Implement run-time linking

Implement run-time linking and link at run-time by default. Still keep
the option to link at compile time.

diff --git a/create-diff-object.c b/create-diff-object.c
index fb9ef0b80883a932e527c901426b8a9b2b408f44..b542ee937f165b3c38753bd85163cac95ff98f5f 100644 (file)
--- a/create-diff-object.c
+++ b/create-diff-object.c
@@ -1457,7 +1457,7 @@ static struct section *create_section_pair(struct xsplice_elf *kelf,
 
 static void xsplice_create_patches_sections(struct xsplice_elf *kelf,
                                            struct lookup_table *table,
-                                           char *hint)
+                                           char *hint, int resolve)
 {
        int nr, index;
        struct section *sec, *relasec;
@@ -1504,7 +1504,11 @@ static void xsplice_create_patches_sections(struct xsplice_elf *kelf,
                                ERROR("%s too small to patch", sym->name);
 
                        /* add entry in text section */
-                       funcs[index].old_addr = result.value;
+                       if (resolve)
+                               funcs[index].old_addr = result.value;
+                       else
+                               /* This will be filled in at module load time */
+                               funcs[index].old_addr = 0;
                        funcs[index].old_size = result.size;
                        funcs[index].new_addr = 0;
                        funcs[index].new_size = sym->sym.st_size;
@@ -1598,12 +1602,14 @@ static void xsplice_reindex_elements(struct xsplice_elf *kelf)
 struct arguments {
        char *args[4];
        int debug;
+       int resolve;
 };
 
 static char args_doc[] = "original.o patched.o kernel-object output.o";
 
 static struct argp_option options[] = {
        {"debug", 'd', 0, 0, "Show debug output" },
+       {"resolve", 'r', 0, 0, "Resolve to-be-patched function addresses" },
        { 0 }
 };
 
@@ -1618,6 +1624,9 @@ static error_t parse_opt (int key, char *arg, struct argp_state *state)
                case 'd':
                        arguments->debug = 1;
                        break;
+               case 'r':
+                       arguments->resolve = 1;
+                       break;
                case ARGP_KEY_ARG:
                        if (state->arg_num >= 4)
                                /* Too many arguments. */
@@ -1648,6 +1657,7 @@ int main(int argc, char *argv[])
        char *hint = NULL;
 
        arguments.debug = 0;
+       arguments.resolve = 0;
        argp_parse (&argp, argc, argv, 0, 0, &arguments);
        if (arguments.debug)
                loglevel = DEBUG;
@@ -1763,7 +1773,8 @@ int main(int argc, char *argv[])
        log_debug("Create strings elements\n");
        xsplice_create_strings_elements(kelf_out);
        log_debug("Create patches sections\n");
-       xsplice_create_patches_sections(kelf_out, lookup, hint);
+       xsplice_create_patches_sections(kelf_out, lookup, hint,
+                                       arguments.resolve);
        xsplice_build_strings_section_data(kelf_out);
 
        /*

diff --git a/xsplice-build b/xsplice-build
index f5495c00f0b82b2a42f7d979b5998ddb4dbdfa5f..a67ebc07af08382611fc0e1d4b0a71473f2a4fd8 100755 (executable)
--- a/xsplice-build
+++ b/xsplice-build
@@ -30,6 +30,7 @@ DEBUG=n
 XEN_DEBUG=n
 SKIP=
 DEPENDS=
+PRELINK=
 XENSYMS=xen-syms
 
 warn() {
@@ -111,7 +112,7 @@ function create_patch()
         mkdir -p "output/$(dirname $i)" || die
         echo "Processing ${i}"
         echo "Run create-diff-object on $i" >> "${OUTPUT}/create-diff-object.log"
-        "${SCRIPTDIR}"/create-diff-object $debugopt "original/$i" "patched/$i" "$XENSYMS" "output/$i" &>> "${OUTPUT}/create-diff-object.log"
+        "${SCRIPTDIR}"/create-diff-object $debugopt $PRELINK "original/$i" "patched/$i" "$XENSYMS" "output/$i" &>> "${OUTPUT}/create-diff-object.log"
         rc="${PIPESTATUS[0]}"
         if [[ $rc = 139 ]]; then
             warn "create-diff-object SIGSEGV"
@@ -143,8 +144,13 @@ function create_patch()
     fi
 
     echo "Creating patch module..."
-    ld -r -o output.o --build-id=sha1 $(find output -type f -name "*.o") || die
-    "${SCRIPTDIR}"/prelink $debugopt output.o "${PATCHNAME}.xsplice" "$XENSYMS" &>> "${OUTPUT}/prelink.log" || die
+    if [ -z "$PRELINK" ]; then
+        ld -r -o "${PATCHNAME}.xsplice" --build-id=sha1 $(find output -type f -name "*.o") || die
+        chmod +x "${PATCHNAME}.xsplice"
+    else
+        ld -r -o output.o --build-id=sha1 $(find output -type f -name "*.o") || die
+        "${SCRIPTDIR}"/prelink $debugopt output.o "${PATCHNAME}.xsplice" "$XENSYMS" &>> "${OUTPUT}/prelink.log" || die
+    fi
 
     objcopy --add-section .xsplice.depends=depends.bin "${PATCHNAME}.xsplice"
     objcopy --set-section-flags .xsplice.depends=alloc,readonly "${PATCHNAME}.xsplice"
@@ -162,9 +168,10 @@ usage() {
     echo "        --xen-debug        Build debug Xen" >&2
     echo "        --xen-syms         Build against a xen-syms" >&2
     echo "        --depends          Required build-id" >&2
+    echo "        --prelink          Prelink" >&2
 }
 
-options=$(getopt -o hs:p:o:j:k:d -l "help,srcdir:patch:output:cpus:,skip:,debug,xen-debug,xen-syms:,depends:" -- "$@") || die "getopt failed"
+options=$(getopt -o hs:p:o:j:k:d -l "help,srcdir:patch:output:cpus:,skip:,debug,xen-debug,xen-syms:,depends:,prelink" -- "$@") || die "getopt failed"
 
 eval set -- "$options"
 
@@ -218,6 +225,10 @@ while [[ $# -gt 0 ]]; do
             DEPENDS="$1"
             shift
             ;;
+        --prelink)
+            PRELINK=--resolve
+            shift
+            ;;
         --)
             shift
             break