[patch 1/4] Linux Kernel Markers - Architecture Independent Code
From: Mathieu Desnoyers
Date: Sun Aug 12 2007 - 11:19:44 EST
The marker activation functions sits in kernel/marker.c. A hash table is used
to keep track of the registered probes and armed markers, so the markers within
a newly loaded module that should be active can be activated at module load
time.
marker_query has been removed. marker_get_first, marker_get_next and
marker_release should be used as iterators on the markers.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx>
---
include/asm-generic/vmlinux.lds.h | 11
include/linux/marker.h | 170 +++++++++
include/linux/module.h | 5
kernel/marker.c | 678 ++++++++++++++++++++++++++++++++++++++
kernel/module.c | 19 +
5 files changed, 882 insertions(+), 1 deletion(-)
Index: linux-2.6-lttng/include/asm-generic/vmlinux.lds.h
===================================================================
--- linux-2.6-lttng.orig/include/asm-generic/vmlinux.lds.h 2007-08-10 19:44:17.000000000 -0400
+++ linux-2.6-lttng/include/asm-generic/vmlinux.lds.h 2007-08-10 19:44:18.000000000 -0400
@@ -12,7 +12,11 @@
/* .data section */
#define DATA_DATA \
*(.data) \
- *(.data.init.refok)
+ *(.data.init.refok) \
+ . = ALIGN(8); \
+ VMLINUX_SYMBOL(__start___markers) = .; \
+ *(__markers) \
+ VMLINUX_SYMBOL(__stop___markers) = .;
#define RO_DATA(align) \
. = ALIGN((align)); \
@@ -129,6 +133,11 @@
VMLINUX_SYMBOL(__stop___immediate) = .; \
} \
\
+ /* Markers: strings */ \
+ __markers_strings : AT(ADDR(__markers_strings) - LOAD_OFFSET) { \
+ *(__markers_strings) \
+ } \
+ \
/* Kernel symbol table: strings */ \
__ksymtab_strings : AT(ADDR(__ksymtab_strings) - LOAD_OFFSET) { \
*(__ksymtab_strings) \
Index: linux-2.6-lttng/include/linux/marker.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6-lttng/include/linux/marker.h 2007-08-10 23:54:35.000000000 -0400
@@ -0,0 +1,170 @@
+#ifndef _LINUX_MARKER_H
+#define _LINUX_MARKER_H
+
+/*
+ * Code markup for dynamic and static tracing.
+ *
+ * See Documentation/marker.txt.
+ *
+ * (C) Copyright 2006 Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx>
+ *
+ * This file is released under the GPLv2.
+ * See the file COPYING for more details.
+ */
+
+#include <linux/immediate.h>
+#include <linux/types.h>
+
+struct module;
+struct __mark_marker;
+
+/**
+ * marker_probe_func - Type of a marker probe function
+ * @mdata: pointer of type struct __mark_marker
+ * @private_data: caller site private data
+ * @fmt: format string
+ * @...: variable argument list
+ *
+ * Type of marker probe functions. They receive the mdata and need to parse the
+ * format string to recover the variable argument list.
+ */
+typedef void marker_probe_func(const struct __mark_marker *mdata,
+ void *private_data, const char *fmt, ...);
+
+struct __mark_marker {
+ const char *name; /* Marker name */
+ const char *format; /* Marker format string, describing the
+ * variable argument list.
+ */
+ const char *args; /* List of arguments litteraly transformed
+ * into a string: "arg1, arg2, arg3".
+ */
+ immediate_char_t state; /* Immediate value state. */
+ marker_probe_func *call;/* Probe handler function pointer */
+ void *pdata; /* Private probe data */
+} __attribute__((aligned(8)));
+
+#ifdef CONFIG_MARKERS
+
+/*
+ * Generic marker flavor always available.
+ * Note : the empty asm volatile with read constraint is used here instead of a
+ * "used" attribute to fix a gcc 4.1.x bug.
