Re: [PATCH v2 05/14] tests/plugin: add test plugin for inline operations

[Pierrick Bouvier <pierrick.bouvier@linaro.org>]

On 1/26/24 20:05, Alex Bennée wrote:
> Pierrick Bouvier <pierrick.bouvier@linaro.org> writes:
> 
>> For now, it simply performs instruction, bb and mem count, and ensure
>> that inline vs callback versions have the same result. Later, we'll
>> extend it when new inline operations are added.
>>
>> Use existing plugins to test everything works is a bit cumbersome, as
>> different events are treated in different plugins. Thus, this new one.
>>
>> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
>> ---
>>   tests/plugin/inline.c    | 182 +++++++++++++++++++++++++++++++++++++++
>>   tests/plugin/meson.build |   2 +-
>>   2 files changed, 183 insertions(+), 1 deletion(-)
>>   create mode 100644 tests/plugin/inline.c
>>
>> diff --git a/tests/plugin/inline.c b/tests/plugin/inline.c
>> new file mode 100644
>> index 00000000000..28d1c3b1e48
>> --- /dev/null
>> +++ b/tests/plugin/inline.c
>> @@ -0,0 +1,182 @@
>> +/*
>> + * Copyright (C) 2023, Pierrick Bouvier <pierrick.bouvier@linaro.org>
>> + *
>> + * Demonstrates and tests usage of inline ops.
>> + *
>> + * License: GNU GPL, version 2 or later.
>> + *   See the COPYING file in the top-level directory.
>> + */
>> +
>> +#include <glib.h>
>> +#include <stdint.h>
>> +#include <stdio.h>
>> +
>> +#include <qemu-plugin.h>
>> +
>> +typedef struct {
>> +    uint64_t count_tb;
>> +    uint64_t count_tb_inline;
>> +    uint64_t count_insn;
>> +    uint64_t count_insn_inline;
>> +    uint64_t count_mem;
>> +    uint64_t count_mem_inline;
>> +} CPUCount;
> 
> I wonder if there is any way to enforce the structures being an array of
> 64 bit counts? I do worry the compiler might want day decide to do
> something silly but legal leading to confusion.
> 
> I guess qemu_plugin_scoreboard_new could:
> 
>    g_assert((element_size % sizeof(uint64_t)) == 0)
> 

Given explaination on patch [02/14], do you see more that CPUCount could 
hold any type, and qemu_plugin_u64 allows to target a specific member in it?

In general, qemu plugin runtime simply is given an offset and total size 
of the struct, so a compiled plugin can have any optimization/padding on 
this struct without this affecting the result.

> ?
> 
>> +static qemu_plugin_u64_t count_tb;
>> +static qemu_plugin_u64_t count_tb_inline;
>> +static qemu_plugin_u64_t count_insn;
>> +static qemu_plugin_u64_t count_insn_inline;
>> +static qemu_plugin_u64_t count_mem;
>> +static qemu_plugin_u64_t count_mem_inline;
> 
> Can't this just be a non scoreboard instance of CPUCount?
> 

We could always use:
CPUCount* count = qemu_plugin_scoreboard_get(score, i);
count->count_tb++;

However, the part where we sum all values would now need some glue code, 
which is longer and more error prone than having those definition here 
(and declaration in install function).

