From: Denys Vlasenko <dvlasenk@redhat.com>
Date: Wed, 8 Jun 2011 23:32:23 +0000 (+0200)
Subject: Do not call umoven to fetch parameters if we have zero params
X-Git-Tag: v4.7~382
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=4660fe610c2b3707b15b170728a981440e1b54d4;p=strace

Do not call umoven to fetch parameters if we have zero params

* syscall.c [I386] (syscall_enter): Do not call umoven
to fetch zero bytes. This is just an optimization.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
---

diff --git a/syscall.c b/syscall.c
index b7fabe00..c9a5b9f8 100644
--- a/syscall.c
+++ b/syscall.c
@@ -2352,8 +2352,9 @@ syscall_enter(struct tcb *tcp)
 		tcp->u_nargs = sysent[tcp->scno].nargs;
 	else
 		tcp->u_nargs = 5;
-	umoven(tcp, tcp->status.PR_REG[UESP] + 4,
-		tcp->u_nargs*sizeof(tcp->u_arg[0]), (char *) tcp->u_arg);
+	if (tcp->u_nargs > 0)
+		umoven(tcp, tcp->status.PR_REG[UESP] + 4,
+			tcp->u_nargs*sizeof(tcp->u_arg[0]), (char *) tcp->u_arg);
 #else
 	I DONT KNOW WHAT TO DO
 #endif /* !HAVE_PR_SYSCALL */