+ * Make sure the alignment of the structure in the __markers section will
+ * not add unwanted padding between the beginning of the section and the
+ * structure. Force alignment to the same alignment as the section start.
+ */
+#define __trace_mark(generic, name, call_data, format, args...) \
+ do { \
+ static const char __mstrtab_name_##name[] \
+ __attribute__((section("__markers_strings"))) \
+ = #name; \
+ static const char __mstrtab_format_##name[] \
+ __attribute__((section("__markers_strings"))) \
+ = format; \
+ static const char __mstrtab_args_##name[] \
+ __attribute__((section("__markers_strings"))) \
+ = #args; \
+ static struct __mark_marker __mark_##name \
+ __attribute__((section("__markers"))) = \
+ { __mstrtab_name_##name, __mstrtab_format_##name, \
+ __mstrtab_args_##name, { 0 }, \
+ __mark_empty_function, NULL }; \
+ asm volatile ( "" : : "i" (&__mark_##name)); \
+ __mark_check_format(format, ## args); \
+ if (!generic) { \
+ immediate_if (&__mark_##name.state) { \
+ preempt_disable(); \
+ (*__mark_##name.call) \
+ (&__mark_##name, call_data, \
+ format, ## args); \
+ preempt_enable(); \
+ } \
+ } else { \
+ _immediate_if (&__mark_##name.state) { \
+ preempt_disable(); \
+ (*__mark_##name.call) \
+ (&__mark_##name, call_data, \
+ format, ## args); \
+ preempt_enable(); \
+ } \
+ } \
+ } while (0)
+
+extern void module_marker_update(struct module *mod);
+#else /* !CONFIG_MARKERS */
+#define __trace_mark(generic, name, call_data, format, args...) \
+ __mark_check_format(format, ## args)
+static inline void module_marker_update(struct module *mod) { }
+#endif /* CONFIG_MARKERS */
+
+/**
+ * trace_mark - Marker using code patching
+ * @name: marker name, not quoted.
+ * @format: format string
+ * @args...: variable argument list
+ *
+ * Places a marker using optimized code patching technique (immediate_if ())
+ * to be enabled.
+ */
+#define trace_mark(name, format, args...) \
+ __trace_mark(0, name, NULL, format, ## args)
+
+/**
+ * _trace_mark - Marker using variable read
+ * @name: marker name, not quoted.
+ * @format: format string
+ * @args...: variable argument list
+ *
+ * Places a marker using a standard memory read (_immediate_if ()) to be
+ * enabled. Should be used for markers in __init and __exit functions and in
+ * lockdep code.
+ */
+#define _trace_mark(name, format, args...) \
+ __trace_mark(1, name, NULL, format, ## args)
+
+#define MARK_MAX_FORMAT_LEN 1024
+
+/**
+ * MARK_NOARGS - Format string for a marker with no argument.
+ */
+#define MARK_NOARGS " "
+
+/* To be used for string format validity checking with gcc */
+static inline void __mark_check_format(const char *fmt, ...)
+ __attribute__ ((format (printf, 1, 2)));
+static inline void __mark_check_format(const char *fmt, ...) { }
+
+extern marker_probe_func __mark_empty_function;
+
+/*
+ * Connect a probe to a markers.
+ * pdata must be a valid allocated memory address, or NULL.
+ */
+extern int marker_probe_register(const char *name, const char *format,
+ marker_probe_func *probe, void *pdata);
+
+/*
+ * Returns the pdata given to marker_probe_register.
+ */
+extern void *marker_probe_unregister(const char *name);
+/*
+ * Unregister a marker by providing the registered pdata.
