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btf_prepare_func_args() is used to understand expectations and
restrictions on global subprog arguments. But current implementation is
hard to extend, as it intermixes BTF-based func prototype parsing and
interpretation logic with setting up register state at subprog entry.
Worse still, those registers are not completely set up inside
btf_prepare_func_args(), requiring some more logic later in
do_check_common(). Like calling mark_reg_unknown() and similar
initialization operations.
This intermixing of BTF interpretation and register state setup is
problematic. First, it causes duplication of BTF parsing logic for global
subprog verification (to set up initial state of global subprog) and
global subprog call sites analysis (when we need to check that whatever
is being passed into global subprog matches expectations), performed in
btf_check_subprog_call().
Given we want to extend global func argument with tags later, this
duplication is problematic. So refactor btf_prepare_func_args() to do
only BTF-based func proto and args parsing, returning high-level
argument "expectations" only, with no regard to specifics of register
state. I.e., if it's a context argument, instead of setting register
state to PTR_TO_CTX, we return ARG_PTR_TO_CTX enum for that argument as
"an argument specification" for further processing inside
do_check_common(). Similarly for SCALAR arguments, PTR_TO_MEM, etc.
This allows to reuse btf_prepare_func_args() in following patches at
global subprog call site analysis time. It also keeps register setup
code consistently in one place, do_check_common().
Besides all this, we cache this argument specs information inside
env->subprog_info, eliminating the need to redo these potentially
expensive BTF traversals, especially if BPF program's BTF is big and/or
there are lots of global subprog calls.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231215011334.2307144-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
We can derive some new information for BPF_JNE in regs_refine_cond_op().
Take following code for example:
/* The type of "a" is u32 */
if (a > 0 && a < 100) {
/* the range of the register for a is [0, 99], not [1, 99],
* and will cause the following error:
*
* invalid zero-sized read
*
* as a can be 0.
*/
bpf_skb_store_bytes(skb, xx, xx, a, 0);
}
In the code above, "a > 0" will be compiled to "jmp xxx if a == 0". In the
TRUE branch, the dst_reg will be marked as known to 0. However, in the
fallthrough(FALSE) branch, the dst_reg will not be handled, which makes
the [min, max] for a is [0, 99], not [1, 99].
For BPF_JNE, we can reduce the range of the dst reg if the src reg is a
const and is exactly the edge of the dst reg.
Signed-off-by: Menglong Dong <menglong8.dong@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20231219134800.1550388-2-menglong8.dong@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
TASK_KILLABLE already includes TASK_UNINTERRUPTIBLE, so there is no
need to add a separate TASK_UNINTERRUPTIBLE.
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
While working on the ring buffer, I found one more bug with the timestamp
code, and the fix for this removed the need for the final 64-bit cmpxchg!
The ring buffer events hold a "delta" from the previous event. If it is
determined that the delta can not be calculated, it falls back to adding an
absolute timestamp value. The way to know if the delta can be used is via
two stored timestamps in the per-cpu buffer meta data:
before_stamp and write_stamp
The before_stamp is written by every event before it tries to allocate its
space on the ring buffer. The write_stamp is written after it allocates its
space and knows that nothing came in after it read the previous
before_stamp and write_stamp and the two matched.
A previous fix dd9394257078 ("ring-buffer: Do not try to put back
write_stamp") removed putting back the write_stamp to match the
before_stamp so that the next event could use the delta, but races were
found where the two would match, but not be for of the previous event.
It was determined to allow the event reservation to not have a valid
write_stamp when it is finished, and this fixed a lot of races.
The last use of the 64-bit timestamp cmpxchg depended on the write_stamp
being valid after an interruption. But this is no longer the case, as if an
event is interrupted by a softirq that writes an event, and that event gets
interrupted by a hardirq or NMI and that writes an event, then the softirq
could finish its reservation without a valid write_stamp.
In the slow path of the event reservation, a delta can still be used if the
write_stamp is valid. Instead of using a cmpxchg against the write stamp,
the before_stamp needs to be read again to validate the write_stamp. The
cmpxchg is not needed.
This updates the slowpath to validate the write_stamp by comparing it to
the before_stamp and removes all rb_time_cmpxchg() as there are no more
users of that function.
The removal of the 32-bit updates of rb_time_t will be done in the next
merge window.
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Merge tag 'trace-v6.7-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing fix from Steven Rostedt:
"While working on the ring buffer, I found one more bug with the
timestamp code, and the fix for this removed the need for the final
64-bit cmpxchg!
The ring buffer events hold a "delta" from the previous event. If it
is determined that the delta can not be calculated, it falls back to
adding an absolute timestamp value. The way to know if the delta can
be used is via two stored timestamps in the per-cpu buffer meta data:
before_stamp and write_stamp
The before_stamp is written by every event before it tries to allocate
its space on the ring buffer. The write_stamp is written after it
allocates its space and knows that nothing came in after it read the
previous before_stamp and write_stamp and the two matched.