>> +
>> +static uint64_t global_count_tb;
>> +static uint64_t global_count_insn;
>> +static uint64_t global_count_mem;
>> +static unsigned int max_cpu_index;
>> +static GMutex tb_lock;
>> +static GMutex insn_lock;
>> +static GMutex mem_lock;
>> +
>> +QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
>> +
>> +static void stats_insn(void)
>> +{
>> +    const uint64_t expected = global_count_insn;
>> +    const uint64_t per_vcpu = qemu_plugin_u64_sum(count_insn);
>> +    const uint64_t inl_per_vcpu =
>> +        qemu_plugin_u64_sum(count_insn_inline);
>> +    printf("insn: %" PRIu64 "\n", expected);
>> +    printf("insn: %" PRIu64 " (per vcpu)\n", per_vcpu);
>> +    printf("insn: %" PRIu64 " (per vcpu inline)\n", inl_per_vcpu);
>> +    g_assert(expected > 0);
>> +    g_assert(per_vcpu == expected);
>> +    g_assert(inl_per_vcpu == expected);
>> +}
>> +
>> +static void stats_tb(void)
>> +{
>> +    const uint64_t expected = global_count_tb;
>> +    const uint64_t per_vcpu = qemu_plugin_u64_sum(count_tb);
>> +    const uint64_t inl_per_vcpu =
>> +        qemu_plugin_u64_sum(count_tb_inline);
>> +    printf("tb: %" PRIu64 "\n", expected);
>> +    printf("tb: %" PRIu64 " (per vcpu)\n", per_vcpu);
>> +    printf("tb: %" PRIu64 " (per vcpu inline)\n", inl_per_vcpu);
>> +    g_assert(expected > 0);
>> +    g_assert(per_vcpu == expected);
>> +    g_assert(inl_per_vcpu == expected);
>> +}
>> +
>> +static void stats_mem(void)
>> +{
>> +    const uint64_t expected = global_count_mem;
>> +    const uint64_t per_vcpu = qemu_plugin_u64_sum(count_mem);
>> +    const uint64_t inl_per_vcpu =
>> +        qemu_plugin_u64_sum(count_mem_inline);
>> +    printf("mem: %" PRIu64 "\n", expected);
>> +    printf("mem: %" PRIu64 " (per vcpu)\n", per_vcpu);
>> +    printf("mem: %" PRIu64 " (per vcpu inline)\n", inl_per_vcpu);
>> +    g_assert(expected > 0);
>> +    g_assert(per_vcpu == expected);
>> +    g_assert(inl_per_vcpu == expected);
>> +}
>> +
>> +static void plugin_exit(qemu_plugin_id_t id, void *udata)
>> +{
>> +    const unsigned int num_cpus = qemu_plugin_scoreboard_size(counts);
>> +    g_assert(num_cpus == max_cpu_index + 1);
>> +
>> +    for (int i = 0; i < num_cpus ; ++i) {
>> +        const uint64_t tb = *qemu_plugin_u64_get(count_tb, i);
>> +        const uint64_t tb_inline = *qemu_plugin_u64_get(count_tb_inline, i);
>> +        const uint64_t insn = *qemu_plugin_u64_get(count_insn, i);
>> +        const uint64_t insn_inline = *qemu_plugin_u64_get(count_insn_inline, i);
>> +        const uint64_t mem = *qemu_plugin_u64_get(count_mem, i);
>> +        const uint64_t mem_inline = *qemu_plugin_u64_get(count_mem_inline, i);
>> +        printf("cpu %d: tb (%" PRIu64 ", %" PRIu64 ") | "
>> +               "insn (%" PRIu64 ", %" PRIu64 ") | "
>> +               "mem (%" PRIu64 ", %" PRIu64 ")"
>> +               "\n",
>> +               i, tb, tb_inline, insn, insn_inline, mem, mem_inline);
>> +        g_assert(tb == tb_inline);
>> +        g_assert(insn == insn_inline);
>> +        g_assert(mem == mem_inline);
>> +    }
>> +
>> +    stats_tb();
>> +    stats_insn();
>> +    stats_mem();
>> +
>> +    qemu_plugin_scoreboard_free(counts);
>> +}
>> +
>> +static void vcpu_tb_exec(unsigned int cpu_index, void *udata)
>> +{
>> +    (*qemu_plugin_u64_get(count_tb, cpu_index))++;
