Add linux device tree entry related to the Meta (Facebook) compute node
system using an AST2600 BMC.
This node is named "Santabarbara". It is a compute node with accelerator
module. The system monitors voltage and temperature for the CPU, switch,
and NIC components on the motherboard and switch board.
Signed-off-by: Fred Chen <fredchen.openbmc@gmail.com>
Link: https://patch.msgid.link/20250625073847.4054971-3-fredchen.openbmc@gmail.com
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
- Enable USB Power Delivery with revision 2.0 for all sleds
- Configure dual power/data roles with sink preference
Signed-off-by: Cosmo Chou <chou.cosmo@gmail.com>
Link: https://patch.msgid.link/20250622034247.3985727-1-chou.cosmo@gmail.com
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
Fix an obvious spelling error in the DTS file for the Lanyang BMC
("lable" -> "label"). This was reported by bugzilla a few years ago
but never got fixed.
Reported-by: Jens Schleusener <Jens.Schleusener@fossies.org>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=205891
Signed-off-by: Ankit Chauhan <ankitchauhan2065@gmail.com>
Link: https://patch.msgid.link/20250612075057.80433-1-ankitchauhan2065@gmail.com
[arj: Replace U+2192 with '->']
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
Add a GPIO expander node at address 0x13 on i2c11 bus
to monitor MMC health status via a dedicated GPIO line.
Signed-off-by: Peter Yin <peteryin.openbmc@gmail.com>
Link: https://patch.msgid.link/20250611080514.3123335-6-peteryin.openbmc@gmail.com
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
Update the GPIO bridge pin configuration for the battery circuit
on the Harma platform to reflect the correct hardware design.
Signed-off-by: Peter Yin <peteryin.openbmc@gmail.com>
Link: https://patch.msgid.link/20250611080514.3123335-5-peteryin.openbmc@gmail.com
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
Add the ADC128D818 device to I2C bus 29 to support voltage monitoring
on the Harma platform. This enables accurate measurement of system
voltages through the onboard ADC.
Signed-off-by: Peter Yin <peteryin.openbmc@gmail.com>
Link: https://patch.msgid.link/20250611080514.3123335-4-peteryin.openbmc@gmail.com
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
Add the E1.S power monitor device node to the Harma device tree
to enable power monitoring functionality for E1.S drives.
Signed-off-by: Peter Yin <peteryin.openbmc@gmail.com>
Link: https://patch.msgid.link/20250611080514.3123335-2-peteryin.openbmc@gmail.com
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
Currently the driver allows the WiFi chip enter power save mode
by checking the transmitting and receiving traffic is very low
per two seconds. But it's hard for some applications to enter
power save mode, like video streaming, which sends burst traffic
regularly for other side to buffer and only send little traffic
at most time. So adjust the criteria to enter power save while
lower than 10Mbps and check it per 100ms. Thus WiFi chip could
reduce power consumption under these applications.
Signed-off-by: Chin-Yen Lee <timlee@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20250701073839.31905-1-pkshih@realtek.com
Enable compilation of the new rtw89_usb and rtw89_8851bu modules.
Tested mostly in station mode, and a little bit in AP mode.
Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/4968a9d5-02c8-4d35-a5ad-b75ece8f5d36@gmail.com
This is the entry point for the new rtw89_8851bu module.
Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/9d40c265-2982-4073-84a3-d3781defdbca@gmail.com
Add basic USB support. No TX/RX aggregation, no switching to USB 3 mode.
RTL8851BU and RTL8832BU work.
Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/f9ad1664-2d63-4a8f-88bf-c7b7bececbfe@gmail.com
Add various register and bit definitions which will be used by the new
USB driver.
Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/5812bb0c-20d0-48df-916d-25225eee8132@gmail.com
Clear some bits in some registers in order to allow RTL8851BU to power
on. This is done both when powering on and when powering off because
that's what the vendor driver does.
Also tested with RTL8832BU and RTL8832CU.
Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/a39da939-d640-4486-ad38-f658f220afc8@gmail.com
There are a few differences in the power on/off functions between PCIE
and USB.
While the RTL8851BU appears to work without these changes, it's
probably best to implement them, in case they are needed in some
situations.
Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/469f6882-1859-464d-8a84-9ef1b6c8ce3e@gmail.com
A few unnecessary error messages are printed when the device is
unplugged. "read swsi busy" in particular can appear ~1000 times when
RTL8851BU is unplugged.
Add a new flag RTW89_FLAG_UNPLUGGED and print some error messages only
when this flag is not set. The new USB driver will set the flag when
the device is unplugged.
Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/cc18b739-6f38-4c1a-a681-1e2a0d4ed60d@gmail.com
In the case of USB the TX descriptor is transmitted in the same buffer
as the 802.11 frame, so add the required headroom.
Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/91fb7579-60e5-4a06-8007-3312639beea6@gmail.com
Disable deep power saving for USB and SDIO because rtw89_mac_send_rpwm()
is called in atomic context and accessing hardware registers results in
"scheduling while atomic" errors.
Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/0f49eceb-0de0-47e2-ba36-3c6a0dddd17d@gmail.com
"hfc" means "hci fc" which is "Host Control Interface Flow Control".
These are some parameters needed for RTL8851BU.
Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/a0dec631-de05-4302-9ef1-e730eb233f08@gmail.com
Add rtw8851b_dle_mem_usb2 and rtw8851b_dle_mem_usb3 and their various
quotas and sizes in struct rtw89_mac_size_set.
"dle" could be "Data Link Engine" or "Double Link Engine". These are
some parameters needed for RTL8851BU.
Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/91622304-614e-4e91-bf2f-7688cf44070b@gmail.com
USB and SDIO will need different sets of values, so make hfc_param_ini
in struct rtw89_chip_info an array.
Also make param_ini a pointer instead of copying the struct.
Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/1356f901-9ebf-451e-827f-50dd3efda534@gmail.com
USB 2, USB 3, and SDIO will need different sets of values compared to
PCIe.
Add a new dle_type member in struct rtw89_hci_info and make dle_mem in
struct rtw89_chip_info an array to hold the four different sets of
values.
Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/c9152735-dbc4-4473-ae29-a79625cfbf78@gmail.com
Make rtw8851b_read_efuse() accept USB devices and load the MAC address
from the correct offset.
Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/6b2a1382-3be4-4038-8005-cf96922e4332@gmail.com
Yonghong Song says:
====================
bpf: Reduce verifier stack frame size
Arnd Bergmann reported an issue ([1]) where clang compiler (less than
llvm18) may trigger an error where the stack frame size exceeds the limit.
I can reproduce the error like below:
kernel/bpf/verifier.c:24491:5: error: stack frame size (2552) exceeds limit (1280) in 'bpf_check'
[-Werror,-Wframe-larger-than]
kernel/bpf/verifier.c:19921:12: error: stack frame size (1368) exceeds limit (1280) in 'do_check'
[-Werror,-Wframe-larger-than]
This patch series fixed the above two errors by reducing stack size.
See each individual patches for details.
[1] https://lore.kernel.org/bpf/20250620113846.3950478-1-arnd@kernel.org/
Changelogs:
v2 -> v3:
- v2: https://lore.kernel.org/bpf/20250702171134.2370432-1-yonghong.song@linux.dev/
- Rename env->callchain to env->callchain_buf so it is clear that
- env->callchain_buf is used for a temp buf.
v1 -> v2:
- v1: https://lore.kernel.org/bpf/20250702053332.1991516-1-yonghong.song@linux.dev/
- Simplify assignment to struct bpf_insn pointer in do_misc_fixups().
- Restore original implementation in opt_hard_wire_dead_code_branches()
as only one insn on the stack.
- Avoid unnecessary insns for 64bit modulo (mod 0/-1) operations.
====================
Link: https://patch.msgid.link/20250703141101.1482025-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add a 'struct bpf_scc_callchain callchain_buf' field in bpf_verifier_env.
This way, the previous bpf_scc_callchain local variables can be
replaced by taking address of env->callchain_buf. This can reduce stack
usage and fix the following error:
kernel/bpf/verifier.c:19921:12: error: stack frame size (1368) exceeds limit (1280) in 'do_check'
[-Werror,-Wframe-larger-than]
Reported-by: Arnd Bergmann <arnd@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20250703141117.1485108-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Arnd Bergmann reported an issue ([1]) where clang compiler (less than
llvm18) may trigger an error where the stack frame size exceeds the limit.
