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module: implement module loading 

This patch adds loading, stamp checking and initialization of modules.

The init function of dynamic module is no longer directly called as
__attribute__((constructor)) in static linked version, it is called
only after passed the checking of presense of stamp symbol:

    qemu_stamp_$RELEASEHASH

where $RELEASEHASH is generated by hashing version strings and content
of configure script.

With this, modules built from a different tree/version/configure will
not be loaded.

The module loading code requires gmodule-2.0.

Modules are searched under
 - CONFIG_MODDIR
 - executable folder (to allow running qemu-{img,io} in the build
   directory)
 - ../ of executable folder (to allow running system emulator in the
   build directory)

Modules are linked under their subdir respectively, then copied to top
level of build directory for above convinience, e.g.:
    $(BUILD_DIR)/block/curl.so -> $(BUILD_DIR)/block-curl.so

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Fam Zheng 2014-02-10 14:48:57 +08:00 committed by Paolo Bonzini
parent 17969268f5
commit e26110cfc6
7 changed files with 217 additions and 12 deletions
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3
Makefile
View File

@ -201,6 +201,9 @@ Makefile: $(version-obj-y) $(version-lobj-y)
libqemustub.a: $(stub-obj-y)
libqemuutil.a: $(util-obj-y) qapi-types.o qapi-visit.o
block-modules = $(foreach o,$(block-obj-m),"$(basename $(subst /,-,$o))",) NULL
util/module.o-cflags = -D'CONFIG_BLOCK_MODULES=$(block-modules)'
######################################################################
qemu-img.o: qemu-img-cmds.h

42
configure vendored
View File

@ -1137,7 +1137,7 @@ Advanced options (experts only):
--libdir=PATH install libraries in PATH
--sysconfdir=PATH install config in PATH$confsuffix
--localstatedir=PATH install local state in PATH (set at runtime on win32)
--with-confsuffix=SUFFIX suffix for QEMU data inside datadir and sysconfdir [$confsuffix]
--with-confsuffix=SUFFIX suffix for QEMU data inside datadir/libdir/sysconfdir [$confsuffix]
--enable-modules enable modules support
--enable-debug-tcg enable TCG debugging
--disable-debug-tcg disable TCG debugging (default)
@ -2362,14 +2362,32 @@ if test "$mingw32" = yes; then
else
glib_req_ver=2.12
fi
if $pkg_config --atleast-version=$glib_req_ver gthread-2.0; then
glib_cflags=`$pkg_config --cflags gthread-2.0`
glib_libs=`$pkg_config --libs gthread-2.0`
CFLAGS="$glib_cflags $CFLAGS"
LIBS="$glib_libs $LIBS"
libs_qga="$glib_libs $libs_qga"
else
error_exit "glib-$glib_req_ver required to compile QEMU"
for i in gthread-2.0 gmodule-2.0; do
if $pkg_config --atleast-version=$glib_req_ver $i; then
glib_cflags=`$pkg_config --cflags $i`
glib_libs=`$pkg_config --libs $i`
CFLAGS="$glib_cflags $CFLAGS"
LIBS="$glib_libs $LIBS"
libs_qga="$glib_libs $libs_qga"
else
error_exit "glib-$glib_req_ver $i is required to compile QEMU"
fi
done
##########################################
# SHA command probe for modules
if test "$modules" = yes; then
shacmd_probe="sha1sum sha1 shasum"
for c in $shacmd_probe; do
if which $c &>/dev/null; then
shacmd="$c"
break
fi
done
if test "$shacmd" = ""; then
error_exit "one of the checksum commands is required to enable modules: $shacmd_probe"
fi
fi
##########################################
@ -3661,6 +3679,7 @@ if test "$mingw32" = "yes" ; then
fi
qemu_confdir=$sysconfdir$confsuffix
qemu_moddir=$libdir$confsuffix
qemu_datadir=$datadir$confsuffix
qemu_localedir="$datadir/locale"
@ -3751,6 +3770,7 @@ echo "Install prefix $prefix"
echo "BIOS directory `eval echo $qemu_datadir`"
echo "binary directory `eval echo $bindir`"
echo "library directory `eval echo $libdir`"
echo "module directory `eval echo $qemu_moddir`"
echo "libexec directory `eval echo $libexecdir`"
echo "include directory `eval echo $includedir`"
echo "config directory `eval echo $sysconfdir`"
@ -3890,6 +3910,7 @@ echo "sysconfdir=$sysconfdir" >> $config_host_mak
echo "qemu_confdir=$qemu_confdir" >> $config_host_mak
echo "qemu_datadir=$qemu_datadir" >> $config_host_mak
echo "qemu_docdir=$qemu_docdir" >> $config_host_mak
echo "qemu_moddir=$qemu_moddir" >> $config_host_mak
if test "$mingw32" = "no" ; then
echo "qemu_localstatedir=$local_statedir" >> $config_host_mak
fi
@ -4023,6 +4044,9 @@ if [ "$docs" = "yes" ] ; then
echo "BUILD_DOCS=yes" >> $config_host_mak
fi
if test "$modules" = "yes"; then
# $shacmd can generate a hash started with digit, which the compiler doesn't
# like as an symbol. So prefix it with an underscore
echo "CONFIG_STAMP=_`(echo $qemu_version; echo $pkgversion; cat $0) | $shacmd - | cut -f1 -d\ `" >> $config_host_mak
echo "CONFIG_MODULES=y" >> $config_host_mak
fi
if test "$sdl" = "yes" ; then

