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libsysprof/perf-event-stream: do local syscall when DBus is unavailable

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If we are setup without a D-Bus connection to use to talk to sysprofd then
try to perform the syscall() directly for perf_event_open.

Generally that means you need to be root.
This commit is contained in:
Christian Hergert
2025-03-21 12:01:57 -07:00
parent 637dfceb85
commit 94af48094d
1 changed files with 101 additions and 86 deletions
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187
src/libsysprof/sysprof-perf-event-stream.c
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@ -40,9 +40,7 @@
#include "config.h" #include "config.h"
#include <errno.h> #include <errno.h>
#include <glib/gstdio.h> #include <linux/perf_event.h>
#include <gio/gio.h>
#include <gio/gunixfdlist.h>
#ifdef HAVE_STDATOMIC_H #ifdef HAVE_STDATOMIC_H
# include <stdatomic.h> # include <stdatomic.h>
#endif #endif
@ -52,6 +50,10 @@
#include <sys/syscall.h> #include <sys/syscall.h>
#include <unistd.h> #include <unistd.h>
#include <glib/gstdio.h>
#include <gio/gio.h>
#include <gio/gunixfdlist.h>
#include "sysprof-perf-event-stream-private.h" #include "sysprof-perf-event-stream-private.h"
/* /*
@ -79,8 +81,6 @@ struct _SysprofPerfEventStream
gpointer callback_data; gpointer callback_data;
GDestroyNotify callback_data_destroy; GDestroyNotify callback_data_destroy;
DexPromise *promise;
int perf_fd; int perf_fd;
struct perf_event_mmap_page *map; struct perf_event_mmap_page *map;
@ -109,6 +109,16 @@ G_DEFINE_FINAL_TYPE (SysprofPerfEventStream, sysprof_perf_event_stream, G_TYPE_O
static GParamSpec *properties [N_PROPS]; static GParamSpec *properties [N_PROPS];
static int
_perf_event_open (const struct perf_event_attr *attr,
pid_t pid,
int cpu,
int group_fd,
unsigned long flags)
{
return syscall (SYS_perf_event_open, attr, pid, cpu, group_fd, flags);
}
GVariant * GVariant *
_sysprof_perf_event_attr_to_variant (const struct perf_event_attr *attr) _sysprof_perf_event_attr_to_variant (const struct perf_event_attr *attr)
{ {
@ -339,8 +349,6 @@ sysprof_perf_event_stream_finalize (GObject *object)
self->callback = NULL; self->callback = NULL;
dex_clear (&self->promise);
g_clear_object (&self->connection); g_clear_object (&self->connection);
if (self->source != NULL) if (self->source != NULL)
@ -351,6 +359,7 @@ sysprof_perf_event_stream_finalize (GObject *object)
} }
g_clear_fd (&self->perf_fd, NULL); g_clear_fd (&self->perf_fd, NULL);
g_clear_fd (&self->group_fd, NULL);
if (self->map != NULL && self->map_size > 0) if (self->map != NULL && self->map_size > 0)
{ {
@ -401,65 +410,102 @@ static void
sysprof_perf_event_stream_init (SysprofPerfEventStream *self) sysprof_perf_event_stream_init (SysprofPerfEventStream *self)
{ {
self->perf_fd = -1; self->perf_fd = -1;
self->group_fd = -1;
self->self_pid = getpid (); self->self_pid = getpid ();
} }
static void static DexFuture *
sysprof_perf_event_stream_new_cb (GObject *object, sysprof_perf_event_stream_new_fiber (gpointer data)
GAsyncResult *result,
gpointer user_data)
{ {
