Yonggang Luo <luoyongg...@gmail.com> writes:
> We removed the need of .symbols file, so is the
> configure script, if we one expose a function to qemu-plugin
> just need prefix the function with QEMU_PLUGIN_EXPORT
>
> Signed-off-by: Yonggang Luo <luoyongg...@gmail.com>
> ---
> Makefile | 1 -
> configure | 71 -------------
> contrib/plugins/hotblocks.c | 1 +
> contrib/plugins/hotpages.c | 1 +
> contrib/plugins/howvec.c | 1 +
> contrib/plugins/lockstep.c | 1 +
> include/qemu/qemu-plugin.h | 197 +++++++++++++++++++++++++++--------
> meson.build | 6 +-
> plugins/api.c | 62 +++++------
> plugins/core.c | 10 +-
> plugins/loader.c | 50 ++++++++-
> plugins/meson.build | 10 +-
> plugins/plugin.h | 1 +
> plugins/qemu-plugins.symbols | 40 -------
> tests/plugin/bb.c | 1 +
> tests/plugin/empty.c | 1 +
> tests/plugin/insn.c | 1 +
> tests/plugin/mem.c | 1 +
> 18 files changed, 251 insertions(+), 205 deletions(-)
> delete mode 100644 plugins/qemu-plugins.symbols
>
> diff --git a/Makefile b/Makefile
> index 54fc1a9d10..9981dd5209 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -105,7 +105,6 @@ config-host.mak: $(SRC_PATH)/configure
> $(SRC_PATH)/pc-bios $(SRC_PATH)/VERSION
>
> # Force configure to re-run if the API symbols are updated
> ifeq ($(CONFIG_PLUGIN),y)
> -config-host.mak: $(SRC_PATH)/plugins/qemu-plugins.symbols
>
> .PHONY: plugins
> plugins:
> diff --git a/configure b/configure
> index 1c21a73c3b..ea447919fc 100755
> --- a/configure
> +++ b/configure
> @@ -5435,61 +5435,6 @@ if compile_prog "" "" ; then
> atomic64=yes
> fi
>
> -#########################################
> -# See if --dynamic-list is supported by the linker
> -ld_dynamic_list="no"
> -if test "$static" = "no" ; then
> - cat > $TMPTXT <<EOF
> -{
> - foo;
> -};
> -EOF
> -
> - cat > $TMPC <<EOF
> -#include <stdio.h>
> -void foo(void);
> -
> -void foo(void)
> -{
> - printf("foo\n");
> -}
> -
> -int main(void)
> -{
> - foo();
> - return 0;
> -}
> -EOF
> -
> - if compile_prog "" "-Wl,--dynamic-list=$TMPTXT" ; then
> - ld_dynamic_list="yes"
> - fi
> -fi
> -
> -#########################################
> -# See if -exported_symbols_list is supported by the linker
> -
> -ld_exported_symbols_list="no"
> -if test "$static" = "no" ; then
> - cat > $TMPTXT <<EOF
> - _foo
> -EOF
> -
> - if compile_prog "" "-Wl,-exported_symbols_list,$TMPTXT" ; then
> - ld_exported_symbols_list="yes"
> - fi
> -fi
> -
> -if test "$plugins" = "yes" &&
> - test "$ld_dynamic_list" = "no" &&
> - test "$ld_exported_symbols_list" = "no" ; then
> - error_exit \
> - "Plugin support requires dynamic linking and specifying a set of
> symbols " \
> - "that are exported to plugins. Unfortunately your linker doesn't " \
> - "support the flag (--dynamic-list or -exported_symbols_list) used " \
> - "for this purpose. You can't build with --static."
> -fi
> -
> ########################################
> # See if __attribute__((alias)) is supported.
> # This false for Xcode 9, but has been remedied for Xcode 10.
