diff options
author | Thomas Gleixner <tglx@linutronix.de> | 2010-02-17 18:27:37 +0100 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2010-02-17 18:28:05 +0100 |
commit | b7e56edba4b02f2079042c326a8cd72a44635817 (patch) | |
tree | b5042002e9747cd8fb1278d61f86d8b92a74c018 /kernel/trace/trace_ksym.c | |
parent | 13ca0fcaa33f6b1984c4111b6ec5df42689fea6f (diff) | |
parent | b0483e78e5c4c9871fc5541875b3bc006846d46b (diff) |
Merge branch 'linus' into x86/mm
x86/mm is on 32-rc4 and missing the spinlock namespace changes which
are needed for further commits into this topic.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/trace/trace_ksym.c')
-rw-r--r-- | kernel/trace/trace_ksym.c | 519 |
1 files changed, 519 insertions, 0 deletions
diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c new file mode 100644 index 00000000000..94103cdcf9d --- /dev/null +++ b/kernel/trace/trace_ksym.c @@ -0,0 +1,519 @@ +/* + * trace_ksym.c - Kernel Symbol Tracer + * + * 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) IBM Corporation, 2009 + */ + +#include <linux/kallsyms.h> +#include <linux/uaccess.h> +#include <linux/debugfs.h> +#include <linux/ftrace.h> +#include <linux/module.h> +#include <linux/fs.h> + +#include "trace_output.h" +#include "trace.h" + +#include <linux/hw_breakpoint.h> +#include <asm/hw_breakpoint.h> + +#include <asm/atomic.h> + +/* + * For now, let us restrict the no. of symbols traced simultaneously to number + * of available hardware breakpoint registers. + */ +#define KSYM_TRACER_MAX HBP_NUM + +#define KSYM_TRACER_OP_LEN 3 /* rw- */ + +struct trace_ksym { + struct perf_event **ksym_hbp; + struct perf_event_attr attr; +#ifdef CONFIG_PROFILE_KSYM_TRACER + atomic64_t counter; +#endif + struct hlist_node ksym_hlist; +}; + +static struct trace_array *ksym_trace_array; + +static unsigned int ksym_filter_entry_count; +static unsigned int ksym_tracing_enabled; + +static HLIST_HEAD(ksym_filter_head); + +static DEFINE_MUTEX(ksym_tracer_mutex); + +#ifdef CONFIG_PROFILE_KSYM_TRACER + +#define MAX_UL_INT 0xffffffff + +void ksym_collect_stats(unsigned long hbp_hit_addr) +{ + struct hlist_node *node; + struct trace_ksym *entry; + + rcu_read_lock(); + hlist_for_each_entry_rcu(entry, node, &ksym_filter_head, ksym_hlist) { + if (entry->attr.bp_addr == hbp_hit_addr) { + atomic64_inc(&entry->counter); + break; + } + } + rcu_read_unlock(); +} +#endif /* CONFIG_PROFILE_KSYM_TRACER */ + +void ksym_hbp_handler(struct perf_event *hbp, int nmi, + struct perf_sample_data *data, + struct pt_regs *regs) +{ + struct ring_buffer_event *event; + struct ksym_trace_entry *entry; + struct ring_buffer *buffer; + int pc; + + if (!ksym_tracing_enabled) + return; + + buffer = ksym_trace_array->buffer; + + pc = preempt_count(); + + event = trace_buffer_lock_reserve(buffer, TRACE_KSYM, + sizeof(*entry), 0, pc); + if (!event) + return; + + entry = ring_buffer_event_data(event); + entry->ip = instruction_pointer(regs); + entry->type = hw_breakpoint_type(hbp); + entry->addr = hw_breakpoint_addr(hbp); + strlcpy(entry->cmd, current->comm, TASK_COMM_LEN); + +#ifdef CONFIG_PROFILE_KSYM_TRACER + ksym_collect_stats(hw_breakpoint_addr(hbp)); +#endif /* CONFIG_PROFILE_KSYM_TRACER */ + + trace_buffer_unlock_commit(buffer, event, 0, pc); +} + +/* Valid access types are represented as + * + * rw- : Set Read/Write Access Breakpoint + * -w- : Set Write Access Breakpoint + * --- : Clear Breakpoints + * --x : Set Execution Break points (Not available yet) + * + */ +static int ksym_trace_get_access_type(char *str) +{ + int access = 0; + + if (str[0] == 'r') + access |= HW_BREAKPOINT_R; + + if (str[1] == 'w') + access |= HW_BREAKPOINT_W; + + if (str[2] == 'x') + access |= HW_BREAKPOINT_X; + + switch (access) { + case HW_BREAKPOINT_R: + case HW_BREAKPOINT_W: + case HW_BREAKPOINT_W | HW_BREAKPOINT_R: + return access; + default: + return -EINVAL; + } +} + +/* + * There can be several possible malformed requests and we attempt to capture + * all of them. We enumerate some of the rules + * 1. We will not allow kernel symbols with ':' since it is used as a delimiter. + * i.e. multiple ':' symbols disallowed. Possible uses are of the form + * <module>:<ksym_name>:<op>. + * 2. No delimiter symbol ':' in the input string + * 3. Spurious operator symbols or symbols not in their respective positions + * 4. <ksym_name>:--- i.e. clear breakpoint request when ksym_name not in file + * 5. Kernel symbol not a part of /proc/kallsyms + * 6. Duplicate requests + */ +static int parse_ksym_trace_str(char *input_string, char **ksymname, + unsigned long *addr) +{ + int ret; + + *ksymname = strsep(&input_string, ":"); + *addr = kallsyms_lookup_name(*ksymname); + + /* Check for malformed request: (2), (1) and (5) */ + if ((!input_string) || + (strlen(input_string) != KSYM_TRACER_OP_LEN) || + (*addr == 0)) + return -EINVAL;; + + ret = ksym_trace_get_access_type(input_string); + + return ret; +} + +int process_new_ksym_entry(char *ksymname, int op, unsigned long addr) +{ + struct trace_ksym *entry; + int ret = -ENOMEM; + + if (ksym_filter_entry_count >= KSYM_TRACER_MAX) { + printk(KERN_ERR "ksym_tracer: Maximum limit:(%d) reached. No" + " new requests for tracing can be accepted now.\n", + KSYM_TRACER_MAX); + return -ENOSPC; + } + + entry = kzalloc(sizeof(struct trace_ksym), GFP_KERNEL); + if (!entry) + return -ENOMEM; + + hw_breakpoint_init(&entry->attr); + + entry->attr.bp_type = op; + entry->attr.bp_addr = addr; + entry->attr.bp_len = HW_BREAKPOINT_LEN_4; + + entry->ksym_hbp = register_wide_hw_breakpoint(&entry->attr, + ksym_hbp_handler); + + if (IS_ERR(entry->ksym_hbp)) { + ret = PTR_ERR(entry->ksym_hbp); + printk(KERN_INFO "ksym_tracer request failed. Try again" + " later!!\n"); + goto err; + } + + hlist_add_head_rcu(&(entry->ksym_hlist), &ksym_filter_head); + ksym_filter_entry_count++; + + return 0; + +err: + kfree(entry); + + return ret; +} + +static ssize_t ksym_trace_filter_read(struct file *filp, char __user *ubuf, + size_t count, loff_t *ppos) +{ + struct trace_ksym *entry; + struct hlist_node *node; + struct trace_seq *s; + ssize_t cnt = 0; + int ret; + + s = kmalloc(sizeof(*s), GFP_KERNEL); + if (!s) + return -ENOMEM; + trace_seq_init(s); + + mutex_lock(&ksym_tracer_mutex); + + hlist_for_each_entry(entry, node, &ksym_filter_head, ksym_hlist) { + ret = trace_seq_printf(s, "%pS:", + (void *)(unsigned long)entry->attr.bp_addr); + if (entry->attr.bp_type == HW_BREAKPOINT_R) + ret = trace_seq_puts(s, "r--\n"); + else if (entry->attr.bp_type == HW_BREAKPOINT_W) + ret = trace_seq_puts(s, "-w-\n"); + else if (entry->attr.bp_type == (HW_BREAKPOINT_W | HW_BREAKPOINT_R)) + ret = trace_seq_puts(s, "rw-\n"); + WARN_ON_ONCE(!ret); + } + + cnt = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len); + + mutex_unlock(&ksym_tracer_mutex); + + kfree(s); + + return cnt; +} + +static void __ksym_trace_reset(void) +{ + struct trace_ksym *entry; + struct hlist_node *node, *node1; + + mutex_lock(&ksym_tracer_mutex); + hlist_for_each_entry_safe(entry, node, node1, &ksym_filter_head, + ksym_hlist) { + unregister_wide_hw_breakpoint(entry->ksym_hbp); + ksym_filter_entry_count--; + hlist_del_rcu(&(entry->ksym_hlist)); + synchronize_rcu(); + kfree(entry); + } + mutex_unlock(&ksym_tracer_mutex); +} + +static ssize_t ksym_trace_filter_write(struct file *file, + const char __user *buffer, + size_t count, loff_t *ppos) +{ + struct trace_ksym *entry; + struct hlist_node *node; + char *buf, *input_string, *ksymname = NULL; + unsigned long ksym_addr = 0; + int ret, op, changed = 0; + + buf = kzalloc(count + 1, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + ret = -EFAULT; + if (copy_from_user(buf, buffer, count)) + goto out; + + buf[count] = '\0'; + input_string = strstrip(buf); + + /* + * Clear all breakpoints if: + * 1: echo > ksym_trace_filter + * 2: echo 0 > ksym_trace_filter + * 3: echo "*:---" > ksym_trace_filter + */ + if (!input_string[0] || !strcmp(input_string, "0") || + !strcmp(input_string, "*:---")) { + __ksym_trace_reset(); + ret = 0; + goto out; + } + + ret = op = parse_ksym_trace_str(input_string, &ksymname, &ksym_addr); + if (ret < 0) + goto out; + + mutex_lock(&ksym_tracer_mutex); + + ret = -EINVAL; + hlist_for_each_entry(entry, node, &ksym_filter_head, ksym_hlist) { + if (entry->attr.bp_addr == ksym_addr) { + /* Check for malformed request: (6) */ + if (entry->attr.bp_type != op) + changed = 1; + else + goto out_unlock; + break; + } + } + if (changed) { + unregister_wide_hw_breakpoint(entry->ksym_hbp); + entry->attr.bp_type = op; + ret = 0; + if (op > 0) { + entry->ksym_hbp = + register_wide_hw_breakpoint(&entry->attr, + ksym_hbp_handler); + if (IS_ERR(entry->ksym_hbp)) + ret = PTR_ERR(entry->ksym_hbp); + else + goto out_unlock; + } + /* Error or "symbol:---" case: drop it */ + ksym_filter_entry_count--; + hlist_del_rcu(&(entry->ksym_hlist)); + synchronize_rcu(); + kfree(entry); + goto out_unlock; + } else { + /* Check for malformed request: (4) */ + if (op) + ret = process_new_ksym_entry(ksymname, op, ksym_addr); + } +out_unlock: + mutex_unlock(&ksym_tracer_mutex); +out: + kfree(buf); + return !ret ? count : ret; +} + +static const struct file_operations ksym_tracing_fops = { + .open = tracing_open_generic, + .read = ksym_trace_filter_read, + .write = ksym_trace_filter_write, +}; + +static void ksym_trace_reset(struct trace_array *tr) +{ + ksym_tracing_enabled = 0; + __ksym_trace_reset(); +} + +static int ksym_trace_init(struct trace_array *tr) +{ + int cpu, ret = 0; + + for_each_online_cpu(cpu) + tracing_reset(tr, cpu); + ksym_tracing_enabled = 1; + ksym_trace_array = tr; + + return ret; +} + +static void ksym_trace_print_header(struct seq_file *m) +{ + seq_puts(m, + "# TASK-PID CPU# Symbol " + "Type Function\n"); + seq_puts(m, + "# | | | " + " | |\n"); +} + +static enum print_line_t ksym_trace_output(struct trace_iterator *iter) +{ + struct trace_entry *entry = iter->ent; + struct trace_seq *s = &iter->seq; + struct ksym_trace_entry *field; + char str[KSYM_SYMBOL_LEN]; + int ret; + + if (entry->type != TRACE_KSYM) + return TRACE_TYPE_UNHANDLED; + + trace_assign_type(field, entry); + + ret = trace_seq_printf(s, "%11s-%-5d [%03d] %pS", field->cmd, + entry->pid, iter->cpu, (char *)field->addr); + if (!ret) + return TRACE_TYPE_PARTIAL_LINE; + + switch (field->type) { + case HW_BREAKPOINT_R: + ret = trace_seq_printf(s, " R "); + break; + case HW_BREAKPOINT_W: + ret = trace_seq_printf(s, " W "); + break; + case HW_BREAKPOINT_R | HW_BREAKPOINT_W: + ret = trace_seq_printf(s, " RW "); + break; + default: + return TRACE_TYPE_PARTIAL_LINE; + } + + if (!ret) + return TRACE_TYPE_PARTIAL_LINE; + + sprint_symbol(str, field->ip); + ret = trace_seq_printf(s, "%s\n", str); + if (!ret) + return TRACE_TYPE_PARTIAL_LINE; + + return TRACE_TYPE_HANDLED; +} + +struct tracer ksym_tracer __read_mostly = +{ + .name = "ksym_tracer", + .init = ksym_trace_init, + .reset = ksym_trace_reset, +#ifdef CONFIG_FTRACE_SELFTEST + .selftest = trace_selftest_startup_ksym, +#endif + .print_header = ksym_trace_print_header, + .print_line = ksym_trace_output +}; + +#ifdef CONFIG_PROFILE_KSYM_TRACER +static int ksym_profile_show(struct seq_file *m, void *v) +{ + struct hlist_node *node; + struct trace_ksym *entry; + int access_type = 0; + char fn_name[KSYM_NAME_LEN]; + + seq_puts(m, " Access Type "); + seq_puts(m, " Symbol Counter\n"); + seq_puts(m, " ----------- "); + seq_puts(m, " ------ -------\n"); + + rcu_read_lock(); + hlist_for_each_entry_rcu(entry, node, &ksym_filter_head, ksym_hlist) { + + access_type = entry->attr.bp_type; + + switch (access_type) { + case HW_BREAKPOINT_R: + seq_puts(m, " R "); + break; + case HW_BREAKPOINT_W: + seq_puts(m, " W "); + break; + case HW_BREAKPOINT_R | HW_BREAKPOINT_W: + seq_puts(m, " RW "); + break; + default: + seq_puts(m, " NA "); + } + + if (lookup_symbol_name(entry->attr.bp_addr, fn_name) >= 0) + seq_printf(m, " %-36s", fn_name); + else + seq_printf(m, " %-36s", "<NA>"); + seq_printf(m, " %15llu\n", + (unsigned long long)atomic64_read(&entry->counter)); + } + rcu_read_unlock(); + + return 0; +} + +static int ksym_profile_open(struct inode *node, struct file *file) +{ + return single_open(file, ksym_profile_show, NULL); +} + +static const struct file_operations ksym_profile_fops = { + .open = ksym_profile_open, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; +#endif /* CONFIG_PROFILE_KSYM_TRACER */ + +__init static int init_ksym_trace(void) +{ + struct dentry *d_tracer; + + d_tracer = tracing_init_dentry(); + + trace_create_file("ksym_trace_filter", 0644, d_tracer, + NULL, &ksym_tracing_fops); + +#ifdef CONFIG_PROFILE_KSYM_TRACER + trace_create_file("ksym_profile", 0444, d_tracer, + NULL, &ksym_profile_fops); +#endif + + return register_tracer(&ksym_tracer); +} +device_initcall(init_ksym_trace); |