diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/Makefile | 1 | ||||
| -rw-r--r-- | kernel/module.c | 66 | ||||
| -rw-r--r-- | kernel/tracepoint.c | 476 |
3 files changed, 542 insertions, 1 deletions
diff --git a/kernel/Makefile b/kernel/Makefile index 4e1d7df7c3e2..8f9ce7ec21b6 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -83,6 +83,7 @@ obj-$(CONFIG_SYSCTL) += utsname_sysctl.o obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o obj-$(CONFIG_TASKSTATS) += taskstats.o tsacct.o obj-$(CONFIG_MARKERS) += marker.o +obj-$(CONFIG_TRACEPOINTS) += tracepoint.o obj-$(CONFIG_LATENCYTOP) += latencytop.o obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += dma-coherent.o obj-$(CONFIG_FTRACE) += trace/ diff --git a/kernel/module.c b/kernel/module.c index 9db11911e04b..661d73db786e 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -46,6 +46,7 @@ #include <asm/cacheflush.h> #include <linux/license.h> #include <asm/sections.h> +#include <linux/tracepoint.h> #if 0 #define DEBUGP printk @@ -1831,6 +1832,8 @@ static noinline struct module *load_module(void __user *umod, #endif unsigned int markersindex; unsigned int markersstringsindex; + unsigned int tracepointsindex; + unsigned int tracepointsstringsindex; struct module *mod; long err = 0; void *percpu = NULL, *ptr = NULL; /* Stops spurious gcc warning */ @@ -2117,6 +2120,9 @@ static noinline struct module *load_module(void __user *umod, markersindex = find_sec(hdr, sechdrs, secstrings, "__markers"); markersstringsindex = find_sec(hdr, sechdrs, secstrings, "__markers_strings"); + tracepointsindex = find_sec(hdr, sechdrs, secstrings, "__tracepoints"); + tracepointsstringsindex = find_sec(hdr, sechdrs, secstrings, + "__tracepoints_strings"); /* Now do relocations. */ for (i = 1; i < hdr->e_shnum; i++) { @@ -2144,6 +2150,12 @@ static noinline struct module *load_module(void __user *umod, mod->num_markers = sechdrs[markersindex].sh_size / sizeof(*mod->markers); #endif +#ifdef CONFIG_TRACEPOINTS + mod->tracepoints = (void *)sechdrs[tracepointsindex].sh_addr; + mod->num_tracepoints = + sechdrs[tracepointsindex].sh_size / sizeof(*mod->tracepoints); +#endif + /* Find duplicate symbols */ err = verify_export_symbols(mod); @@ -2162,11 +2174,16 @@ static noinline struct module *load_module(void __user *umod, add_kallsyms(mod, sechdrs, symindex, strindex, secstrings); + if (!mod->taints) { #ifdef CONFIG_MARKERS - if (!mod->taints) marker_update_probe_range(mod->markers, mod->markers + mod->num_markers); #endif +#ifdef CONFIG_TRACEPOINTS + tracepoint_update_probe_range(mod->tracepoints, + mod->tracepoints + mod->num_tracepoints); +#endif + } err = module_finalize(hdr, sechdrs, mod); if (err < 0) goto cleanup; @@ -2717,3 +2734,50 @@ void module_update_markers(void) mutex_unlock(&module_mutex); } #endif + +#ifdef CONFIG_TRACEPOINTS +void module_update_tracepoints(void) +{ + struct module *mod; + + mutex_lock(&module_mutex); + list_for_each_entry(mod, &modules, list) + if (!mod->taints) + tracepoint_update_probe_range(mod->tracepoints, + mod->tracepoints + mod->num_tracepoints); + mutex_unlock(&module_mutex); +} + +/* + * Returns 0 if current not found. + * Returns 1 if current found. + */ +int module_get_iter_tracepoints(struct tracepoint_iter *iter) +{ + struct module *iter_mod; + int found = 0; + + mutex_lock(&module_mutex); + list_for_each_entry(iter_mod, &modules, list) { + if (!iter_mod->taints) { + /* + * Sorted module list + */ + if (iter_mod < iter->module) + continue; + else if (iter_mod > iter->module) + iter->tracepoint = NULL; + found = tracepoint_get_iter_range(&iter->tracepoint, + iter_mod->tracepoints, + iter_mod->tracepoints + + iter_mod->num_tracepoints); + if (found) { + iter->module = iter_mod; + break; + } + } + } + mutex_unlock(&module_mutex); + return found; +} +#endif diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c new file mode 100644 index 000000000000..42e86ddbd2a0 --- /dev/null +++ b/kernel/tracepoint.c @@ -0,0 +1,476 @@ +/* + * Copyright (C) 2008 Mathieu Desnoyers + * + * 