![Steven Rostedt](/assets/img/avatar_default.png)
Currently the syscall_meta structures for the syscall tracepoints are placed in the __syscall_metadata section, and at link time, the linker makes one large array of all these syscall metadata structures. On boot up, this array is read (much like the initcall sections) and the syscall data is processed. The problem is that there is no guarantee that gcc will place complex structures nicely together in an array format. Two structures in the same file may be placed awkwardly, because gcc has no clue that they are suppose to be in an array. A hack was used previous to force the alignment to 4, to pack the structures together. But this caused alignment issues with other architectures (sparc). Instead of packing the structures into an array, the structures' addresses are now put into the __syscall_metadata section. As pointers are always the natural alignment, gcc should always pack them tightly together (otherwise initcall, extable, etc would also fail). By having the pointers to the structures in the section, we can still iterate the trace_events without causing unnecessary alignment problems with other architectures, or depending on the current behaviour of gcc that will likely change in the future just to tick us kernel developers off a little more. The __syscall_metadata section is also moved into the .init.data section as it is now only needed at boot up. Suggested-by: David Miller <davem@davemloft.net> Acked-by: David S. Miller <davem@davemloft.net> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
673 lines
16 KiB
C
673 lines
16 KiB
C
#include <trace/syscall.h>
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#include <trace/events/syscalls.h>
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#include <linux/slab.h>
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#include <linux/kernel.h>
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#include <linux/ftrace.h>
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#include <linux/perf_event.h>
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#include <asm/syscall.h>
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#include "trace_output.h"
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#include "trace.h"
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static DEFINE_MUTEX(syscall_trace_lock);
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static int sys_refcount_enter;
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static int sys_refcount_exit;
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static DECLARE_BITMAP(enabled_enter_syscalls, NR_syscalls);
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static DECLARE_BITMAP(enabled_exit_syscalls, NR_syscalls);
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static int syscall_enter_register(struct ftrace_event_call *event,
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enum trace_reg type);
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static int syscall_exit_register(struct ftrace_event_call *event,
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enum trace_reg type);
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static int syscall_enter_define_fields(struct ftrace_event_call *call);
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static int syscall_exit_define_fields(struct ftrace_event_call *call);
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static struct list_head *
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syscall_get_enter_fields(struct ftrace_event_call *call)
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{
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struct syscall_metadata *entry = call->data;
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return &entry->enter_fields;
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}
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struct trace_event_functions enter_syscall_print_funcs = {
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.trace = print_syscall_enter,
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};
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struct trace_event_functions exit_syscall_print_funcs = {
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.trace = print_syscall_exit,
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};
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struct ftrace_event_class event_class_syscall_enter = {
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.system = "syscalls",
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.reg = syscall_enter_register,
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.define_fields = syscall_enter_define_fields,
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.get_fields = syscall_get_enter_fields,
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.raw_init = init_syscall_trace,
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};
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struct ftrace_event_class event_class_syscall_exit = {
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.system = "syscalls",
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.reg = syscall_exit_register,
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.define_fields = syscall_exit_define_fields,
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.fields = LIST_HEAD_INIT(event_class_syscall_exit.fields),
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.raw_init = init_syscall_trace,
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};
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extern struct syscall_metadata *__start_syscalls_metadata[];
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extern struct syscall_metadata *__stop_syscalls_metadata[];
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static struct syscall_metadata **syscalls_metadata;
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static __init struct syscall_metadata *
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find_syscall_meta(unsigned long syscall)
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{
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struct syscall_metadata **start;
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struct syscall_metadata **stop;
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char str[KSYM_SYMBOL_LEN];
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start = __start_syscalls_metadata;
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stop = __stop_syscalls_metadata;
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kallsyms_lookup(syscall, NULL, NULL, NULL, str);
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for ( ; start < stop; start++) {
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/*
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* Only compare after the "sys" prefix. Archs that use
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* syscall wrappers may have syscalls symbols aliases prefixed
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* with "SyS" instead of "sys", leading to an unwanted
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* mismatch.
