[PATCH v1 8/9] plugins: new hwprofile plugin

[Alex Bennée]

This is a plugin intended to help with profiling access to various
bits of system hardware. It only really makes sense for system
emulation.

It takes advantage of the recently exposed helper API that allows us
to see the device name (memory region name) associated with a device.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
 tests/plugin/hwprofile.c | 248 +++++++++++++++++++++++++++++++++++++++
 tests/plugin/Makefile    |   1 +
 2 files changed, 249 insertions(+)
 create mode 100644 tests/plugin/hwprofile.c

diff --git a/tests/plugin/hwprofile.c b/tests/plugin/hwprofile.c
new file mode 100644
index 00000000000..f5e0639e762
--- /dev/null
+++ b/tests/plugin/hwprofile.c
@@ -0,0 +1,248 @@
+/*
+ * Copyright (C) 2020, Alex Bennée <alex.bennee@linaro.org>
+ *
+ * HW Profile - breakdown access patterns for IO to devices
+ *
+ * License: GNU GPL, version 2 or later.
+ *   See the COPYING file in the top-level directory.
+ */
+
+#include <inttypes.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <inttypes.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <glib.h>
+
+#include <qemu-plugin.h>
+
+QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
+
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+
+typedef struct {
+    uint64_t offset;
+    int size;
+    int cpu_read;
+    int cpu_write;
+    uint64_t reads;
+    uint64_t writes;
+} IOLocationCounts;
+
+typedef struct {
+    const char *name;
+    uint64_t base;
+    int cpu_read;
+    int cpu_write;
+    uint64_t total_writes;
+    uint64_t total_reads;
+    GHashTable *access_pattern;
+} DeviceCounts;
+
+static GMutex lock;
+static GHashTable *devices;
+static bool detail;
+
+static enum qemu_plugin_mem_rw rw = QEMU_PLUGIN_MEM_RW;
+
+static inline bool track_reads(void)
+{
+    return rw == QEMU_PLUGIN_MEM_RW || rw == QEMU_PLUGIN_MEM_R;
+}
+
+static inline bool track_writes(void)
+{
+    return rw == QEMU_PLUGIN_MEM_RW || rw == QEMU_PLUGIN_MEM_W;
+}
+
+static void plugin_init(void)
+{
+    devices = g_hash_table_new(g_str_hash, g_str_equal);
+}
+
+static gint sort_cmp(gconstpointer a, gconstpointer b)
+{
+    DeviceCounts *ea = (DeviceCounts *) a;
+    DeviceCounts *eb = (DeviceCounts *) b;
+    return ea->total_reads + ea->total_writes >
+        eb->total_reads + eb->total_writes ? -1 : 1;
+}
+
+static gint sort_off(gconstpointer a, gconstpointer b)
+{
+    IOLocationCounts *ea = (IOLocationCounts *) a;
+    IOLocationCounts *eb = (IOLocationCounts *) b;
+    return ea->offset > eb->offset;
+}
+
+static void plugin_exit(qemu_plugin_id_t id, void *p)
+{
+    g_autoptr(GString) report = g_string_new("");
+    GList *counts;
+
+    if (!detail) {
+        g_string_printf(report, "Device, Address");
+        if (track_reads()) {
+            g_string_append_printf(report, ", RCPUs, Reads");
+        }
+        if (track_writes()) {
+            g_string_append_printf(report, ",  WCPUs, Writes");
+        }
+        g_string_append_c(report, '\n');
+    }
+
+    counts = g_hash_table_get_values(devices);
+    if (counts && g_list_next(counts)) {
+        GList *it;
+
+        it = g_list_sort(counts, sort_cmp);
+
+        while (it) {
+            DeviceCounts *rec = (DeviceCounts *) it->data;
+            if (detail) {
+                GList *accesses = g_hash_table_get_values(rec->access_pattern);
+                GList *io_it = g_list_sort(accesses, sort_off);
+                g_string_append_printf(report, "%s @ 0x%"PRIx64"\n", 
rec->name, rec->base);
+                while (io_it) {
+                    IOLocationCounts *loc = (IOLocationCounts *) io_it->data;
+                    g_string_append_printf(report, "  off:%08"PRIx64, 
loc->offset);
+                    if (track_reads()) {
+                        g_string_append_printf(report, ", 0x%04x, %"PRId64,
+                                               loc->cpu_read, loc->reads);
+                    }
+                    if (track_writes()) {
+                       g_string_append_printf(report, ", 0x%04x, %"PRId64,
+                                               loc->cpu_write, loc->writes);
+                    }
+                    g_string_append_c(report,'\n');
+                    io_it = io_it->next;
+                }
