From e8014f37a2661ba5c463f3f099418c7a7e1e4016 Mon Sep 17 00:00:00 2001
From: Anders Kaseorg <andersk@mit.edu>
Date: Thu, 19 Jun 2008 21:33:59 -0400
Subject: [PATCH] Clean up run-pre matching loop structure.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>
---
 kmodsrc/helper.c | 55 ++++++++++++++++++++++++-------------------------------
 kmodsrc/helper.h |  2 +-
 2 files changed, 25 insertions(+), 32 deletions(-)

diff --git a/kmodsrc/helper.c b/kmodsrc/helper.c
index 4c7bcb1..0167deb 100644
--- a/kmodsrc/helper.c
+++ b/kmodsrc/helper.c
@@ -212,15 +212,14 @@ try_addr(struct ksplice_size *s, long run_addr, long pre_addr,
 
 int run_pre_cmp(long run_addr, long pre_addr, int size, int rerun)
 {
-	int run_o, pre_o, lenient = 0, prev_c3 = 0, recent_5b = 0;
+	int run_o = 0, pre_o = 0, lenient = 0, prev_c3 = 0, recent_5b = 0;
 	unsigned char run, pre;
 	struct reloc_addrmap *map;
 
 	if (size == 0)
 		return 1;
 
-	for (run_o = 0, pre_o = 0; run_o < size && pre_o < size;
-	     pre_o++, run_o++) {
+	while (run_o < size && pre_o < size) {
 		if (lenient > 0)
 			lenient--;
 		if (prev_c3 > 0)
@@ -230,6 +229,18 @@ int run_pre_cmp(long run_addr, long pre_addr, int size, int rerun)
 
 		if (!virtual_address_mapped(run_addr + run_o))
 			return 1;
+
+		if ((map = find_addrmap(pre_addr + pre_o)) != NULL) {
+			if (handle_myst_reloc
+			    (pre_addr, &pre_o, run_addr, &run_o, map,
+			     rerun) == 1)
+				return 1;
+			continue;
+		}
+
+		if (match_nop(run_addr, &run_o) || match_nop(pre_addr, &pre_o))
+			continue;
+
 		run = *(unsigned char *)(run_addr + run_o);
 		pre = *(unsigned char *)(pre_addr + pre_o);
 
@@ -237,44 +248,27 @@ int run_pre_cmp(long run_addr, long pre_addr, int size, int rerun)
 			printk("%02x/%02x ", run, pre);
 
 		if (run == pre) {
-			if ((map = find_addrmap(pre_addr + pre_o)) != NULL) {
-				if (handle_myst_reloc
-				    (pre_addr, &pre_o, run_addr, &run_o,
-				     map, rerun) == 1)
-					return 1;
-				continue;
-			}
 			if (pre == 0xc3)
 				prev_c3 = 1 + 1;
 			if (pre == 0x5b)
 				recent_5b = 10 + 1;
 			if (jumplen[pre])
 				lenient = max(jumplen[pre] + 1, lenient);
-			if (match_nop(run_addr, &run_o, &pre_o) ||
-			    match_nop(pre_addr, &pre_o, &run_o))
-				continue;
+			pre_o++, run_o++;
 			continue;
 		}
 
-		if ((map = find_addrmap(pre_addr + pre_o)) != NULL) {
-			if (handle_myst_reloc
-			    (pre_addr, &pre_o, run_addr, &run_o, map,
-			     rerun) == 1)
-				return 1;
-			continue;
-		}
 		if (prev_c3 && recent_5b)
 			return 0;
-		if (match_nop(run_addr, &run_o, &pre_o) ||
-		    match_nop(pre_addr, &pre_o, &run_o))
-			continue;
 		if (jumplen[run] && jumplen[pre]) {
-			run_o += jumplen[run];
-			pre_o += jumplen[pre];
+			run_o += 1 + jumplen[run];
+			pre_o += 1 + jumplen[pre];
 			continue;
 		}
-		if (lenient)
+		if (lenient) {
+			pre_o++, run_o++;
 			continue;
+		}
 		if (rerun) {
 			printk("[p_o=%08x] ! %02x/%02x %02x/%02x",
 			       pre_o,
@@ -331,14 +325,14 @@ handle_myst_reloc(long pre_addr, int *pre_o, long run_addr,
 		}
 	}
 
-	*pre_o += map->size - offset - 1;
-	*run_o += map->size - offset - 1;
+	*pre_o += map->size - offset;
+	*run_o += map->size - offset;
 	return 0;
 }
 
 /* TODO: The recommended way to pad 64bit code is to use NOPs preceded by
    maximally four 0x66 prefixes.  */
-int match_nop(long addr, int *o, int *other_o)
+int match_nop(long addr, int *o)
 {
 	int i, j;
 	for (i = NUM_NOPS - 1; i >= 0; i--) {
@@ -349,8 +343,7 @@ int match_nop(long addr, int *o, int *other_o)
 				break;
 		}
 		if (j == i + 1) {
-			*o += i;
-			(*other_o)--;
+			*o += j;
 			return 1;
 		}
 
diff --git a/kmodsrc/helper.h b/kmodsrc/helper.h
index 4edaa45..0a6f956 100644
--- a/kmodsrc/helper.h
+++ b/kmodsrc/helper.h
@@ -11,7 +11,7 @@ int try_addr(struct ksplice_size *s, long run_addr, long pre_addr,
 int run_pre_cmp(long run_addr, long pre_addr, int size, int rerun);
 int handle_myst_reloc(long pre_addr, int *pre_z, long run_addr,
 		      int *run_z, struct reloc_addrmap *map, int rerun);
-int match_nop(long addr, int *main_o, int *other_o);
+int match_nop(long addr, int *main_o);
 void brute_search_all_mods(struct ksplice_size *s);
 
 static inline int virtual_address_mapped(long addr)
-- 
2.11.4.GIT