tracing/syscalls: support for syscalls tracing on x86

Extend x86 architecture syscall tracing support with syscall
metadata table details.

(The upcoming core syscall tracing modifications rely on this.)

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1236955332-10133-3-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index db24c22..bd2c651 100644 (file)
--- 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 a85da17..1d0d7f4 100644 (file)
--- 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