diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/Makefile | 1 | ||||
| -rw-r--r-- | kernel/hw_breakpoint.c | 378 | ||||
| -rw-r--r-- | kernel/trace/Kconfig | 21 | ||||
| -rw-r--r-- | kernel/trace/Makefile | 1 | ||||
| -rw-r--r-- | kernel/trace/trace.h | 18 | ||||
| -rw-r--r-- | kernel/trace/trace_ksym.c | 551 | ||||
| -rw-r--r-- | kernel/trace/trace_selftest.c | 53 |
7 files changed, 1023 insertions, 0 deletions
diff --git a/kernel/Makefile b/kernel/Makefile index 961379c..69943fd 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -97,6 +97,7 @@ obj-$(CONFIG_X86_DS) += trace/ obj-$(CONFIG_RING_BUFFER) += trace/ obj-$(CONFIG_SMP) += sched_cpupri.o obj-$(CONFIG_SLOW_WORK) += slow-work.o +obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o obj-$(CONFIG_PERF_COUNTERS) += perf_counter.o ifneq ($(CONFIG_SCHED_OMIT_FRAME_POINTER),y) diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c new file mode 100644 index 0000000..c1f64e6 --- /dev/null +++ b/kernel/hw_breakpoint.c @@ -0,0 +1,378 @@ +/* + * 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) 2007 Alan Stern + * Copyright (C) IBM Corporation, 2009 + */ + +/* + * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility, + * using the CPU's debug registers. + * This file contains the arch-independent routines. + */ + +#include <linux/irqflags.h> +#include <linux/kallsyms.h> +#include <linux/notifier.h> +#include <linux/kprobes.h> +#include <linux/kdebug.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/percpu.h> +#include <linux/sched.h> +#include <linux/init.h> +#include <linux/smp.h> + +#include <asm/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]; + +/* + * Load the debug registers during startup of a CPU. + */ +void load_debug_registers(void) +{ + 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); +} + +/* + * 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; + } + } + + 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); +} + +/* + * 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) +{ + /* + * 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; +} + +static int __register_user_hw_breakpoint(int pos, struct task_struct *tsk, + struct hw_breakpoint *bp) +{ + struct thread_struct *thread = &(tsk->thread); + int rc; + + /* Do not overcommit. Fail if kernel has used the hbp registers */ + if (pos >= hbp_kernel_pos) + return -ENOSPC; + + rc = arch_validate_hwbkpt_settings(bp, tsk); + if (rc) + return rc; + + thread->hbp[pos] = bp; + hbp_user_refcount[pos]++; + + 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); + + return rc; +} + +/* + * 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() + */ +static int __modify_user_hw_breakpoint(int pos, struct task_struct *tsk, + struct hw_breakpoint *bp) +{ + 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; + /* + * 'pos' must be that of a hbp register already used by 'tsk' + * Otherwise arch_modify_user_hw_breakpoint() will fail + */ + arch_update_user_hw_breakpoint(pos, tsk); + + if (tsk == current) + arch_install_thread_hw_breakpoint(tsk); + + return 0; +} + +static void __unregister_user_hw_breakpoint(int pos, struct task_struct *tsk) +{ + hbp_user_refcount[pos]--; + tsk->thread.hbp[pos] = NULL; + + arch_update_user_hw_breakpoint(pos, tsk); + + if (tsk == current) + arch_install_thread_hw_breakpoint(tsk); +} + +/** + * register_user_hw_breakpoint - register a hardware breakpoint for user space + * @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 + * + */ +int register_user_hw_breakpoint(struct task_struct *tsk, + struct hw_breakpoint *bp) +{ + 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; +} +EXPORT_SYMBOL_GPL(register_user_hw_breakpoint); + +/** + * modify_user_hw_breakpoint - modify a user-space hardware breakpoint + * @tsk: pointer to 'task_struct' of the process to which the address belongs + * @bp: the breakpoint structure to unregister + * + */ +int modify_user_hw_breakpoint(struct task_struct *tsk, struct hw_breakpoint *bp) +{ + struct thread_struct *thread = &(tsk->thread); + int i, ret = -ENOENT; + + 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; +} +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 + * @bp: the breakpoint structure to unregister + * + */ +void unregister_user_hw_breakpoint(struct task_struct *tsk, + struct hw_breakpoint *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); +} +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 + * + */ +int register_kernel_hw_breakpoint(struct hw_breakpoint *bp) +{ + int rc; + + rc = arch_validate_hwbkpt_settings(bp, NULL); + if (rc) + return rc; + + spin_lock_bh(&hw_breakpoint_lock); + + 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; + } + + spin_unlock_bh(&hw_breakpoint_lock); + return