> @@ -7074,22 +7019,6 @@ fi
>
> if test "$plugins" = "yes" ; then
> echo "CONFIG_PLUGIN=y" >> $config_host_mak
> - # Copy the export object list to the build dir
> - if test "$ld_dynamic_list" = "yes" ; then
> - echo "CONFIG_HAS_LD_DYNAMIC_LIST=yes" >> $config_host_mak
> - ld_symbols=qemu-plugins-ld.symbols
> - cp "$source_path/plugins/qemu-plugins.symbols" $ld_symbols
> - elif test "$ld_exported_symbols_list" = "yes" ; then
> - echo "CONFIG_HAS_LD_EXPORTED_SYMBOLS_LIST=yes" >> $config_host_mak
> - ld64_symbols=qemu-plugins-ld64.symbols
> - echo "# Automatically generated by configure - do not modify" >
> $ld64_symbols
> - grep 'qemu_' "$source_path/plugins/qemu-plugins.symbols" | sed 's/;//g'
> | \
> - sed -E 's/^[[:space:]]*(.*)/_\1/' >> $ld64_symbols
> - else
> - error_exit \
> - "If \$plugins=yes, either \$ld_dynamic_list or " \
> - "\$ld_exported_symbols_list should have been set to 'yes'."
> - fi
> fi
>
> if test -n "$gdb_bin" ; then
> diff --git a/contrib/plugins/hotblocks.c b/contrib/plugins/hotblocks.c
> index 37435a3fc7..39e77d2980 100644
> --- a/contrib/plugins/hotblocks.c
> +++ b/contrib/plugins/hotblocks.c
> @@ -13,6 +13,7 @@
> #include <stdio.h>
> #include <glib.h>
>
> +#define QEMU_PLUGIN_IMPLEMENTATION
> #include <qemu-plugin.h>
As mentioned in earlier patch we should be able to just have the tweak
in api.c and avoid touching all the plugins themselves.
>
> -#define QEMU_PLUGIN_VERSION 0
> +#define QEMU_PLUGIN_VERSION 1
> +
> +typedef void *(*qemu_plugin_global_dlsym_t)(void* context, const char *name);
>
> typedef struct {
> /* string describing architecture */
> @@ -73,8 +71,23 @@ typedef struct {
> int max_vcpus;
> } system;
> };
> + void *context;
> + qemu_plugin_global_dlsym_t dlsym;
> } qemu_info_t;
>
> +/**
> + * qemu_plugin_initialize() - Initialize a plugin before install
> + * @info: a block describing some details about the guest
> + *
> + * All plugins must export this symbol, and in most case using qemu-plugin.h
> + * provided implementation directly.
> + * For plugin provide this function, the QEMU_PLUGIN_VERSION should >= 1
> + *
> + * Note: This function only used to loading qemu's exported functions,
> nothing
> + * else should doding in this function.
> + */
> +QEMU_PLUGIN_EXPORT int qemu_plugin_initialize(const qemu_info_t *info);
> +
So this is essentially working around the linker/dlopen stage and
manually linking in all the API functions? Does this affect the
efficiency of the API calls?
> -void qemu_plugin_outs(const char *string);
> +typedef void (*qemu_plugin_outs_t)(const char *string);
> +
> +#if !defined(QEMU_PLUGIN_API_IMPLEMENTATION)
> +#if defined(QEMU_PLUGIN_IMPLEMENTATION)
> +#define QEMU_PLUGIN_EXTERN
> +#else
> +#define QEMU_PLUGIN_EXTERN extern
> +#endif
As mentioned in the earlier patch I want to understand why the extern is
required. Could we avoid it with a parameter to the compiler when
building plugins?