23
include/qemu/module.h
View File

@ -14,11 +14,31 @@
#ifndef QEMU_MODULE_H
#define QEMU_MODULE_H
#include "qemu/osdep.h"
#define DSO_STAMP_FUN glue(qemu_stamp, CONFIG_STAMP)
#define DSO_STAMP_FUN_STR stringify(DSO_STAMP_FUN)
#ifdef BUILD_DSO
void DSO_STAMP_FUN(void);
/* This is a dummy symbol to identify a loaded DSO as a QEMU module, so we can
* distinguish "version mismatch" from "not a QEMU module", when the stamp
* check fails during module loading */
void qemu_module_dummy(void);
#define module_init(function, type) \
static void __attribute__((constructor)) do_qemu_init_ ## function(void) \
{ \
register_dso_module_init(function, type); \
}
#else
/* This should not be used directly. Use block_init etc. instead. */
#define module_init(function, type) \
static void __attribute__((constructor)) do_qemu_init_ ## function(void) { \
static void __attribute__((constructor)) do_qemu_init_ ## function(void) \
{ \
register_module_init(function, type); \
}
#endif
typedef enum {
MODULE_INIT_BLOCK,
@ -34,6 +54,7 @@ typedef enum {
#define type_init(function) module_init(function, MODULE_INIT_QOM)
void register_module_init(void (*fn)(void), module_init_type type);
void register_dso_module_init(void (*fn)(void), module_init_type type);
void module_call_init(module_init_type type);

10
module-common.c Normal file
View File

@ -0,0 +1,10 @@
#include "config-host.h"
#include "qemu/module.h"
void qemu_module_dummy(void)
{
}
void DSO_STAMP_FUN(void)
{
}

3
rules.mak
View File

@ -82,6 +82,8 @@ DSO_CFLAGS := -fPIC -DBUILD_DSO
%$(DSOSUF): LDFLAGS += $(LDFLAGS_SHARED)
%$(DSOSUF): %.mo libqemustub.a
$(call LINK,$^)
@# Copy to build root so modules can be loaded when program started without install
$(if $(findstring /,$@),$(call quiet-command,cp $@ $(subst /,-,$@), " CP $(subst /,-,$@)"))
.PHONY: modules
modules:
@ -211,6 +213,7 @@ $(foreach o,$(filter %.o,$($1)),
$(eval $(patsubst %.o,%.mo,$o): $o) \
$(eval $(patsubst %.o,%.mo,$o)-objs := $o))
$(foreach o,$(filter-out $(modules-m), $(patsubst %.o,%.mo,$($1))), \
$(eval $o-objs += module-common.o)
$(eval $o: $($o-objs))
$(eval modules-objs-m += $($o-objs))
$(eval modules-m += $o)

3
scripts/create_config
View File

@ -108,6 +108,9 @@ case $line in
value=${line#*=}
echo "#define $name $value"
;;
DSOSUF=*)
echo "#define HOST_DSOSUF \"${line#*=}\""
;;
esac
done # read

