kernel/git/stable/linux.git/Documentation/trace, branch linux-rolling-lts

perf hisi-ptt: Fix PTT trace TLP header parsing

2026-09-11T09:49:14+00:00

commit 2b8a2e5d424f0b3369054305d0bf6a5b9faee6c1 upstream. TLP Headers traced by HiSilicon PCIe tune and trace device (PTT) in 4DW format are shown in the document as below: bits [31:30] [ 29:25 ][24][23][22][21][ 20:11 ][ 10:0 ] |-----|---------|---|---|---|---|-------------|-------------| DW0 [ Fmt ][ Type ][T9][T8][TH][SO][ Length ][ Time ] DW1 [ Header DW1 ] DW2 [ Header DW2 ] DW3 [ Header DW3 ] Problem: The DW0 bit field layout of the hisi_ptt_4dw union does not match the actual bit ordering in little-endian memory, causing incorrect field decoding. Test on Kunpeng 930 SOC, generating data flow with `iperf` commands: - server side: iperf -s - client side: iperf -c $ip_addr -t 30 Trace the TLP headers with hisi_ptt on server side at the same time: perf record -e hisi_ptt12_0/type=4,filter=0x05101,direction=2,format=0/ \ --max-size 50M -o perf.data & The trace aims to capture completion TLPs, learn more in the document: https://docs.kernel.org/trace/hisi-ptt.html Decode perf.data with hisi_ptt decoder: perf report -D The hisi_ptt decoder produces the following result: [...perf headers and other information] . ... HISI PTT data: size 8388608 bytes . 00000000: 68 87 20 94 Format 3 Type 1a T9 0 T8 1 TH 1 SO 1 Length 10 Time 4a1 . 00000004: 40 00 00 00 Header DW1 . 00000008: 40 00 01 51 Header DW2 . 0000000c: 00 00 00 00 Header DW3 [...other hisi_ptt TLP headers] According to PCIe r5.0 sec 2.2.1, the Fmt & Type of Cpl/CplD is supposed to be 8b'00001010' / 8b'01001010' However, the Format & Type decoder analyzing result is 8b'01111010'. It does not match field encodings of any TLP. Correct decoder result should be: [...perf headers and other information] . ... HISI PTT data: size 8388608 bytes . 00000000: 94 20 87 68 Format 2 Type a T9 0 T8 0 TH 0 SO 1 Length 10 Time 768 . 00000004: 00 00 00 40 Header DW1 . 00000008: 51 01 00 40 Header DW2 . 0000000c: 00 00 00 00 Header DW3 [...other hisi_ptt TLP headers] To solve the problem: 1. Drop the union and C bitfield struct, store the raw DW value in a plain uint32_t, and extract the fields with FIELD_GET() against GENMASK/BIT masks declared in the header so they can be reused by other translation units. The masks are portable across endianness and compilers. 2. Print all DW hex values in big-endian byte order for readability, matching the bit field layout shown in the 4DW format diagram. 3. Read the DW value with get_unaligned_le32() instead of an unaligned pointer cast, avoiding both strict-aliasing violations and alignment hazards on hosts that do not support unaligned access. Cc: stable@vger.kernel.org Fixes: 5e91e57e6809 ("perf auxtrace arm64: Add support for parsing HiSilicon PCIe Trace packet") Reviewed-by: James Clark Signed-off-by: Sizhe Liu Signed-off-by: Namhyung Kim Signed-off-by: Greg Kroah-Hartman