GDBusConnection *connection = (GDBusConnection *)object; SysprofPerfEventStream *self = data;
g_autoptr(SysprofPerfEventStream) self = user_data; g_autofd int perf_fd = -1;
g_autoptr(GUnixFDList) fd_list = NULL; gsize map_size;
g_autoptr(GVariant) ret = NULL; guint8 *map;
g_autoptr(GError) error = NULL;
g_assert (G_IS_DBUS_CONNECTION (connection));
g_assert (G_IS_ASYNC_RESULT (result));
g_assert (SYSPROF_IS_PERF_EVENT_STREAM (self)); g_assert (SYSPROF_IS_PERF_EVENT_STREAM (self));
if ((ret = g_dbus_connection_call_with_unix_fd_list_finish (connection, &fd_list, result, &error))) if (self->connection != NULL)
{ {
g_autoptr(GUnixFDList) fd_list = NULL;
g_autoptr(GUnixFDList) out_fd_list = NULL;
g_autoptr(GVariant) options = _sysprof_perf_event_attr_to_variant (&self->attr);
g_autoptr(DexFuture) future = NULL;
g_autoptr(GVariant) reply = NULL;
g_autoptr(GError) error = NULL;
int group_fd_handle = -1;
int handle; int handle;
int fd;
g_variant_get (ret, "(h)", &handle); if (self->group_fd > -1)
if (-1 != (fd = g_unix_fd_list_get (fd_list, handle, &error)))
{ {
gsize map_size; fd_list = g_unix_fd_list_new ();
guint8 *map; group_fd_handle = g_unix_fd_list_append (fd_list, self->group_fd, NULL);
}
self->perf_fd = fd; future = dex_dbus_connection_call_with_unix_fd_list (self->connection,
"org.gnome.Sysprof3",
"/org/gnome/Sysprof3",
"org.gnome.Sysprof3.Service",
"PerfEventOpen",
g_variant_new ("(@a{sv}iiht)",
options,
-1,
self->cpu,
group_fd_handle,
self->flags),
G_VARIANT_TYPE ("(h)"),
G_DBUS_CALL_FLAGS_NONE,
G_MAXUINT,
fd_list);
map_size = N_PAGES * sysprof_getpagesize () + sysprof_getpagesize (); if (!dex_await (dex_ref (future), &error))
map = mmap (NULL, map_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); return dex_future_new_for_error (g_steal_pointer (&error));
if ((gpointer)map == MAP_FAILED) g_assert (DEX_IS_FUTURE_SET (future));
{
int errsv = errno; if (!(out_fd_list = dex_await_object (dex_ref (dex_future_set_get_future_at (DEX_FUTURE_SET (future), 1)), &error)) ||
g_set_error_literal (&error, !(reply = dex_await_variant (dex_ref (dex_future_set_get_future_at (DEX_FUTURE_SET (future), 0)), &error)))
G_IO_ERROR, return dex_future_new_for_error (g_steal_pointer (&error));
g_io_error_from_errno (errsv),
g_strerror (errsv)); g_variant_get (reply, "(h)", &handle);
}
else if (-1 == (perf_fd = g_unix_fd_list_get (out_fd_list, handle, &error)))
{ return dex_future_new_for_error (g_steal_pointer (&error));
self->map_size = map_size; }
self->map = (gpointer)map; else
self->map_data = map + sysprof_getpagesize (); {
self->tail = 0; perf_fd = _perf_event_open (&self->attr, -1, self->cpu, self->group_fd, self->flags);
}
if (perf_fd < 0)
{
int errsv = errno;
return dex_future_new_reject (G_IO_ERROR,
g_io_error_from_errno (errsv),
"%s", g_strerror (errsv));
} }
} }
if (error != NULL) g_assert (self->perf_fd == -1);
dex_promise_reject (self->promise, g_steal_pointer (&error)); g_assert (perf_fd > -1);
else
dex_promise_resolve_object (self->promise, g_object_ref (self));
dex_clear (&self->promise); self->perf_fd = g_steal_fd (&perf_fd);
map_size = N_PAGES * sysprof_getpagesize () + sysprof_getpagesize ();
