--- /dev/null
+/*
+ * SPDX-License-Identifier: LGPL-2.1-only
+ *
+ * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng UST trace/channel/event context management.
+ */
+
+#define _LGPL_SOURCE
+#include <lttng/ust-events.h>
+#include <lttng/ust-tracer.h>
+#include <ust-context-provider.h>
+#include <lttng/urcu/pointer.h>
+#include <lttng/urcu/urcu-ust.h>
+#include <usterr-signal-safe.h>
+#include <ust-helper.h>
+#include <stddef.h>
+#include <string.h>
+#include <assert.h>
+#include <limits.h>
+#include "tracepoint-internal.h"
+
+#include "context-internal.h"
+
+/*
+ * The filter implementation requires that two consecutive "get" for the
+ * same context performed by the same thread return the same result.
+ */
+
+int lttng_find_context(struct lttng_ust_ctx *ctx, const char *name)
+{
+ unsigned int i;
+ const char *subname;
+
+ if (!ctx)
+ return 0;
+ if (strncmp(name, "$ctx.", strlen("$ctx.")) == 0) {
+ subname = name + strlen("$ctx.");
+ } else {
+ subname = name;
+ }
+ for (i = 0; i < ctx->nr_fields; i++) {
+ /* Skip allocated (but non-initialized) contexts */
+ if (!ctx->fields[i].event_field->name)
+ continue;
+ if (!strcmp(ctx->fields[i].event_field->name, subname))
+ return 1;
+ }
+ return 0;
+}
+
+int lttng_get_context_index(struct lttng_ust_ctx *ctx, const char *name)
+{
+ unsigned int i;
+ const char *subname;
+
+ if (!ctx)
+ return -1;
+ if (strncmp(name, "$ctx.", strlen("$ctx.")) == 0) {
+ subname = name + strlen("$ctx.");
+ } else {
+ subname = name;
+ }
+ for (i = 0; i < ctx->nr_fields; i++) {
+ /* Skip allocated (but non-initialized) contexts */
+ if (!ctx->fields[i].event_field->name)
+ continue;
+ if (!strcmp(ctx->fields[i].event_field->name, subname))
+ return i;
+ }
+ return -1;
+}
+
+static int lttng_find_context_provider(struct lttng_ust_ctx *ctx, const char *name)
+{
+ unsigned int i;
+
+ for (i = 0; i < ctx->nr_fields; i++) {
+ /* Skip allocated (but non-initialized) contexts */
+ if (!ctx->fields[i].event_field->name)
+ continue;
+ if (!strncmp(ctx->fields[i].event_field->name, name,
+ strlen(name)))
+ return 1;
+ }
+ return 0;
+}
+
+/*
+ * Note: as we append context information, the pointer location may change.
+ * lttng_ust_context_add_field leaves the new last context initialized to NULL.
+ */
+static
+int lttng_ust_context_add_field(struct lttng_ust_ctx **ctx_p)
+{
+ struct lttng_ust_ctx *ctx;
+
+ if (!*ctx_p) {
+ *ctx_p = zmalloc(sizeof(struct lttng_ust_ctx));
+ if (!*ctx_p)
+ return -ENOMEM;
+ (*ctx_p)->largest_align = 1;
+ }
+ ctx = *ctx_p;
+ if (ctx->nr_fields + 1 > ctx->allocated_fields) {
+ struct lttng_ust_ctx_field *new_fields;
+
+ ctx->allocated_fields = max_t(size_t, 1, 2 * ctx->allocated_fields);
+ new_fields = zmalloc(ctx->allocated_fields * sizeof(*new_fields));
+ if (!new_fields)
+ return -ENOMEM;
+ /* Copy elements */
+ if (ctx->fields)
+ memcpy(new_fields, ctx->fields, sizeof(*ctx->fields) * ctx->nr_fields);
+ free(ctx->fields);
+ ctx->fields = new_fields;
+ }
+ ctx->nr_fields++;
+ return 0;
+}
+
+static size_t get_type_max_align(const struct lttng_ust_type_common *type)
+{
+ switch (type->type) {
+ case lttng_ust_type_integer:
+ return lttng_ust_get_type_integer(type)->alignment;
+ case lttng_ust_type_string:
+ return CHAR_BIT;
+ case lttng_ust_type_dynamic:
+ return 0;
+ case lttng_ust_type_enum:
+ return get_type_max_align(lttng_ust_get_type_enum(type)->container_type);
+ case lttng_ust_type_array:
+ return max_t(size_t, get_type_max_align(lttng_ust_get_type_array(type)->elem_type),
+ lttng_ust_get_type_array(type)->alignment);
+ case lttng_ust_type_sequence:
+ return max_t(size_t, get_type_max_align(lttng_ust_get_type_sequence(type)->elem_type),
+ lttng_ust_get_type_sequence(type)->alignment);
+ case lttng_ust_type_struct:
+ {
+ unsigned int i;
+ size_t field_align = 0;
+ const struct lttng_ust_type_struct *struct_type = lttng_ust_get_type_struct(type);
+
+ for (i = 0; i < struct_type->nr_fields; i++) {
+ field_align = max_t(size_t,
+ get_type_max_align(struct_type->fields[i]->type),
+ field_align);
+ }
+ return field_align;
+ }
+ default:
+ WARN_ON_ONCE(1);
+ return 0;
+ }
+}
+
+/*
+ * lttng_context_update() should be called at least once between context
+ * modification and trace start.
