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.
The goal here is to break up libsysprof into a library for recording
profiles (using libsysprof-capture) and a library for analyzing profiles
(both used by the sysprof UI).
This adds a GListModel that we can use to load capture files. The goal here
is to map the entire capture into memory so we can avoid reading lots of
buffers. That also allows for the model items to live as long as the model
is alive (or underlying file map, really).
The next goal is to stack features on top of this such as implementing the
callgraph as a filter of the model, or generic filters between the
callgraph model and the actual data source model.
With this change, sysprof can be consumed as a subproject without
making any changes to the build files of a project. All you need to do
is provide a wrap file with a `[provide]` section:
https://mesonbuild.com/Wrap-dependency-system-manual.html#provide-section
This is also necessary because otherwise projects need to hard-code
the subproject name, which might be `sysprof` when using `wrap-git` or
`sysprof-3.46.0` when using `wrap-file` (to build from a release
tarball). This can cause conflicts between different subprojects that
consume sysprof differently.
Other projects like glib, cairo, pango, etc already do this.
This code uses the hashtable directly to avoid the overhead of calling
the path which creates ProcessInfo entries. So we need to also handle
the chance the lookaside is NULL.
If we have tooling that can toggle -finstrument-functions, Builder for
example, then we'd be able to use an LD_PRELOAD to inject the various
function callbacks to record samples.
I dont think we want to use the sample frame type for this though. We
really want something focused on tracing instead and visualize it a bit
differently than the stack trace visualizer.
This also builds the agent statically with libsysprof_static_dep since
we'd need that to avoid installing libsysprof when that isn't wanted.
It also ensures the LD_PRELOAD libraries are installed for use by the
agent.
This is useful so that we can know when a subprocess has spawned by the
profiler in tooling which allows sysprof to spawn a process and monitor
said process. Additionally, we need to know when it exits so that we can
be correct in when we can call get_if_exited() from tooling.
pathnames are listed unescaped in /proc/[pid]/maps, so using %s as the
conversion specifier cuts pathnames off at space characters. Use %[^\n]
instead, to read everything until the end of the line.
Also, the scanf manpage states: "String input conversions store a
terminating null byte ('\0') to mark the end of the input; the maximum
field width does not include this terminator". So set the maximum field
width to 511 instead of 512, to leave one free byte in the buffer for
the terminating null byte.
Fixes#70
The order in which the argument list is evaluated is unspecified, so it
was possible for g_steal_pointer to set self = NULL before
self->old_governor was evaluated, resulting in a crash:
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x00007f6efc678d84 in enable_paranoid_cb (object=0x561a4d147c80, result=0x561a4d173560, user_data=0x561a4d09d610) at ../src/libsysprof/sysprof-governor-source.c:290
290 self->old_governor,
[Current thread is 1 (Thread 0x7f6efae4b600 (LWP 122786))]
(gdb) bt
#0 0x00007f6efc678d84 in enable_paranoid_cb (object=0x561a4d147c80 [SysprofHelpers], result=0x561a4d173560, user_data=0x561a4d09d610) at ../src/libsysprof/sysprof-governor-source.c:290
#1 0x00007f6efd51b389 in g_task_return_now (task=0x561a4d173560 [GTask]) at ../../../gio/gtask.c:1219
#2 0x00007f6efd51becb in g_task_return (type=<optimized out>, task=0x561a4d173560 [GTask]) at ../../../gio/gtask.c:1289
#3 g_task_return (task=0x561a4d173560 [GTask], type=<optimized out>) at ../../../gio/gtask.c:1245
#4 0x00007f6efc6a6060 in sysprof_helpers_set_paranoid_cb (object=0x561a4cf9df90 [IpcServiceProxy], result=0x561a4d1736e0, user_data=0x561a4d173560) at ../src/libsysprof/sysprof-helpers.c:788
#5 0x00007f6efd51b389 in g_task_return_now (task=0x561a4d1736e0 [GTask]) at ../../../gio/gtask.c:1219
#6 0x00007f6efd51becb in g_task_return (type=<optimized out>, task=0x561a4d1736e0 [GTask]) at ../../../gio/gtask.c:1289
#7 g_task_return (task=0x561a4d1736e0 [GTask], type=<optimized out>) at ../../../gio/gtask.c:1245
#8 0x00007f6efd5830cb in reply_cb (connection=<optimized out>, res=<optimized out>, user_data=user_data@entry=0x561a4d1736e0) at ../../../gio/gdbusproxy.c:2568
#9 0x00007f6efd51b389 in g_task_return_now (task=0x561a4d22b000 [GTask]) at ../../../gio/gtask.c:1219
#10 0x00007f6efd51becb in g_task_return (type=<optimized out>, task=0x561a4d22b000 [GTask]) at ../../../gio/gtask.c:1289
#11 g_task_return (task=0x561a4d22b000 [GTask], type=<optimized out>) at ../../../gio/gtask.c:1245
#12 0x00007f6efd577cbf in g_dbus_connection_call_done (source=<optimized out>, result=0x561a4d22b0c0, user_data=user_data@entry=0x561a4d22b000) at ../../../gio/gdbusconnection.c:5797
#13 0x00007f6efd51b389 in g_task_return_now (task=0x561a4d22b0c0 [GTask]) at ../../../gio/gtask.c:1219
#14 0x00007f6efd51b3c9 in complete_in_idle_cb (task=0x561a4d22b0c0) at ../../../gio/gtask.c:1233
#15 0x00007f6efd32db84 in g_main_dispatch (context=0x561a4cb60af0) at ../../../glib/gmain.c:3381
#16 g_main_context_dispatch (context=0x561a4cb60af0) at ../../../glib/gmain.c:4099
#17 0x00007f6efd32df28 in g_main_context_iterate (context=context@entry=0x561a4cb60af0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at ../../../glib/gmain.c:4175
#18 0x00007f6efd32dfdf in g_main_context_iteration (context=context@entry=0x561a4cb60af0, may_block=may_block@entry=1) at ../../../glib/gmain.c:4240
#19 0x00007f6efd54a06d in g_application_run (application=0x561a4cb56120 [SysprofApplication], argc=<optimized out>, argv=<optimized out>) at ../../../gio/gapplication.c:2569
#20 0x0000561a4b2edd14 in main (argc=1, argv=0x7ffddcebb708) at ../src/sysprof/sysprof.c:44
(gdb) info locals
helpers = 0x561a4d147c80 [SysprofHelpers]
self = 0x0
error = 0x0
old_governor = -1
__func__ = "enable_paranoid_cb"
The /sysroot/ convention is something we see on OSTree-based systems
such as Silverblue or CoreOS which contains the running image. We can
skip that part of the path so that symbol resolving continues as normal.
We are starting to come into a situation where we need more advanced
path translations because we keep having to do things like this. Until
Linux figures out file-system namespaces at a higher level at least.
