Re: [GIT PULL] tracing: Updates for 5.10
On Thu, 15 Oct 2020 23:54:44 -0400 Steven Rostedt wrote: > On Fri, 16 Oct 2020 11:53:23 +0900 > Masami Hiramatsu wrote: > > > > > > > I'll have to think about how to untangle this. Is there some kind of > > > annotation that makes it show that a path can only be called at boot up > > > and > > > not later? > > > > What happen if we use Peter's static_call() and update it after boot up? > > I think that's a bit over engineering ;-) > > > Or, we might need to break apart the trace_array_create() and restruct > > it as __init trace_array_early_create() and trace_array_create(). > > That will likely make the code a bit more complex and possibly add as much > code as we save from the __init sections. > > I think the best solution is what you proposed, and removing the __init, > and possibly making that function inline as well. > > Care to send an official patch? Sure, I'll send it. Thank you, -- Masami Hiramatsu
Re: [GIT PULL] tracing: Updates for 5.10
On Fri, 16 Oct 2020 11:53:23 +0900 Masami Hiramatsu wrote: > > > > I'll have to think about how to untangle this. Is there some kind of > > annotation that makes it show that a path can only be called at boot up and > > not later? > > What happen if we use Peter's static_call() and update it after boot up? I think that's a bit over engineering ;-) > Or, we might need to break apart the trace_array_create() and restruct > it as __init trace_array_early_create() and trace_array_create(). That will likely make the code a bit more complex and possibly add as much code as we save from the __init sections. I think the best solution is what you proposed, and removing the __init, and possibly making that function inline as well. Care to send an official patch? Thanks! -- Steve
Re: [GIT PULL] tracing: Updates for 5.10
On Thu, 15 Oct 2020 22:21:39 -0400
Steven Rostedt wrote:
> On Thu, 15 Oct 2020 18:54:34 -0700
> Linus Torvalds wrote:
>
> > On Thu, Oct 15, 2020 at 10:53 AM Steven Rostedt wrote:
> > >
> > > Updates for tracing and bootconfig:
> >
> > Hmm. I haven't verified that this came from you, but it seems likely..
> > Once again my clang build shows something that I don't see in my
> > allmodconfig gcc build:
> >
> >WARNING: modpost: vmlinux.o(.text+0x1e5b06): Section mismatch in
> > reference from the function __trace_early_add_events() to the function
> > .init.text:__trace_early_add_new_event()
> >The function __trace_early_add_events() references
> >the function __init __trace_early_add_new_event().
> >This is often because __trace_early_add_events lacks a __init
> >annotation or the annotation of __trace_early_add_new_event is wrong.
> >
> > Hmm?
> >
> >Linus
>
> I see the issue, and I wonder if it has to do with optimization, for gcc
> not to warn.
I also couldn't reproduce it even with CONFIG_DEBUG_SECTION_MISMATCH=y.
It seems that the __trace_early_add_new_event() is inlined in
__trace_early_add_events().
$ eu-readelf -w kernel/trace/trace_events.o
...
[ 1af20]subprogram abbrev: 53
name (strp) "__trace_early_add_new_event"
decl_file(data1) trace_events.c (1)
decl_line(data2) 2502
decl_column (data1) 1
prototyped (flag_present) yes
type (ref4) [cc]
inline (data1) inlined (1)
$ gcc -v
...
gcc version 9.3.0 (Ubuntu 9.3.0-17ubuntu1~20.04)
>
> The issue is that we have:
>
> trace_array_create() that can be called at any time. And it has:
>
> if (trace_instance_dir) {
> ret = trace_array_create_dir(tr);
> if (ret)
> goto out_free_tr;
> } else
> __trace_early_add_events(tr);
>
>
> Where trace_instance_dir gets set at boot up, and thus the else statement
> will never get called after that.
>
> The __trace_early_add_events() then calls __trace_early_add_new_events()
> which is __init.
>
> I don't know how gcc didn't trigger this and clang does.
>
> I'll have to think about how to untangle this. Is there some kind of
> annotation that makes it show that a path can only be called at boot up and
> not later?
What happen if we use Peter's static_call() and update it after boot up?
Or, we might need to break apart the trace_array_create() and restruct
it as __init trace_array_early_create() and trace_array_create().
