Merge pull request #573 from arges/493

livepatch-patch-hook: add support for livepatch sympos structures

kmod/patch/kpatch-patch.h

@@ -27,6 +27,7 @@ struct kpatch_patch_func {
 	unsigned long new_size;
 	unsigned long old_addr;
 	unsigned long old_size;
+	unsigned long sympos;
 	char *name;
 	char *objname;
 };
@@ -35,6 +36,7 @@ struct kpatch_patch_dynrela {
 	unsigned long dest;
 	unsigned long src;
 	unsigned long type;
+	unsigned long sympos;
 	char *name;
 	char *objname;
 	int external;

kmod/patch/livepatch-patch-hook.c

@@ -24,6 +24,7 @@
 #include <linux/module.h>
 #include <linux/list.h>
 #include <linux/slab.h>
+#include <linux/version.h>
 
 #include <linux/livepatch.h>
 
@@ -237,7 +238,11 @@ static int __init patch_init(void)
 			lfunc = &lfuncs[j];
 			lfunc->old_name = func->kfunc->name;
 			lfunc->new_func = (void *)func->kfunc->new_addr;
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 5, 0)
+			lfunc->old_sympos = func->kfunc->sympos;
+#else
 			lfunc->old_addr = func->kfunc->old_addr;
+#endif
 			j++;
 		}
 
@@ -250,7 +255,11 @@ static int __init patch_init(void)
 		list_for_each_entry(reloc, &object->relocs, list) {
 			lreloc = &lrelocs[j];
 			lreloc->loc = reloc->kdynrela->dest;
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 5, 0)
+			lreloc->sympos = reloc->kdynrela->sympos;
+#else
 			lreloc->val = reloc->kdynrela->src;
+#endif
 			lreloc->type = reloc->kdynrela->type;
 			lreloc->name = reloc->kdynrela->name;
 			lreloc->addend = reloc->kdynrela->addend;

kpatch-build/create-diff-object.c

@@ -2539,6 +2539,7 @@ void kpatch_create_patches_sections(struct kpatch_elf *kelf,
 			funcs[index].old_addr = result.value;
 			funcs[index].old_size = result.size;
 			funcs[index].new_size = sym->sym.st_size;
+			funcs[index].sympos = result.pos;
 
 			/*
 			 * Add a relocation that will populate
@@ -2715,6 +2716,7 @@ void kpatch_create_dynamic_rela_sections(struct kpatch_elf *kelf,
 			dynrelas[index].addend = rela->addend;
 			dynrelas[index].type = rela->type;
 			dynrelas[index].external = external;
+			dynrelas[index].sympos = result.pos;
 
 			/* add rela to fill in dest field */
 			ALLOC_LINK(dynrela, &relasec->relas);

kpatch-build/lookup.c

@@ -148,6 +148,7 @@ int lookup_local_symbol(struct lookup_table *table, char *name, char *hint,
 {
 	struct symbol *sym, *match = NULL;
 	int i;
+	unsigned long pos = 0;
 	char *curfile = NULL;
 
 	memset(result, 0, sizeof(*result));
@@ -159,19 +160,30 @@ int lookup_local_symbol(struct lookup_table *table, char *name, char *hint,
 			} else if (curfile)
 				curfile = NULL; /* end hint file symbols */
 		}
-		if (!curfile)
-			continue;
-		if (sym->bind == STB_LOCAL && !strcmp(sym->name, name)) {
-			if (match)
-				/* dup file+symbol, unresolvable ambiguity */
-				return 1;
-			match = sym;
+		if (sym->bind == STB_LOCAL) {
+			if (sym->name && !strcmp(sym->name, name)) {
+				/*
+				 * need to count any occurrence of the symbol
+				 * name, unless we've already found a match
+				 */
+				if (!match)
+					pos++;
+
+				if (!curfile)
+					continue;
+
+				if (match)
+					/* dup file+symbol, unresolvable ambiguity */
+					return 1;
+				match = sym;
+			}
 		}
 	}
 
 	if (!match)
 		return 1;
 
+	result->pos = pos;
 	result->value = match->value;
 	result->size = match->size;
 	return 0;
@@ -189,6 +201,7 @@ int lookup_global_symbol(struct lookup_table *table, char *name,
 		    !strcmp(sym->name, name)) {
 			result->value = sym->value;
 			result->size = sym->size;
+			result->pos = 0; /* always 0 for global symbols */
 			return 0;
 		}
 
@@ -220,9 +233,9 @@ static void find_this(struct lookup_table *table, char *sym, char *hint)
 	else
 		lookup_global_symbol(table, sym, &result);
 
-	printf("%s %s w/ %s hint at 0x%016lx len %lu\n",
+	printf("%s %s w/ %s hint at 0x%016lx len %lu pos %lu\n",
 	       hint ? "local" : "global", sym, hint ? hint : "no",
-	       result.value, result.size);
+	       result.value, result.size, result.pos);
 }
 
 int main(int argc, char **argv)

kpatch-build/lookup.h

@@ -6,6 +6,7 @@ struct lookup_table;
 struct lookup_result {
 	unsigned long value;
 	unsigned long size;
+	unsigned long pos;
 };
 
 struct lookup_table *lookup_open(char *path);