How to trace compat syscalls? [Was Re: [PATCH] MIPS: use 32-bit wrapper for compat_sys_futex]
From: Yong Zhang <hidden>
Date: 2011-08-19 03:51:04
Also in:
linux-mips, lkml
Subsystem:
abi/api, the rest · Maintainer:
Linus Torvalds
Cc'ing more people. On Thu, Aug 18, 2011 at 09:19:11PM +0100, Ralf Baechle wrote:
quoted
But really I think this patch fixes things at the wrong level. Each architecture potentially needs a similar patch. What would happen if we did something like:quoted
+++ b/kernel/futex_compat.c@@ -180,9 +180,9 @@ err_unlock: return ret; } -asmlinkage long compat_sys_futex(u32 __user *uaddr, int op, u32 val, - struct compat_timespec __user *utime, u32 __user *uaddr2, - u32 val3) +SYSCALL_DEFINE6(compat_sys_futex, u32 __user *, uaddr, int , op, u32, val, + struct compat_timespec __user *, utime, u32 __user *, uaddr2, + u32, val3) { struct timespec ts; ktime_t t, *tp = NULL;Obviously the function name is wrong, but a varient of SYSCALL_DEFINE*() could be created so the proper function names are produced.Right now none of the the generic compat_ functions is wrapped in SYSCALL_DEFINE* because for some architectures a further wrapper function is needed. It seems some architectures call compat_ calls directly without SYSCALL_DEFINE* which with CONFIG_FTRACE_SYSCALLS is a bug ...
Just checked some archs which have HAVE_SYSCALL_TRACEPOINTS=y and could call compat_* syscalls when run 32bit process on 64bit kernel, I don't find any special code against FTRACE_SYSCALLS. So that means we could not trace compat syscalls even if we want to(Am I missing something?). So I think if we want to trace it, the easy way is just like what we have done on normal syscalls, IOW, we could SYSCALL_DEFINE all of the compat syscalls. Thought? BTW, I have make a trival patch to introduce COMPAT_SYSCALL_DEFINE, it's just for calling of inspiration(no test no build, and I leave SYSCALL_METADATA etc untouched.) Thanks, Yong ---
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 8c03b98..e79027f 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h@@ -221,26 +221,38 @@ extern struct trace_event_functions exit_syscall_print_funcs; __SC_STR_ADECL##x(__VA_ARGS__) \ }; \ SYSCALL_METADATA(sname, x); \ - __SYSCALL_DEFINEx(x, sname, __VA_ARGS__) + __SYSCALL_DEFINEx(, x, sname, __VA_ARGS__) + +#define COMPAT_SYSCALL_DEFINEx(x, sname, ...) \ + static const char *types_compat_##sname[] = { \ + __SC_STR_TDECL##x(__VA_ARGS__) \ + }; \ + static const char *args_compat_##sname[] = { \ + __SC_STR_ADECL##x(__VA_ARGS__) \ + }; \ + SYSCALL_METADATA(compat, sname, x); \ + __SYSCALL_DEFINEx(cmopat_, x, sname, __VA_ARGS__) #else #define SYSCALL_DEFINEx(x, sname, ...) \ - __SYSCALL_DEFINEx(x, sname, __VA_ARGS__) + __SYSCALL_DEFINEx(, x, sname, __VA_ARGS__) +#define COMPAT_SYSCALL_DEFINEx(x, sname, ...) \ + __SYSCALL_DEFINEx(compat_, x, sname, __VA_ARGS__) #endif #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS -#define SYSCALL_DEFINE(name) static inline long SYSC_##name +#define SYSCALL_DEFINE(compat, name) static inline long compat##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_DEFINEx(compat, x, name, ...) \ + asmlinkage long compat##sys##name(__SC_DECL##x(__VA_ARGS__)); \ + static inline long compat##SYSC##name(__SC_DECL##x(__VA_ARGS__));\ + asmlinkage long compat##SyS##name(__SC_LONG##x(__VA_ARGS__)) \ { \ __SC_TEST##x(__VA_ARGS__); \ - return (long) SYSC##name(__SC_CAST##x(__VA_ARGS__)); \ + return (long) compat##SYSC##name(__SC_CAST##x(__VA_ARGS__));\ } \ - SYSCALL_ALIAS(sys##name, SyS##name); \ - static inline long SYSC##name(__SC_DECL##x(__VA_ARGS__)) + SYSCALL_ALIAS(compat##sys##name, compat##SyS##name); \ + static inline long compat##SYSC##name(__SC_DECL##x(__VA_ARGS__)) #else /* CONFIG_HAVE_SYSCALL_WRAPPERS */