Thank you,
--
Masami Hiramatsu
Re: [GIT PULL] tracing: Updates for 5.10
On Thu, 15 Oct 2020 18:54:34 -0700
Linus Torvalds wrote:
> On Thu, Oct 15, 2020 at 10:53 AM Steven Rostedt wrote:
> >
> > Updates for tracing and bootconfig:
>
> Hmm. I haven't verified that this came from you, but it seems likely..
> Once again my clang build shows something that I don't see in my
> allmodconfig gcc build:
>
>WARNING: modpost: vmlinux.o(.text+0x1e5b06): Section mismatch in
> reference from the function __trace_early_add_events() to the function
> .init.text:__trace_early_add_new_event()
>The function __trace_early_add_events() references
>the function __init __trace_early_add_new_event().
>This is often because __trace_early_add_events lacks a __init
>annotation or the annotation of __trace_early_add_new_event is wrong.
>
> Hmm?
Oops, that's my fault.
The commit 720dee53ad8d ("tracing/boot: Initialize per-instance event list
in early boot") removes __init from __trace_early_add_events() but I
forgot to do same on __trace_early_add_new_event().
Would this work?
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 851ab37058dd..e705f06c68c6 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -2498,7 +2498,7 @@ __trace_add_new_event(struct trace_event_call *call,
struct trace_array *tr)
* for enabling events at boot. We want to enable events before
* the filesystem is initialized.
*/
-static __init int
+static int
__trace_early_add_new_event(struct trace_event_call *call,
struct trace_array *tr)
{
--
Masami Hiramatsu
Re: [GIT PULL] tracing: Updates for 5.10
On Thu, 15 Oct 2020 18:54:34 -0700
Linus Torvalds wrote:
> On Thu, Oct 15, 2020 at 10:53 AM Steven Rostedt wrote:
> >
> > Updates for tracing and bootconfig:
>
> Hmm. I haven't verified that this came from you, but it seems likely..
> Once again my clang build shows something that I don't see in my
> allmodconfig gcc build:
>
>WARNING: modpost: vmlinux.o(.text+0x1e5b06): Section mismatch in
> reference from the function __trace_early_add_events() to the function
> .init.text:__trace_early_add_new_event()
>The function __trace_early_add_events() references
>the function __init __trace_early_add_new_event().
>This is often because __trace_early_add_events lacks a __init
>annotation or the annotation of __trace_early_add_new_event is wrong.
>
> Hmm?
>
>Linus
I see the issue, and I wonder if it has to do with optimization, for gcc
not to warn.
The issue is that we have:
trace_array_create() that can be called at any time. And it has:
if (trace_instance_dir) {
ret = trace_array_create_dir(tr);
if (ret)
goto out_free_tr;
} else
__trace_early_add_events(tr);
Where trace_instance_dir gets set at boot up, and thus the else statement
will never get called after that.
The __trace_early_add_events() then calls __trace_early_add_new_events()
which is __init.
I don't know how gcc didn't trigger this and clang does.
I'll have to think about how to untangle this. Is there some kind of
annotation that makes it show that a path can only be called at boot up and
not later?
-- Steve
Re: [GIT PULL] tracing: Updates for 5.10
On Thu, Oct 15, 2020 at 10:53 AM Steven Rostedt wrote: > > Updates for tracing and bootconfig: Hmm. I haven't verified that this came from you, but it seems likely.. Once again my clang build shows something that I don't see in my allmodconfig gcc build: WARNING: modpost: vmlinux.o(.text+0x1e5b06): Section mismatch in reference from the function __trace_early_add_events() to the function .init.text:__trace_early_add_new_event() The function __trace_early_add_events() references the function __init __trace_early_add_new_event(). This is often because __trace_early_add_events lacks a __init annotation or the annotation of __trace_early_add_new_event is wrong. Hmm? Linus
Re: [GIT PULL] tracing: Updates for 5.10
The pull request you sent on Thu, 15 Oct 2020 13:53:45 -0400: > git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git > trace-v5.10 has been merged into torvalds/linux.git: https://git.kernel.org/torvalds/c/fefa636d815975b34afc45f50852a2810fb23ba9 Thank you! -- Deet-doot-dot, I am a bot. https://korg.docs.kernel.org/prtracker.html
[GIT PULL] tracing: Updates for 5.10
Linus,
Updates for tracing and bootconfig:
- Add support for "bool" type in synthetic events
- Add per instance tracing for bootconfig