map = mmap (NULL, map_size, PROT_READ | PROT_WRITE, MAP_SHARED, self->perf_fd, 0);
if ((gpointer)map == MAP_FAILED)
{
int errsv = errno;
return dex_future_new_reject (G_IO_ERROR,
g_io_error_from_errno (errsv),
"%s", g_strerror (errsv));
}
self->map_size = map_size;
self->map = (gpointer)map;
self->map_data = map + sysprof_getpagesize ();
self->tail = 0;
return dex_future_new_take_object (g_object_ref (self));
} }
DexFuture * DexFuture *
@ -474,29 +520,22 @@ sysprof_perf_event_stream_new (GDBusConnection *connection,
{ {
SysprofPerfEventSource *source; SysprofPerfEventSource *source;
g_autoptr(SysprofPerfEventStream) self = NULL; g_autoptr(SysprofPerfEventStream) self = NULL;
g_autoptr(GUnixFDList) fd_list = NULL;
g_autoptr(DexPromise) promise = NULL;
g_autoptr(GVariant) options = NULL;
g_autofree char *name = NULL; g_autofree char *name = NULL;
int group_fd_handle = -1;
g_return_val_if_fail (G_IS_DBUS_CONNECTION (connection), NULL); g_return_val_if_fail (!connection || G_IS_DBUS_CONNECTION (connection), NULL);
g_return_val_if_fail (attr != NULL, NULL); g_return_val_if_fail (attr != NULL, NULL);
g_return_val_if_fail (cpu > -1, NULL); g_return_val_if_fail (cpu > -1, NULL);
g_return_val_if_fail (group_fd >= -1, NULL); g_return_val_if_fail (group_fd >= -1, NULL);
promise = dex_promise_new ();
self = g_object_new (SYSPROF_TYPE_PERF_EVENT_STREAM, NULL); self = g_object_new (SYSPROF_TYPE_PERF_EVENT_STREAM, NULL);
self->connection = g_object_ref (connection); self->connection = connection ? g_object_ref (connection) : NULL;
self->attr = *attr; self->attr = *attr;
self->cpu = cpu; self->cpu = cpu;
self->group_fd = group_fd; self->group_fd = group_fd > -1 ? dup (group_fd) : -1;
self->flags = flags; self->flags = flags;
self->callback = callback; self->callback = callback;
self->callback_data = callback_data; self->callback_data = callback_data;
self->callback_data_destroy = callback_data_destroy; self->callback_data_destroy = callback_data_destroy;
self->promise = dex_ref (promise);
source = (SysprofPerfEventSource *) source = (SysprofPerfEventSource *)
g_source_new (&source_funcs, sizeof (SysprofPerfEventSource)); g_source_new (&source_funcs, sizeof (SysprofPerfEventSource));
@ -511,34 +550,10 @@ sysprof_perf_event_stream_new (GDBusConnection *connection,
g_source_set_name (self->source, name); g_source_set_name (self->source, name);
g_source_attach (self->source, NULL); g_source_attach (self->source, NULL);
if (group_fd > -1) return dex_scheduler_spawn (NULL, 0,
{ sysprof_perf_event_stream_new_fiber,
fd_list = g_unix_fd_list_new (); g_object_ref (self),
group_fd_handle = g_unix_fd_list_append (fd_list, group_fd, NULL); g_object_unref);
}
options = _sysprof_perf_event_attr_to_variant (attr);
g_dbus_connection_call_with_unix_fd_list (connection,
"org.gnome.Sysprof3",
"/org/gnome/Sysprof3",
"org.gnome.Sysprof3.Service",
"PerfEventOpen",
g_variant_new ("(@a{sv}iiht)",
options,
-1,
cpu,
group_fd_handle,
flags),
G_VARIANT_TYPE ("(h)"),
G_DBUS_CALL_FLAGS_NONE,
G_MAXUINT,
fd_list,
dex_promise_get_cancellable (promise),
sysprof_perf_event_stream_new_cb,
g_object_ref (self));
return DEX_FUTURE (g_steal_pointer (&promise));
} }
gboolean gboolean