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*/
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if ((*start)->name && !strcmp((*start)->name + 3, str + 3))
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return *start;
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}
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return NULL;
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}
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static struct syscall_metadata *syscall_nr_to_meta(int nr)
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{
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if (!syscalls_metadata || nr >= NR_syscalls || nr < 0)
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return NULL;
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return syscalls_metadata[nr];
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}
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enum print_line_t
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print_syscall_enter(struct trace_iterator *iter, int flags,
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struct trace_event *event)
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{
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struct trace_seq *s = &iter->seq;
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struct trace_entry *ent = iter->ent;
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struct syscall_trace_enter *trace;
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struct syscall_metadata *entry;
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int i, ret, syscall;
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trace = (typeof(trace))ent;
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syscall = trace->nr;
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entry = syscall_nr_to_meta(syscall);
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if (!entry)
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goto end;
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if (entry->enter_event->event.type != ent->type) {
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WARN_ON_ONCE(1);
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goto end;
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}
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ret = trace_seq_printf(s, "%s(", entry->name);
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if (!ret)
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return TRACE_TYPE_PARTIAL_LINE;
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for (i = 0; i < entry->nb_args; i++) {
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/* parameter types */
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if (trace_flags & TRACE_ITER_VERBOSE) {
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ret = trace_seq_printf(s, "%s ", entry->types[i]);
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if (!ret)
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return TRACE_TYPE_PARTIAL_LINE;
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}
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/* parameter values */
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ret = trace_seq_printf(s, "%s: %lx%s", entry->args[i],
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trace->args[i],
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i == entry->nb_args - 1 ? "" : ", ");
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if (!ret)
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return TRACE_TYPE_PARTIAL_LINE;
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}
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ret = trace_seq_putc(s, ')');
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if (!ret)
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return TRACE_TYPE_PARTIAL_LINE;
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end:
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ret = trace_seq_putc(s, '\n');
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if (!ret)
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return TRACE_TYPE_PARTIAL_LINE;
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return TRACE_TYPE_HANDLED;
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}
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enum print_line_t
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print_syscall_exit(struct trace_iterator *iter, int flags,
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struct trace_event *event)
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{
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struct trace_seq *s = &iter->seq;
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struct trace_entry *ent = iter->ent;
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struct syscall_trace_exit *trace;
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int syscall;
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struct syscall_metadata *entry;
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int ret;
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trace = (typeof(trace))ent;
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syscall = trace->nr;
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entry = syscall_nr_to_meta(syscall);
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if (!entry) {
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trace_seq_printf(s, "\n");
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return TRACE_TYPE_HANDLED;
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}
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if (entry->exit_event->event.type != ent->type) {
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WARN_ON_ONCE(1);
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return TRACE_TYPE_UNHANDLED;
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}
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ret = trace_seq_printf(s, "%s -> 0x%lx\n", entry->name,
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trace->ret);
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if (!ret)
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return TRACE_TYPE_PARTIAL_LINE;
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return TRACE_TYPE_HANDLED;
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}
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extern char *__bad_type_size(void);
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#define SYSCALL_FIELD(type, name) \
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sizeof(type) != sizeof(trace.name) ? \
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__bad_type_size() : \
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#type, #name, offsetof(typeof(trace), name), \
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sizeof(trace.name), is_signed_type(type)
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static
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int __set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len)
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{
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int i;
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int pos = 0;
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/* When len=0, we just calculate the needed length */
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#define LEN_OR_ZERO (len ? len - pos : 0)
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pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
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for (i = 0; i < entry->nb_args; i++) {
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pos += snprintf(buf + pos, LEN_OR_ZERO, "%s: 0x%%0%zulx%s",
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entry->args[i], sizeof(unsigned long),
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i == entry->nb_args - 1 ? "" : ", ");
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}
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pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
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for (i = 0; i < entry->nb_args; i++) {
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pos += snprintf(buf + pos, LEN_OR_ZERO,
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", ((unsigned long)(REC->%s))", entry->args[i]);
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}
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#undef LEN_OR_ZERO
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/* return the length of print_fmt */
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return pos;
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}
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static int set_syscall_print_fmt(struct ftrace_event_call *call)
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{
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char *print_fmt;
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int len;
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struct syscall_metadata *entry = call->data;
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if (entry->enter_event != call) {
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call->print_fmt = "\"0x%lx\", REC->ret";
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return 0;
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}
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/* First: called with 0 length to calculate the needed length */
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len = __set_enter_print_fmt(entry, NULL, 0);
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print_fmt = kmalloc(len + 1, GFP_KERNEL);
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if (!print_fmt)
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return -ENOMEM;
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/* Second: actually write the @print_fmt */
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__set_enter_print_fmt(entry, print_fmt, len + 1);