+ */
+static
+void lttng_context_update(struct lttng_ust_ctx *ctx)
+{
+ int i;
+ size_t largest_align = 8; /* in bits */
+
+ for (i = 0; i < ctx->nr_fields; i++) {
+ size_t field_align = 8;
+
+ field_align = get_type_max_align(ctx->fields[i].event_field->type);
+ largest_align = max_t(size_t, largest_align, field_align);
+ }
+ ctx->largest_align = largest_align >> 3; /* bits to bytes */
+}
+
+int lttng_ust_context_append_rcu(struct lttng_ust_ctx **ctx_p,
+ const struct lttng_ust_ctx_field *f)
+{
+ struct lttng_ust_ctx *old_ctx = *ctx_p, *new_ctx = NULL;
+ struct lttng_ust_ctx_field *new_fields = NULL;
+ int ret;
+
+ if (old_ctx) {
+ new_ctx = zmalloc(sizeof(struct lttng_ust_ctx));
+ if (!new_ctx)
+ return -ENOMEM;
+ *new_ctx = *old_ctx;
+ new_fields = zmalloc(new_ctx->allocated_fields * sizeof(*new_fields));
+ if (!new_fields) {
+ free(new_ctx);
+ return -ENOMEM;
+ }
+ /* Copy elements */
+ memcpy(new_fields, old_ctx->fields,
+ sizeof(*old_ctx->fields) * old_ctx->nr_fields);
+ new_ctx->fields = new_fields;
+ }
+ ret = lttng_ust_context_add_field(&new_ctx);
+ if (ret) {
+ free(new_fields);
+ free(new_ctx);
+ return ret;
+ }
+ new_ctx->fields[new_ctx->nr_fields - 1] = *f;
+ lttng_context_update(new_ctx);
+ lttng_ust_rcu_assign_pointer(*ctx_p, new_ctx);
+ lttng_ust_urcu_synchronize_rcu();
+ if (old_ctx) {
+ free(old_ctx->fields);
+ free(old_ctx);
+ }
+ return 0;
+}
+
+int lttng_ust_context_append(struct lttng_ust_ctx **ctx_p,
+ const struct lttng_ust_ctx_field *f)
+{
+ int ret;
+
+ ret = lttng_ust_context_add_field(ctx_p);
+ if (ret)
+ return ret;
+ (*ctx_p)->fields[(*ctx_p)->nr_fields - 1] = *f;
+ lttng_context_update(*ctx_p);
+ return 0;
+}
+
+void lttng_destroy_context(struct lttng_ust_ctx *ctx)
+{
+ int i;
+
+ if (!ctx)
+ return;
+ for (i = 0; i < ctx->nr_fields; i++) {
+ if (ctx->fields[i].destroy)
+ ctx->fields[i].destroy(ctx->fields[i].priv);
+ }
+ free(ctx->fields);
+ free(ctx);
+}
+
+/*
+ * Can be safely performed concurrently with tracing using the struct
+ * lttng_ctx. Using RCU update. Needs to match RCU read-side handling of
+ * contexts.
+ *
+ * This does not allow adding, removing, or changing typing of the
+ * contexts, since this needs to stay invariant for metadata. However,
+ * it allows updating the handlers associated with all contexts matching
+ * a provider (by name) while tracing is using it, in a way that ensures
+ * a single RCU read-side critical section see either all old, or all
+ * new handlers.
+ */
+int lttng_ust_context_set_provider_rcu(struct lttng_ust_ctx **_ctx,
+ const char *name,
+ size_t (*get_size)(void *priv, size_t offset),
+ void (*record)(void *priv, struct lttng_ust_lib_ring_buffer_ctx *ctx,
+ struct lttng_ust_channel_buffer *chan),
+ void (*get_value)(void *priv, struct lttng_ust_ctx_value *value),
+ void *priv)
+{
+ int i, ret;
+ struct lttng_ust_ctx *ctx = *_ctx, *new_ctx;
+ struct lttng_ust_ctx_field *new_fields;
+
+ if (!ctx || !lttng_find_context_provider(ctx, name))
+ return 0;
+ /*
+ * We have at least one instance of context for the provider.
