struct *thread = &(tsk->thread);
- int i, ret = -ENOENT;
+ /*
+ * FIXME: do it without unregistering
+ * - We don't want to lose our slot
+ * - If the new bp is incorrect, don't lose the older one
+ */
+ unregister_hw_breakpoint(bp);
- spin_lock_bh(&hw_breakpoint_lock);
- for (i = 0; i < hbp_kernel_pos; i++) {
- if (bp == thread->hbp[i]) {
- ret = __modify_user_hw_breakpoint(i, tsk, bp);
- break;
- }
- }
- spin_unlock_bh(&hw_breakpoint_lock);
- return ret;
+ return register_user_hw_breakpoint(addr, len, type, triggered,
+ tsk, active);
}
EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint);
/**
- * unregister_user_hw_breakpoint - unregister a user-space hardware breakpoint
- * @tsk: pointer to 'task_struct' of the process to which the address belongs
+ * unregister_hw_breakpoint - unregister a user-space hardware breakpoint
* @bp: the breakpoint structure to unregister
- *
*/
-void unregister_user_hw_breakpoint(struct task_struct *tsk,
- struct hw_breakpoint *bp)
+void unregister_hw_breakpoint(struct perf_event *bp)
{
- struct thread_struct *thread = &(tsk->thread);
- int i, pos = -1, hbp_counter = 0;
-
- spin_lock_bh(&hw_breakpoint_lock);
- for (i = 0; i < hbp_kernel_pos; i++) {
- if (thread->hbp[i])
- hbp_counter++;
- if (bp == thread->hbp[i])
- pos = i;
- }
- if (pos >= 0) {
- __unregister_user_hw_breakpoint(pos, tsk);
- hbp_counter--;
- }
- if (!hbp_counter)
- clear_tsk_thread_flag(tsk, TIF_DEBUG);
-
- spin_unlock_bh(&hw_breakpoint_lock);
+ if (!bp)
+ return;
+ perf_event_release_kernel(bp);
+}
+EXPORT_SYMBOL_GPL(unregister_hw_breakpoint);
+
+static struct perf_event *
+register_kernel_hw_breakpoint_cpu(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ int cpu,
+ bool active)
+{
+ return register_user_hw_breakpoint_cpu(addr, len, type, triggered,
+ -1, cpu, active);
}
-EXPORT_SYMBOL_GPL(unregister_user_hw_breakpoint);
/**
- * register_kernel_hw_breakpoint - register a hardware breakpoint for kernel space
- * @bp: the breakpoint structure to register
- *
- * @bp.info->name or @bp.info->address, @bp.info->len, @bp.info->type and
- * @bp->triggered must be set properly before invocation
+ * register_wide_hw_breakpoint - register a wide breakpoint in the kernel
+ * @addr: is the memory address that triggers the breakpoint
+ * @len: the length of the access to the memory (1 byte, 2 bytes etc...)
+ * @type: the type of the access to the memory (read/write/exec)
+ * @triggered: callback to trigger when we hit the breakpoint
+ * @active: should we activate it while registering it
*
+ * @return a set of per_cpu pointers to perf events
*/
-int register_kernel_hw_breakpoint(struct hw_breakpoint *bp)
+struct perf_event **
+register_wide_hw_breakpoint(unsigned long addr,
+ int len,
+ int type,
+ perf_callback_t triggered,
+ bool active)
{
- int rc;
+ struct perf_event **cpu_events, **pevent, *bp;
+ long err;
+ int cpu;
+
+ cpu_events = alloc_percpu(typeof(*cpu_events));
+ if (!cpu_events)
+ return ERR_PTR(-ENOMEM);
- rc = arch_validate_hwbkpt_settings(bp, NULL);
- if (rc)
- return rc;
+ for_each_possible_cpu(cpu) {
+ pevent = per_cpu_ptr(cpu_events, cpu);
+ bp = register_kernel_hw_breakpoint_cpu(addr, len, type,
+ triggered, cpu, active);
- spin_lock_bh(&hw_breakpoint_lock);
+ *pevent = bp;
- rc = -ENOSPC;
- /* Check if we are over-committing */
- if ((hbp_kernel_pos > 0) && (!hbp_user_refcount[hbp_kernel_pos-1])) {
- hbp_kernel_pos--;
- hbp_kernel[hbp_kernel_pos] = bp;
- on_each_cpu(arch_update_kernel_hw_breakpoint, NULL, 1);
- rc = 0;
+ if (IS_ERR(bp) || !bp) {
+ err = PTR_ERR(bp);
+ goto fail;
+ }
}
- spin_unlock_bh(&hw_breakpoint_lock);
- return rc;
+ return cpu_events;
+
+fail:
+ for_each_possible_cpu(cpu) {
+ pevent = per_cpu_ptr(cpu_events, cpu);
+ if (IS_ERR(*pevent) || !*pevent)
+ break;
+ unregister_hw_breakpoint(*pevent);
+ }
+ free_percpu(cpu_events);
+ /* return the error if any */
+ return ERR_PTR(err);
}
-EXPORT_SYMBOL_GPL(register_kernel_hw_breakpoint);
/**
- * unregister_kernel_hw_breakpoint - unregister a HW breakpoint for kernel space
- * @bp: the breakpoint structure to unregister
- *
- * Uninstalls and unregisters @bp.
+ * unregister_wide_hw_breakpoint - unregister a wide breakpoint in the kernel
+ * @cpu_events: the per cpu set of events to unregister
*/
-void unregister_kernel_hw_breakpoint(struct hw_breakpoint *bp)
+void unregister_wide_hw_breakpoint(struct perf_event **cpu_events)
{
- int i, j;
-
- spin_lock_bh(&hw_breakpoint_lock);
-
- /* Find the 'bp' in our list of breakpoints for kernel */
- for (i = hbp_kernel_pos; i < HBP_NUM; i++)
- if (bp == hbp_kernel[i])
- break;
+ int cpu;
+ struct perf_event **pevent;
- /* Check if we did not find a match for 'bp'. If so return early */
- if (i == HBP_NUM) {
- spin_unlock_bh(&hw_breakpoint_lock);
- return;
+ for_each_possible_cpu(cpu) {
+ pevent = per_cpu_ptr(cpu_events, cpu);
+ unregister_hw_breakpoint(*pevent);
}
-
- /*
- * We'll shift the breakpoints one-level above to compact if
- * unregistration creates a hole
- */
- for (j = i; j > hbp_kernel_pos; j--)
- hbp_kernel[j] = hbp_kernel[j-1];
-
- hbp_kernel[hbp_kernel_pos] = NULL;
- on_each_cpu(arch_update_kernel_hw_breakpoint, NULL, 1);
- hbp_kernel_pos++;
-
- spin_unlock_bh(&hw_breakpoint_lock);
+ free_percpu(cpu_events);
}
-EXPORT_SYMBOL_GPL(unregister_kernel_hw_breakpoint);
+
static struct notifier_block hw_breakpoint_exceptions_nb = {
.notifier_call = hw_breakpoint_exceptions_notify,
{
return register_die_notifier(&hw_breakpoint_exceptions_nb);
}
-
core_initcall(init_hw_breakpoint);
+
+
+struct pmu perf_ops_bp = {
+ .enable = arch_install_hw_breakpoint,
+ .disable = arch_uninstall_hw_breakpoint,
+ .read = hw_breakpoint_pmu_read,
+ .unthrottle = hw_breakpoint_pmu_unthrottle
+};
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff