[tip:tracing/syscalls] tracing/syscalls: support for syscalls tracing on x86

Frederic Weisbecker
2009-03-13T16:10:30Z

Commit-ID: f58ba100678f421bdcb000a3c71793f432dfab93
Gitweb: http://git.kernel.org/tip/f58ba100678f421bdcb000a3c71793f432dfab93
Author: Frederic Weisbecker <fweisbec@gmail.com>
AuthorDate: Fri, 13 Mar 2009 15:42:12 +0100
Commit: Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 13 Mar 2009 16:57:42 +0100

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>

---
arch/x86/include/asm/ftrace.h | 7 ++++
arch/x86/kernel/ftrace.c | 63 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 70 insertions(+), 0 deletions(-)

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