I can reproduce the error like below:
kernel/bpf/verifier.c:24491:5: error: stack frame size (2552) exceeds limit (1280) in 'bpf_check'
[-Werror,-Wframe-larger-than]
kernel/bpf/verifier.c:19921:12: error: stack frame size (1368) exceeds limit (1280) in 'do_check'
[-Werror,-Wframe-larger-than]
Use env->insn_buf for bpf insns instead of putting these insns on the
stack. This can resolve the above 'bpf_check' error. The 'do_check' error
will be resolved in the next patch.
[1] https://lore.kernel.org/bpf/20250620113846.3950478-1-arnd@kernel.org/
Reported-by: Arnd Bergmann <arnd@kernel.org>
Tested-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20250703141111.1484521-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In verifier.c, the following code patterns (in two places)
struct bpf_insn *patch = &insn_buf[0];
can be simplified to
struct bpf_insn *patch = insn_buf;
which is easier to understand.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20250703141106.1483216-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Before handling the tail call in record_func_key(), we check that the
map is of the expected type and log a verifier error if it isn't. Such
an error however doesn't indicate anything wrong with the verifier. The
check for map<>func compatibility is done after record_func_key(), by
check_map_func_compatibility().
Therefore, this patch logs the error as a typical reject instead of a
verifier error.
Fixes: d2e4c1e6c2 ("bpf: Constant map key tracking for prog array pokes")
Fixes: 0df1a55afa ("bpf: Warn on internal verifier errors")
Reported-by: syzbot+efb099d5833bca355e51@syzkaller.appspotmail.com
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/1f395b74e73022e47e04a31735f258babf305420.1751578055.git.paul.chaignon@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Kumar Kartikeya Dwivedi says:
====================
BPF Standard Streams
This set introduces a standard output interface with two streams, namely
stdout and stderr, for BPF programs. The idea is that these streams will
be written to by BPF programs and the kernel, and serve as standard
interfaces for informing user space of any BPF runtime violations. Users
can also utilize them for printing normal messages for debugging usage,
as is the case with bpf_printk() and trace pipe interface.
BPF programs and the kernel can use these streams to output messages.
User space can dump these messages using bpftool.
The stream interface itself is implemented using a lockless list, so
that we can queue messages from any context. Every printk statement into
the stream leads to memory allocation. Allocation itself relies on
try_alloc_pages() to construct a bespoke bump allocator to carve out
elements. If this fails, we finally give up and drop the message.
See commit logs for more details.
Two scenarios are covered:
- Deadlocks and timeouts in rqspinlock.
- Timeouts for may_goto.
In each we provide the stack trace and source information for the
offending BPF programs. Both the C source line and the file and line
numbers are printed. The output format is as follows:
ERROR: AA or ABBA deadlock detected for bpf_res_spin_lock
Attempted lock = 0xff11000108f3a5e0
Total held locks = 1
Held lock[ 0] = 0xff11000108f3a5e0
CPU: 48 UID: 0 PID: 786 Comm: test_progs
Call trace:
bpf_stream_stage_dump_stack+0xb0/0xd0
bpf_prog_report_rqspinlock_violation+0x10b/0x130
bpf_res_spin_lock+0x8c/0xa0
bpf_prog_3699ea119d1f6ed8_foo+0xe5/0x140
if (!bpf_res_spin_lock(&v2->lock)) @ stream_bpftool.c:62
bpf_prog_9b324ec4a1b2a5c0_stream_bpftool_dump_prog_stream+0x7e/0x2d0
foo(stream); @ stream_bpftool.c:93
bpf_prog_test_run_syscall+0x102/0x240
__sys_bpf+0xd68/0x2bf0
__x64_sys_bpf+0x1e/0x30
do_syscall_64+0x68/0x140
entry_SYSCALL_64_after_hwframe+0x76/0x7e
ERROR: Timeout detected for may_goto instruction
CPU: 48 UID: 0 PID: 786 Comm: test_progs
Call trace:
bpf_stream_stage_dump_stack+0xb0/0xd0
bpf_prog_report_may_goto_violation+0x6a/0x90
bpf_check_timed_may_goto+0x4d/0xa0
arch_bpf_timed_may_goto+0x21/0x40
bpf_prog_3699ea119d1f6ed8_foo+0x12f/0x140
while (can_loop) @ stream_bpftool.c:71
bpf_prog_9b324ec4a1b2a5c0_stream_bpftool_dump_prog_stream+0x7e/0x2d0
foo(stream); @ stream_bpftool.c:93
bpf_prog_test_run_syscall+0x102/0x240
__sys_bpf+0xd68/0x2bf0
__x64_sys_bpf+0x1e/0x30
do_syscall_64+0x68/0x140
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Changelog:
----------
v4 -> v5
v4: https://lore.kernel.org/bpf/20250702031737.407548-1-memxor@gmail.com
* Add acks from Emil.