A previous fix dd9394257078 ("ring-buffer: Do not try to put back
write_stamp") removed putting back the write_stamp to match the
before_stamp so that the next event could use the delta, but races
were found where the two would match, but not be for of the previous
event.
It was determined to allow the event reservation to not have a valid
write_stamp when it is finished, and this fixed a lot of races.
The last use of the 64-bit timestamp cmpxchg depended on the
write_stamp being valid after an interruption. But this is no longer
the case, as if an event is interrupted by a softirq that writes an
event, and that event gets interrupted by a hardirq or NMI and that
writes an event, then the softirq could finish its reservation without
a valid write_stamp.
In the slow path of the event reservation, a delta can still be used
if the write_stamp is valid. Instead of using a cmpxchg against the
write stamp, the before_stamp needs to be read again to validate the
write_stamp. The cmpxchg is not needed.
This updates the slowpath to validate the write_stamp by comparing it
to the before_stamp and removes all rb_time_cmpxchg() as there are no
more users of that function.
The removal of the 32-bit updates of rb_time_t will be done in the
next merge window"
* tag 'trace-v6.7-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
ring-buffer: Fix slowpath of interrupted event
kmap_atomic() has been deprecated in favor of kmap_local_page().
kmap_atomic() disables page-faults and preemption (the latter
only for !PREEMPT_RT kernels).The code between the mapping and
un-mapping in this patch does not depend on the above-mentioned
side effects.So simply replaced kmap_atomic() with kmap_local_page().
Signed-off-by: Chen Haonan <chen.haonan2@zte.com.cn>
[ rjw: Subject edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The check_buffer() which checks the timestamps of the ring buffer
sub-buffer page, when enabled, only checks if the adding of deltas of the
events from the last absolute timestamp or the timestamp of the sub-buffer
page adds up to the current event.
What it does not check is if the absolute timestamp causes the time of the
events to go backwards, as that can cause issues elsewhere.
Test for the timestamp going backwards too.
This also fixes a slight issue where if the warning triggers at boot up
(because of the resetting of the tsc), it will disable all further checks,
even those that are after boot Have it continue checking if the warning
was ignored during boot up.
Link: https://lore.kernel.org/linux-trace-kernel/20231219074732.18b092d4@gandalf.local.home
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
When the ring buffer timestamp verifier triggers, it dumps the content of
the sub-buffer. But currently it only dumps the timestamps and the offset
of the data as well as the deltas. It would be even more informative if
the event data also showed the interrupt context level it was in.
That is, if each event showed that the event was written in normal,
softirq, irq or NMI context. Then a better idea about how the events may
have been interrupted from each other.
As the payload of the ring buffer is really a black box of the ring
buffer, just assume that if the payload is larger than a trace entry, that
it is a trace entry. As trace entries have the interrupt context
information saved in a flags field, look at that location and report the
output of the flags.
If the payload is not a trace entry, there's no way to really know, and
the information will be garbage. But that's OK, because this is for
debugging only (this output is not used in production as the buffer check
that calls it causes a huge overhead to the tracing). This information,
when available, is crucial for debugging timestamp issues. If it's
garbage, it will also be pretty obvious that its garbage too.
As this output usually happens in kselftests of the tracing code, the user
will know what the payload is at the time.
Link: https://lore.kernel.org/linux-trace-kernel/20231219074542.6f304601@gandalf.local.home
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Suggested-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Each event has a 27 bit timestamp delta that is used to hold the delta
from the last event. If the time between events is greater than 2^27, then
a timestamp is added that holds a 59 bit absolute timestamp.
Until a389d86f7fd09 ("ring-buffer: Have nested events still record running
time stamp"), if an interrupt interrupted an event in progress, all the
events delta would be zero to not deal with the races that need to be
handled. The commit a389d86f7fd09 changed that to handle the races giving
all events, even those that preempt other events, still have an accurate
timestamp.
To handle those races requires performing 64-bit cmpxchg on the
timestamps. But doing 64-bit cmpxchg on 32-bit architectures is considered
very slow. To try to deal with this the timestamp logic was broken into
two and then three 32-bit cmpxchgs, with the thought that two (or three)
32-bit cmpxchgs are still faster than a single 64-bit cmpxchg on 32-bit
architectures.
Part of the problem with this is that I didn't have any 32-bit
architectures to test on. After hitting several subtle bugs in this code,
an effort was made to try and see if three 32-bit cmpxchgs are indeed
faster than a single 64-bit. After a few people brushed off the dust of
their old 32-bit machines, tests were done, and even though 32-bit cmpxchg
was faster than a single 64-bit, it was in the order of 50% at best, not
300%.
