From: Jeremy Fitzhardinge <jeremy@valgrind.org>
Date: Mon, 19 Jan 2004 21:47:25 +0000 (+0000)
Subject: Add some comments
X-Git-Tag: svn/VALGRIND_2_1_1~102
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=2c56057c32cf40ae9abd1086092bed2fa23b039a;p=thirdparty%2Fvalgrind.git

Add some comments


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@2205
---

diff --git a/coregrind/x86/ume_go.c b/coregrind/x86/ume_go.c
index 0f25f62ee5..038a27057b 100644
--- a/coregrind/x86/ume_go.c
+++ b/coregrind/x86/ume_go.c
@@ -26,11 +26,16 @@
 
 #include "ume_arch.h"
 
+/* 
+   Jump to a particular EIP with a particular ESP.  This is intended
+   to simulate the initial CPU state when the kernel starts an program
+   after exec; it therefore also clears all the other registers.
+ */
 void ume_go(addr_t eip, addr_t esp)
 {
-   asm volatile ("movl %1, %%esp;"
-		 "pushl %%eax;"
-		 "xorl	%%eax,%%eax;"
+   asm volatile ("movl %1, %%esp;"	/* set esp */
+		 "pushl %%eax;"		/* push esp */
+		 "xorl	%%eax,%%eax;"	/* clear registers */
 		 "xorl	%%ebx,%%ebx;"
 		 "xorl	%%ecx,%%ecx;"
 		 "xorl	%%edx,%%edx;"
@@ -42,5 +47,5 @@ void ume_go(addr_t eip, addr_t esp)
 		 : : "a" (eip), "r" (esp));
    /* we should never get here */
    for(;;)
-	   ;
+	   asm volatile("ud2");
 }