+ */
+extern void *marker_probe_unregister_pdata(void *pdata);
+
+extern int marker_arm(const char *name);
+extern int marker_disarm(const char *name);
+
+struct marker_iter {
+ struct module *module;
+ struct __mark_marker *marker;
+};
+
+extern void marker_iter_start(struct marker_iter *iter);
+extern void marker_iter_next(struct marker_iter *iter);
+extern void marker_iter_stop(struct marker_iter *iter);
+extern void marker_iter_reset(struct marker_iter *iter);
+extern void *marker_get_pdata(const char *name);
+
+#endif
Index: linux-2.6-lttng/include/linux/module.h
===================================================================
--- linux-2.6-lttng.orig/include/linux/module.h 2007-08-10 19:44:17.000000000 -0400
+++ linux-2.6-lttng/include/linux/module.h 2007-08-10 23:54:38.000000000 -0400
@@ -16,6 +16,7 @@
#include <linux/kobject.h>
#include <linux/moduleparam.h>
#include <linux/immediate.h>
+#include <linux/marker.h>
#include <asm/local.h>
#include <asm/module.h>
@@ -380,6 +381,10 @@ struct module
const struct __immediate *immediate;
unsigned int num_immediate;
#endif
+#ifdef CONFIG_MARKERS
+ struct __mark_marker *markers;
+ unsigned int num_markers;
+#endif
};
#ifndef MODULE_ARCH_INIT
#define MODULE_ARCH_INIT {}
Index: linux-2.6-lttng/kernel/module.c
===================================================================
--- linux-2.6-lttng.orig/kernel/module.c 2007-08-10 19:44:18.000000000 -0400
+++ linux-2.6-lttng/kernel/module.c 2007-08-10 23:54:38.000000000 -0400
@@ -1722,6 +1722,8 @@ static struct module *load_module(void _
unsigned int unusedgplindex;
unsigned int unusedgplcrcindex;
unsigned int immediateindex = 0;
+ unsigned int markersindex = 0;
+ unsigned int markersstringsindex = 0;
struct module *mod;
long err = 0;
void *percpu = NULL, *ptr = NULL; /* Stops spurious gcc warning */
@@ -1821,6 +1823,10 @@ static struct module *load_module(void _
#ifdef CONFIG_IMMEDIATE
immediateindex = find_sec(hdr, sechdrs, secstrings, "__immediate");
#endif
+#ifdef CONFIG_MARKERS
+ markersindex = find_sec(hdr, sechdrs, secstrings, "__markers");
+ markersstringsindex = find_sec(hdr, sechdrs, secstrings, "__markers_strings");
+#endif
/* Don't keep modinfo section */
sechdrs[infoindex].sh_flags &= ~(unsigned long)SHF_ALLOC;
@@ -1980,6 +1986,10 @@ static struct module *load_module(void _
sechdrs[immediateindex].sh_size / sizeof(*mod->immediate);
}
#endif
+ if (markersindex)
+ sechdrs[markersindex].sh_flags |= SHF_ALLOC;
+ if (markersstringsindex)
+ sechdrs[markersstringsindex].sh_flags |= SHF_ALLOC;
mod->unused_syms = (void *)sechdrs[unusedindex].sh_addr;
if (unusedcrcindex)
@@ -2021,6 +2031,13 @@ static struct module *load_module(void _
if (err < 0)
goto cleanup;
}
+#ifdef CONFIG_MARKERS
+ if (markersindex) {
+ mod->markers = (void *)sechdrs[markersindex].sh_addr;
+ mod->num_markers =
+ sechdrs[markersindex].sh_size / sizeof(*mod->markers);
+ }
+#endif
/* Find duplicate symbols */
err = verify_export_symbols(mod);
@@ -2046,6 +2063,8 @@ static struct module *load_module(void _
}
#endif
+ module_marker_update(mod);
+
module_immediate_setup(mod);
err = module_finalize(hdr, sechdrs, mod);
Index: linux-2.6-lttng/kernel/marker.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6-lttng/kernel/marker.c 2007-08-10 19:44:18.000000000 -0400
@@ -0,0 +1,678 @@
+/*
+ * Copyright (C) 2007 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/marker.h>
+#include <linux/err.h>
+#include <linux/immediate.h>
+
+extern struct __mark_marker __start___markers[];
+extern struct __mark_marker __stop___markers[];
+
+/*
+ * module_mutex nests inside markers_mutex. Markers mutex protects the builtin
+ * and module markers, the hash table and deferred_sync.