<snip>
>
> static int plugin_load(struct qemu_plugin_desc *desc, const qemu_info_t
> *info)
> {
> + qemu_plugin_initialize_func_t initialize = NULL;
> qemu_plugin_install_func_t install;
> struct qemu_plugin_ctx *ctx;
> gpointer sym;
> int rc;
> + int version = -1;
>
> ctx = qemu_memalign(qemu_dcache_linesize, sizeof(*ctx));
> memset(ctx, 0, sizeof(*ctx));
> @@ -184,7 +187,7 @@ static int plugin_load(struct qemu_plugin_desc *desc,
> const qemu_info_t *info)
> desc->path, g_module_error());
> goto err_symbol;
> } else {
> - int version = *(int *)sym;
> + version = *(int *)sym;
> if (version < QEMU_PLUGIN_MIN_VERSION) {
> error_report("TCG plugin %s requires API version %d, but "
> "this QEMU supports only a minimum version of %d",
> @@ -198,6 +201,21 @@ static int plugin_load(struct qemu_plugin_desc *desc,
> const qemu_info_t *info)
> }
> }
>
> + if (version >= QEMU_PLUGIN_VERSION_1) {
> + /* This version should call to qemu_plugin_initialize first */
> + if (!g_module_symbol(ctx->handle, "qemu_plugin_initialize", &sym)) {
> + error_report("%s: %s", __func__, g_module_error());
> + goto err_symbol;
> + }
> + initialize = (qemu_plugin_initialize_func_t) sym;
> + /* symbol was found; it could be NULL though */
> + if (initialize == NULL) {
> + error_report("%s: %s: qemu_plugin_initialize is NULL",
> + __func__, desc->path);
> + goto err_symbol;
> + }
> + }
> +
> qemu_rec_mutex_lock(&plugin.lock);
>
> /* find an unused random id with &ctx as the seed */
> @@ -216,6 +234,16 @@ static int plugin_load(struct qemu_plugin_desc *desc,
> const qemu_info_t *info)
> }
> }
> QTAILQ_INSERT_TAIL(&plugin.ctxs, ctx, entry);
> + if (initialize != NULL) {
> + rc = initialize(info);
> + if (rc) {
> + error_report("%s: qemu_plugin_initialize returned error code %d",
> + __func__, rc);
> + /* qemu_plugin_initialize only loading function symbols */
> + goto err_symbol;
> + }
> + }
> +
> ctx->installing = true;
> rc = install(ctx->id, info, desc->argc, desc->argv);
> ctx->installing = false;
> @@ -254,6 +282,17 @@ static void plugin_desc_free(struct qemu_plugin_desc
> *desc)
> g_free(desc);
> }
>
> +static void *qemu_plugin_global_dlsym(void* context, const char *name)
> +{
> + GModule *global_handle = context;
> + gpointer sym = NULL;
> + if (!g_module_symbol(global_handle, name, &sym)) {
> + error_report("%s: %s", __func__, g_module_error());
> + return NULL;
> + }
> + return sym;
> +}
> +
> /**
> * qemu_plugin_load_list - load a list of plugins
> * @head: head of the list of descriptors of the plugins to be loaded
> @@ -267,6 +306,7 @@ int qemu_plugin_load_list(QemuPluginList *head)
> {
> struct qemu_plugin_desc *desc, *next;
> g_autofree qemu_info_t *info = g_new0(qemu_info_t, 1);
> + GModule *global_handle = NULL;
>
> info->target_name = TARGET_NAME;
> info->version.min = QEMU_PLUGIN_MIN_VERSION;
> @@ -276,6 +316,12 @@ int qemu_plugin_load_list(QemuPluginList *head)
> info->system_emulation = true;
> info->system.smp_vcpus = ms->smp.cpus;
> info->system.max_vcpus = ms->smp.max_cpus;
> + global_handle = g_module_open(NULL, G_MODULE_BIND_LOCAL);
> + if (global_handle == NULL) {
> + goto err_dlopen;
> + }
> + info->dlsym = qemu_plugin_global_dlsym;
> + info->context = (void*)global_handle;
> #else
> info->system_emulation = false;
> #endif
> @@ -289,6 +335,8 @@ int qemu_plugin_load_list(QemuPluginList *head)
> }
> QTAILQ_REMOVE(head, desc, entry);
> }
> +
> +err_dlopen:
> return 0;
This doesn't compile cleanly for both linux-user and softmmu:
Compiling C object libqemu-aarch64-linux-user.fa.p/tcg_tcg-common.c.o
../../plugins/loader.c: In function ‘qemu_plugin_load_list’:
../../plugins/loader.c:339:1: error: label ‘err_dlopen’ defined but not used
[-Werror=unused-label]
err_dlopen:
^~~~~~~~~~
../../plugins/loader.c:309:14: error: unused variable ‘global_handle’
[-Werror=unused-variable]
GModule *global_handle = NULL;
^~~~~~~~~~~~~
At top level:
../../plugins/loader.c:285:14: error: ‘qemu_plugin_global_dlsym’ defined but
not used [-Werror=unused-function]
static void *qemu_plugin_global_dlsym(void* context, const char *name)
^~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make: *** [Makefile.ninja:6703:
libqemu-aarch64-linux-user.fa.p/plugins_loader.c.o] Error 1
make: *** Waiting for unfinished jobs....
--
Alex Bennée
