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libsysprof: include gzip'd /proc/kallsyms in capture

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Compressed, this adds about 2.5mb to the capture file for the contents of
the kallsyms. However, that is useful so that we can decode kernel symbols
after the fact without relying on __symbols__ to be tacked on by the
recording machine.
This commit is contained in:
Christian Hergert
2023-05-15 12:15:08 -07:00
parent 580889f8cb
commit 11f0531591
1 changed files with 95 additions and 1 deletions
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96
src/libsysprof/sysprof-proc-source.c
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@ -39,11 +39,12 @@
#include "config.h"
#include <json-glib/json-glib.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <json-glib/json-glib.h>
#include "sysprof-helpers.h"
#include "sysprof-podman.h"
#include "sysprof-proc-source.h"
@ -375,6 +376,86 @@ sysprof_proc_source_get_process_info_cb (GObject *object,
sysprof_source_emit_finished (SYSPROF_SOURCE (self));
}
typedef struct _StreamToCapture
{
SysprofCaptureWriter *writer;
GInputStream *stream;
guint8 *buf;
gsize buflen;
} StreamToCapture;
static void
stream_to_capture_free (StreamToCapture *state)
{
g_clear_pointer (&state->writer, sysprof_capture_writer_unref);
g_clear_pointer (&state->buf, g_free);
g_clear_object (&state->stream);
g_free (state);
}
static gboolean
stream_to_capture (StreamToCapture *state)
{
gssize n_read;
g_assert (state != NULL);
g_assert (state->writer != NULL);
g_assert (state->buf != NULL);
g_assert (state->buflen > 0);
g_assert (G_IS_INPUT_STREAM (state->stream));
n_read = g_input_stream_read (state->stream, state->buf, state->buflen, NULL, NULL);
if (n_read >= 0)
sysprof_capture_writer_add_file (state->writer,
SYSPROF_CAPTURE_CURRENT_TIME,
-1,
-1,
"/proc/kallsyms.gz",
n_read == 0,
state->buf,
n_read);
return n_read > 0;
}
static void
get_kallsyms_cb (GObject *object,
GAsyncResult *result,
gpointer user_data)
{
SysprofHelpers *helpers = (SysprofHelpers *)object;
g_autoptr(SysprofProcSource) self = user_data;
g_autoptr(GZlibCompressor) compressor = NULL;
g_autoptr(GInputStream) base_stream = NULL;
g_autoptr(GInputStream) gz_stream = NULL;
g_autoptr(GError) error = NULL;
g_autofree char *contents = NULL;
StreamToCapture *state;
g_assert (SYSPROF_IS_HELPERS (helpers));
g_assert (G_IS_ASYNC_RESULT (result));
g_assert (SYSPROF_IS_PROC_SOURCE (self));
if (!sysprof_helpers_get_proc_file_finish (helpers, result, &contents, &error))
return;
base_stream = g_memory_input_stream_new_from_data (g_steal_pointer (&contents), -1, g_free);
compressor = g_zlib_compressor_new (G_ZLIB_COMPRESSOR_FORMAT_GZIP, 6);
gz_stream = g_converter_input_stream_new (base_stream, G_CONVERTER (compressor));
state = g_new0 (StreamToCapture, 1);
state->stream = g_object_ref (gz_stream);
state->writer = sysprof_capture_writer_ref (self->writer);
state->buflen = 16100; /* 16kb write buffer - framing overhead */
state->buf = g_malloc (state->buflen);
g_idle_add_full (G_PRIORITY_HIGH,
(GSourceFunc)stream_to_capture,
state,
(GDestroyNotify)stream_to_capture_free);
}
static void
sysprof_proc_source_start (SysprofSource *source)
{
@ -389,6 +470,19 @@ sysprof_proc_source_start (SysprofSource *source)
NULL,
sysprof_proc_source_get_process_info_cb,
g_object_ref (self));
/* We must read kallsyms from sysprofd because if we ask for a FD and read
* it back from our current process, it's likely the kernel will censor our
* addresses making them useless.
*
* That means a pretty large (couple MB transfer) over D-Bus which is not
* great but also not the end of the world so long as we do it async.
*/
sysprof_helpers_get_proc_file_async (helpers,
"/proc/kallsyms",
NULL,
get_kallsyms_cb,
g_object_ref (self));
}
static void