+ */
+DEFINE_MUTEX(markers_mutex);
+
+/*
+ * Marker deferred synchronization.
+ * Upon marker probe_unregister, we delay call to synchronize_sched() to
+ * accelerate mass unregistration (only when there is no more reference to a
+ * give module do we call synchronize_sched()). However, we need to make sure
+ * every critical region have ended before we re-arm a marker that has been
+ * unregistered and then registered back with a different probe data.
+ */
+static int deferred_sync;
+
+/*
+ * Marker hash table, containing the active markers.
+ * Protected by module_mutex.
+ */
+#define MARKER_HASH_BITS 6
+#define MARKER_TABLE_SIZE (1 << MARKER_HASH_BITS)
+
+struct marker_entry {
+ struct hlist_node hlist;
+ char *format;
+ marker_probe_func *probe;
+ void *pdata;
+ int refcount; /* Number of times armed. 0 if disarmed. */
+ char name[0]; /* Contains name'\0'format'\0' */
+};
+
+static struct hlist_head marker_table[MARKER_TABLE_SIZE];
+
+/**
+ * __mark_empty_function - Empty probe callback
+ * @mdata: pointer of type const struct __mark_marker
+ * @fmt: format string
+ * @...: variable argument list
+ *
+ * Empty callback provided as a probe to the markers. By providing this to a
+ * disabled marker, we makes sure the execution flow is always valid even
+ * though the function pointer change and the marker enabling are two distinct
+ * operations that modifies the execution flow of preemptible code.
+ */
+void __mark_empty_function(const struct __mark_marker *mdata,
+ void *private_data,
+ const char *fmt, ...)
+{ }
+EXPORT_SYMBOL_GPL(__mark_empty_function);
+
+/*
+ * Get marker if the marker is present in the marker hash table.
+ * Must be called with markers_mutex held.
+ * Returns NULL if not present.
+ */
+static struct marker_entry *_get_marker(const char *name)
+{
+ struct hlist_head *head;
+ struct hlist_node *node;
+ struct marker_entry *e;
+ size_t len = strlen(name) + 1;
+ u32 hash = jhash(name, len-1, 0);
+
+ head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)];
+ hlist_for_each_entry(e, node, head, hlist) {
+ if (!strcmp(name, e->name))
+ return e;
+ }
+ return NULL;
+}
+
+/*
+ * Add the marker to the marker hash table. Must be called with markers_mutex
+ * held.
+ */
+static int _add_marker(const char *name,
+ const char *format, marker_probe_func *probe, void *pdata)
+{
+ struct hlist_head *head;
+ struct hlist_node *node;
+ struct marker_entry *e;
+ size_t name_len = strlen(name) + 1;
+ size_t format_len = 0;
+ u32 hash = jhash(name, name_len-1, 0);
+
+ if (format)
+ format_len = strlen(format) + 1;
+ head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)];
+ hlist_for_each_entry(e, node, head, hlist) {
+ if (!strcmp(name, e->name)) {
+ printk(KERN_NOTICE
+ "Marker %s busy, probe %p already installed\n",
+ name, e->probe);
+ return -EBUSY; /* Already there */
+ }
+ }
+ /*
+ * Using kmalloc here to allocate a variable length element. Could
+ * cause some memory fragmentation if overused.