rc; +} +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. + */ +void unregister_kernel_hw_breakpoint(struct hw_breakpoint *bp) +{ + 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; + + /* 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; + } + + /* + * 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); +} +EXPORT_SYMBOL_GPL(unregister_kernel_hw_breakpoint); + +static struct notifier_block hw_breakpoint_exceptions_nb = { + .notifier_call = hw_breakpoint_exceptions_notify, + /* we need to be notified first */ + .priority = 0x7fffffff +}; + +static int __init init_hw_breakpoint(void) +{ + return register_die_notifier(&hw_breakpoint_exceptions_nb); +} + +core_initcall(init_hw_breakpoint); diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 1ea0d12..5efeb42 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -329,6 +329,27 @@ config POWER_TRACER power management decisions, specifically the C-state and P-state behavior. +config KSYM_TRACER + bool "Trace read and write access on kernel memory locations" + depends on HAVE_HW_BREAKPOINT + select TRACING + help + This tracer helps find read and write operations on any given kernel + symbol i.e. /proc/kallsyms. + +config PROFILE_KSYM_TRACER + bool "Profile all kernel memory accesses on 'watched' variables" + depends on KSYM_TRACER + help + This tracer profiles kernel accesses on variables watched through the + ksym tracer ftrace plugin. Depending upon the hardware, all read + and write operations on kernel variables can be monitored for + accesses. + + The results will be displayed in: + /debugfs/tracing/profile_ksym + + Say N if unsure. config STACK_TRACER bool "Trace max stack" diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index 844164d..ce3b1cd 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -54,5 +54,6 @@ obj-$(CONFIG_EVENT_TRACING) += trace_export.o obj-$(CONFIG_FTRACE_SYSCALLS) += trace_syscalls.o obj-$(CONFIG_EVENT_PROFILE) += trace_event_profile.o obj-$(CONFIG_EVENT_TRACING) += trace_events_filter.o +obj-$(CONFIG_KSYM_TRACER) += trace_ksym.o libftrace-y := ftrace.o diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index fa1dccb..ea7e0bc 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -15,6 +15,10 @@ #include <linux/trace_seq.h> #include <linux/ftrace_event.h> +#ifdef CONFIG_KSYM_TRACER +#include <asm/hw_breakpoint.h> +#endif + enum trace_type { __TRACE_FIRST_TYPE = 0, @@ -38,6 +42,7 @@ enum trace_type { TRACE_KMEM_FREE, TRACE_POWER, TRACE_BLK, + TRACE_KSYM, __TRACE_LAST_TYPE, }; @@ -205,6 +210,16 @@ struct syscall_trace_exit { unsigned long ret; }; +#define KSYM_SELFTEST_ENTRY "ksym_selftest_dummy" +extern int process_new_ksym_entry(char *ksymname, int op, unsigned long addr); + +struct ksym_trace_entry { + struct trace_entry ent; + unsigned long ip; + unsigned char type; + char ksym_name[KSYM_NAME_LEN]; + char cmd[TASK_COMM_LEN]; +}; /* * trace_flag_type is an enumeration that holds different @@ -315,6 +330,7 @@ extern void __ftrace_bad_type(void); TRACE_KMEM_ALLOC); \ IF_ASSIGN(var, ent, struct kmemtrace_free_entry, \ TRACE_KMEM_FREE); \ + IF_ASSIGN(var, ent, struct ksym_trace_entry, TRACE_KSYM);\ __ftrace_bad_type(); \ } while (0) @@ -558,6 +574,8 @@ extern int trace_selftest_startup_branch(struct tracer *trace, struct trace_array *tr); extern int trace_selftest_startup_hw_branches(struct tracer *trace, struct trace_array *tr); +extern int trace_selftest_startup_ksym(struct tracer *trace, + struct trace_array *tr); #endif /* CONFIG_FTRACE_STARTUP_TEST */ extern void *head_page(struct trace_array_cpu *data); diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c new file mode 100644 index 0000000..6d5609c --- /dev/null +++ b/kernel/trace/trace_ksym.c @@ -0,0 +1,551 @@ +/* + * 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- */ + +struct trace_ksym { + struct hw_breakpoint *ksym_hbp; + unsigned long ksym_addr; +#ifdef CONFIG_PROFILE_KSYM_TRACER + unsigned long 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->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 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 = hbp->info.type; + strlcpy(entry->ksym_name, hbp->info.name, KSYM_SYMBOL_LEN); + strlcpy(entry->cmd, 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(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 += 4; + else if (str[0] != '-') + return -EINVAL; + + if (str[1] == 'w') + access += 2; + else if (str[1] != '-') + return -EINVAL; + + if (str[2] != '-') + return -EINVAL; + + switch (access) { + case 6: + access = HW_BREAKPOINT_RW; + break; + case 4: + access = -EINVAL; + break; + case 2: + access = HW_BREAKPOINT_WRITE; + break; + } + + 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) +{ + 