Reorganize syscall entry and leave handling.

Extend struct sysvec with three new elements:
sv_fetch_syscall_args - the method to fetch syscall arguments from
  usermode into struct syscall_args. The structure is machine-depended
  (this might be reconsidered after all architectures are converted).
sv_set_syscall_retval - the method to set a return value for usermode
  from the syscall. It is a generalization of
  cpu_set_syscall_retval(9) to allow ABIs to override the way to set a
  return value.
sv_syscallnames - the table of syscall names.

Use sv_set_syscall_retval in kern_sigsuspend() instead of hardcoding
the call to cpu_set_syscall_retval().

The new functions syscallenter(9) and syscallret(9) are provided that
use sv_*syscall* pointers and contain the common repeated code from
the syscall() implementations for the architecture-specific syscall
trap handlers.

Syscallenter() fetches arguments, calls syscall implementation from
ABI sysent table, and set up return frame. The end of syscall
bookkeeping is done by syscallret().

Take advantage of single place for MI syscall handling code and
implement ptrace_lwpinfo pl_flags PL_FLAG_SCE, PL_FLAG_SCX and
PL_FLAG_EXEC. The SCE and SCX flags notify the debugger that the
thread is stopped at syscall entry or return point respectively.  The
EXEC flag augments SCX and notifies debugger that the process address
space was changed by one of exec(2)-family syscalls.

The i386, amd64, sparc64, sun4v, powerpc and ia64 syscall()s are
changed to use syscallenter()/syscallret(). MIPS and arm are not
converted and use the mostly unchanged syscall() implementation.

Reviewed by:	jhb, marcel, marius, nwhitehorn, stas
Tested by:	marcel (ia64), marius (sparc64), nwhitehorn (powerpc),
	stas (mips)
MFC after:	1 month

2 files changed, 10 insertions, 1 deletions

diff --git a/sys/compat/ia32/ia32_sysvec.c b/sys/compat/ia32/ia32_sysvec.c
index 79448a5..d7ac5d0 100644
--- a/sys/compat/ia32/ia32_sysvec.c
+++ b/sys/compat/ia32/ia32_sysvec.c
@@ -93,6 +93,8 @@ CTASSERT(sizeof(struct ia32_ucontext4) == 324);
 CTASSERT(sizeof(struct ia32_sigframe4) == 408);
 #endif
 
+extern const char *freebsd32_syscallnames[];
+
 static void ia32_fixlimit(struct rlimit *rl, int which);
 
 SYSCTL_NODE(_compat, OID_AUTO, ia32, CTLFLAG_RW, 0, "ia32 mode");
@@ -135,7 +137,10 @@ struct sysentvec ia32_freebsd_sysvec = {
 	.sv_setregs	= ia32_setregs,
 	.sv_fixlimit	= ia32_fixlimit,
 	.sv_maxssiz	= &ia32_maxssiz,
-	.sv_flags	= SV_ABI_FREEBSD | SV_IA32 | SV_ILP32
+	.sv_flags	= SV_ABI_FREEBSD | SV_IA32 | SV_ILP32,
+	.sv_set_syscall_retval = ia32_set_syscall_retval,
+	.sv_fetch_syscall_args = ia32_fetch_syscall_args,
+	.sv_syscallnames = freebsd32_syscallnames,
 };
 
 
diff --git a/sys/compat/ia32/ia32_util.h b/sys/compat/ia32/ia32_util.h
index a2b88cb..d91bfde 100644
--- a/sys/compat/ia32/ia32_util.h
+++ b/sys/compat/ia32/ia32_util.h
@@ -47,3 +47,7 @@
 #define	IA32_MAXDSIZ	(512*1024*1024)		/* 512MB */
 #define	IA32_MAXSSIZ	(64*1024*1024)		/* 64MB */
 #define IA32_MAXVMEM	0			/* Unlimited */
+
+struct syscall_args;
+int ia32_fetch_syscall_args(struct thread *td, struct syscall_args *sa);
+void ia32_set_syscall_retval(struct thread *, int);