+ */
+ e = kmalloc(sizeof(struct marker_entry) + name_len + format_len,
+ GFP_KERNEL);
+ if (!e)
+ return -ENOMEM;
+ memcpy(&e->name[0], name, name_len);
+ if (format) {
+ e->format = &e->name[name_len];
+ memcpy(e->format, format, format_len);
+ trace_mark(core_marker_format, "name %s format %s",
+ e->name, e->format);
+ } else
+ e->format = NULL;
+ e->probe = probe;
+ e->pdata = pdata;
+ e->refcount = 0;
+ hlist_add_head(&e->hlist, head);
+ return 0;
+}
+
+/*
+ * Remove the marker from the marker hash table. Must be called with mutex_lock
+ * held.
+ */
+static void *_remove_marker(const char *name)
+{
+ struct hlist_head *head;
+ struct hlist_node *node;
+ struct marker_entry *e;
+ int found = 0;
+ size_t len = strlen(name) + 1;
+ void *pdata = NULL;
+ u32 hash = jhash(name, len-1, 0);
+
+ head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)];
+ hlist_for_each_entry(e, node, head, hlist) {
+ if (!strcmp(name, e->name)) {
+ found = 1;
+ break;
+ }
+ }
+ if (found) {
+ pdata = e->pdata;
+ hlist_del(&e->hlist);
+ kfree(e);
+ }
+ return pdata;
+}
+
+/*
+ * Set the mark_entry format to the format found in the element.
+ */
+static int _marker_set_format(struct marker_entry **entry, const char *format)
+{
+ struct marker_entry *e;
+ size_t name_len = strlen((*entry)->name) + 1;
+ size_t format_len = strlen(format) + 1;
+
+ e = kmalloc(sizeof(struct marker_entry) + name_len + format_len,
+ GFP_KERNEL);
+ if (!e)
+ return -ENOMEM;
+ memcpy(&e->name[0], (*entry)->name, name_len);
+ e->format = &e->name[name_len];
+ memcpy(e->format, format, format_len);
+ e->probe = (*entry)->probe;
+ e->pdata = (*entry)->pdata;
+ e->refcount = (*entry)->refcount;
+ hlist_add_before(&e->hlist, &(*entry)->hlist);
+ hlist_del(&(*entry)->hlist);
+ kfree(*entry);
+ *entry = e;
+ trace_mark(core_marker_format, "name %s format %s",
+ e->name, e->format);
+ return 0;
+}
+
+/*
+ * Sets the probe callback corresponding to one marker.
+ */
+static int _set_marker(struct marker_entry **entry,
+ struct __mark_marker *elem)
+{
+ int ret;
+ BUG_ON(strcmp((*entry)->name, elem->name) != 0);
+
+ if ((*entry)->format) {
+ if (strcmp((*entry)->format, elem->format) != 0) {
+ printk(KERN_NOTICE
+ "Format mismatch for probe %s "
+ "(%s), marker (%s)\n",
+ (*entry)->name,
+ (*entry)->format,
+ elem->format);
+ return -EPERM;
+ }
+ } else {
+ ret = _marker_set_format(entry, elem->format);
+ if (ret)
+ return ret;
+ }
+ elem->call = (*entry)->probe;
+ elem->pdata = (*entry)->pdata;
+ _immediate_set(&elem->state, 1);
+ return 0;
+}
+
+/*
+ * Disable a marker and its probe callback.
+ * Note: only after a synchronize_sched() issued after setting elem->call to the
+ * empty function insures that the original callback is not used anymore. This
+ * insured by preemption disabling around the call site.
+ */
+static void _disable_marker(struct __mark_marker *elem)
+{
+ _immediate_set(&elem->state, 0);
+ elem->call = __mark_empty_function;
+ /*
+ * Leave the pdata and id there, because removal is racy and should be
+ * done only after a synchronize_sched(). There are never used until
+ * the next initialization anyway.
+ */
+}
+
+/*
+ * Updates the probe callback corresponding to a range of markers.
+ * Must be called with markers_mutex held.
