ddb: print the actual syscall name

Some architectures will pretty-print a system call trap in the
backtrace. Rather than printing the symbol, use the syscallname()
function to pull the string from the sv_syscallnames array corresponding
to the process. This simplifies the function somewhat.

Mostly, this will result in dropping the "sys" prefix, e.g. "sys_exit"
will now be printed simply as "exit".

Make two minor tweaks to the function signature: use a u_int for the
syscall number since this is a more correct type (see the 'code' member
of struct syscall_args), and make the thread pointer the first argument.
The latter is more natural and conventional.

Suggested by:   jrtc27
Reviewed by:	jrtc27, markj, jhb
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D37200

(cherry picked from commit aba921bd9e1869dae9ae4cc6e0c048f997401034)

1 files changed, 1 insertions, 1 deletions

diff --git a/sys/i386/i386/db_trace.c b/sys/i386/i386/db_trace.c
index aee90ee058de..47057906fa58 100644
--- a/sys/i386/i386/db_trace.c
+++ b/sys/i386/i386/db_trace.c
@@ -372,7 +372,7 @@ db_nextframe(struct i386_frame **fp, db_addr_t *ip, struct thread *td)
 		break;
 	case SYSCALL:
 		db_printf("--- syscall");
-		db_decode_syscall(tf->tf_eax, td);
+		db_decode_syscall(td, tf->tf_eax);
 		break;
 	case INTERRUPT:
 		db_printf("--- interrupt");