* Address various nits.
* Add extra failure tests.
* Make deadlock test a little more robust to catch problems.
v3 -> v4
v3: https://lore.kernel.org/bpf/20250624031252.2966759-1-memxor@gmail.com
* Switch to alloc_pages_nolock(), avoid incorrect memcg accounting. (Alexei)
* We will figure out proper accounting later.
* Drop error limit logic, restrict stream capacity to 100,000 bytes. (Alexei)
* Remove extra invocation of is_bpf_text_address(). (Jiri)
* Avoid emitting NULL byte into the stream text, adjust regex in selftests. (Alexei)
* Add comment around rcu_read_lock() for bpf_prog_ksym_find. (Alexei)
* Tighten stream capacity check selftest.
* Add acks from Andrii.
v2 -> v3
v2: https://lore.kernel.org/bpf/20250524011849.681425-1-memxor@gmail.com
* Fix bug when handling single element stream stage. (Eduard)
* Move to mutex for protection of stream read and copy_to_user(). (Alexei)
* Split bprintf refactor into its own patch. (Alexei)
* Move kfunc definition to common_btf_ids to avoid initcall proliferation. (Alexei)
* Return line number by reference in bpf_prog_get_file_line. (Alexei)
* Remove NULL checks for BTF name pointer. (Alexei)
* Add WARN_ON_ONCE(!rcu_read_lock_held()) in bpf_prog_ksym_find. (Eduard)
* Remove hardcoded stream stage from macros. (Alexei, Eduard)
* Move refactoring hunks to their own patch. (Alexei)
* Add empty opts parameter for future extensibility to libbpf API. (Andrii, Eduard)
* Add BPF_STREAM_{STDOUT,STDERR} to UAPI. (Andrii)
* Add code to match on backtrace output. (Eduard)
* Fix misc nits.
* Add acks.
v1 -> v2
v1: https://lore.kernel.org/bpf/20250507171720.1958296-1-memxor@gmail.com
* Drop arena page fault prints, will be done as follow up. (Alexei)
* Defer Andrii's request to reuse code and Alan's suggestion of error
counts to follow up.
* Drop bpf_dynptr_from_mem_slice patch.
* Drop some acks due to heavy reworking.
* Fix KASAN splat in bpf_prog_get_file_line. (Eduard)
* Collapse bpf_prog_ksym_find and is_bpf_text_address into single
call. (Eduard)
* Add missing RCU read lock in bpf_prog_ksym_find.
* Fix incorrect error handling in dump_stack_cb.
* Simplify libbpf macro. (Eduard, Andrii)
* Introduce bpf_prog_stream_read() libbpf API. (Eduard, Alexei, Andrii)
* Drop BPF prog from the bpftool, use libbpf API.
* Rework selftests.
RFC v1 -> v1
RFC v1: https://lore.kernel.org/bpf/20250414161443.1146103-1-memxor@gmail.com
* Rebase on bpf-next/master.
* Change output in dump_stack to also print source line. (Alexei)
* Simplify API to single pop() operation. (Eduard, Alexei)
* Add kdoc for bpf_dynptr_from_mem_slice.
* Fix -EINVAL returned from prog_dump_stream. (Eduard)
* Split dump_stack() patch into multiple commits.
* Add macro wrapping stream staging API.