+            } else {
+                g_string_append_printf(report, "%s, 0x%"PRIx64,
+                                       rec->name, rec->base);
+                if (track_reads()) {
+                    g_string_append_printf(report, ", 0x%04x, %"PRId64,
+                                           rec->cpu_read, rec->total_reads);
+                }
+                if (track_writes()) {
+                    g_string_append_printf(report, ", 0x%04x, %"PRId64,
+                                           rec->cpu_write, rec->total_writes);
+                }
+                g_string_append_c(report, '\n');
+            }
+            it = it->next;
+        };
+        g_list_free(it);
+    }
+
+    qemu_plugin_outs(report->str);
+}
+
+static DeviceCounts * new_count(char *name, uint64_t base)
+{
+    DeviceCounts *count = g_new0(DeviceCounts, 1);
+    count->name = name;
+    count->base = base;
+    if (detail) {
+        count->access_pattern = g_hash_table_new(g_int64_hash, g_int64_equal);
+    }
+    g_hash_table_insert(devices, name, count);
+    return count;
+}
+
+static IOLocationCounts * new_location(uint64_t offset)
+{
+    IOLocationCounts *loc = g_new0(IOLocationCounts, 1);
+    loc->offset = offset;
+    return loc;
+}
+
+static void vcpu_haddr(unsigned int cpu_index, qemu_plugin_meminfo_t meminfo,
+                       uint64_t vaddr, void *udata)
+{
+    struct qemu_plugin_hwaddr *hwaddr = qemu_plugin_get_hwaddr(meminfo, vaddr);
+
+    if (!hwaddr || !qemu_plugin_hwaddr_is_io(hwaddr)) {
+        return;
+    } else {
+        char *name = qemu_plugin_hwaddr_device_name(hwaddr);
+        DeviceCounts *counts;
+
+        g_mutex_lock(&lock);
+        counts = (DeviceCounts *) g_hash_table_lookup(devices, name);
+        if (!counts) {
+            uint64_t off = qemu_plugin_hwaddr_device_offset(hwaddr);
+            uint64_t base = vaddr - off;
+            counts = new_count(name, base);
+        } else {
+            g_free(name);
+        }
+
+        if (detail) {
+            uint64_t off = qemu_plugin_hwaddr_device_offset(hwaddr);
+            IOLocationCounts *io_count = 
g_hash_table_lookup(counts->access_pattern, &off);
+            if (!io_count) {
+                io_count = new_location(off);
+                g_hash_table_insert(counts->access_pattern, &off, io_count);
+            }
+            if (qemu_plugin_mem_is_store(meminfo)) {
+                io_count->writes++;
+                io_count->cpu_write |= (1 << cpu_index);
+            } else {
+                io_count->reads++;
+                io_count->cpu_read |= (1 << cpu_index);
+            }
+        } else {
+            if (qemu_plugin_mem_is_store(meminfo)) {
+                counts->total_writes++;
+                counts->cpu_write |= (1 << cpu_index);
+            } else {
+                counts->total_reads++;
+                counts->cpu_read |= (1 << cpu_index);
+            }
+        }
+        g_mutex_unlock(&lock);
+    }
+}
+
+static void vcpu_tb_trans(qemu_plugin_id_t id, 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);
+        qemu_plugin_register_vcpu_mem_cb(insn, vcpu_haddr,
+                                         QEMU_PLUGIN_CB_NO_REGS,
+                                         rw, NULL);
+    }
+}
+
+QEMU_PLUGIN_EXPORT
+int qemu_plugin_install(qemu_plugin_id_t id, const qemu_info_t *info,
+                        int argc, char **argv)
+{
+    int i;
+
+    for (i = 0; i < argc; i++) {
+        char *opt = argv[i];
+        if (g_strcmp0(opt, "read") == 0) {
+            rw = QEMU_PLUGIN_MEM_R;
+        } else if (g_strcmp0(opt, "write") == 0) {
+            rw = QEMU_PLUGIN_MEM_W;
+        } else if (g_strcmp0(opt, "detail") == 0) {
+            detail = true;
+        } else {
+            fprintf(stderr, "option parsing failed: %s\n", opt);
+            return -1;
+        }
+    }
+
+    plugin_init();
+
+    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/Makefile b/tests/plugin/Makefile
index b3250e2504c..d87b8d40699 100644
--- a/tests/plugin/Makefile
+++ b/tests/plugin/Makefile
@@ -14,6 +14,7 @@ NAMES += hotblocks
 NAMES += howvec
 NAMES += hotpages
 NAMES += lockstep
+NAMES += hwprofile
 
 SONAMES := $(addsuffix .so,$(addprefix lib,$(NAMES)))
 
-- 
2.20.1