Re: [Qemu-devel] [RFC 48/48] plugin: add a couple of very simple examples

[Alex Bennée]

Emilio G. Cota <address@hidden> writes:

> Signed-off-by: Emilio G. Cota <address@hidden>
> ---
>  plugin-examples/bbcount_avgsize_racy.c | 50 ++++++++++++++++++++++
>  plugin-examples/mem_count_racy_both.c  | 58 ++++++++++++++++++++++++++
>  plugin-examples/Makefile               | 31 ++++++++++++++

So I think we need to be putting these somewhere else and also building
the examples by default. As plugins only make sense with tcg guests
maybe a layout like:

  tcg/plugins/plugin.c
  tcg/plugins/examples/

>  3 files changed, 139 insertions(+)
>  create mode 100644 plugin-examples/bbcount_avgsize_racy.c
>  create mode 100644 plugin-examples/mem_count_racy_both.c
>  create mode 100644 plugin-examples/Makefile
>
> diff --git a/plugin-examples/bbcount_avgsize_racy.c 
> b/plugin-examples/bbcount_avgsize_racy.c
> new file mode 100644
> index 0000000000..ccdf96c1fa
> --- /dev/null
> +++ b/plugin-examples/bbcount_avgsize_racy.c
> @@ -0,0 +1,50 @@
> +#include <inttypes.h>
> +#include <assert.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <stdio.h>
> +
> +#include <qemu-plugin.h>

-#include <qemu-plugin.h>
+#include <plugin-api.h>

> +
> +static uint64_t bb_count;
> +static uint64_t insn_count;
> +const char *filename;
> +static int stdout_fd;
> +
> +static void plugin_exit(qemu_plugin_id_t id, void *p)
> +{
> +    dprintf(stdout_fd, "insns: %" PRIu64", bb: %" PRIu64 ", "
> +            "avg insns/bb: %.2f\n",
> +            insn_count, bb_count, (double)insn_count / bb_count);
> +}
> +
> +static void vcpu_tb_exec(unsigned int cpu_index, void *udata)
> +{
> +    unsigned long n_insns = (unsigned long)udata;
> +
> +    insn_count += n_insns;
> +    bb_count++;
> +}
> +
> +static void vcpu_tb_trans(qemu_plugin_id_t id, unsigned int cpu_index,
> +                          struct qemu_plugin_tb *tb)
> +{
> +    unsigned long n_insns = qemu_plugin_tb_n_insns(tb);
> +
> +    qemu_plugin_register_vcpu_tb_exec_cb(tb, vcpu_tb_exec,
> +                                         QEMU_PLUGIN_CB_NO_REGS,
> +                                         (void *)n_insns);
> +}
> +
> +QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id, int argc,
> +                                           char **argv)
> +{
> +    /* plugin_exit might write to stdout after stdout has been closed */
> +    stdout_fd = dup(STDOUT_FILENO);
> +    assert(stdout_fd);
> +
> +    qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans);
> +    qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);
> +    return 0;
> +}
> diff --git a/plugin-examples/mem_count_racy_both.c 
> b/plugin-examples/mem_count_racy_both.c
> new file mode 100644
> index 0000000000..a47f2025bf
> --- /dev/null
> +++ b/plugin-examples/mem_count_racy_both.c
> @@ -0,0 +1,58 @@
> +#include <inttypes.h>
> +#include <assert.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <stdio.h>
> +
> +#include <qemu-plugin.h>

-#include <qemu-plugin.h>
+#include <plugin-api.h>

> +
> +static uint64_t mem_count;
> +static int stdout_fd;
> +static bool do_inline;
> +
> +static void plugin_exit(qemu_plugin_id_t id, void *p)
> +{
> +    dprintf(stdout_fd, "accesses: %" PRIu64 "\n", mem_count);
> +}
> +
> +static void vcpu_mem(unsigned int cpu_index, qemu_plugin_meminfo_t meminfo,
> +                     uint64_t vaddr, void *udata)
> +{
> +    mem_count++;
> +}
> +
> +static void vcpu_tb_trans(qemu_plugin_id_t id, unsigned int cpu_index,
> +                          struct qemu_plugin_tb *tb)
> +{
> +    size_t n = qemu_plugin_tb_n_insns(tb);
> +    size_t i;
> +
> +    for (i = 0; i < n; i++) {
> +        struct qemu_plugin_insn *insn = qemu_plugin_tb_get_insn(tb, i);
> +
> +        if (do_inline) {
> +            qemu_plugin_register_vcpu_mem_inline(insn,
> +                                                 QEMU_PLUGIN_INLINE_ADD_U64,
> +                                                 &mem_count, 1);
> +        } else {
> +            qemu_plugin_register_vcpu_mem_cb(insn, vcpu_mem,
> +                                             QEMU_PLUGIN_CB_NO_REGS, NULL);
> +        }
> +    }
> +}
> +
> +QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id, int argc,
> +                                           char **argv)
> +{
> +    if (argc && strcmp(argv[0], "inline") == 0) {
> +        do_inline = true;
> +    }
> +    /* plugin_exit might write to stdout after stdout has been closed */
> +    stdout_fd = dup(STDOUT_FILENO);
> +    assert(stdout_fd);
> +
> +    qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans);
> +    qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);
> +    return 0;
> +}
> diff --git a/plugin-examples/Makefile b/plugin-examples/Makefile
> new file mode 100644
> index 0000000000..71bbcda7a8
> --- /dev/null
> +++ b/plugin-examples/Makefile
> @@ -0,0 +1,31 @@
> +NAMES :=
> +NAMES += bbcount_avgsize_racy
> +NAMES += mem_count_racy_both
> +
> +SONAMES := $(addsuffix .so,$(addprefix lib,$(NAMES)))
> +
> +# QEMU installed path, set by --prefix during configure
> +QEMU_PATH ?= /data/src/qemu-inst/plugin-test

I guess we should use SRC_PATH (or maybe QEMU_SRC_PATH) if we want the
Makefile to be both invoked as a sub-make from a normal QEMU build and
to be used as an example for out-of-tree builds.

> +
> +CC := gcc
> +CFLAGS :=
> +CFLAGS += -O2 -Werror -Wall
> +CFLAGS += -Wundef -Wwrite-strings -Wmissing-prototypes
> +CFLAGS += -Wstrict-prototypes -Wredundant-decls
> +CFLAGS += -fno-strict-aliasing -fno-common -fwrapv
> +CFLAGS += -I$(QEMU_PATH)/include

-CFLAGS += -I$(QEMU_PATH)/include
+CFLAGS += -I$(QEMU_PATH)/include/qemu

--
Alex Bennée