>> +    g_mutex_lock(&tb_lock);
>> +    max_cpu_index = MAX(max_cpu_index, cpu_index);
>> +    global_count_tb++;
>> +    g_mutex_unlock(&tb_lock);
>> +}
>> +
>> +static void vcpu_insn_exec(unsigned int cpu_index, void *udata)
>> +{
>> +    (*qemu_plugin_u64_get(count_insn, cpu_index))++;
>> +    g_mutex_lock(&insn_lock);
>> +    global_count_insn++;
>> +    g_mutex_unlock(&insn_lock);
>> +}
>> +
>> +static void vcpu_mem_access(unsigned int cpu_index,
>> +                            qemu_plugin_meminfo_t info,
>> +                            uint64_t vaddr,
>> +                            void *userdata)
>> +{
>> +    (*qemu_plugin_u64_get(count_mem, cpu_index))++;
>> +    g_mutex_lock(&mem_lock);
>> +    global_count_mem++;
>> +    g_mutex_unlock(&mem_lock);
>> +}
>> +
>> +static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
>> +{
>> +    qemu_plugin_register_vcpu_tb_exec_cb(
>> +        tb, vcpu_tb_exec, QEMU_PLUGIN_CB_NO_REGS, 0);
>> +    qemu_plugin_register_vcpu_tb_exec_inline_per_vcpu(
>> +        tb, QEMU_PLUGIN_INLINE_ADD_U64, count_tb_inline, 1);
>> +
>> +    for (int idx = 0; idx < qemu_plugin_tb_n_insns(tb); ++idx) {
>> +        struct qemu_plugin_insn *insn = qemu_plugin_tb_get_insn(tb, idx);
>> +        qemu_plugin_register_vcpu_insn_exec_cb(
>> +            insn, vcpu_insn_exec, QEMU_PLUGIN_CB_NO_REGS, 0);
>> +        qemu_plugin_register_vcpu_insn_exec_inline_per_vcpu(
>> +            insn, QEMU_PLUGIN_INLINE_ADD_U64, count_insn_inline, 1);
>> +        qemu_plugin_register_vcpu_mem_cb(insn, &vcpu_mem_access,
>> +                                         QEMU_PLUGIN_CB_NO_REGS,
>> +                                         QEMU_PLUGIN_MEM_RW, 0);
>> +        qemu_plugin_register_vcpu_mem_inline_per_vcpu(
>> +            insn, QEMU_PLUGIN_MEM_RW,
>> +            QEMU_PLUGIN_INLINE_ADD_U64,
>> +            count_mem_inline, 1);
>> +    }
>> +}
>> +
>> +QEMU_PLUGIN_EXPORT
>> +int qemu_plugin_install(qemu_plugin_id_t id, const qemu_info_t *info,
>> +                        int argc, char **argv)
>> +{
>> +    counts = qemu_plugin_scoreboard_new(sizeof(CPUCount));
>> +    count_tb = qemu_plugin_u64_struct(counts, CPUCount, count_tb);
>> +    count_insn = qemu_plugin_u64_struct(counts, CPUCount, count_insn);
>> +    count_mem = qemu_plugin_u64_struct(counts, CPUCount, count_mem);
>> +    count_tb_inline = qemu_plugin_u64_struct(counts, CPUCount, count_tb_inline);
>> +    count_insn_inline =
>> +        qemu_plugin_u64_struct(counts, CPUCount, count_insn_inline);
>> +    count_mem_inline =
>> +        qemu_plugin_u64_struct(counts, CPUCount, count_mem_inline);
>> +    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/tests/plugin/meson.build b/tests/plugin/meson.build
>> index e18183aaeda..9eece5bab51 100644
>> --- a/tests/plugin/meson.build
>> +++ b/tests/plugin/meson.build
>> @@ -1,6 +1,6 @@
>>   t = []
>>   if get_option('plugins')
>> -  foreach i : ['bb', 'empty', 'insn', 'mem', 'syscall']
>> +  foreach i : ['bb', 'empty', 'inline', 'insn', 'mem', 'syscall']
>>       if host_os == 'windows'
>>         t += shared_module(i, files(i + '.c') + '../../contrib/plugins/win32_linker.c',
>>                           include_directories: '../../include/qemu',
> 
> Otherwise:
> 
> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
>