After some more refactoring of the code, all 4 64-bit cmpxchg were removed:
https://lore.kernel.org/linux-trace-kernel/20231211114420.36dde01b@gandalf.local.homehttps://lore.kernel.org/linux-trace-kernel/20231214222921.193037a7@gandalf.local.homehttps://lore.kernel.org/linux-trace-kernel/20231215081810.1f4f38fe@rorschach.local.homehttps://lore.kernel.org/linux-trace-kernel/20231218230712.3a76b081@gandalf.local.home/
With all the 64-bit cmpxchg removed, the complex 32-bit workaround can also be
removed.
The 32-bit and 64-bit logic is now exactly the same.
Link: https://lore.kernel.org/all/20231213214632.15047c40@gandalf.local.home/
Link: https://lore.kernel.org/linux-trace-kernel/20231219074303.28f9abda@gandalf.local.home
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
There's no reason to give an arbitrary limit to the size of a raw trace
marker. Just let it be as big as the size that is allowed by the ring
buffer itself.
And there's also no reason to artificially break up the write to
TRACE_BUF_SIZE, as that's not even used.
Link: https://lore.kernel.org/linux-trace-kernel/20231213104218.2efc70c1@gandalf.local.home
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
If a trace_marker write is bigger than what trace_seq can hold, then it
will print "LINE TOO BIG" message and not what was written.
Instead, check if the write is bigger than the trace_seq and break it
up by that size.
Ideally, we could make the trace_seq dynamic that could hold this. But
that's for another time.
Link: https://lore.kernel.org/linux-trace-kernel/20231212190422.1eaf224f@gandalf.local.home
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Now that trace_marker can hold more than 1KB string, and can write as much
as the ring buffer can hold, the trace_seq is not big enough to hold
writes:
~# a="1234567890"
~# cnt=4080
~# s=""
~# while [ $cnt -gt 10 ]; do
~# s="${s}${a}"
~# cnt=$((cnt-10))
~# done
~# echo $s > trace_marker
~# cat trace
# tracer: nop
#
# entries-in-buffer/entries-written: 2/2 #P:8
#
# _-----=> irqs-off/BH-disabled
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / _-=> migrate-disable
# |||| / delay
# TASK-PID CPU# ||||| TIMESTAMP FUNCTION
# | | | ||||| | |
<...>-860 [002] ..... 105.543465: tracing_mark_write[LINE TOO BIG]
<...>-860 [002] ..... 105.543496: tracing_mark_write: 789012345678901234567890
By increasing the trace_seq buffer to almost two pages, it can now print
out the first line.
This also subtracts the rest of the trace_seq fields from the buffer, so
that the entire trace_seq is now PAGE_SIZE aligned.
Link: https://lore.kernel.org/linux-trace-kernel/20231209175220.19867af4@gandalf.local.home
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Allow a trace write to be as big as the ring buffer tracing data will
allow. Currently, it only allows writes of 1KB in size, but there's no
reason that it cannot allow what the ring buffer can hold.
Link: https://lore.kernel.org/linux-trace-kernel/20231212131901.5f501e72@gandalf.local.home
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
On bugs that have the ring buffer timestamp get out of sync, the config
CONFIG_RING_BUFFER_VALIDATE_TIME_DELTAS, that checks for it and if it is
detected it causes a dump of the bad sub buffer.
It shows each event and their timestamp as well as the delta in the event.
But it's also good to see the offset into the subbuffer for that event to
know if how close to the end it is.
Also print where the last event actually ended compared to where it was
expected to end.
Link: https://lore.kernel.org/linux-trace-kernel/20231211131623.59eaebd2@gandalf.local.home
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
A trace instance may only need to enable specific events. As the eventfs
directory of an instance currently creates all events which adds overhead,
allow internal instances to be created with just the events in systems
that they care about. This currently only deals with systems and not
individual events, but this should bring down the overhead of creating
instances for specific use cases quite bit.
The trace_array_get_by_name() now has another parameter "systems". This
parameter is a const string pointer of a comma/space separated list of
event systems that should be created by the trace_array. (Note if the
trace_array already exists, this parameter is ignored).
The list of systems is saved and if a module is loaded, its events will
not be added unless the system for those events also match the systems
string.
Link: https://lore.kernel.org/linux-trace-kernel/20231213093701.03fddec0@gandalf.local.home
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Arun Easi <aeasi@marvell.com>
Cc: Daniel Wagner <dwagner@suse.de>
Tested-by: Dmytro Maluka <dmaluka@chromium.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
To synchronize the timestamps with the ring buffer reservation, there are
two timestamps that are saved in the buffer meta data.
1. before_stamp
2. write_stamp
When the two are equal, the write_stamp is considered valid, as in, it may
be used to calculate the delta of the next event as the write_stamp is the
timestamp of the previous reserved event on the buffer.
This is done by the following:
/*A*/ w = current position on the ring buffer
before = before_stamp
after = write_stamp
ts = read current timestamp
if (before != after) {
write_stamp is not valid, force adding an absolute
timestamp.