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; + + entry->ksym_hbp = kzalloc(sizeof(struct hw_breakpoint), GFP_KERNEL); + if (!entry->ksym_hbp) + goto err; + + entry->ksym_hbp->info.name = kstrdup(ksymname, GFP_KERNEL); + if (!entry->ksym_hbp->info.name) + goto err; + + 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"); + ret = -EAGAIN; + goto err; + } + hlist_add_head_rcu(&(entry->ksym_hlist), &ksym_filter_head); + ksym_filter_entry_count++; + return 0; +err: + if (entry->ksym_hbp) + kfree(entry->ksym_hbp->info.name); + kfree(entry->ksym_hbp); + 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, "%s:", entry->ksym_hbp->info.name); + if (entry->ksym_hbp->info.type == HW_BREAKPOINT_WRITE) + ret = trace_seq_puts(s, "-w-\n"); + else if (entry->ksym_hbp->info.type == HW_BREAKPOINT_RW) + 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_kernel_hw_breakpoint(entry->ksym_hbp); + ksym_filter_entry_count--; + hlist_del_rcu(&(entry->ksym_hlist)); + synchronize_rcu(); + kfree(entry->ksym_hbp->info.name); + kfree(entry->ksym_hbp); + 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 *input_string, *ksymname = NULL; + unsigned long ksym_addr = 0; + int ret, op, changed = 0; + + input_string = kzalloc(count + 1, GFP_KERNEL); + if (!input_string) + return -ENOMEM; + + if (copy_from_user(input_string, buffer, count)) { + kfree(input_string); + return -EFAULT; + } + input_string[count] = '\0'; + + strstrip(input_string); + + /* + * 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(); + kfree(input_string); + return count; + } + + 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 out; + 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) + goto out; + } + ksym_filter_entry_count--; + hlist_del_rcu(&(entry->ksym_hlist)); + synchronize_rcu(); + kfree(entry->ksym_hbp->info.name); + kfree(entry->ksym_hbp); + kfree(entry); + ret = 0; + goto out; + } else { + /* Check for malformed request: (4) */ + if (op == 0) + goto out; + ret = process_new_ksym_entry(ksymname, op, ksym_addr); + } +out: + mutex_unlock(&ksym_tracer_mutex); + + kfree(input_string); + + if (!ret) + ret = count; + 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) +{ + 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] %-30s ", field->cmd, + entry->pid, iter->cpu, field->ksym_name); + if (!ret) + return TRACE_TYPE_PARTIAL_LINE; + + switch (field->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, "%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 +}; + +__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_puts(m, " Access Type "); + seq_puts(m, " Symbol Counter\n"); + seq_puts(m, " ----------- "); + seq_puts(m, " ------ -------\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_puts(m, " W "); + break; + case HW_BREAKPOINT_RW: + seq_puts(m, " RW "); + break; + default: + seq_puts(m, " NA "); + } + + if (lookup_symbol_name(entry->ksym_addr, fn_name) >= 0) + seq_printf(m, " %-36s", fn_name); + else + seq_printf(m, " %-36s", "<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 */ diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c index d2cdbab..7179c12 100644 --- a/kernel/trace/trace_selftest.c +++ b/kernel/trace/trace_selftest.c @@ -17,6 +17,7 @@ static inline int trace_valid_entry(struct trace_entry *entry) case TRACE_GRAPH_ENT: case TRACE_GRAPH_RET: case TRACE_HW_BRANCHES: + case TRACE_KSYM: return 1; } return 0; @@ -808,3 +809,55 @@ trace_selftest_startup_hw_branches(struct tracer *trace, return ret; } #endif /* CONFIG_HW_BRANCH_TRACER */ + +#ifdef CONFIG_KSYM_TRACER +static int ksym_selftest_dummy; + +int +trace_selftest_startup_ksym(struct tracer *trace, struct trace_array *tr) +{ + unsigned long count; + int ret; + + /* start the tracing */ + ret = tracer_init(trace, tr); + if (ret) { + warn_failed_init_tracer(trace, ret); + return ret; + } + + ksym_selftest_dummy = 0; + /* Register the read-write tracing request */ + ret = process_new_ksym_entry(KSYM_SELFTEST_ENTRY, HW_BREAKPOINT_RW, + (unsigned long)(&ksym_selftest_dummy)); + + if (ret < 0) { + printk(KERN_CONT "ksym_trace read-write startup test failed\n"); + goto ret_path; + } + /* Perform a read and a write operation over the dummy variable to + * trigger the tracer + */ + if (ksym_selftest_dummy == 0) + ksym_selftest_dummy++; + + /* stop the tracing. */ + tracing_stop(); + /* check the trace buffer */ + ret = trace_test_buffer(tr, &count); + trace->reset(tr); + tracing_start(); + + /* read & write operations - one each is performed on the dummy variable + * triggering two entries in the trace buffer + */ + if (!ret && count != 2) { + printk(KERN_CONT "Ksym tracer startup test failed"); + ret = -1; + } + +ret_path: + return ret; +} +#endif /* CONFIG_KSYM_TRACER */ + |