145
util/module.c
View File

@ -13,6 +13,8 @@
* GNU GPL, version 2 or (at your option) any later version.
*/
#include <stdlib.h>
#include <gmodule.h>
#include "qemu-common.h"
#include "qemu/queue.h"
#include "qemu/module.h"
@ -21,13 +23,16 @@ typedef struct ModuleEntry
{
void (*init)(void);
QTAILQ_ENTRY(ModuleEntry) node;
module_init_type type;
} ModuleEntry;
typedef QTAILQ_HEAD(, ModuleEntry) ModuleTypeList;
static ModuleTypeList init_type_list[MODULE_INIT_MAX];
static void init_types(void)
static ModuleTypeList dso_init_list;
static void init_lists(void)
{
static int inited;
int i;
@ -40,6 +45,8 @@ static void init_types(void)
QTAILQ_INIT(&init_type_list[i]);
}
QTAILQ_INIT(&dso_init_list);
inited = 1;
}
@ -48,7 +55,7 @@ static ModuleTypeList *find_type(module_init_type type)
{
ModuleTypeList *l;
init_types();
init_lists();
l = &init_type_list[type];
@ -62,20 +69,154 @@ void register_module_init(void (*fn)(void), module_init_type type)
e = g_malloc0(sizeof(*e));
e->init = fn;
e->type = type;
l = find_type(type);
QTAILQ_INSERT_TAIL(l, e, node);
}
void register_dso_module_init(void (*fn)(void), module_init_type type)
{
ModuleEntry *e;
init_lists();
e = g_malloc0(sizeof(*e));
e->init = fn;
e->type = type;
QTAILQ_INSERT_TAIL(&dso_init_list, e, node);
}
static void module_load(module_init_type type);
void module_call_init(module_init_type type)
{
ModuleTypeList *l;
ModuleEntry *e;
module_load(type);
l = find_type(type);
QTAILQ_FOREACH(e, l, node) {
e->init();
}
}
#ifdef CONFIG_MODULES
static int module_load_file(const char *fname)
{
GModule *g_module;
void (*sym)(void);
const char *dsosuf = HOST_DSOSUF;
int len = strlen(fname);
int suf_len = strlen(dsosuf);
ModuleEntry *e, *next;
int ret;
if (len <= suf_len || strcmp(&fname[len - suf_len], dsosuf)) {
/* wrong suffix */
ret = -EINVAL;
goto out;
}
if (access(fname, F_OK)) {
ret = -ENOENT;
goto out;
}
assert(QTAILQ_EMPTY(&dso_init_list));
g_module = g_module_open(fname, G_MODULE_BIND_LAZY | G_MODULE_BIND_LOCAL);
if (!g_module) {
fprintf(stderr, "Failed to open module: %s\n",
g_module_error());
ret = -EINVAL;
goto out;
}
if (!g_module_symbol(g_module, DSO_STAMP_FUN_STR, (gpointer *)&sym)) {
fprintf(stderr, "Failed to initialize module: %s\n",
fname);
/* Print some info if this is a QEMU module (but from different build),
* this will make debugging user problems easier. */
if (g_module_symbol(g_module, "qemu_module_dummy", (gpointer *)&sym)) {
fprintf(stderr,
"Note: only modules from the same build can be loaded.\n");
}
g_module_close(g_module);
ret = -EINVAL;
} else {
QTAILQ_FOREACH(e, &dso_init_list, node) {
register_module_init(e->init, e->type);
}
ret = 0;
}
QTAILQ_FOREACH_SAFE(e, &dso_init_list, node, next) {
QTAILQ_REMOVE(&dso_init_list, e, node);
g_free(e);
}
out:
return ret;
}
#endif
void module_load(module_init_type type)
{
#ifdef CONFIG_MODULES
char *fname = NULL;
const char **mp;
static const char *block_modules[] = {
CONFIG_BLOCK_MODULES
};
char *exec_dir;
char *dirs[3];
int i = 0;
int ret;
if (!g_module_supported()) {
fprintf(stderr, "Module is not supported by system.\n");
return;
}
switch (type) {
case MODULE_INIT_BLOCK:
mp = block_modules;
break;
default:
/* no other types have dynamic modules for now*/
return;
}
exec_dir = qemu_get_exec_dir();
dirs[i++] = g_strdup_printf("%s", CONFIG_QEMU_MODDIR);
dirs[i++] = g_strdup_printf("%s/..", exec_dir ? : "");
dirs[i++] = g_strdup_printf("%s", exec_dir ? : "");
assert(i == ARRAY_SIZE(dirs));
g_free(exec_dir);
exec_dir = NULL;
for ( ; *mp; mp++) {
for (i = 0; i < ARRAY_SIZE(dirs); i++) {
fname = g_strdup_printf("%s/%s%s", dirs[i], *mp, HOST_DSOSUF);
ret = module_load_file(fname);
/* Try loading until loaded a module file */
if (!ret) {
break;
}
g_free(fname);
fname = NULL;
}
if (ret == -ENOENT) {
fprintf(stderr, "Can't find module: %s\n", *mp);
}
g_free(fname);
}
for (i = 0; i < ARRAY_SIZE(dirs); i++) {
g_free(dirs[i]);
}
#endif
}