* Change bpftool command from dump to tracelog. (Quentin)
* Add bpftool documentation and bash completion. (Quentin)
* Change license of bpftool to Dual BSD/GPL.
* Simplify memory allocator. (Alexei)
* No overflow into second page.
* Remove bpf_mem_alloc() fallback.
* Symlink bpftool BPF program and exercise as selftest. (Eduard)
* Verify output after dumping from ringbuf. (Eduard)
* More failure cases to check API invariants.
* Remove patches for dynptr lifetime fixes (split into separate set).
* Limit maximum error messages, and add stream capacity. (Eduard)
====================
Link: https://patch.msgid.link/20250703204818.925464-1-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add selftests to stress test the various facets of the stream API,
memory allocation pattern, and ensuring dumping support is tested and
functional.
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250703204818.925464-13-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add support for printing the BPF stream contents of a program in
bpftool. The new bpftool prog tracelog command is extended to take
stdout and stderr arguments, and then the prog specification.
The bpf_prog_stream_read() API added in previous patch is simply reused
to grab data and then it is dumped to the respective file. The stdout
data is sent to stdout, and stderr is printed to stderr.
Cc: Quentin Monnet <qmo@kernel.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250703204818.925464-12-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Introduce a libbpf API so that users can read data from a given BPF
stream for a BPF prog fd. For now, only the low-level syscall wrapper
is provided, we can add a bpf_program__* accessor as a follow up if
needed.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250703204818.925464-11-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add a convenience macro to print data to the BPF streams. BPF_STDOUT and
BPF_STDERR stream IDs in the vmlinux.h can be passed to the macro to
print to the respective streams.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250703204818.925464-10-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Introduce a kernel function which is the analogue of dump_stack()
printing some useful information and the stack trace. This is not
exposed to BPF programs yet, but can be made available in the future.
When we have a program counter for a BPF program in the stack trace,
also additionally output the filename and line number to make the trace
helpful. The rest of the trace can be passed into ./decode_stacktrace.sh
to obtain the line numbers for kernel symbols.
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250703204818.925464-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In preparation of figuring out the closest program that led to the
current point in the kernel, implement a function that scans through the
stack trace and finds out the closest BPF program when walking down the
stack trace.
Special care needs to be taken to skip over kernel and BPF subprog
frames. We basically scan until we find a BPF main prog frame. The
assumption is that if a program calls into us transitively, we'll
hit it along the way. If not, we end up returning NULL.
Contextually the function will be used in places where we know the
program may have called into us.
Due to reliance on arch_bpf_stack_walk(), this function only works on
x86 with CONFIG_UNWINDER_ORC, arm64, and s390. Remove the warning from
arch_bpf_stack_walk as well since we call it outside bpf_throw()
context.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250703204818.925464-6-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add a warning to ensure RCU lock is held around tree lookup, and then
fix one of the invocations in bpf_stack_walker. The program has an
active stack frame and won't disappear. Use the opportunity to remove
unneeded invocation of is_bpf_text_address.
Fixes: f18b03faba ("bpf: Implement BPF exceptions")
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250703204818.925464-5-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Prepare a function for use in future patches that can extract the file
info, line info, and the source line number for a given BPF program
provided it's program counter.
Only the basename of the file path is provided, given it can be
excessively long in some cases.
This will be used in later patches to print source info to the BPF
stream.
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250703204818.925464-4-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add support for a stream API to the kernel and expose related kfuncs to
BPF programs. Two streams are exposed, BPF_STDOUT and BPF_STDERR. These
can be used for printing messages that can be consumed from user space,
thus it's similar in spirit to existing trace_pipe interface.
The kernel will use the BPF_STDERR stream to notify the program of any
errors encountered at runtime. BPF programs themselves may use both
streams for writing debug messages. BPF library-like code may use
BPF_STDERR to print warnings or errors on misuse at runtime.
The implementation of a stream is as follows. Everytime a message is
emitted from the kernel (directly, or through a BPF program), a record
is allocated by bump allocating from per-cpu region backed by a page
obtained using alloc_pages_nolock(). This ensures that we can allocate
memory from any context. The eventual plan is to discard this scheme in
favor of Alexei's kmalloc_nolock() [0].