tracing/eprobes: Allow use of BTF names to dereference pointers

2026-07-24T14:16:42+00:00

[ Upstream commit 69efd863a78584b9416ed6be0e1e7349124b4a00 ] Add syntax to the parsing of eprobes to be able to typecast a trace event field that is a pointer to a structure. Currently, a dereference must be a number, where the user has to figure out manually the offset of a member of a structure that they want to dereference. But for event probes that records a field that happens to be a pointer to a structure, it cannot dereference these values with BTF naming, but must use numerical offsets. For example, to find out what device a sk_buff is pointing to in the net_dev_xmit trace event, one must first use gdb to find the offsets of the members of the structures: (gdb) p &((struct sk_buff *)0)->dev $1 = (struct net_device **) 0x10 (gdb) p &((struct net_device *)0)->name $2 = (char (*)[16]) 0x118 And then use the raw numbers to dereference: # echo 'e:xmit net.net_dev_xmit +0x118(+0x10($skbaddr)):string' >> dynamic_events If BTF is in the kernel, then instead, the skbaddr can be typecast to sk_buff and use the normal dereference logic. # echo 'e:xmit net.net_dev_xmit (sk_buff)skbaddr->dev->name:string' >> dynamic_events # echo 1 > events/eprobes/xmit/enable # cat trace [..] sshd-session-1022 [000] b..2. 860.249343: xmit: (net.net_dev_xmit) arg1="enp7s0" sshd-session-1022 [000] b..2. 860.250061: xmit: (net.net_dev_xmit) arg1="enp7s0" sshd-session-1022 [000] b..2. 860.250142: xmit: (net.net_dev_xmit) arg1="enp7s0" sshd-session-1022 [000] b..2. 860.263553: xmit: (net.net_dev_xmit) arg1="enp7s0" sshd-session-1022 [000] b..2. 860.283820: xmit: (net.net_dev_xmit) arg1="enp7s0" sshd-session-1022 [000] b..2. 860.302716: xmit: (net.net_dev_xmit) arg1="enp7s0" sshd-session-1022 [000] b..2. 860.322905: xmit: (net.net_dev_xmit) arg1="enp7s0" sshd-session-1022 [000] b..2. 860.342828: xmit: (net.net_dev_xmit) arg1="enp7s0" sshd-session-1022 [000] b..2. 860.362268: xmit: (net.net_dev_xmit) arg1="enp7s0" sshd-session-1022 [000] b..2. 860.382335: xmit: (net.net_dev_xmit) arg1="enp7s0" sshd-session-1022 [000] b..2. 860.400856: xmit: (net.net_dev_xmit) arg1="enp7s0" sshd-session-1022 [000] b..2. 860.419893: xmit: (net.net_dev_xmit) arg1="enp7s0" The syntax is simply: (STRUCT)(FIELD)->MEMBER[->MEMBER..] Also add comments around the #else and #endif of #ifdef CONFIG_PROBE_EVENTS_BTF_ARGS to know what they are for. Link: https://lore.kernel.org/all/20260601130746.2139d926@gandalf.local.home/ Signed-off-by: Steven Rostedt (Google) Signed-off-by: Masami Hiramatsu (Google) Stable-dep-of: 251a8fe1b9ae ("tracing/probes: Remove WARN_ON_ONCE from parse_btf_arg") Signed-off-by: Sasha Levin

Documentation/rv: Replace stale website link

2026-07-24T14:15:45+00:00

[ Upstream commit 49cbd359e4a7501e9d6694c072031d9ae6b2d1a5 ] The sched monitor page was linking to Daniel's website which is now down. The main purpose of the link was to point to a source for the models from the original author and that can be found also in his published paper. Replace the link with a reference to Daniel's "A thread synchronization model for the PREEMPT_RT Linux kernel" which can be found online and includes the models definitions as well as the work behind them (not the original patches but since they're based on a 5.0 kernel and are mostly included upstream, there's little value in keeping them in the docs). Fixes: 03abeaa63c08 ("Documentation/rv: Add docs for the sched monitors") Signed-off-by: Gabriele Monaco Acked-by: Matteo Martelli Tested-by: Matteo Martelli Tested-by: Randy Dunlap Acked-by: Randy Dunlap Signed-off-by: Jonathan Corbet Message-ID: <20260427131709.170505-2-gmonaco@redhat.com> Signed-off-by: Sasha Levin