- Support perf-style return probe ("SYMBOL%return") in kprobes and uprobes
- Allow for kprobes to be enabled earlier in boot up
- Added tracepoint helper function to allow testing if tracepoints are
enabled in headers
- Synthetic events can now have dynamic strings (variable length)
- Various fixes and cleanups
Please pull the latest trace-v5.10 tree, which can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
trace-v5.10
Tag SHA1: 26ab68b2a2fa3a0e3724d4b025ca3a15dd7ec1f3
Head SHA1: 6107742d15832011cd0396d821f3225b52551f1f
Axel Rasmussen (1):
tracing: support "bool" type in synthetic trace events
Dan Carpenter (1):
tracing: remove a pointless assignment
Davidlohr Bueso (1):
fgraph: Convert ret_stack tasklist scanning to rcu
Gaurav Kohli (1):
tracing: Fix race in trace_open and buffer resize call
Jarkko Sakkinen (1):
kprobes: Use module_name() macro
Masami Hiramatsu (21):
tools/bootconfig: Show bootconfig compact tree from bootconfig file
tools/bootconfig: Add list option
tools/bootconfig: Make all functions static
tools/bootconfig: Add a script to generate ftrace shell-command from
bootconfig
tools/bootconfig: Add a script to generates bootconfig from ftrace
tools/bootconfig: Add --init option for bconf2ftrace.sh
tracing/boot: Add per-instance tracing_on option support
Documentation: tracing: Add tracing_on option to boot-time tracer
tracing/kprobes: Support perf-style return probe
tracing/uprobes: Support perf-style return probe
Documentation: tracing: Add %return suffix description
Documentation: tracing: boot: Add an example of tracing function-calls
selftests/ftrace: Add %return suffix tests
kprobes: Init kprobes in early_initcall
tracing: Define event fields early stage
tracing: Enable adding dynamic events early stage
tracing: Enable creating new instance early boot
tracing/boot, kprobe, synth: Initialize boot-time tracing earlier
Documentation: tracing: Add the startup timing of boot-time tracing
tracing/boot: Initialize per-instance event list in early boot
tracing/boot: Add ftrace.instance.*.alloc_snapshot option
Qiujun Huang (2):
ftrace: Fix some typos in comment
tracing: Fix some typos in comments
Randy Dunlap (1):
tracing: Delete repeated words in comments
Steven Rostedt (VMware) (8):
tracepoints: Add helper to test if tracepoint is enabled in a header
mm/page_ref: Convert the open coded tracepoint enabled to the new helper
x86: Use tracepoint_enabled() for msr tracepoints instead of open coding
it
tracing: Change synthetic event string format to limit printed length
ftrace: Simplify the hash calculation
ftrace: Format variable declarations of ftrace_allocate_records
tracing: Fix synthetic print fmt check for use of __get_str()
tracing: Check return value of __create_val_fields() before using its
result
Sudip Mukherjee (1):
tracing: Remove a pointless assignment
Tom Zanussi (13):
tracing: Change STR_VAR_MAX_LEN
tracing: Fix parse_synth_field() error handling
tracing: Save normal string variables
tracing: Add support for dynamic strings to synthetic events
tracing: Add README information for synthetic_events file
selftests/ftrace: Add test case for synthetic event dynamic strings
tracing: Don't show dynamic string internals in synthetic event
description
tracing: Move is_good_name() from trace_probe.h to trace.h
tracing: Check that the synthetic event and field names are legal
tracing: Add synthetic event error logging
selftests/ftrace: Change synthetic event name for inter-event-combined
test
tracing: Handle synthetic event array field type checking correctly
selftests/ftrace: Add test case for synthetic event syntax errors
Wei Yang (6):
tracing: toplevel d_entry already initialized
tracing: make tracing_init_dentry() returns an integer instead of a
d_entry pointer
ftrace: Use fls() to get the bits for dup_hash()
ftrace: Simplify the dyn_ftrace->flags macro
ftrace: Simplify the calculation of page number for ftrace_page->records
ftrace: ftrace_global_list is renamed to ftrace_ops_list
Xianting Tian (1):
tracing: Use __this_cpu_read() in trace_buffered_event_enable()
Documentation/trace/boottime-trace.rst | 38 ++
Documentation/trace/events.rst | 15 +-
Documentation/trace/histogram.rst | 18 +
Documentation/trace/kprobetrace.rst| 2 +
Documentation/trace/tracepoints.rst| 27 ++
Documentation/trace/uprobetracer.rst | 2 +
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