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. + */ +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/types.h> +#include <linux/jhash.h> +#include <linux/list.h> +#include <linux/rcupdate.h> +#include <linux/tracepoint.h> +#include <linux/err.h> +#include <linux/slab.h> + +extern struct tracepoint __start___tracepoints[]; +extern struct tracepoint __stop___tracepoints[]; + +/* Set to 1 to enable tracepoint debug output */ +static const int tracepoint_debug; + +/* + * tracepoints_mutex nests inside module_mutex. Tracepoints mutex protects the + * builtin and module tracepoints and the hash table. + */ +static DEFINE_MUTEX(tracepoints_mutex); + +/* + * Tracepoint hash table, containing the active tracepoints. + * Protected by tracepoints_mutex. + */ +#define TRACEPOINT_HASH_BITS 6 +#define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS) + +/* + * Note about RCU : + * It is used to to delay the free of multiple probes array until a quiescent + * state is reached. + * Tracepoint entries modifications are protected by the tracepoints_mutex. + */ +struct tracepoint_entry { + struct hlist_node hlist; + void **funcs; + int refcount; /* Number of times armed. 0 if disarmed. */ + struct rcu_head rcu; + void *oldptr; + unsigned char rcu_pending:1; + char name[0]; +}; + +static struct hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE]; + +static void free_old_closure(struct rcu_head *head) +{ + struct tracepoint_entry *entry = container_of(head, + struct tracepoint_entry, rcu); + kfree(entry->oldptr); + /* Make sure we free the data before setting the pending flag to 0 */ + smp_wmb(); + entry->rcu_pending = 0; +} + +static void tracepoint_entry_free_old(struct tracepoint_entry *entry, void *old) +{ + if (!old) + return; + entry->oldptr = old; + entry->rcu_pending = 1; + /* write rcu_pending before calling the RCU callback */ + smp_wmb(); +#ifdef CONFIG_PREEMPT_RCU + synchronize_sched(); /* Until we have the call_rcu_sched() */ +#endif + call_rcu(&entry->rcu, free_old_closure); +} + +static void debug_print_probes(struct tracepoint_entry *entry) +{ + int i; + + if (!tracepoint_debug) + return; + + for (i = 0; entry->funcs[i]; i++) + printk(KERN_DEBUG "Probe %d : %p\n", i, entry->funcs[i]); +} + +static void * +tracepoint_entry_add_probe(struct tracepoint_entry *entry, void *probe) +{ + int nr_probes = 0; + void **old, **new; + + WARN_ON(!probe); + + debug_print_probes(entry); + old = entry->funcs; + if (old) { + /* (N -> N+1), (N != 0, 1) probes */ + for (nr_probes = 0; old[nr_probes]; nr_probes++) + if (old[nr_probes] == probe) + return ERR_PTR(-EEXIST); + } + /* + 2 : one for new probe, one for NULL func */ + new = kzalloc((nr_probes + 2) * sizeof(void *), GFP_KERNEL); + if (new == NULL) + return ERR_PTR(-ENOMEM); + if (old) + memcpy(new, old, nr_probes * sizeof(void *)); + new[nr_probes] = probe; + entry->refcount = nr_probes + 1; + entry->funcs = new; + debug_print_probes(entry); + return old; +} + +static void * +tracepoint_entry_remove_probe(struct tracepoint_entry *entry, void *probe) +{ + int nr_probes = 0, nr_del = 0, i; + void **old, **new; + + old = entry->funcs; + + debug_print_probes(entry); + /* (N -> M), (N > 1, M >= 0) probes */ + for (nr_probes = 0; old[nr_probes]; nr_probes++) { + if ((!probe || old[nr_probes] == probe)) + nr_del++; + } + + if (nr_probes - nr_del == 0) { + /* N -> 0, (N > 1) */ + entry->funcs = NULL; + entry->refcount = 0; + debug_print_probes(entry); + return old; + } else { + int j = 0; + /* N -> M, (N > 1, M > 0) */ + /* + 1 for NULL */ + new = kzalloc((nr_probes - nr_del + 1) + * sizeof(void *), GFP_KERNEL); + if (new == NULL) + return ERR_PTR(-ENOMEM); + for (i = 0; old[i]; i++) + if ((probe && old[i] != probe)) + new[j++] = old[i]; + entry->refcount = nr_probes - nr_del; + entry->funcs = new; + } + debug_print_probes(entry); + return old; +} + +/* + * Get tracepoint if the tracepoint is present in the tracepoint hash table. + * Must be called with tracepoints_mutex held. + * Returns NULL if not present. + */ +static struct