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call->print_fmt = print_fmt;
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return 0;
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}
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static void free_syscall_print_fmt(struct ftrace_event_call *call)
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{
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struct syscall_metadata *entry = call->data;
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if (entry->enter_event == call)
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kfree(call->print_fmt);
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}
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static int syscall_enter_define_fields(struct ftrace_event_call *call)
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{
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struct syscall_trace_enter trace;
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struct syscall_metadata *meta = call->data;
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int ret;
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int i;
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int offset = offsetof(typeof(trace), args);
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ret = trace_define_field(call, SYSCALL_FIELD(int, nr), FILTER_OTHER);
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if (ret)
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return ret;
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for (i = 0; i < meta->nb_args; i++) {
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ret = trace_define_field(call, meta->types[i],
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meta->args[i], offset,
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sizeof(unsigned long), 0,
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FILTER_OTHER);
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offset += sizeof(unsigned long);
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}
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return ret;
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}
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static int syscall_exit_define_fields(struct ftrace_event_call *call)
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{
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struct syscall_trace_exit trace;
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int ret;
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ret = trace_define_field(call, SYSCALL_FIELD(int, nr), FILTER_OTHER);
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if (ret)
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return ret;
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ret = trace_define_field(call, SYSCALL_FIELD(long, ret),
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FILTER_OTHER);
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return ret;
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}
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void ftrace_syscall_enter(void *ignore, struct pt_regs *regs, long id)
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{
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struct syscall_trace_enter *entry;
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struct syscall_metadata *sys_data;
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struct ring_buffer_event *event;
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struct ring_buffer *buffer;
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int size;
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int syscall_nr;
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syscall_nr = syscall_get_nr(current, regs);
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if (syscall_nr < 0)
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return;
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if (!test_bit(syscall_nr, enabled_enter_syscalls))
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return;
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sys_data = syscall_nr_to_meta(syscall_nr);
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if (!sys_data)
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return;
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size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
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event = trace_current_buffer_lock_reserve(&buffer,
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sys_data->enter_event->event.type, size, 0, 0);
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if (!event)
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return;
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entry = ring_buffer_event_data(event);
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entry->nr = syscall_nr;
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syscall_get_arguments(current, regs, 0, sys_data->nb_args, entry->args);
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if (!filter_current_check_discard(buffer, sys_data->enter_event,
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entry, event))
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trace_current_buffer_unlock_commit(buffer, event, 0, 0);
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}
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void ftrace_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
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{
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struct syscall_trace_exit *entry;
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struct syscall_metadata *sys_data;
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struct ring_buffer_event *event;
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struct ring_buffer *buffer;
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int syscall_nr;
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syscall_nr = syscall_get_nr(current, regs);
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if (syscall_nr < 0)
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return;
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if (!test_bit(syscall_nr, enabled_exit_syscalls))
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return;
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sys_data = syscall_nr_to_meta(syscall_nr);
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if (!sys_data)
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return;
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event = trace_current_buffer_lock_reserve(&buffer,
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sys_data->exit_event->event.type, sizeof(*entry), 0, 0);
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if (!event)
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return;
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entry = ring_buffer_event_data(event);
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entry->nr = syscall_nr;
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entry->ret = syscall_get_return_value(current, regs);
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if (!filter_current_check_discard(buffer, sys_data->exit_event,
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entry, event))
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trace_current_buffer_unlock_commit(buffer, event, 0, 0);
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}
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int reg_event_syscall_enter(struct ftrace_event_call *call)
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{
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int ret = 0;
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int num;
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num = ((struct syscall_metadata *)call->data)->syscall_nr;
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if (num < 0 || num >= NR_syscalls)
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return -ENOSYS;
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mutex_lock(&syscall_trace_lock);
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if (!sys_refcount_enter)
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ret = register_trace_sys_enter(ftrace_syscall_enter, NULL);
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if (!ret) {
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set_bit(num, enabled_enter_syscalls);
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sys_refcount_enter++;
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}
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mutex_unlock(&syscall_trace_lock);
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return ret;
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}
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void unreg_event_syscall_enter(struct ftrace_event_call *call)
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{
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int num;
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num = ((struct syscall_metadata *)call->data)->syscall_nr;
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if (num < 0 || num >= NR_syscalls)
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return;
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mutex_lock(&syscall_trace_lock);
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sys_refcount_enter--;
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clear_bit(num, enabled_enter_syscalls);
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if (!sys_refcount_enter)
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unregister_trace_sys_enter(ftrace_syscall_enter, NULL);
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mutex_unlock(&syscall_trace_lock);
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}
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int reg_event_syscall_exit(struct ftrace_event_call *call)
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{
