Messages in this thread Patch in this message |  | | | From | Will Drewry <> | | Subject | [PATCH 6/7] include/linux/syscalls.h: add __ layer of macros with return types. | | Date | Wed, 27 Apr 2011 22:08:50 -0500 |
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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
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