2 files changed, 70 insertions, 0 deletions

diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index db24c2278be0..bd2c6511c887 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -28,6 +28,13 @@
 
 #endif
 
+/* FIXME: I don't want to stay hardcoded */
+#ifdef CONFIG_X86_64
+# define FTRACE_SYSCALL_MAX     296
+#else
+# define FTRACE_SYSCALL_MAX     333
+#endif
+
 #ifdef CONFIG_FUNCTION_TRACER
 #define MCOUNT_ADDR             ((long)(mcount))
 #define MCOUNT_INSN_SIZE        5 /* sizeof mcount call */
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index a85da1764b1c..1d0d7f42efe3 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -453,3 +453,66 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
         }
 }
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
+#ifdef CONFIG_FTRACE_SYSCALLS
+
+extern unsigned long __start_syscalls_metadata[];
+extern unsigned long __stop_syscalls_metadata[];
+extern unsigned long *sys_call_table;
+
+static struct syscall_metadata **syscalls_metadata;
+
+static struct syscall_metadata *find_syscall_meta(unsigned long *syscall)
+{
+        struct syscall_metadata *start;
+        struct syscall_metadata *stop;
+        char str[KSYM_SYMBOL_LEN];
+
+
+        start = (struct syscall_metadata *)__start_syscalls_metadata;
+        stop = (struct syscall_metadata *)__stop_syscalls_metadata;
+        kallsyms_lookup((unsigned long) syscall, NULL, NULL, NULL, str);
+
+        for ( ; start < stop; start++) {
+                if (start->name && !strcmp(start->name, str))
+                        return start;
+        }
+        return NULL;
+}
+
+struct syscall_metadata *syscall_nr_to_meta(int nr)
+{
+        if (!syscalls_metadata || nr >= FTRACE_SYSCALL_MAX || nr < 0)
+                return NULL;
+
+        return syscalls_metadata[nr];
+}
+
+void arch_init_ftrace_syscalls(void)
+{
+        int i;
+        struct syscall_metadata *meta;
+        unsigned long **psys_syscall_table = &sys_call_table;
+        static atomic_t refs;
+
+        if (atomic_inc_return(&refs) != 1)
+                goto end;
+
+        syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) *
+                                        FTRACE_SYSCALL_MAX, GFP_KERNEL);
+        if (!syscalls_metadata) {
+                WARN_ON(1);
+                return;
+        }
+
+        for (i = 0; i < FTRACE_SYSCALL_MAX; i++) {
+                meta = find_syscall_meta(psys_syscall_table[i]);
+                syscalls_metadata[i] = meta;
+        }
+        return;
+
+        /* Paranoid: avoid overflow */
+end:
+        atomic_dec(&refs);
+}
+#endif