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int ret = 0;
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int num;
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num = ((struct syscall_metadata *)call->data)->syscall_nr;
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if (num < 0 || num >= NR_syscalls)
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return -ENOSYS;
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mutex_lock(&syscall_trace_lock);
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if (!sys_refcount_exit)
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ret = register_trace_sys_exit(ftrace_syscall_exit, NULL);
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if (!ret) {
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set_bit(num, enabled_exit_syscalls);
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sys_refcount_exit++;
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}
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mutex_unlock(&syscall_trace_lock);
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return ret;
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}
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void unreg_event_syscall_exit(struct ftrace_event_call *call)
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{
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int num;
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num = ((struct syscall_metadata *)call->data)->syscall_nr;
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if (num < 0 || num >= NR_syscalls)
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return;
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mutex_lock(&syscall_trace_lock);
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sys_refcount_exit--;
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clear_bit(num, enabled_exit_syscalls);
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if (!sys_refcount_exit)
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unregister_trace_sys_exit(ftrace_syscall_exit, NULL);
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mutex_unlock(&syscall_trace_lock);
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}
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int init_syscall_trace(struct ftrace_event_call *call)
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{
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int id;
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if (set_syscall_print_fmt(call) < 0)
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return -ENOMEM;
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id = trace_event_raw_init(call);
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if (id < 0) {
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free_syscall_print_fmt(call);
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return id;
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}
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return id;
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}
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unsigned long __init arch_syscall_addr(int nr)
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{
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return (unsigned long)sys_call_table[nr];
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}
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int __init init_ftrace_syscalls(void)
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{
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struct syscall_metadata *meta;
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unsigned long addr;
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int i;
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syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) *
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NR_syscalls, GFP_KERNEL);
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if (!syscalls_metadata) {
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WARN_ON(1);
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return -ENOMEM;
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}
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for (i = 0; i < NR_syscalls; i++) {
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addr = arch_syscall_addr(i);
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meta = find_syscall_meta(addr);
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if (!meta)
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continue;
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meta->syscall_nr = i;
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syscalls_metadata[i] = meta;
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}
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return 0;
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}
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core_initcall(init_ftrace_syscalls);
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#ifdef CONFIG_PERF_EVENTS
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static DECLARE_BITMAP(enabled_perf_enter_syscalls, NR_syscalls);
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static DECLARE_BITMAP(enabled_perf_exit_syscalls, NR_syscalls);
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static int sys_perf_refcount_enter;
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static int sys_perf_refcount_exit;
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static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
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{
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struct syscall_metadata *sys_data;
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struct syscall_trace_enter *rec;
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struct hlist_head *head;
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int syscall_nr;
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int rctx;
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int size;
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syscall_nr = syscall_get_nr(current, regs);
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if (!test_bit(syscall_nr, enabled_perf_enter_syscalls))
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return;
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sys_data = syscall_nr_to_meta(syscall_nr);
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if (!sys_data)
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return;
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/* get the size after alignment with the u32 buffer size field */
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size = sizeof(unsigned long) * sys_data->nb_args + sizeof(*rec);
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size = ALIGN(size + sizeof(u32), sizeof(u64));
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size -= sizeof(u32);
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if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
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"perf buffer not large enough"))
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return;
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rec = (struct syscall_trace_enter *)perf_trace_buf_prepare(size,
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sys_data->enter_event->event.type, regs, &rctx);
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if (!rec)
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return;
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rec->nr = syscall_nr;
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syscall_get_arguments(current, regs, 0, sys_data->nb_args,
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(unsigned long *)&rec->args);
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head = this_cpu_ptr(sys_data->enter_event->perf_events);
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perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head);
|
|
}
|
|
|
|
int perf_sysenter_enable(struct ftrace_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;
|
|
}
|
|
|
|
void perf_sysenter_disable(struct ftrace_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 = syscall_get_nr(current, regs);
|
|
if (!test_bit(syscall_nr, enabled_perf_exit_syscalls))
|
|
return;
|
|
|
|
sys_data = syscall_nr_to_meta(syscall_nr);
|
|
if (!sys_data)
|
|
return;
|
|
|
|
/* We can probably do that at build time */
|
|
size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64));
|
|
size -= sizeof(u32);
|
|
|
|
/*
|
|
* Impossible, but be paranoid with the future
|
|
* How to put this check outside runtime?
|
|
*/
|
|
if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
|
|
"exit event has grown above perf buffer size"))
|
|
return;
|
|
|
|
rec = (struct syscall_trace_exit *)perf_trace_buf_prepare(size,
|
|
sys_data->exit_event->event.type, regs, &rctx);
|
|
if (!rec)
|
|
return;
|
|
|
|
rec->nr = syscall_nr;
|
|
rec->ret = syscall_get_return_value(current, regs);
|
|
|
|
head = this_cpu_ptr(sys_data->exit_event->perf_events);
|
|
perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head);
|
|
}
|
|
|
|
int perf_sysexit_enable(struct ftrace_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;
|
|
}
|
|
|
|
void perf_sysexit_disable(struct ftrace_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 ftrace_event_call *event,
|
|
enum trace_reg type)
|
|
{
|
|
switch (type) {
|
|
case TRACE_REG_REGISTER:
|
|
return reg_event_syscall_enter(event);
|
|
case TRACE_REG_UNREGISTER:
|
|
unreg_event_syscall_enter(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;
|
|
#endif
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int syscall_exit_register(struct ftrace_event_call *event,
|
|
enum trace_reg type)
|
|
{
|
|
switch (type) {
|
|
case TRACE_REG_REGISTER:
|
|
return reg_event_syscall_exit(event);
|
|
case TRACE_REG_UNREGISTER:
|
|
unreg_event_syscall_exit(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;
|
|
#endif
|
|
}
|
|
return 0;
|
|
}
|