+ */
+static void _marker_update_probe_range(
+ struct __mark_marker *begin,
+ struct __mark_marker *end,
+ struct module *probe_module,
+ int *refcount)
+{
+ struct __mark_marker *iter;
+ struct marker_entry *mark_entry;
+
+ for (iter = begin; iter < end; iter++) {
+ mark_entry = _get_marker(iter->name);
+ if (mark_entry && mark_entry->refcount) {
+ _set_marker(&mark_entry, iter);
+ /*
+ * ignore error, continue
+ */
+ if (probe_module)
+ if (probe_module ==
+ __module_text_address((unsigned long)mark_entry->probe))
+ (*refcount)++;
+ } else {
+ _disable_marker(iter);
+ }
+ }
+}
+
+#ifdef CONFIG_MODULES
+/*
+ * Update module probes.
+ * Must be called with markers_mutex held.
+ */
+static inline void __marker_update_probes_modules(struct module *probe_module,
+ int *refcount)
+{
+ struct module *mod;
+
+ list_for_each_entry(mod, &modules, list) {
+ if (!mod->taints) {
+ _marker_update_probe_range(mod->markers,
+ mod->markers+mod->num_markers,
+ probe_module, refcount);
+ }
+ }
+}
+#else
+static inline void __marker_update_probes_modules(struct module *probe_module,
+ int *refcount)
+{ }
+#endif
+
+/*
+ * Update probes, removing the faulty probes.
+ * Issues a synchronize_sched() when no reference to the module passed
+ * as parameter is found in the probes so the probe module can be
+ * safely unloaded from now on.
+ */
+static inline void __marker_update_probes(struct module *probe_module)
+{
+ int refcount = 0;
+
+ /* Core kernel markers */
+ _marker_update_probe_range(__start___markers,
+ __stop___markers, probe_module, &refcount);
+ /* Markers in modules. */
+ __marker_update_probes_modules(probe_module, &refcount);
+ if (probe_module && refcount == 0) {
+ synchronize_sched();
+ deferred_sync = 0;
+ }
+}
+
+#ifdef CONFIG_MODULES
+/**
+ * module_marker_update - Update module's markers
+ * @mod: pointer of type struct module identifying the target module
+ *
+ * Setup the marker according to the data present in the marker hash table
+ * upon module load. Must be called with module_mutex held. Since the
+ * probe_module parameter is NULL, it is safe for refcount to be NULL.
+ */
+void module_marker_update(struct module *mod)
+{
+ if (!mod->taints)
+ _marker_update_probe_range(mod->markers,
+ mod->markers+mod->num_markers, NULL, NULL);
+}
+
+/*
+ * Update the system wide probes, with modules.
+ */
+static inline void _marker_update_probes(struct module *probe_module)
+{
+ mutex_lock(&module_mutex);
+ __marker_update_probes(probe_module);
+ mutex_unlock(&module_mutex);
+}
+#else
+/*
+ * Update the system wide probes, without modules.
+ */
+static inline void _marker_update_probes(struct module *probe_module)
+{
+ __marker_update_probes(probe_module);
+}
+#endif
+
+/**
+ * marker_probe_register - Connect a probe to a marker
+ * @name: marker name
+ * @format: format string
+ * @probe: probe handler
+ * @pdata: probe private data
+ *
+ * pdata must be a valid allocated memory address, or NULL.
+ * Returns 0 if ok, error value on error.
+ */
+int marker_probe_register(const char *name, const char *format,
+ marker_probe_func *probe, void *pdata)
+{
+ struct marker_entry *entry;
+ int ret = 0;
+
+ mutex_lock(&markers_mutex);
+ entry = _get_marker(name);
+ if (entry && entry->refcount) {
+ ret = -EBUSY;
+ goto end;
+ }
+ if (deferred_sync) {
+ synchronize_sched();
+ deferred_sync = 0;
+ }
+ ret = _add_marker(name, format, probe, pdata);
+ if (ret)
+ goto end;
+ _marker_update_probes(NULL);
+end:
+ mutex_unlock(&markers_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(marker_probe_register);
+
+/**
+ * marker_probe_unregister - Disconnect a probe from a marker
+ * @name: marker name
+ *
+ * Returns the pdata given to marker_probe_register, or an ERR_PTR().