This record is then locklessly inserted into a list (llist_add()) so
that the printing side doesn't require holding any locks, and works in
any context. Each stream has a maximum capacity of 4MB of text, and each
printed message is accounted against this limit.
Messages from a program are emitted using the bpf_stream_vprintk kfunc,
which takes a stream_id argument in addition to working otherwise
similar to bpf_trace_vprintk.
The bprintf buffer helpers are extracted out to be reused for printing
the string into them before copying it into the stream, so that we can
(with the defined max limit) format a string and know its true length
before performing allocations of the stream element.
For consuming elements from a stream, we expose a bpf(2) syscall command
named BPF_PROG_STREAM_READ_BY_FD, which allows reading data from the
stream of a given prog_fd into a user space buffer. The main logic is
implemented in bpf_stream_read(). The log messages are queued in
bpf_stream::log by the bpf_stream_vprintk kfunc, and then pulled and
ordered correctly in the stream backlog.
For this purpose, we hold a lock around bpf_stream_backlog_peek(), as
llist_del_first() (if we maintained a second lockless list for the
backlog) wouldn't be safe from multiple threads anyway. Then, if we
fail to find something in the backlog log, we splice out everything from
the lockless log, and place it in the backlog log, and then return the
head of the backlog. Once the full length of the element is consumed, we
will pop it and free it.
The lockless list bpf_stream::log is a LIFO stack. Elements obtained
using a llist_del_all() operation are in LIFO order, thus would break
the chronological ordering if printed directly. Hence, this batch of
messages is first reversed. Then, it is stashed into a separate list in
the stream, i.e. the backlog_log. The head of this list is the actual
message that should always be returned to the caller. All of this is
done in bpf_stream_backlog_fill().
From the kernel side, the writing into the stream will be a bit more
involved than the typical printk. First, the kernel typically may print
a collection of messages into the stream, and parallel writers into the
stream may suffer from interleaving of messages. To ensure each group of
messages is visible atomically, we can lift the advantage of using a
lockless list for pushing in messages.
To enable this, we add a bpf_stream_stage() macro, and require kernel
users to use bpf_stream_printk statements for the passed expression to
write into the stream. Underneath the macro, we have a message staging
API, where a bpf_stream_stage object on the stack accumulates the
messages being printed into a local llist_head, and then a commit
operation splices the whole batch into the stream's lockless log list.
This is especially pertinent for rqspinlock deadlock messages printed to
program streams. After this change, we see each deadlock invocation as a
non-interleaving contiguous message without any confusion on the
reader's part, improving their user experience in debugging the fault.
While programs cannot benefit from this staged stream writing API, they
could just as well hold an rqspinlock around their print statements to
serialize messages, hence this is kept kernel-internal for now.
Overall, this infrastructure provides NMI-safe any context printing of
messages to two dedicated streams.
Later patches will add support for printing splats in case of BPF arena
page faults, rqspinlock deadlocks, and cond_break timeouts, and
integration of this facility into bpftool for dumping messages to user
space.
[0]: https://lore.kernel.org/bpf/20250501032718.65476-1-alexei.starovoitov@gmail.com
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250703204818.925464-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Refactor code to be able to get and put bprintf buffers and use
bpf_printf_prepare independently. This will be used in the next patch to
implement BPF streams support, particularly as a staging buffer for
strings that need to be formatted and then allocated and pushed into a
stream.
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20250703204818.925464-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Alexei suggested, 'link_type' can be more precise and differentiate
for human in fdinfo. In fact BPF_LINK_TYPE_KPROBE_MULTI includes
kretprobe_multi type, the same as BPF_LINK_TYPE_UPROBE_MULTI, so we
can show it more concretely.
link_type: kprobe_multi
link_id: 1
prog_tag: d2b307e915f0dd37
...
link_type: kretprobe_multi
link_id: 2
prog_tag: ab9ea0545870781d
...
link_type: uprobe_multi
link_id: 9
prog_tag: e729f789e34a8eca
...
link_type: uretprobe_multi
link_id: 10
prog_tag: 7db356c03e61a4d4
Co-developed-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
Link: https://lore.kernel.org/r/20250702153958.639852-1-chen.dylane@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
