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Masami Hiramatsu (Google) a8b9cf62ad ftrace: Fix DIRECT_CALLS to use SAVE_REGS by default The commit `60c8971899` ("ftrace: Make DIRECT_CALLS work WITH_ARGS and !WITH_REGS") changed DIRECT_CALLS to use SAVE_ARGS when there are multiple ftrace_ops at the same function, but since the x86 only support to jump to direct_call from ftrace_regs_caller, when we set the function tracer on the same target function on x86, ftrace-direct does not work as below (this actually works on arm64.) At first, insmod ftrace-direct.ko to put a direct_call on 'wake_up_process()'. # insmod kernel/samples/ftrace/ftrace-direct.ko # less trace ... <idle>-0 [006] ..s1. 564.686958: my_direct_func: waking up rcu_preempt-17 <idle>-0 [007] ..s1. 564.687836: my_direct_func: waking up kcompactd0-63 <idle>-0 [006] ..s1. 564.690926: my_direct_func: waking up rcu_preempt-17 <idle>-0 [006] ..s1. 564.696872: my_direct_func: waking up rcu_preempt-17 <idle>-0 [007] ..s1. 565.191982: my_direct_func: waking up kcompactd0-63 Setup a function filter to the 'wake_up_process' too, and enable it. # cd /sys/kernel/tracing/ # echo wake_up_process > set_ftrace_filter # echo function > current_tracer # less trace ... <idle>-0 [006] ..s3. 686.180972: wake_up_process <-call_timer_fn <idle>-0 [006] ..s3. 686.186919: wake_up_process <-call_timer_fn <idle>-0 [002] ..s3. 686.264049: wake_up_process <-call_timer_fn <idle>-0 [002] d.h6. 686.515216: wake_up_process <-kick_pool <idle>-0 [002] d.h6. 686.691386: wake_up_process <-kick_pool Then, only function tracer is shown on x86. But if you enable 'kprobe on ftrace' event (which uses SAVE_REGS flag) on the same function, it is shown again. # echo 'p wake_up_process' >> dynamic_events # echo 1 > events/kprobes/p_wake_up_process_0/enable # echo > trace # less trace ... <idle>-0 [006] ..s2. 2710.345919: p_wake_up_process_0: (wake_up_process+0x4/0x20) <idle>-0 [006] ..s3. 2710.345923: wake_up_process <-call_timer_fn <idle>-0 [006] ..s1. 2710.345928: my_direct_func: waking up rcu_preempt-17 <idle>-0 [006] ..s2. 2710.349931: p_wake_up_process_0: (wake_up_process+0x4/0x20) <idle>-0 [006] ..s3. 2710.349934: wake_up_process <-call_timer_fn <idle>-0 [006] ..s1. 2710.349937: my_direct_func: waking up rcu_preempt-17 To fix this issue, use SAVE_REGS flag for multiple ftrace_ops flag of direct_call by default. Link: https://lore.kernel.org/linux-trace-kernel/170484558617.178953.1590516949390270842.stgit@devnote2 Fixes: `60c8971899` ("ftrace: Make DIRECT_CALLS work WITH_ARGS and !WITH_REGS") Cc: stable@vger.kernel.org Cc: Florent Revest <revest@chromium.org> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Tested-by: Mark Rutland <mark.rutland@arm.com> [arm64] Acked-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>		2024-02-09 04:58:22 -05:00
arch	powerpc fixes for 6.8 #2	2024-01-21 11:04:29 -08:00
block	for-6.8/block-2024-01-18	2024-01-18 18:22:40 -08:00
certs	This update includes the following changes:	2023-11-02 16:15:30 -10:00
crypto	crypto: scomp - fix req->dst buffer overflow	2023-12-29 11:25:56 +08:00
Documentation	Updates for time and clocksources:	2024-01-21 11:14:40 -08:00
drivers	Updates for time and clocksources:	2024-01-21 11:14:40 -08:00
fs	eventfs: Keep all directory links at 1	2024-02-01 11:53:53 -05:00
include	header cleanup fixup for 6.8-rc1	2024-01-21 10:21:43 -08:00
init	Driver core changes for 6.8-rc1	2024-01-18 09:48:40 -08:00
io_uring	for-6.8/io_uring-2024-01-18	2024-01-18 18:17:57 -08:00
ipc	shm: Slim down dependencies	2023-12-20 19:26:31 -05:00
kernel	ftrace: Fix DIRECT_CALLS to use SAVE_REGS by default	2024-02-09 04:58:22 -05:00
lib	RISC-V Patches for the 6.8 Merge Window, Part 4	2024-01-20 11:06:04 -08:00
LICENSES	LICENSES: Add the copyleft-next-0.3.1 license	2022-11-08 15:44:01 +01:00
mm	vfs-6.8.netfs	2024-01-19 09:10:23 -08:00
net	Assorted CephFS fixes and cleanups with nothing standing out.	2024-01-19 09:58:55 -08:00
rust	Rust changes for v6.8	2024-01-11 13:05:41 -08:00
samples	RISC-V Patches for the 6.8 Merge Window, Part 4	2024-01-20 11:06:04 -08:00
scripts	Coccinelle change for v6.8	2024-01-20 14:20:34 -08:00
security	+ Features	2024-01-19 10:53:55 -08:00
sound	sound fixes for 6.8-rc1	2024-01-19 12:30:29 -08:00
tools	RISC-V Patches for the 6.8 Merge Window, Part 4	2024-01-20 11:06:04 -08:00
usr	Kbuild updates for v6.8	2024-01-18 17:57:07 -08:00
virt	Generic:	2024-01-17 13:03:37 -08:00
.clang-format	clang-format: Update with v6.7-rc4's `for_each` macro list	2023-12-08 23:54:38 +01:00
.cocciconfig	scripts: add Linux .cocciconfig for coccinelle	2016-07-22 12:13:39 +02:00
.editorconfig	Add .editorconfig file for basic formatting	2023-12-28 16:22:47 +09:00
.get_maintainer.ignore	get_maintainer: add Alan to .get_maintainer.ignore	2022-08-20 15:17:44 -07:00
.gitattributes	.gitattributes: set diff driver for Rust source code files	2023-05-31 17:48:25 +02:00
.gitignore	Add .editorconfig file for basic formatting	2023-12-28 16:22:47 +09:00
.mailmap	Char/Misc and other Driver changes for 6.8-rc1	2024-01-17 16:47:17 -08:00
.rustfmt.toml	rust: add `.rustfmt.toml`	2022-09-28 09:02:20 +02:00
COPYING	COPYING: state that all contributions really are covered by this file	2020-02-10 13:32:20 -08:00
CREDITS	Including fixes from bpf and netfilter.	2024-01-18 17:33:50 -08:00
Kbuild	Kbuild updates for v6.1	2022-10-10 12:00:45 -07:00
Kconfig	kbuild: ensure full rebuild when the compiler is updated	2020-05-12 13:28:33 +09:00
MAINTAINERS	Various smb client fixes, including multichannel and for SMB3.1.1 POSIX extensions	2024-01-20 16:48:07 -08:00
Makefile	Linux 6.8-rc1	2024-01-21 14:11:32 -08:00
README	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.