lkml.org 
[lkml]   [2011]   [Apr]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 6/7] include/linux/syscalls.h: add __ layer of macros with return types.
Date
This change addresses two issues directly:
1. The inability for ftrace to hook system calls that don't return
a long.
2. The fact that SYSCALL_DEFINE() does not touch ftrace at all

1 is fixed by adding __SYSCALL_DEFINEx/0 and __SYSCALL_TRACEx/0
macros which lay underneath the normal call,
SYSCALL_DEFINE0, and SYSCALL_DEFINE[1-6]. All existing calls will
continue to work normally and SYSCALL_DEFINE calls will become
ftrace-able but without argument inspection support.

2 is addressed by separating out SYSCALL_TRACE0 and pulling it under
SYSCALL_DEFINE. It means that calls that may lack argument
introspection will still be traceable in a binary way without any
additional code changes.

There are still some challenges for wrapping calls that have a
trampoline directly in the assembly, like the ptregs calls in
arch/x86/kernel (e.g., sys_clone). Given that the arguments to the
function do not directly map to those of the system call, the main
macros are not friendly for use. However, the SYSCALL_TRACE0 macro in
this change could be used as a placeholder (declared above the function
definition) to allow limited tracing functionality until a better
solution is presented.

Signed-off-by: Will Drewry <wad@chromium.org>
---
include/linux/syscalls.h | 52 +++++++++++++++++++++++++++++++---------------
1 files changed, 35 insertions(+), 17 deletions(-)
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 83ecc17..1c4a3fb 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -171,7 +171,7 @@ extern struct trace_event_functions exit_syscall_print_funcs;
__attribute__((section("__syscalls_metadata"))) \
*__p_syscall_meta_##sname = &__syscall_meta_##sname;

-#define SYSCALL_DEFINE0(sname) \
+#define __SYSCALL_TRACE0(linkage, ret, sname) \
SYSCALL_TRACE_ENTER_EVENT(_##sname); \
SYSCALL_TRACE_EXIT_EVENT(_##sname); \
static struct syscall_metadata __used \
@@ -185,12 +185,16 @@ extern struct trace_event_functions exit_syscall_print_funcs;
}; \
static struct syscall_metadata __used \
__attribute__((section("__syscalls_metadata"))) \
- *__p_syscall_meta_##sname = &__syscall_meta__##sname; \
- asmlinkage long sys_##sname(void)
+ *__p_syscall_meta_##sname = &__syscall_meta__##sname;
#else
-#define SYSCALL_DEFINE0(name) asmlinkage long sys_##name(void)
+#define __SYSCALL_TRACE0(linkage, ret, sname)
#endif

+#define __SYSCALL_DEFINE0(linkage, ret, sname) \
+ __SYSCALL_TRACE0(linkage, ret, sname) \
+ linkage ret sys_##sname(void)
+
+#define SYSCALL_DEFINE0(name) __SYSCALL_DEFINE0(asmlinkage, long, name)
#define SYSCALL_DEFINE1(name, ...) SYSCALL_DEFINEx(1, _##name, __VA_ARGS__)
#define SYSCALL_DEFINE2(name, ...) SYSCALL_DEFINEx(2, _##name, __VA_ARGS__)
#define SYSCALL_DEFINE3(name, ...) SYSCALL_DEFINEx(3, _##name, __VA_ARGS__)
@@ -214,39 +218,53 @@ extern struct trace_event_functions exit_syscall_print_funcs;

#ifdef CONFIG_FTRACE_SYSCALLS
#define SYSCALL_DEFINEx(x, sname, ...) \
+ __SYSCALL_DEFINEx(asmlinkage, long, x, sname, __VA_ARGS__)
+
+#define __SYSCALL_TRACEx(linkage, ret, x, sname, ...) \
static const char *types_##sname[] = { \
__SC_STR_TDECL##x(__VA_ARGS__) \
}; \
static const char *args_##sname[] = { \
__SC_STR_ADECL##x(__VA_ARGS__) \
}; \
- SYSCALL_METADATA(sname, x); \
- __SYSCALL_DEFINEx(x, sname, __VA_ARGS__)
+ SYSCALL_METADATA(sname, x);
#else
#define SYSCALL_DEFINEx(x, sname, ...) \
- __SYSCALL_DEFINEx(x, sname, __VA_ARGS__)
+ __SYSCALL_DEFINEx(asmlinkage, long, x, sname, __VA_ARGS__)
+#define __SYSCALL_TRACEx(linkage, ret, x, sname, ...)
#endif

#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS

-#define SYSCALL_DEFINE(name) static inline long SYSC_##name
-
-#define __SYSCALL_DEFINEx(x, name, ...) \
- asmlinkage long sys##name(__SC_DECL##x(__VA_ARGS__)); \
- static inline long SYSC##name(__SC_DECL##x(__VA_ARGS__)); \
- asmlinkage long SyS##name(__SC_LONG##x(__VA_ARGS__)) \
+#define SYSCALL_DEFINE(name) \
+ __SYSCALL_DEFINE(long, name)
+#define __SYSCALL_DEFINE(ret, name) \
+ __SYSCALL_TRACE0(, ret, name)
+ static inline ret SYSC_##name
+
+#define __SYSCALL_DEFINEx(linkage, ret, x, name, ...) \
+ __SYSCALL_TRACEx(linkage, ret, x, name, __VA_ARGS__) \
+ linkage ret sys##name(__SC_DECL##x(__VA_ARGS__)); \
+ static inline ret SYSC##name(__SC_DECL##x(__VA_ARGS__)); \
+ linkage ret SyS##name(__SC_LONG##x(__VA_ARGS__)) \
{ \
__SC_TEST##x(__VA_ARGS__); \
- return (long) SYSC##name(__SC_CAST##x(__VA_ARGS__)); \
+ return (ret) SYSC##name(__SC_CAST##x(__VA_ARGS__)); \
} \
SYSCALL_ALIAS(sys##name, SyS##name); \
- static inline long SYSC##name(__SC_DECL##x(__VA_ARGS__))
+ static inline ret SYSC##name(__SC_DECL##x(__VA_ARGS__))

#else /* CONFIG_HAVE_SYSCALL_WRAPPERS */

-#define SYSCALL_DEFINE(name) asmlinkage long sys_##name
-#define __SYSCALL_DEFINEx(x, name, ...) \
- asmlinkage long sys##name(__SC_DECL##x(__VA_ARGS__))
+#define SYSCALL_DEFINE(name) \
+ __SYSCALL_DEFINE(asmlinkage, long, name)
+#define __SYSCALL_DEFINE(linkage, ret, name) \
+ __SYSCALL_TRACE0(linkage, ret, name) \
+ linkage ret sys_##name
+
+#define __SYSCALL_DEFINEx(linkage, ret, x, name, ...) \
+ __SYSCALL_TRACEx(linkage, ret, x, name, __VA_ARGS__) \
+ linkage ret sys##name(__SC_DECL##x(__VA_ARGS__))

#endif /* CONFIG_HAVE_SYSCALL_WRAPPERS */

--
1.7.0.4


\
 
 \ /
  Last update: 2011-04-28 05:21    [from the cache]
©2003-2011 Jasper Spaans