}
/*B*/ before_stamp = ts
/*C*/ write = local_add_return(event length, position on ring buffer)
if (w == write - event length) {
/* Nothing interrupted between A and C */
/*E*/ write_stamp = ts;
delta = ts - after
/*
* If nothing interrupted again,
* before_stamp == write_stamp and write_stamp
* can be used to calculate the delta for
* events that come in after this one.
*/
} else {
/*
* The slow path!
* Was interrupted between A and C.
*/
This is the place that there's a bug. We currently have:
after = write_stamp
ts = read current timestamp
/*F*/ if (write == current position on the ring buffer &&
after < ts && cmpxchg(write_stamp, after, ts)) {
delta = ts - after;
} else {
delta = 0;
}
The assumption is that if the current position on the ring buffer hasn't
moved between C and F, then it also was not interrupted, and that the last
event written has a timestamp that matches the write_stamp. That is the
write_stamp is valid.
But this may not be the case:
If a task context event was interrupted by softirq between B and C.
And the softirq wrote an event that got interrupted by a hard irq between
C and E.
and the hard irq wrote an event (does not need to be interrupted)
We have:
/*B*/ before_stamp = ts of normal context
---> interrupted by softirq
/*B*/ before_stamp = ts of softirq context
---> interrupted by hardirq
/*B*/ before_stamp = ts of hard irq context
/*E*/ write_stamp = ts of hard irq context
/* matches and write_stamp valid */
<----
/*E*/ write_stamp = ts of softirq context
/* No longer matches before_stamp, write_stamp is not valid! */
<---
w != write - length, go to slow path
// Right now the order of events in the ring buffer is:
//
// |-- softirq event --|-- hard irq event --|-- normal context event --|
//
after = write_stamp (this is the ts of softirq)
ts = read current timestamp
if (write == current position on the ring buffer [true] &&
after < ts [true] && cmpxchg(write_stamp, after, ts) [true]) {
delta = ts - after [Wrong!]
The delta is to be between the hard irq event and the normal context
event, but the above logic made the delta between the softirq event and
the normal context event, where the hard irq event is between the two. This
will shift all the remaining event timestamps on the sub-buffer
incorrectly.
The write_stamp is only valid if it matches the before_stamp. The cmpxchg
does nothing to help this.
Instead, the following logic can be done to fix this:
before = before_stamp
ts = read current timestamp
before_stamp = ts
after = write_stamp
if (write == current position on the ring buffer &&
after == before && after < ts) {
delta = ts - after
} else {
delta = 0;
}
The above will only use the write_stamp if it still matches before_stamp
and was tested to not have changed since C.
As a bonus, with this logic we do not need any 64-bit cmpxchg() at all!
This means the 32-bit rb_time_t workaround can finally be removed. But
that's for a later time.
Link: https://lore.kernel.org/linux-trace-kernel/20231218175229.58ec3daf@gandalf.local.home/
Link: https://lore.kernel.org/linux-trace-kernel/20231218230712.3a76b081@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Fixes: dd93942570789 ("ring-buffer: Do not try to put back write_stamp")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Alexei Starovoitov says:
====================
pull-request: bpf-next 2023-12-18
This PR is larger than usual and contains changes in various parts
of the kernel.
The main changes are:
1) Fix kCFI bugs in BPF, from Peter Zijlstra.
End result: all forms of indirect calls from BPF into kernel
and from kernel into BPF work with CFI enabled. This allows BPF
to work with CONFIG_FINEIBT=y.
2) Introduce BPF token object, from Andrii Nakryiko.
It adds an ability to delegate a subset of BPF features from privileged
daemon (e.g., systemd) through special mount options for userns-bound
BPF FS to a trusted unprivileged application. The design accommodates
suggestions from Christian Brauner and Paul Moore.
Example:
$ sudo mkdir -p /sys/fs/bpf/token
$ sudo mount -t bpf bpffs /sys/fs/bpf/token \
-o delegate_cmds=prog_load:MAP_CREATE \
-o delegate_progs=kprobe \
-o delegate_attachs=xdp
3) Various verifier improvements and fixes, from Andrii Nakryiko, Andrei Matei.
- Complete precision tracking support for register spills
- Fix verification of possibly-zero-sized stack accesses
- Fix access to uninit stack slots
- Track aligned STACK_ZERO cases as imprecise spilled registers.
It improves the verifier "instructions processed" metric from single
digit to 50-60% for some programs.
- Fix verifier retval logic
4) Support for VLAN tag in XDP hints, from Larysa Zaremba.
5) Allocate BPF trampoline via bpf_prog_pack mechanism, from Song Liu.
End result: better memory utilization and lower I$ miss for calls to BPF
via BPF trampoline.
6) Fix race between BPF prog accessing inner map and parallel delete,
from Hou Tao.
7) Add bpf_xdp_get_xfrm_state() kfunc, from Daniel Xu.
