diff options
Diffstat (limited to 'kernel/trace/trace_ksym.c')
-rw-r--r-- | kernel/trace/trace_ksym.c | 525 |
1 files changed, 525 insertions, 0 deletions
diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c new file mode 100644 index 00000000000..eef97e7c8db --- /dev/null +++ b/kernel/trace/trace_ksym.c @@ -0,0 +1,525 @@ +/* + * 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_stat.h" +#include "trace.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- */ +#define KSYM_FILTER_ENTRY_LEN (KSYM_NAME_LEN + KSYM_TRACER_OP_LEN + 1) + +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->ksym_addr == hbp_hit_addr) && + (entry->counter <= MAX_UL_INT)) { + entry->counter++; + break; + } + } + rcu_read_unlock(); +} +#endif /* CONFIG_PROFILE_KSYM_TRACER */ + +void ksym_hbp_handler(struct hw_breakpoint *hbp, struct pt_regs *regs) +{ + struct ring_buffer_event *event; + struct trace_array *tr; + struct trace_ksym *entry; + int pc; + + if (!ksym_tracing_enabled) + return; + + tr = ksym_trace_array; + pc = preempt_count(); + + event = trace_buffer_lock_reserve(tr, TRACE_KSYM, + sizeof(*entry), 0, pc); + if (!event) + return; + + entry = ring_buffer_event_data(event); + strlcpy(entry->ksym_name, hbp->info.name, KSYM_SYMBOL_LEN); + entry->ksym_hbp = hbp; + entry->ip = instruction_pointer(regs); + strlcpy(entry->p_name, current->comm, TASK_COMM_LEN); +#ifdef CONFIG_PROFILE_KSYM_TRACER + ksym_collect_stats(hbp->info.address); +#endif /* CONFIG_PROFILE_KSYM_TRACER */ + + trace_buffer_unlock_commit(tr, 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 *access_str) +{ + int pos, access = 0; + + for (pos = 0; pos < KSYM_TRACER_OP_LEN; pos++) { + switch (access_str[pos]) { + case 'r': + access += (pos == 0) ? 4 : -1; + break; + case 'w': + access += (pos == 1) ? 2 : -1; + break; + case '-': + break; + default: + return -EINVAL; + } + } + + switch (access) { + case 6: + access = HW_BREAKPOINT_RW; + break; + case 2: + access = HW_BREAKPOINT_WRITE; + break; + case 0: + access = 0; + } + + return access; +} + +/* + * 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) +{ + char *delimiter = ":"; + int ret; + + ret = -EINVAL; + *ksymname = strsep(&input_string, delimiter); + *addr = kallsyms_lookup_name(*ksymname); + + /* Check for malformed request: (2), (1) and (5) */ + if ((!input_string) || + (strlen(input_string) != (KSYM_TRACER_OP_LEN + 1)) || + (*addr == 0)) + goto return_code; + ret = ksym_trace_get_access_type(input_string); + +return_code: + return ret; +} + +int process_new_ksym_entry(char *ksymname, int op, unsigned long addr) +{ + struct trace_ksym *entry; + int ret; + + 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; + + entry->ksym_hbp = kzalloc(sizeof(struct hw_breakpoint), GFP_KERNEL); + if (!entry->ksym_hbp) { + kfree(entry); + return -ENOMEM; + } + + entry->ksym_hbp->info.name = ksymname; + entry->ksym_hbp->info.type = op; + entry->ksym_addr = entry->ksym_hbp->info.address = addr; +#ifdef CONFIG_X86 + entry->ksym_hbp->info.len = HW_BREAKPOINT_LEN_4; +#endif + entry->ksym_hbp->triggered = (void *)ksym_hbp_handler; + + ret = register_kernel_hw_breakpoint(entry->ksym_hbp); + if (ret < 0) { + printk(KERN_INFO "ksym_tracer request failed. Try again" + " later!!\n"); + kfree(entry->ksym_hbp); + kfree(entry); + return -EAGAIN; + } + hlist_add_head_rcu(&(entry->ksym_hlist), &ksym_filter_head); + ksym_filter_entry_count++; + + return 0; +} + +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; + char buf[KSYM_FILTER_ENTRY_LEN * KSYM_TRACER_MAX]; + ssize_t ret, cnt = 0; + + mutex_lock(&ksym_tracer_mutex); + + hlist_for_each_entry(entry, node, &ksym_filter_head, ksym_hlist) { + cnt += snprintf(&buf[cnt], KSYM_FILTER_ENTRY_LEN - cnt, "%s:", + entry->ksym_hbp->info.name); + if (entry->ksym_hbp->info.type == HW_BREAKPOINT_WRITE) + cnt += snprintf(&buf[cnt], KSYM_FILTER_ENTRY_LEN - cnt, + "-w-\n"); + else if (entry->ksym_hbp->info.type == HW_BREAKPOINT_RW) + cnt += snprintf(&buf[cnt], KSYM_FILTER_ENTRY_LEN - cnt, + "rw-\n"); + } + ret = simple_read_from_buffer(ubuf, count, ppos, buf, strlen(buf)); + mutex_unlock(&ksym_tracer_mutex); + + return ret; +} + +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 *input_string, *ksymname = NULL; + unsigned long ksym_addr = 0; + int ret, op, changed = 0; + + /* Ignore echo "" > ksym_trace_filter */ + if (count == 0) + return 0; + + input_string = kzalloc(count, GFP_KERNEL); + if (!input_string) + return -ENOMEM; + + if (copy_from_user(input_string, buffer, count)) { + kfree(input_string); + return -EFAULT; + } + + ret = op = parse_ksym_trace_str(input_string, &ksymname, &ksym_addr); + if (ret < 0) { + kfree(input_string); + return ret; + } + + mutex_lock(&ksym_tracer_mutex); + + ret = -EINVAL; + hlist_for_each_entry(entry, node, &ksym_filter_head, ksym_hlist) { + if (entry->ksym_addr == ksym_addr) { + /* Check for malformed request: (6) */ + if (entry->ksym_hbp->info.type != op) + changed = 1; + else + goto err_ret; + break; + } + } + if (changed) { + unregister_kernel_hw_breakpoint(entry->ksym_hbp); + entry->ksym_hbp->info.type = op; + if (op > 0) { + ret = register_kernel_hw_breakpoint(entry->ksym_hbp); + if (ret == 0) { + ret = count; + goto unlock_ret_path; + } + } + ksym_filter_entry_count--; + hlist_del_rcu(&(entry->ksym_hlist)); + synchronize_rcu(); + kfree(entry->ksym_hbp); + kfree(entry); + ret = count; + goto err_ret; + } else { + /* Check for malformed request: (4) */ + if (op == 0) + goto err_ret; + ret = process_new_ksym_entry(ksymname, op, ksym_addr); + if (ret) + goto err_ret; + } + ret = count; + goto unlock_ret_path; + +err_ret: + kfree(input_string); + +unlock_ret_path: + mutex_unlock(&ksym_tracer_mutex); + return 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) +{ + struct trace_ksym *entry; + struct hlist_node *node, *node1; + + ksym_tracing_enabled = 0; + + mutex_lock(&ksym_tracer_mutex); + hlist_for_each_entry_safe(entry, node, node1, &ksym_filter_head, + ksym_hlist) { + unregister_kernel_hw_breakpoint(entry->ksym_hbp); + ksym_filter_entry_count--; + hlist_del_rcu(&(entry->ksym_hlist)); + synchronize_rcu(); + /* Free the 'input_string' only if reset + * after startup self-test + */ +#ifdef CONFIG_FTRACE_SELFTEST + if (strncmp(entry->ksym_hbp->info.name, KSYM_SELFTEST_ENTRY, + strlen(KSYM_SELFTEST_ENTRY)) != 0) +#endif /* CONFIG_FTRACE_SELFTEST*/ + kfree(entry->ksym_hbp->info.name); + kfree(entry->ksym_hbp); + kfree(entry); + } + mutex_unlock(&ksym_tracer_mutex); +} + +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 trace_ksym *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, "%-15s %-5d %-3d %-20s ", field->p_name, + entry->pid, iter->cpu, field->ksym_name); + if (!ret) + return TRACE_TYPE_PARTIAL_LINE; + + switch (field->ksym_hbp->info.type) { + case HW_BREAKPOINT_WRITE: + ret = trace_seq_printf(s, " W "); + break; + case HW_BREAKPOINT_RW: + 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, "%-20s\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 +}; + +__init static int init_ksym_trace(void) +{ + struct dentry *d_tracer; + struct dentry *entry; + + d_tracer = tracing_init_dentry(); + ksym_filter_entry_count = 0; + + entry = debugfs_create_file("ksym_trace_filter", 0644, d_tracer, + NULL, &ksym_tracing_fops); + if (!entry) + pr_warning("Could not create debugfs " + "'ksym_trace_filter' file\n"); + + return register_tracer(&ksym_tracer); +} +device_initcall(init_ksym_trace); + + +#ifdef CONFIG_PROFILE_KSYM_TRACER +static int ksym_tracer_stat_headers(struct seq_file *m) +{ + seq_printf(m, " Access type "); + seq_printf(m, " Symbol Counter \n"); + return 0; +} + +static int ksym_tracer_stat_show(struct seq_file *m, void *v) +{ + struct hlist_node *stat = v; + struct trace_ksym *entry; + int access_type = 0; + char fn_name[KSYM_NAME_LEN]; + + entry = hlist_entry(stat, struct trace_ksym, ksym_hlist); + + if (entry->ksym_hbp) + access_type = entry->ksym_hbp->info.type; + + switch (access_type) { + case HW_BREAKPOINT_WRITE: + seq_printf(m, " W "); + break; + case HW_BREAKPOINT_RW: + seq_printf(m, " RW "); + break; + default: + seq_printf(m, " NA "); + } + + if (lookup_symbol_name(entry->ksym_addr, fn_name) >= 0) + seq_printf(m, " %s ", fn_name); + else + seq_printf(m, " <NA> "); + + seq_printf(m, "%15lu\n", entry->counter); + return 0; +} + +static void *ksym_tracer_stat_start(struct tracer_stat *trace) +{ + return &(ksym_filter_head.first); +} + +static void * +ksym_tracer_stat_next(void *v, int idx) +{ + struct hlist_node *stat = v; + + return stat->next; +} + +static struct tracer_stat ksym_tracer_stats = { + .name = "ksym_tracer", + .stat_start = ksym_tracer_stat_start, + .stat_next = ksym_tracer_stat_next, + .stat_headers = ksym_tracer_stat_headers, + .stat_show = ksym_tracer_stat_show +}; + +__init static int ksym_tracer_stat_init(void) +{ + int ret; + + ret = register_stat_tracer(&ksym_tracer_stats); + if (ret) { + printk(KERN_WARNING "Warning: could not register " + "ksym tracer stats\n"); + return 1; + } + + return 0; +} +fs_initcall(ksym_tracer_stat_init); +#endif /* CONFIG_PROFILE_KSYM_TRACER */ |