+ */
+void *marker_probe_unregister(const char *name)
+{
+ struct module *probe_module;
+ struct marker_entry *entry;
+ void *pdata;
+
+ mutex_lock(&markers_mutex);
+ entry = _get_marker(name);
+ if (!entry) {
+ pdata = ERR_PTR(-ENOENT);
+ goto end;
+ }
+ entry->refcount = 0;
+ /* In what module is the probe handler ? */
+ probe_module = __module_text_address((unsigned long)entry->probe);
+ pdata = _remove_marker(name);
+ deferred_sync = 1;
+ _marker_update_probes(probe_module);
+end:
+ mutex_unlock(&markers_mutex);
+ return pdata;
+}
+EXPORT_SYMBOL_GPL(marker_probe_unregister);
+
+/**
+ * marker_probe_unregister - Disconnect a probe from a marker
+ * @pdata: probe private data
+ *
+ * Unregister a marker by providing the registered pdata.
+ * Returns the pdata given to marker_probe_register, or an ERR_PTR().
+ */
+void *marker_probe_unregister_pdata(void *pdata)
+{
+ struct module *probe_module;
+ struct hlist_head *head;
+ struct hlist_node *node;
+ struct marker_entry *entry;
+ int found = 0;
+ unsigned int i;
+
+ mutex_lock(&markers_mutex);
+ for (i = 0; i < MARKER_TABLE_SIZE; i++) {
+ head = &marker_table[i];
+ hlist_for_each_entry(entry, node, head, hlist) {
+ if (entry->pdata == pdata) {
+ found = 1;
+ goto iter_end;
+ }
+ }
+ }
+iter_end:
+ if (!found) {
+ pdata = ERR_PTR(-ENOENT);
+ goto end;
+ }
+ entry->refcount = 0;
+ /* In what module is the probe handler ? */
+ probe_module = __module_text_address((unsigned long)entry->probe);
+ pdata = _remove_marker(entry->name);
+ deferred_sync = 1;
+ _marker_update_probes(probe_module);
+end:
+ mutex_unlock(&markers_mutex);
+ return pdata;
+}
+EXPORT_SYMBOL_GPL(marker_probe_unregister_pdata);
+
+/**
+ * marker_arm - Arm a marker
+ * @name: marker name
+ *
+ * Activate a marker. It keeps a reference count of the number of
+ * arming/disarming done.
+ * Returns 0 if ok, error value on error.
+ */
+int marker_arm(const char *name)
+{
+ struct marker_entry * entry;
+ int ret = 0;
+
+ mutex_lock(&markers_mutex);
+ entry = _get_marker(name);
+ if (!entry) {
+ ret = -ENOENT;
+ goto end;
+ }
+ /*
+ * Only need to update probes when refcount passes from 0 to 1.
+ */
+ if (entry->refcount++)
+ goto end;
+ _marker_update_probes(NULL);
+end:
+ mutex_unlock(&markers_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(marker_arm);
+
+/**
+ * marker_disarm - Disarm a marker
+ * @name: marker name
+ *
+ * Disarm a marker. It keeps a reference count of the number of arming/disarming
+ * done.
+ * Returns 0 if ok, error value on error.
+ */
+int marker_disarm(const char *name)
+{
+ struct marker_entry * entry;
+ int ret = 0;
+
+ mutex_lock(&markers_mutex);
+ entry = _get_marker(name);
+ if (!entry) {
+ ret = -ENOENT;
+ goto end;
+ }
+ /*
+ * Only permit decrement refcount if higher than 0.
+ * Do probe update only on 1 -> 0 transition.