It allows BPF interact with IPSEC infra. The intent is to support
software RSS (via XDP) for the upcoming ipsec pcpu work.
Experiments on AWS demonstrate single tunnel pcpu ipsec reaching
line rate on 100G ENA nics.
8) Expand bpf_cgrp_storage to support cgroup1 non-attach, from Yafang Shao.
9) BPF file verification via fsverity, from Song Liu.
It allows BPF progs get fsverity digest.
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (164 commits)
bpf: Ensure precise is reset to false in __mark_reg_const_zero()
selftests/bpf: Add more uprobe multi fail tests
bpf: Fail uprobe multi link with negative offset
selftests/bpf: Test the release of map btf
s390/bpf: Fix indirect trampoline generation
selftests/bpf: Temporarily disable dummy_struct_ops test on s390
x86/cfi,bpf: Fix bpf_exception_cb() signature
bpf: Fix dtor CFI
cfi: Add CFI_NOSEAL()
x86/cfi,bpf: Fix bpf_struct_ops CFI
x86/cfi,bpf: Fix bpf_callback_t CFI
x86/cfi,bpf: Fix BPF JIT call
cfi: Flip headers
selftests/bpf: Add test for abnormal cnt during multi-kprobe attachment
selftests/bpf: Don't use libbpf_get_error() in kprobe_multi_test
selftests/bpf: Add test for abnormal cnt during multi-uprobe attachment
bpf: Limit the number of kprobes when attaching program to multiple kprobes
bpf: Limit the number of uprobes when attaching program to multiple uprobes
bpf: xdp: Register generic_kfunc_set with XDP programs
selftests/bpf: utilize string values for delegate_xxx mount options
...
====================
Link: https://lore.kernel.org/r/20231219000520.34178-1-alexei.starovoitov@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
It is safe to always start with imprecise SCALAR_VALUE register.
Previously __mark_reg_const_zero() relied on caller to reset precise
mark, but it's very error prone and we already missed it in a few
places. So instead make __mark_reg_const_zero() reset precision always,
as it's a safe default for SCALAR_VALUE. Explanation is basically the
same as for why we are resetting (or rather not setting) precision in
current state. If necessary, precision propagation will set it to
precise correctly.
As such, also remove a big comment about forward precision propagation
in mark_reg_stack_read() and avoid unnecessarily setting precision to
true after reading from STACK_ZERO stack. Again, precision propagation
will correctly handle this, if that SCALAR_VALUE register will ever be
needed to be precise.
Reported-by: Maxim Mikityanskiy <maxtram95@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Maxim Mikityanskiy <maxtram95@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20231218173601.53047-1-andrii@kernel.org
Add KUNIT_INIT_TABLE to the INIT_DATA linker section.
Alter the KUnit macros to create init tests:
kunit_test_init_section_suites
Update lib/kunit/executor.c to run both the suites in KUNIT_TABLE and
KUNIT_INIT_TABLE.
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Rae Moar <rmoar@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Currently the __uprobe_register will return 0 (success) when called with
negative offset. The reason is that the call to register_for_each_vma and
then build_map_info won't return error for negative offset. They just won't
do anything - no matching vma is found so there's no registered breakpoint
for the uprobe.
I don't think we can change the behaviour of __uprobe_register and fail
for negative uprobe offset, because apps might depend on that already.
But I think we can still make the change and check for it on bpf multi
link syscall level.
Also moving the __get_user call and check for the offsets to the top of
loop, to fail early without extra __get_user calls for ref_ctr_offset
and cookie arrays.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/bpf/20231217215538.3361991-2-jolsa@kernel.org
because there are none, and thus prevent a lockdep splat
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Merge tag 'perf_urgent_for_v6.7_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fix from Borislav Petkov:
- Avoid iterating over newly created group leader event's siblings
because there are none, and thus prevent a lockdep splat
* tag 'perf_urgent_for_v6.7_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf: Fix perf_event_validate_size() lockdep splat
- Fix alloc_free_mem_region()'s scan for address space, prevent false
negative out-of-space events
- Fix sleeping lock acquisition from CXL trace event (atomic context)
- Fix put_device() like for the new CXL PMU driver
- Fix wrong pointer freed on error path
- Fixup several lockdep reports (missing lock hold) from new assertion
in cxl_num_decoders_committed() and new tests
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Merge tag 'cxl-fixes-6.7-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl
Pull CXL (Compute Express Link) fixes from Dan Williams:
"A collection of CXL fixes.
The touch outside of drivers/cxl/ is for a helper that allocates
physical address space. Device hotplug tests showed that the driver
failed to utilize (skipped over) valid capacity when allocating a new
memory region. Outside of that, new tests uncovered a small crop of
lockdep reports.
There is also some miscellaneous error path and leak fixups that are
not urgent, but useful to cleanup now.