+ */
+ new_ctx = zmalloc(sizeof(*new_ctx));
+ if (!new_ctx)
+ return -ENOMEM;
+ *new_ctx = *ctx;
+ new_fields = zmalloc(sizeof(*new_fields) * ctx->allocated_fields);
+ if (!new_fields) {
+ ret = -ENOMEM;
+ goto field_error;
+ }
+ /* Copy elements */
+ memcpy(new_fields, ctx->fields,
+ sizeof(*new_fields) * ctx->allocated_fields);
+ for (i = 0; i < ctx->nr_fields; i++) {
+ if (strncmp(new_fields[i].event_field->name,
+ name, strlen(name)) != 0)
+ continue;
+ new_fields[i].get_size = get_size;
+ new_fields[i].record = record;
+ new_fields[i].get_value = get_value;
+ new_fields[i].priv = priv;
+ }
+ new_ctx->fields = new_fields;
+ lttng_ust_rcu_assign_pointer(*_ctx, new_ctx);
+ lttng_ust_urcu_synchronize_rcu();
+ free(ctx->fields);
+ free(ctx);
+ return 0;
+
+field_error:
+ free(new_ctx);
+ return ret;
+}
+
+int lttng_context_init_all(struct lttng_ust_ctx **ctx)
+{
+ int ret;
+
+ ret = lttng_add_pthread_id_to_ctx(ctx);
+ if (ret) {
+ WARN("Cannot add context lttng_add_pthread_id_to_ctx");
+ goto error;
+ }
+ ret = lttng_add_vtid_to_ctx(ctx);
+ if (ret) {
+ WARN("Cannot add context lttng_add_vtid_to_ctx");
+ goto error;
+ }
+ ret = lttng_add_vpid_to_ctx(ctx);
+ if (ret) {
+ WARN("Cannot add context lttng_add_vpid_to_ctx");
+ goto error;
+ }
+ ret = lttng_add_procname_to_ctx(ctx);
+ if (ret) {
+ WARN("Cannot add context lttng_add_procname_to_ctx");
+ goto error;
+ }
+ ret = lttng_add_cpu_id_to_ctx(ctx);
+ if (ret) {
+ WARN("Cannot add context lttng_add_cpu_id_to_ctx");
+ goto error;
+ }
+ ret = lttng_add_cgroup_ns_to_ctx(ctx);
+ if (ret) {
+ WARN("Cannot add context lttng_add_cgroup_ns_to_ctx");
+ goto error;
+ }
+ ret = lttng_add_ipc_ns_to_ctx(ctx);
+ if (ret) {
+ WARN("Cannot add context lttng_add_ipc_ns_to_ctx");
+ goto error;
+ }
+ ret = lttng_add_mnt_ns_to_ctx(ctx);
+ if (ret) {
+ WARN("Cannot add context lttng_add_mnt_ns_to_ctx");
+ goto error;
+ }
+ ret = lttng_add_net_ns_to_ctx(ctx);
+ if (ret) {
+ WARN("Cannot add context lttng_add_net_ns_to_ctx");
+ goto error;
+ }
+ ret = lttng_add_pid_ns_to_ctx(ctx);
+ if (ret) {
+ WARN("Cannot add context lttng_add_pid_ns_to_ctx");
+ goto error;
+ }
+ ret = lttng_add_time_ns_to_ctx(ctx);
+ if (ret) {
+ WARN("Cannot add context lttng_add_time_ns_to_ctx");
+ goto error;
+ }
+ ret = lttng_add_user_ns_to_ctx(ctx);
+ if (ret) {
+ WARN("Cannot add context lttng_add_user_ns_to_ctx");
+ goto error;
+ }
+ ret = lttng_add_uts_ns_to_ctx(ctx);
+ if (ret) {
+ WARN("Cannot add context lttng_add_uts_ns_to_ctx");
+ goto error;
+ }
+ ret = lttng_add_vuid_to_ctx(ctx);
+ if (ret) {
+ WARN("Cannot add context lttng_add_vuid_to_ctx");
+ goto error;
+ }
+ ret = lttng_add_veuid_to_ctx(ctx);
+ if (ret) {
+ WARN("Cannot add context lttng_add_veuid_to_ctx");
+ goto error;
+ }
+ ret = lttng_add_vsuid_to_ctx(ctx);
+ if (ret) {
+ WARN("Cannot add context lttng_add_vsuid_to_ctx");
+ goto error;
+ }
+ ret = lttng_add_vgid_to_ctx(ctx);
+ if (ret) {
+ WARN("Cannot add context lttng_add_vgid_to_ctx");
+ goto error;
+ }
+ ret = lttng_add_vegid_to_ctx(ctx);
+ if (ret) {
+ WARN("Cannot add context lttng_add_vegid_to_ctx");
+ goto error;
+ }
+ ret = lttng_add_vsgid_to_ctx(ctx);
+ if (ret) {
+ WARN("Cannot add context lttng_add_vsgid_to_ctx");
+ goto error;
+ }
+ lttng_context_update(*ctx);
+ return 0;
+
+error:
+ lttng_destroy_context(*ctx);
+ return ret;
+}