+ */
+ if (entry->refcount) {
+ if (--entry->refcount)
+ goto end;
+ } else {
+ ret = -EPERM;
+ goto end;
+ }
+ _marker_update_probes(NULL);
+end:
+ mutex_unlock(&markers_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(marker_disarm);
+
+/**
+ * marker_get_pdata - Get a marker's probe private data
+ * @name: marker name
+ *
+ * Returns the pdata pointer, or an ERR_PTR.
+ * The pdata pointer should _only_ be dereferenced if the caller is the owner of
+ * the data, or its content could vanish. This is mostly used to confirm that a
+ * caller is the owner of a registered probe.
+ */
+void *marker_get_pdata(const char *name)
+{
+ struct hlist_head *head;
+ struct hlist_node *node;
+ struct marker_entry *e;
+ size_t name_len = strlen(name) + 1;
+ u32 hash = jhash(name, name_len-1, 0);
+ int found = 0;
+
+ head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)];
+ hlist_for_each_entry(e, node, head, hlist) {
+ if (!strcmp(name, e->name)) {
+ found = 1;
+ return e->pdata;
+ }
+ }
+ return ERR_PTR(-ENOENT);
+}
+EXPORT_SYMBOL_GPL(marker_get_pdata);
+
+static inline int _marker_get_iter_range(struct __mark_marker **marker,
+ struct __mark_marker *begin,
+ struct __mark_marker *end)
+{
+ int found = 0;
+
+ if (!*marker && begin != end) {
+ found = 1;
+ *marker = begin;
+ } else if (*marker >= begin && *marker < end) {
+ found = 1;
+ /*
+ * *marker is known to be a valid marker from now on.
+ */
+ }
+ return found;
+}
+
+#ifdef CONFIG_MODULES
+/*
+ * Returns 0 if current not foud.
+ * Returns 1 if current found.
+ * Should be called with module_mutex taken.
+ */
+static inline int marker_get_iter_modules(struct marker_iter *iter)
+{
+ struct module *iter_mod;
+ int found = 0;
+
+ 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->marker = NULL;
+ } else {
+ }
+ found = _marker_get_iter_range(&iter->marker,
+ iter_mod->markers,
+ iter_mod->markers + iter_mod->num_markers);
+ if (found) {
+ iter->module = iter_mod;
+ break;
+ }
+
+ }
+ }
+ return found;
+}
+#else
+static inline int marker_get_iter_modules(struct marker_iter *iter)
+{
+ return 0;
+}
+#endif
+
+static inline void marker_get_iter(struct marker_iter *iter)
+{
+ int found = 0;
+
+ /* Core kernel markers */
+ if (!iter->module) {
+ found = _marker_get_iter_range(&iter->marker,
+ __start___markers, __stop___markers);
+ if (found)
+ goto end;
+ }
+ /* Markers in modules. */
+ found = marker_get_iter_modules(iter);
+end:
+ if (!found)
+ marker_iter_reset(iter);
+}
+
+void marker_iter_start(struct marker_iter *iter)
+{
+ mutex_lock(&module_mutex);
+ marker_get_iter(iter);
+}
+EXPORT_SYMBOL_GPL(marker_iter_start);
+
+void marker_iter_next(struct marker_iter *iter)
+{
+ iter->marker++;
+ /*
+ * iter->marker may be invalid because we blindly incremented it.
+ * Make sure it is valid by marshalling on the markers, getting the
+ * markers from following modules if necessary.
+ */
+ marker_get_iter(iter);
+}
+EXPORT_SYMBOL_GPL(marker_iter_next);
+
+void marker_iter_stop(struct marker_iter *iter)
+{
+ mutex_unlock(&module_mutex);
+}
+EXPORT_SYMBOL_GPL(marker_iter_stop);
+
+void marker_iter_reset(struct marker_iter *iter)
+{
+ iter->module = NULL;
+ iter->marker = NULL;
+}
+EXPORT_SYMBOL_GPL(marker_iter_reset);
--
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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