Documentation: tracing: Add PCI tracepoint documentation

2026-02-26T22:59:16+00:00

[ Upstream commit 8236fc613d44e59f6736d6c3e9efffaf26ab7f00 ] The PCI tracing system provides tracepoints to monitor critical hardware events that can impact system performance and reliability. Add documentation about it. Signed-off-by: Shuai Xue [bhelgaas: squash fixes: https://lore.kernel.org/r/20260108013956.14351-2-bagasdotme@gmail.com https://lore.kernel.org/r/20260108013956.14351-3-bagasdotme@gmail.com] Signed-off-by: Bjorn Helgaas Reviewed-by: Ilpo Järvinen Link: https://patch.msgid.link/20251210132907.58799-4-xueshuai@linux.alibaba.com Signed-off-by: Sasha Levin

Documentation: trace: histogram: Convert ftrace docs cross-reference

2025-09-18T17:49:26+00:00

In brief "Extended error information" section, details on error condition is referred to ftrace docs, which is written in :file: directive instead of a proper cross-reference. Convert it. Reviewed-by: Tom Zanussi Signed-off-by: Bagas Sanjaya Acked-by: Steven Rostedt (Google) Signed-off-by: Jonathan Corbet Message-ID: <20250916054202.582074-7-bagasdotme@gmail.com>

Documentation: trace: histogram-design: Wrap introductory note in note:: directive

2025-09-18T17:49:26+00:00

Use Sphinx note:: directive for the introductory note at the beginning of docs, instead of aligned-text paragraph that renders as definition list. Reviewed-by: Tom Zanussi Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Bagas Sanjaya Acked-by: Steven Rostedt (Google) Signed-off-by: Jonathan Corbet Message-ID: <20250916054202.582074-6-bagasdotme@gmail.com>

Documentation: trace: historgram-design: Separate sched_waking histogram section heading and the following diagram

2025-09-18T17:49:26+00:00

Section heading for sched_waking histogram is shown as normal paragraph instead due to codeblock marker for the following diagram being in the same line as the section underline. Separate them. Fixes: daceabf1b494 ("tracing/doc: Fix ascii-art in histogram-design.rst") Reviewed-by: Tom Zanussi Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Bagas Sanjaya Acked-by: Steven Rostedt (Google) Signed-off-by: Jonathan Corbet Message-ID: <20250916054202.582074-5-bagasdotme@gmail.com>

Documentation: trace: histogram-design: Trim trailing vertices in diagram explanation text

2025-09-18T17:49:26+00:00

Diagram explanation text is supposed to be interleaved commentary between diagram parts that are spread out, but it outputs ugly in htmldocs due to trailing vertices as if both the explanation and the diagram are in the same literal code block. Trim trailing vertices. Reviewed-by: Tom Zanussi Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Bagas Sanjaya Acked-by: Steven Rostedt (Google) Signed-off-by: Jonathan Corbet Message-ID: <20250916054202.582074-4-bagasdotme@gmail.com>

Documentation: trace: histogram: Fix histogram trigger subsection number order

2025-09-18T17:49:26+00:00

Section numbering in subsections of "Histogram Trigger Command" sections is inconsistent in order. In particular, "'hist' trigger examples" is erroneously numbered as 6.2, which is a leftover from b8df4a3634e08a ("tracing: Move hist trigger Documentation to histogram.txt"). Fix the order. Reviewed-by: Tom Zanussi Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Bagas Sanjaya Acked-by: Steven Rostedt (Google) Signed-off-by: Jonathan Corbet Message-ID: <20250916054202.582074-3-bagasdotme@gmail.com>

tracing: fix grammar error in debugging.rst

2025-09-03T21:31:48+00:00

Signed-off-by: Ryan Chung Acked-by: Steven Rostedt (Google) Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20250831101736.11519-3-seokwoo.chung130@gmail.com