tracepoint_entry *get_tracepoint(const char *name) +{ + struct hlist_head *head; + struct hlist_node *node; + struct tracepoint_entry *e; + u32 hash = jhash(name, strlen(name), 0); + + head = &tracepoint_table[hash & ((1 << TRACEPOINT_HASH_BITS)-1)]; + hlist_for_each_entry(e, node, head, hlist) { + if (!strcmp(name, e->name)) + return e; + } + return NULL; +} + +/* + * Add the tracepoint to the tracepoint hash table. Must be called with + * tracepoints_mutex held. + */ +static struct tracepoint_entry *add_tracepoint(const char *name) +{ + struct hlist_head *head; + struct hlist_node *node; + struct tracepoint_entry *e; + size_t name_len = strlen(name) + 1; + u32 hash = jhash(name, name_len-1, 0); + + head = &tracepoint_table[hash & ((1 << TRACEPOINT_HASH_BITS)-1)]; + hlist_for_each_entry(e, node, head, hlist) { + if (!strcmp(name, e->name)) { + printk(KERN_NOTICE + "tracepoint %s busy\n", name); + return ERR_PTR(-EEXIST); /* Already there */ + } + } + /* + * Using kmalloc here to allocate a variable length element. Could + * cause some memory fragmentation if overused. + */ + e = kmalloc(sizeof(struct tracepoint_entry) + name_len, GFP_KERNEL); + if (!e) + return ERR_PTR(-ENOMEM); + memcpy(&e->name[0], name, name_len); + e->funcs = NULL; + e->refcount = 0; + e->rcu_pending = 0; + hlist_add_head(&e->hlist, head); + return e; +} + +/* + * Remove the tracepoint from the tracepoint hash table. Must be called with + * mutex_lock held. + */ +static int remove_tracepoint(const char *name) +{ + struct hlist_head *head; + struct hlist_node *node; + struct tracepoint_entry *e; + int found = 0; + size_t len = strlen(name) + 1; + u32 hash = jhash(name, len-1, 0); + + head = &tracepoint_table[hash & ((1 << TRACEPOINT_HASH_BITS)-1)]; + hlist_for_each_entry(e, node, head, hlist) { + if (!strcmp(name, e->name)) { + found = 1; + break; + } + } + if (!found) + return -ENOENT; + if (e->refcount) + return -EBUSY; + hlist_del(&e->hlist); + /* Make sure the call_rcu has been executed */ + if (e->rcu_pending) + rcu_barrier(); + kfree(e); + return 0; +} + +/* + * Sets the probe callback corresponding to one tracepoint. + */ +static void set_tracepoint(struct tracepoint_entry **entry, + struct tracepoint *elem, int active) +{ + WARN_ON(strcmp((*entry)->name, elem->name) != 0); + + /* + * rcu_assign_pointer has a smp_wmb() which makes sure that the new + * probe callbacks array is consistent before setting a pointer to it. + * This array is referenced by __DO_TRACE from + * include/linux/tracepoints.h. A matching smp_read_barrier_depends() + * is used. + */ + rcu_assign_pointer(elem->funcs, (*entry)->funcs); + elem->state = active; +} + +/* + * Disable a tracepoint and its probe callback. + * Note: only waiting an RCU period after setting elem->call to the empty + * function insures that the original callback is not used anymore. This insured + * by preempt_disable around the call site. + */ +static void disable_tracepoint(struct tracepoint *elem) +{ + elem->state = 0; +} + +/** + * tracepoint_update_probe_range - Update a probe range + * @begin: beginning of the range + * @end: end of the range + * + * Updates the probe callback corresponding to a range of tracepoints. + */ +void tracepoint_update_probe_range(struct tracepoint *begin, + struct tracepoint *end) +{ + struct tracepoint *iter; + struct tracepoint_entry *mark_entry; + + mutex_lock(&tracepoints_mutex); + for (iter = begin; iter < end; iter++) { + mark_entry = get_tracepoint(iter->name); + if (mark_entry) { + set_tracepoint(&mark_entry, iter, + !!mark_entry->refcount); + } else { + disable_tracepoint(iter); + } + } + mutex_unlock(&tracepoints_mutex); +} + +/* + * Update probes, removing the faulty probes. + */ +static void tracepoint_update_probes(void) +{ + /* Core kernel tracepoints */ + tracepoint_update_probe_range(__start___tracepoints, + __stop___tracepoints); + /* tracepoints in modules. */ + module_update_tracepoints(); +} + +/** + * tracepoint_probe_register - Connect a probe to a tracepoint + * @name: tracepoint name + * @probe: probe handler + * + * Returns 0 if ok, error value on error. + * The probe address must at least be aligned on the architecture pointer size. + */ +int tracepoint_probe_register(const char *name, void *probe) +{ + struct tracepoint_entry *entry; + int ret = 0; + void *old; + + mutex_lock(&tracepoints_mutex); + entry = get_tracepoint(name); + if (!entry) { + entry = add_tracepoint(name); + if (IS_ERR(entry)) { + ret = PTR_ERR(entry); + goto end; + } + } + /* + * If we detect that a call_rcu is pending for this tracepoint, + * make sure it's executed now. + */ + if (entry->rcu_pending) + rcu_barrier(); + old = tracepoint_entry_add_probe(entry, probe); + if (IS_ERR(old)) { + ret = PTR_ERR(old); + goto end; + } + mutex_unlock(&tracepoints_mutex); + tracepoint_update_probes(); /* may update entry */ + mutex_lock(&tracepoints_mutex); + entry = get_tracepoint(name); + WARN_ON(!entry); + tracepoint_entry_free_old(entry, old); +end: + mutex_unlock(&tracepoints_mutex); + return ret; +} +EXPORT_SYMBOL_GPL(tracepoint_probe_register); + +/** + * tracepoint_probe_unregister - Disconnect a probe from a tracepoint + * @name: tracepoint name + * @probe: probe function pointer + * + * We do not need to call a synchronize_sched to make sure the probes have + * finished running before doing a module unload, because the module unload + * itself uses stop_machine(), which insures that every preempt disabled section + * have finished. + */ +int tracepoint_probe_unregister(const char *name, void *probe) +{ + struct tracepoint_entry *entry; + void *old; + int ret = -ENOENT; + + mutex_lock(&tracepoints_mutex); + entry = get_tracepoint(name); + if (!entry) + goto end; + if (entry->rcu_pending) + rcu_barrier(); + old = tracepoint_entry_remove_probe(entry, probe); + mutex_unlock(&tracepoints_mutex); + tracepoint_update_probes(); /* may update entry */ + mutex_lock(&tracepoints_mutex); + entry = get_tracepoint(name); + if (!entry) + goto end; + tracepoint_entry_free_old(entry, old); + remove_tracepoint(name); /* Ignore busy error message */ + ret = 0; +end: + mutex_unlock(&tracepoints_mutex); + return ret; +} +EXPORT_SYMBOL_GPL(tracepoint_probe_unregister); + +/** + * tracepoint_get_iter_range - Get a next tracepoint iterator given a range. + * @tracepoint: current tracepoints (in), next tracepoint (out) + * @begin: beginning of the range + * @end: end of the range + * + * Returns whether a next tracepoint has been found (1) or not (0). + * Will return the first tracepoint in the range if the input tracepoint is + * NULL. + */ +int tracepoint_get_iter_range(struct tracepoint **tracepoint, + struct tracepoint *begin, struct tracepoint *end) +{ + if (!*tracepoint && begin != end) { + *tracepoint = begin; + return 1; + } + if (*tracepoint >= begin && *tracepoint < end) + return 1; + return 0; +} +EXPORT_SYMBOL_GPL(tracepoint_get_iter_range); + +static void tracepoint_get_iter(struct tracepoint_iter *iter) +{ + int found = 0; + + /* Core kernel tracepoints */ + if (!iter->module) { + found = tracepoint_get_iter_range(&iter->tracepoint, + __start___tracepoints, __stop___tracepoints); + if (found) + goto end; + } + /* tracepoints in modules. */ + found = module_get_iter_tracepoints(iter); +end: + if (!found) + tracepoint_iter_reset(iter); +} + +void tracepoint_iter_start(struct tracepoint_iter *iter) +{ + tracepoint_get_iter(iter); +} +EXPORT_SYMBOL_GPL(tracepoint_iter_start); + +void tracepoint_iter_next(struct tracepoint_iter *iter) +{ + iter->tracepoint++; + /* + * iter->tracepoint may be invalid because we blindly incremented it. + * Make sure it is valid by marshalling on the tracepoints, getting the + * tracepoints from following modules if necessary. + */ + tracepoint_get_iter(iter); +} +EXPORT_SYMBOL_GPL(tracepoint_iter_next); + +void tracepoint_iter_stop(struct tracepoint_iter *iter) +{ +} +EXPORT_SYMBOL_GPL(tracepoint_iter_stop); + +void tracepoint_iter_reset(struct tracepoint_iter *iter) +{ + iter->module = NULL; + iter->tracepoint = NULL; +} +EXPORT_SYMBOL_GPL(tracepoint_iter_reset); |
