#include <trace/syscall.h> #include <trace/events/syscalls.h> #include <linux/syscalls.h> #include <linux/slab.h> #include <linux/kernel.h> #include <linux/module.h> /* for MODULE_NAME_LEN via KSYM_SYMBOL_LEN */ #include <linux/ftrace.h> #include <linux/perf_event.h> #include <asm/syscall.h> #include "trace_output.h" #include "trace.h" static DEFINE_MUTEX(syscall_trace_lock); static int syscall_enter_register(struct trace_event_call *event, enum trace_reg type, void *data); static int syscall_exit_register(struct trace_event_call *event, enum trace_reg type, void *data); static struct list_head * syscall_get_enter_fields(struct trace_event_call *call) { struct syscall_metadata *entry = call->data; return &entry->enter_fields; } extern struct syscall_metadata *__start_syscalls_metadata[]; extern struct syscall_metadata *__stop_syscalls_metadata[]; static struct syscall_metadata **syscalls_metadata; #ifndef ARCH_HAS_SYSCALL_MATCH_SYM_NAME static inline bool arch_syscall_match_sym_name(const char *sym, const char *name) { /* * Only compare after the "sys" prefix. Archs that use * syscall wrappers may have syscalls symbols aliases prefixed * with ".SyS" or ".sys" instead of "sys", leading to an unwanted * mismatch. */ return !strcmp(sym + 3, name + 3); } #endif #ifdef ARCH_TRACE_IGNORE_COMPAT_SYSCALLS /* * Some architectures that allow for 32bit applications * to run on a 64bit kernel, do not map the syscalls for * the 32bit tasks the same as they do for 64bit tasks. * * *cough*x86*cough* * * In such a case, instead of reporting the wrong syscalls, * simply ignore them. * * For an arch to ignore the compat syscalls it needs to * define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS as well as * define the function arch_trace_is_compat_syscall() to let * the tracing system know that it should ignore it. */ static int trace_get_syscall_nr(struct task_struct *task, struct pt_regs *regs) { if (unlikely(arch_trace_is_compat_syscall(regs))) return -1; return syscall_get_nr(task, regs); } #else static inline int trace_get_syscall_nr(struct task_struct *task, struct pt_regs *regs) { return syscall_get_nr(task, regs); } #endif /* ARCH_TRACE_IGNORE_COMPAT_SYSCALLS */ static __init struct syscall_metadata * find_syscall_meta(unsigned long syscall) { struct syscall_metadata **start; struct syscall_metadata **stop; char str[KSYM_SYMBOL_LEN]; start = __start_syscalls_metadata; stop = __stop_syscalls_metadata; kallsyms_lookup(syscall, NULL, NULL, NULL, str); if (arch_syscall_match_sym_name(str, "sys_ni_syscall")) return NULL; for ( ; start < stop; start++) { if ((*start)->name && arch_syscall_match_sym_name(str, (*start)->name)) return *start; } return NULL; } static struct syscall_metadata *syscall_nr_to_meta(int nr) { if (!syscalls_metadata || nr >= NR_syscalls || nr < 0) return NULL; return syscalls_metadata[nr]; } const char *get_syscall_name(int syscall) { struct syscall_metadata *entry; entry = syscall_nr_to_meta(syscall); if (!entry) return NULL; return entry->name; } static enum print_line_t print_syscall_enter(struct trace_iterator *iter, int flags, struct trace_event *event) { struct trace_array *tr = iter->tr; struct trace_seq *s = &iter->seq; struct trace_entry *ent = iter->ent; struct syscall_trace_enter *trace; struct syscall_metadata *entry; int i, syscall; trace = (typeof(trace))ent; syscall = trace->nr; entry = syscall_nr_to_meta(syscall); if (!entry) goto end; if (entry->enter_event->event.type != ent->type) { WARN_ON_ONCE(1); goto end; } trace_seq_printf(s, "%s(", entry->name); for (i = 0; i < entry->nb_args; i++) { if (trace_seq_has_overflowed(s)) goto