- Fix alloc_free_mem_region()'s scan for address space, prevent false
negative out-of-space events
- Fix sleeping lock acquisition from CXL trace event (atomic context)
- Fix put_device() like for the new CXL PMU driver
- Fix wrong pointer freed on error path
- Fixup several lockdep reports (missing lock hold) from new
assertion in cxl_num_decoders_committed() and new tests"
* tag 'cxl-fixes-6.7-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl:
cxl/pmu: Ensure put_device on pmu devices
cxl/cdat: Free correct buffer on checksum error
cxl/hdm: Fix dpa translation locking
kernel/resource: Increment by align value in get_free_mem_region()
cxl: Add cxl_num_decoders_committed() usage to cxl_test
cxl/memdev: Hold region_rwsem during inject and clear poison ops
cxl/core: Always hold region_rwsem while reading poison lists
cxl/hdm: Fix a benign lockdep splat
Trying to probe update_sd_lb_stats() using perf results in the below
message in the kernel log:
trace_kprobe: Could not probe notrace function _text
This is because 'perf probe' specifies the kprobe location as an offset
from '_text':
$ sudo perf probe -D update_sd_lb_stats
p:probe/update_sd_lb_stats _text+1830728
However, the error message is misleading and doesn't help convey the
actual notrace function that is being probed. Fix this by looking up the
actual function name that is being probed. With this fix, we now get the
below message in the kernel log:
trace_kprobe: Could not probe notrace function update_sd_lb_stats.constprop.0
Link: https://lore.kernel.org/all/20231214051702.1687300-1-naveen@kernel.org/
Signed-off-by: Naveen N Rao <naveen@kernel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
- Fix eventfs to check creating new files for events with names greater than
NAME_MAX. The eventfs lookup needs to check the return result of
simple_lookup().
- Fix the ring buffer to check the proper max data size. Events must be able to
fit on the ring buffer sub-buffer, if it cannot, then it fails to be written
and the logic to add the event is avoided. The code to check if an event can
fit failed to add the possible absolute timestamp which may make the event
not be able to fit. This causes the ring buffer to go into an infinite loop
trying to find a sub-buffer that would fit the event. Luckily, there's a check
that will bail out if it looped over a 1000 times and it also warns.
The real fix is not to add the absolute timestamp to an event that is
starting at the beginning of a sub-buffer because it uses the sub-buffer
timestamp. By avoiding the timestamp at the start of the sub-buffer allows
events that pass the first check to always find a sub-buffer that it can fit
on.
- Have large events that do not fit on a trace_seq to print "LINE TOO BIG" like
it does for the trace_pipe instead of what it does now which is to silently
drop the output.
- Fix a memory leak of forgetting to free the spare page that is saved by a
trace instance.
- Update the size of the snapshot buffer when the main buffer is updated if the
snapshot buffer is allocated.
- Fix ring buffer timestamp logic by removing all the places that tried to put
the before_stamp back to the write stamp so that the next event doesn't add
an absolute timestamp. But each of these updates added a race where by making
the two timestamp equal, it was validating the write_stamp so that it can be
incorrectly used for calculating the delta of an event.
- There's a temp buffer used for printing the event that was using the event
data size for allocation when it needed to use the size of the entire event
(meta-data and payload data)
- For hardening, use "%.*s" for printing the trace_marker output, to limit the
amount that is printed by the size of the event. This was discovered by
development that added a bug that truncated the '\0' and caused a crash.
- Fix a use-after-free bug in the use of the histogram files when an instance
is being removed.
- Remove a useless update in the rb_try_to_discard of the write_stamp. The
before_stamp was already changed to force the next event to add an absolute
timestamp that the write_stamp is not used. But the write_stamp is modified
again using an unneeded 64-bit cmpxchg.
- Fix several races in the 32-bit implementation of the rb_time_cmpxchg() that
does a 64-bit cmpxchg.
- While looking at fixing the 64-bit cmpxchg, I noticed that because the ring
buffer uses normal cmpxchg, and this can be done in NMI context, there's some
architectures that do not have a working cmpxchg in NMI context. For these
architectures, fail recording events that happen in NMI context.
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Merge tag 'trace-v6.7-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing fixes from Steven Rostedt:
- Fix eventfs to check creating new files for events with names greater
than NAME_MAX. The eventfs lookup needs to check the return result of
simple_lookup().
- Fix the ring buffer to check the proper max data size. Events must be
able to fit on the ring buffer sub-buffer, if it cannot, then it
fails to be written and the logic to add the event is avoided. The
code to check if an event can fit failed to add the possible absolute
timestamp which may make the event not be able to fit. This causes
the ring buffer to go into an infinite loop trying to find a
sub-buffer that would fit the event. Luckily, there's a check that
will bail out if it looped over a 1000 times and it also warns.
The real fix is not to add the absolute timestamp to an event that is
starting at the beginning of a sub-buffer because it uses the
sub-buffer timestamp.
