tracing/syscalls: use a dedicated file header

Impact: fix build warnings and possibe compat misbehavior on IA64

Building a kernel on ia64 might trigger these ugly build warnings:

CC      arch/ia64/ia32/sys_ia32.o
In file included from arch/ia64/ia32/sys_ia32.c:55:
arch/ia64/ia32/ia32priv.h:290:1: warning: "elf_check_arch" redefined
In file included from include/linux/elf.h:7,
                 from include/linux/module.h:14,
                 from include/linux/ftrace.h:8,
                 from include/linux/syscalls.h:68,
                 from arch/ia64/ia32/sys_ia32.c:18:
arch/ia64/include/asm/elf.h:19:1: warning: this is the location of the previous definition
[...]

sys_ia32.c includes linux/syscalls.h which in turn includes linux/ftrace.h
to import the syscalls tracing prototypes.

But including ftrace.h can pull too much things for a low level file,
especially on ia64 where the ia32 private headers conflict with higher
level headers.

Now we isolate the syscall tracing headers in their own lightweight file.
Reported-by: Tony Luck <tony.luck@intel.com>
Tested-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Jason Baron <jbaron@redhat.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Jiaying Zhang <jiayingz@google.com>
Cc: Michael Rubin <mrubin@google.com>
Cc: Martin Bligh <mbligh@google.com>
Cc: Michael Davidson <md@google.com>
LKML-Reference: <20090408184058.GB6017@nowhere>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/ftrace.c

@@ -18,6 +18,8 @@
 #include <linux/init.h>
 #include <linux/list.h>
 
+#include <trace/syscall.h>
+
 #include <asm/cacheflush.h>
 #include <asm/ftrace.h>
 #include <asm/nops.h>

arch/x86/kernel/ptrace.c

@@ -21,7 +21,6 @@
 #include <linux/audit.h>
 #include <linux/seccomp.h>
 #include <linux/signal.h>
-#include <linux/ftrace.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -35,6 +34,8 @@
 #include <asm/proto.h>
 #include <asm/ds.h>
 
+#include <trace/syscall.h>
+
 #include "tls.h"
 
 enum x86_regset {

include/linux/ftrace.h

@@ -511,33 +511,4 @@ static inline void trace_hw_branch_oops(void) {}
 
 #endif /* CONFIG_HW_BRANCH_TRACER */
 
-/*
- * A syscall entry in the ftrace syscalls array.
- *
- * @name: name of the syscall
- * @nb_args: number of parameters it takes
- * @types: list of types as strings
- * @args: list of args as strings (args[i] matches types[i])
- */
-struct syscall_metadata {
-	const char	*name;
-	int		nb_args;
-	const char	**types;
-	const char	**args;
-};
-
-#ifdef CONFIG_FTRACE_SYSCALLS
-extern void arch_init_ftrace_syscalls(void);
-extern struct syscall_metadata *syscall_nr_to_meta(int nr);
-extern void start_ftrace_syscalls(void);
-extern void stop_ftrace_syscalls(void);
-extern void ftrace_syscall_enter(struct pt_regs *regs);
-extern void ftrace_syscall_exit(struct pt_regs *regs);
-#else
-static inline void start_ftrace_syscalls(void) { }
-static inline void stop_ftrace_syscalls(void) { }
-static inline void ftrace_syscall_enter(struct pt_regs *regs) { }
-static inline void ftrace_syscall_exit(struct pt_regs *regs) { }
-#endif
-
 #endif /* _LINUX_FTRACE_H */

include/linux/syscalls.h

@@ -65,7 +65,7 @@ struct old_linux_dirent;
 #include <asm/signal.h>
 #include <linux/quota.h>
 #include <linux/key.h>
-#include <linux/ftrace.h>
+#include <trace/syscall.h>
 
 #define __SC_DECL1(t1, a1)	t1 a1
 #define __SC_DECL2(t2, a2, ...) t2 a2, __SC_DECL1(__VA_ARGS__)

include/trace/syscall.h

+#ifndef _TRACE_SYSCALL_H
+#define _TRACE_SYSCALL_H
+
+#include <asm/ptrace.h>
+
+/*
+ * A syscall entry in the ftrace syscalls array.
+ *
+ * @name: name of the syscall
+ * @nb_args: number of parameters it takes
+ * @types: list of types as strings
+ * @args: list of args as strings (args[i] matches types[i])
+ */
+struct syscall_metadata {
+	const char	*name;
+	int		nb_args;
+	const char	**types;
+	const char	**args;
+};
+
+#ifdef CONFIG_FTRACE_SYSCALLS
+extern void arch_init_ftrace_syscalls(void);
+extern struct syscall_metadata *syscall_nr_to_meta(int nr);
+extern void start_ftrace_syscalls(void);
+extern void stop_ftrace_syscalls(void);
+extern void ftrace_syscall_enter(struct pt_regs *regs);
+extern void ftrace_syscall_exit(struct pt_regs *regs);
+#else
+static inline void start_ftrace_syscalls(void)			{ }
+static inline void stop_ftrace_syscalls(void)			{ }
+static inline void ftrace_syscall_enter(struct pt_regs *regs)	{ }
+static inline void ftrace_syscall_exit(struct pt_regs *regs)	{ }
+#endif
+
+#endif /* _TRACE_SYSCALL_H */

kernel/trace/trace_syscalls.c

+#include <trace/syscall.h>
 #include <linux/kernel.h>
-#include <linux/ftrace.h>
 #include <asm/syscall.h>
 
 #include "trace_output.h"