end; /* parameter types */ if (tr->trace_flags & TRACE_ITER_VERBOSE) trace_seq_printf(s, "%s ", entry->types[i]); /* parameter values */ trace_seq_printf(s, "%s: %lx%s", entry->args[i], trace->args[i], i == entry->nb_args - 1 ? "" : ", "); } trace_seq_putc(s, ')'); end: trace_seq_putc(s, '\n'); return trace_handle_return(s); } static enum print_line_t print_syscall_exit(struct trace_iterator *iter, int flags, struct trace_event *event) { struct trace_seq *s = &iter->seq; struct trace_entry *ent = iter->ent; struct syscall_trace_exit *trace; int syscall; struct syscall_metadata *entry; trace = (typeof(trace))ent; syscall = trace->nr; entry = syscall_nr_to_meta(syscall); if (!entry) { trace_seq_putc(s, '\n'); goto out; } if (entry->exit_event->event.type != ent->type) { WARN_ON_ONCE(1); return TRACE_TYPE_UNHANDLED; } trace_seq_printf(s, "%s -> 0x%lx\n", entry->name, trace->ret); out: return trace_handle_return(s); } extern char *__bad_type_size(void); #define SYSCALL_FIELD(type, field, name) \ sizeof(type) != sizeof(trace.field) ? \ __bad_type_size() : \ #type, #name, offsetof(typeof(trace), field), \ sizeof(trace.field), is_signed_type(type) static int __init __set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len) { int i; int pos = 0; /* When len=0, we just calculate the needed length */ #define LEN_OR_ZERO (len ? len - pos : 0) pos += snprintf(buf + pos, LEN_OR_ZERO, "\""); for (i = 0; i < entry->nb_args; i++) { pos += snprintf(buf + pos, LEN_OR_ZERO, "%s: 0x%%0%zulx%s", entry->args[i], sizeof(unsigned long), i == entry->nb_args - 1 ? "" : ", "); } pos += snprintf(buf + pos, LEN_OR_ZERO, "\""); for (i = 0; i < entry->nb_args; i++) { pos += snprintf(buf + pos, LEN_OR_ZERO, ", ((unsigned long)(REC->%s))", entry->args[i]); } #undef LEN_OR_ZERO /* return the length of print_fmt */ return pos; } static int __init set_syscall_print_fmt(struct trace_event_call *call) { char *print_fmt; int len; struct syscall_metadata *entry = call->data; if (entry->enter_event != call) { call->print_fmt = "\"0x%lx\", REC->ret"; return 0; } /* First: called with 0 length to calculate the needed length */ len = __set_enter_print_fmt(entry, NULL, 0); print_fmt = kmalloc(len + 1, GFP_KERNEL); if (!print_fmt) return -ENOMEM; /* Second: actually write the @print_fmt */ __set_enter_print_fmt(entry, print_fmt, len + 1); call->print_fmt = print_fmt; return 0; } static void __init free_syscall_print_fmt(struct trace_event_call *call) { struct syscall_metadata *entry = call->data; if (entry->enter_event == call) kfree(call->print_fmt); } static int __init syscall_enter_define_fields(struct trace_event_call *call) { struct syscall_trace_enter trace; struct syscall_metadata *meta = call->data; int ret; int i; int offset = offsetof(typeof(trace), args); ret = trace_define_field(call, SYSCALL_FIELD(int, nr, __syscall_nr), FILTER_OTHER); if (ret) return ret; for (i = 0; i < meta->nb_args; i++) { ret = trace_define_field(call, meta->types[i], meta->args[i], offset, sizeof(unsigned long), 0, FILTER_OTHER); offset += sizeof(unsigned long); } return ret; } static int __init syscall_exit_define_fields(struct trace_event_call *call) { struct syscall_trace_exit trace; int ret; ret = trace_define_field(call, SYSCALL_FIELD(int, nr, __syscall_nr), FILTER_OTHER); if (ret) return ret; ret = trace_define_field(call, SYSCALL_FIELD(long, ret, ret), FILTER_OTHER); return ret; } static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id) { struct trace_array *tr = data; struct trace_event_file *trace_file; struct syscall_trace_enter *entry; struct syscall_metadata *sys_data; struct ring_buffer_event *event; struct ring_buffer *buffer; unsigned long irq_flags; int pc; int syscall_nr; int size; syscall_nr = trace_get_syscall_nr(current, regs); if (syscall_nr < 0 || syscall_nr >= NR_syscalls) return; /* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE) */ trace_file = rcu_dereference_sched(tr->enter_syscall_files[syscall_nr]); if (!trace_file) return; if (trace_trigger_soft_disabled(trace_file)) return; sys_data = syscall_nr_to_meta(syscall_nr); if (!sys_data) return; size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args; local_save_flags(irq_flags); pc = preempt_count(); buffer = tr->trace_buffer.buffer; event = trace_buffer_lock_reserve(buffer, sys_data->enter_event->event.type, size, irq_flags, pc); if (!event) return; entry = ring_buffer_event_data(event); entry->nr = syscall_nr; syscall_get_arguments(current, regs, 0, sys_data->nb_args, entry->args); event_trigger_unlock_commit(trace_file, buffer, event, entry, irq_flags, pc); } static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret) { struct trace_array *tr = data; struct trace_event_file *trace_file; struct syscall_trace_exit *entry; struct syscall_metadata *sys_data; struct ring_buffer_event *event; struct ring_buffer *buffer; unsigned long irq_flags; int pc; int syscall_nr; syscall_nr = trace_get_syscall_nr(current, regs); if (syscall_nr < 0 || syscall_nr >= NR_syscalls) return; /* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE()) */ trace_file = rcu_dereference_sched(tr->exit_syscall_files[syscall_nr]); if (!trace_file) return; if (trace_trigger_soft_disabled(trace_file)) return; sys_data = syscall_nr_to_meta(syscall_nr); if (!sys_data) return; local_save_flags(irq_flags); pc = preempt_count(); buffer = tr->trace_buffer.buffer; event = trace_buffer_lock_reserve(buffer, sys_data->exit_event->event.type, sizeof(*entry), irq_flags, pc); if (!event) return; entry = ring_buffer_event_data(event); entry->nr = syscall_nr; entry->ret = syscall_get_return_value(current, regs); event_trigger_unlock_commit(trace_file, buffer, event, entry, irq_flags, pc); } static int reg_event_syscall_enter(struct trace_event_file *file, struct trace_event_call *call) { struct trace_array *tr = file->tr; int ret = 0; int num; num = ((struct syscall_metadata *)call->data)->syscall_nr; if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls)) return -ENOSYS; mutex_lock(&syscall_trace_lock); if (!tr->sys_refcount_enter) ret = register_trace_sys_enter(ftrace_syscall_enter, tr); if (!ret) { rcu_assign_pointer(tr->enter_syscall_files[num], file); tr->sys_refcount_enter++; } mutex_unlock(&syscall_trace_lock); return ret; } static void unreg_event_syscall_enter(struct trace_event_file *file, struct trace_event_call *call) { struct trace_array *tr = file->tr; int num; num = ((struct syscall_metadata *)call->data)->syscall_nr; if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls)) return; mutex_lock(&syscall_trace_lock); tr->sys_refcount_enter--; RCU_INIT_POINTER(tr->enter_syscall_files[num], NULL); if (!tr->sys_refcount_enter) unregister_trace_sys_enter(ftrace_syscall_enter, tr); mutex_unlock(&syscall_trace_lock); } static int reg_event_syscall_exit(struct trace_event_file *file, struct trace_event_call *call) { struct trace_array *tr = file->tr; int ret = 0; int num; num = ((struct syscall_metadata *)call->data)->syscall_nr; if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls)) return -ENOSYS; mutex_lock(&syscall_trace_lock); if (!tr->sys_refcount_exit) ret = register_trace_sys_exit(ftrace_syscall_exit, tr); if (!ret) { rcu_assign_pointer(tr->exit_syscall_files[num], file); tr->sys_refcount_exit++; } mutex_unlock(&syscall_trace_lock); return ret; } static void unreg_event_syscall_exit(struct trace_event_file *file, struct trace_event_call *call) { struct trace_array *tr = file->tr; int num; num = ((struct syscall_metadata *)call->data)->syscall_nr; if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls)) return; mutex_lock(&syscall_trace_lock); tr->sys_refcount_exit--; RCU_INIT_POINTER(tr->exit_syscall_files[num], NULL); if (!tr->sys_refcount_exit) unregister_trace_sys_exit(ftrace_syscall_exit, tr); mutex_unlock(&syscall_trace_lock); } static int __init init_syscall_trace(struct trace_event_call *call) { int id; int num; num = ((struct syscall_metadata *)call->data)->syscall_nr; if (num < 0 || num >= NR_syscalls) { pr_debug("syscall %s metadata not mapped, disabling ftrace event\n", ((struct syscall_metadata *)call->data)->name); return -ENOSYS; } if (set_syscall_print_fmt(call) < 0) return -ENOMEM; id = trace_event_raw_init(call); if (id < 0) { free_syscall_print_fmt(call); return id; } return id; } struct trace_event_functions enter_syscall_print_funcs = { .trace = print_syscall_enter, }; struct trace_event_functions exit_syscall_print_funcs = { .trace = print_syscall_exit, }; struct trace_event_class __refdata event_class_syscall_enter = { .system = "syscalls", .reg = syscall_enter_register, .define_fields = syscall_enter_define_fields, .get_fields = syscall_get_enter_fields, .raw_init = init_syscall_trace, }; struct trace_event_class __refdata event_class_syscall_exit = { .system = "syscalls", .reg = syscall_exit_register, .define_fields = syscall_exit_define_fields, .fields = LIST_HEAD_INIT(event_class_syscall_exit.fields), .raw_init = init_syscall_trace, }; unsigned long __init __weak arch_syscall_addr(int nr) { return (unsigned long)sys_call_table[nr]; } void __init init_ftrace_syscalls(void) { struct syscall_metadata *meta; unsigned long addr; int i; syscalls_metadata = kcalloc(NR_syscalls, sizeof(*syscalls_metadata), GFP_KERNEL); if (!syscalls_metadata) { WARN_ON(1); return; } for (i = 0; i < NR_syscalls; i++) { addr = arch_syscall_addr(i); meta = find_syscall_meta(addr); if (!meta) continue; meta->syscall_nr = i; syscalls_metadata[i] = meta; } } #ifdef CONFIG_PERF_EVENTS static DECLARE_BITMAP(enabled_perf_enter_syscalls, NR_syscalls); static DECLARE_BITMAP(enabled_perf_exit_syscalls, NR_syscalls); static int sys_perf_refcount_enter; static int sys_perf_refcount_exit; static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id) { struct syscall_metadata *sys_data; struct syscall_trace_enter *rec; struct hlist_head *head; int syscall_nr; int rctx; int size; syscall_nr = trace_get_syscall_nr(current, regs); if (syscall_nr < 0 || syscall_nr >= NR_syscalls) return; if (!test_bit(syscall_nr, enabled_perf_enter_syscalls)) return; sys_data = syscall_nr_to_meta(syscall_nr); if (!sys_data) return; head = this_cpu_ptr(sys_data->enter_event->perf_events); if (hlist_empty(head)) return; /* get the size after alignment with the u32 buffer size field */ size = sizeof(unsigned long) * sys_data->nb_args + sizeof(*rec); size = ALIGN(size + sizeof(u32), sizeof(u64)); size -= sizeof(u32); rec = perf_trace_buf_alloc(size, NULL, &rctx); if (!rec) return; rec->nr = syscall_nr; syscall_get_arguments(current, regs, 0, sys_data->nb_args, (unsigned long *)&rec->args); perf_trace_buf_submit(rec, size, rctx, sys_data->enter_event->event.type, 1, regs, head, NULL); } static int perf_sysenter_enable(struct trace_event_call *call) { int ret = 0; int num; num = ((struct syscall_metadata *)call->data)->syscall_nr; mutex_lock(&syscall_trace_lock); if (!sys_perf_refcount_enter) ret = register_trace_sys_enter(perf_syscall_enter, NULL); if (ret) { pr_info("event trace: Could not activate syscall entry trace point"); } else { set_bit(num, enabled_perf_enter_syscalls); sys_perf_refcount_enter++; } mutex_unlock(&syscall_trace_lock); return ret; } static void perf_sysenter_disable(struct trace_event_call *call) { int num; num = ((struct syscall_metadata *)call->data)->syscall_nr; mutex_lock(&syscall_trace_lock); sys_perf_refcount_enter--; clear_bit(num, enabled_perf_enter_syscalls); if (!sys_perf_refcount_enter) unregister_trace_sys_enter(perf_syscall_enter, NULL); mutex_unlock(&syscall_trace_lock); } static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret) { struct syscall_metadata *sys_data; struct syscall_trace_exit *rec; struct hlist_head *head; int syscall_nr; int rctx; int size; syscall_nr = trace_get_syscall_nr(current, regs); if (syscall_nr < 0 || syscall_nr >= NR_syscalls) return; if (!test_bit(syscall_nr, enabled_perf_exit_syscalls)) return; sys_data = syscall_nr_to_meta(syscall_nr); if (!sys_data) return; head = this_cpu_ptr(sys_data->exit_event->perf_events); if (hlist_empty(head)) return; /* We can probably do that at build time */ size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64)); size -= sizeof(u32); rec = perf_trace_buf_alloc(size, NULL, &rctx); if (!rec) return; rec->nr = syscall_nr; rec->ret = syscall_get_return_value(current, regs); perf_trace_buf_submit(rec, size, rctx, sys_data->exit_event->event.type, 1, regs, head, NULL); } static int perf_sysexit_enable(struct trace_event_call *call) { int ret = 0; int num; num = ((struct syscall_metadata *)call->data)->syscall_nr; mutex_lock(&syscall_trace_lock); if (!sys_perf_refcount_exit) ret = register_trace_sys_exit(perf_syscall_exit, NULL); if (ret) { pr_info("event trace: Could not activate syscall exit trace point"); } else { set_bit(num, enabled_perf_exit_syscalls); sys_perf_refcount_exit++; } mutex_unlock(&syscall_trace_lock); return ret; } static void perf_sysexit_disable(struct trace_event_call *call) { int num; num = ((struct syscall_metadata *)call->data)->syscall_nr; mutex_lock(&syscall_trace_lock); sys_perf_refcount_exit--; clear_bit(num, enabled_perf_exit_syscalls); if (!sys_perf_refcount_exit) unregister_trace_sys_exit(perf_syscall_exit, NULL); mutex_unlock(&syscall_trace_lock); } #endif /* CONFIG_PERF_EVENTS */ static int syscall_enter_register(struct trace_event_call *event, enum trace_reg type, void *data) { struct trace_event_file *file = data; switch (type) { case TRACE_REG_REGISTER: return reg_event_syscall_enter(file, event); case TRACE_REG_UNREGISTER: unreg_event_syscall_enter(file, event); return 0; #ifdef CONFIG_PERF_EVENTS case TRACE_REG_PERF_REGISTER: return perf_sysenter_enable(event); case TRACE_REG_PERF_UNREGISTER: perf_sysenter_disable(event); return 0; case TRACE_REG_PERF_OPEN: case TRACE_REG_PERF_CLOSE: case TRACE_REG_PERF_ADD: case TRACE_REG_PERF_DEL: return 0; #endif } return 0; } static int syscall_exit_register(struct trace_event_call *event, enum trace_reg type, void *data) { struct trace_event_file *file = data; switch (type) { case TRACE_REG_REGISTER: return reg_event_syscall_exit(file, event); case TRACE_REG_UNREGISTER: unreg_event_syscall_exit(file, event); return 0; #ifdef CONFIG_PERF_EVENTS case TRACE_REG_PERF_REGISTER: return perf_sysexit_enable(event); case TRACE_REG_PERF_UNREGISTER: perf_sysexit_disable(event); return 0; case TRACE_REG_PERF_OPEN: case TRACE_REG_PERF_CLOSE: case TRACE_REG_PERF_ADD: case TRACE_REG_PERF_DEL: return 0; #endif } return 0; }