By avoiding the timestamp at the start of the sub-buffer allows
events that pass the first check to always find a sub-buffer that it
can fit on.
- Have large events that do not fit on a trace_seq to print "LINE TOO
BIG" like it does for the trace_pipe instead of what it does now
which is to silently drop the output.
- Fix a memory leak of forgetting to free the spare page that is saved
by a trace instance.
- Update the size of the snapshot buffer when the main buffer is
updated if the snapshot buffer is allocated.
- Fix ring buffer timestamp logic by removing all the places that tried
to put the before_stamp back to the write stamp so that the next
event doesn't add an absolute timestamp. But each of these updates
added a race where by making the two timestamp equal, it was
validating the write_stamp so that it can be incorrectly used for
calculating the delta of an event.
- There's a temp buffer used for printing the event that was using the
event data size for allocation when it needed to use the size of the
entire event (meta-data and payload data)
- For hardening, use "%.*s" for printing the trace_marker output, to
limit the amount that is printed by the size of the event. This was
discovered by development that added a bug that truncated the '\0'
and caused a crash.
- Fix a use-after-free bug in the use of the histogram files when an
instance is being removed.
- Remove a useless update in the rb_try_to_discard of the write_stamp.
The before_stamp was already changed to force the next event to add
an absolute timestamp that the write_stamp is not used. But the
write_stamp is modified again using an unneeded 64-bit cmpxchg.
- Fix several races in the 32-bit implementation of the
rb_time_cmpxchg() that does a 64-bit cmpxchg.
- While looking at fixing the 64-bit cmpxchg, I noticed that because
the ring buffer uses normal cmpxchg, and this can be done in NMI
context, there's some architectures that do not have a working
cmpxchg in NMI context. For these architectures, fail recording
events that happen in NMI context.
* tag 'trace-v6.7-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
ring-buffer: Do not record in NMI if the arch does not support cmpxchg in NMI
ring-buffer: Have rb_time_cmpxchg() set the msb counter too
ring-buffer: Fix 32-bit rb_time_read() race with rb_time_cmpxchg()
ring-buffer: Fix a race in rb_time_cmpxchg() for 32 bit archs
ring-buffer: Remove useless update to write_stamp in rb_try_to_discard()
ring-buffer: Do not try to put back write_stamp
tracing: Fix uaf issue when open the hist or hist_debug file
tracing: Add size check when printing trace_marker output
ring-buffer: Have saved event hold the entire event
ring-buffer: Do not update before stamp when switching sub-buffers
tracing: Update snapshot buffer on resize if it is allocated
ring-buffer: Fix memory leak of free page
eventfs: Fix events beyond NAME_MAX blocking tasks
tracing: Have large events show up as '[LINE TOO BIG]' instead of nothing
ring-buffer: Fix writing to the buffer with max_data_size
Ensure the various dtor functions match their prototype and retain
their CFI signatures, since they don't have their address taken, they
are prone to not getting CFI, making them impossible to call
indirectly.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20231215092707.799451071@infradead.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
BPF struct_ops uses __arch_prepare_bpf_trampoline() to write
trampolines for indirect function calls. These tramplines much have
matching CFI.
In order to obtain the correct CFI hash for the various methods, add a
matching structure that contains stub functions, the compiler will
generate correct CFI which we can pilfer for the trampolines.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20231215092707.566977112@infradead.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The current BPF call convention is __nocfi, except when it calls !JIT things,
then it calls regular C functions.
It so happens that with FineIBT the __nocfi and C calling conventions are
incompatible. Specifically __nocfi will call at func+0, while FineIBT will have
endbr-poison there, which is not a valid indirect target. Causing #CP.
Notably this only triggers on IBT enabled hardware, which is probably why this
hasn't been reported (also, most people will have JIT on anyway).
Implement proper CFI prologues for the BPF JIT codegen and drop __nocfi for
x86.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20231215092707.345270396@infradead.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This code is rarely (never?) enabled by distros, and it hasn't caught
anything in decades. Let's kill off this legacy debug code.
Suggested-by: Linus Torvalds <torvalds@linuxfoundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are multiple ways to grab references to credentials, and the only
protection we have against overflowing it is the memory required to do
so.
With memory sizes only moving in one direction, let's bump the reference
count to 64-bit and move it outside the realm of feasibly overflowing.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
An abnormally big cnt may also be assigned to kprobe_multi.cnt when
attaching multiple kprobes. It will trigger the following warning in
kvmalloc_node():
if (unlikely(size > INT_MAX)) {
WARN_ON_ONCE(!(flags & __GFP_NOWARN));
return NULL;
}
Fix the warning by limiting the maximal number of kprobes in
bpf_kprobe_multi_link_attach(). If the number of kprobes is greater than
MAX_KPROBE_MULTI_CNT, the attachment will fail and return -E2BIG.
Fixes: 0dcac2725406 ("bpf: Add multi kprobe link")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231215100708.2265609-3-houtao@huaweicloud.com
An abnormally big cnt may be passed to link_create.uprobe_multi.cnt,
and it will trigger the following warning in kvmalloc_node():
if (unlikely(size > INT_MAX)) {
WARN_ON_ONCE(!(flags & __GFP_NOWARN));
return NULL;
}
Fix the warning by limiting the maximal number of uprobes in
bpf_uprobe_multi_link_attach(). If the number of uprobes is greater than
MAX_UPROBE_MULTI_CNT, the attachment will return -E2BIG.
Fixes: 89ae89f53d20 ("bpf: Add multi uprobe link")
Reported-by: Xingwei Lee <xrivendell7@gmail.com>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Closes: https://lore.kernel.org/bpf/CABOYnLwwJY=yFAGie59LFsUsBAgHfroVqbzZ5edAXbFE3YiNVA@mail.gmail.com
Link: https://lore.kernel.org/bpf/20231215100708.2265609-2-houtao@huaweicloud.com
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Merge tag 'mm-hotfixes-stable-2023-12-15-07-11' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull misc fixes from Andrew Morton:
"17 hotfixes. 8 are cc:stable and the other 9 pertain to post-6.6
issues"
* tag 'mm-hotfixes-stable-2023-12-15-07-11' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
mm/mglru: reclaim offlined memcgs harder
mm/mglru: respect min_ttl_ms with memcgs
mm/mglru: try to stop at high watermarks
mm/mglru: fix underprotected page cache
mm/shmem: fix race in shmem_undo_range w/THP
Revert "selftests: error out if kernel header files are not yet built"
crash_core: fix the check for whether crashkernel is from high memory
x86, kexec: fix the wrong ifdeffery CONFIG_KEXEC
sh, kexec: fix the incorrect ifdeffery and dependency of CONFIG_KEXEC
mips, kexec: fix the incorrect ifdeffery and dependency of CONFIG_KEXEC
m68k, kexec: fix the incorrect ifdeffery and build dependency of CONFIG_KEXEC
loongarch, kexec: change dependency of object files
mm/damon/core: make damon_start() waits until kdamond_fn() starts
selftests/mm: cow: print ksft header before printing anything else
mm: fix VMA heap bounds checking
riscv: fix VMALLOC_START definition
kexec: drop dependency on ARCH_SUPPORTS_KEXEC from CRASH_DUMP
One of the last remaining users of strlcpy() in the kernel is
kernfs_path_from_node_locked(), which passes back the problematic "length
we _would_ have copied" return value to indicate truncation. Convert the
chain of all callers to use the negative return value (some of which
already doing this explicitly). All callers were already also checking
for negative return values, so the risk to missed checks looks very low.
In this analysis, it was found that cgroup1_release_agent() actually
didn't handle the "too large" condition, so this is technically also a
bug fix. :)
Here's the chain of callers, and resolution identifying each one as now
handling the correct return value:
kernfs_path_from_node_locked()
kernfs_path_from_node()
pr_cont_kernfs_path()
returns void
kernfs_path()
sysfs_warn_dup()
return value ignored
cgroup_path()
blkg_path()
bfq_bic_update_cgroup()
return value ignored
TRACE_IOCG_PATH()
return value ignored
TRACE_CGROUP_PATH()
return value ignored
perf_event_cgroup()
return value ignored
task_group_path()
return value ignored
damon_sysfs_memcg_path_eq()
return value ignored
get_mm_memcg_path()
return value ignored
lru_gen_seq_show()
return value ignored
cgroup_path_from_kernfs_id()
return value ignored
cgroup_show_path()
already converted "too large" error to negative value
cgroup_path_ns_locked()
cgroup_path_ns()
bpf_iter_cgroup_show_fdinfo()
return value ignored
cgroup1_release_agent()
wasn't checking "too large" error
proc_cgroup_show()
already converted "too large" to negative value
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan.x@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Waiman Long <longman@redhat.com>
Cc: <cgroups@vger.kernel.org>
Co-developed-by: Azeem Shaikh <azeemshaikh38@gmail.com>
Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
Link: https://lore.kernel.org/r/20231116192127.1558276-3-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20231212211741.164376-3-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
By passing the fsugid to kernfs_create_dir_ns(), we don't need
cgroup_kn_set_ugid() any longer. That function was added for exactly
this purpose by commit 49957f8e2a43 ("cgroup: newly created dirs and
files should be owned by the creator").
Eliminating this piece of duplicate code means we benefit from future
improvements to kernfs_create_dir_ns(); for example, both are lacking
S_ISGID support currently, which my next patch will add to
kernfs_create_dir_ns(). It cannot (easily) be added to
cgroup_kn_set_ugid() because we can't dereference struct kernfs_iattrs
from there.
--
v1 -> v2: 12-digit commit id
Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20231208093310.297233-1-max.kellermann@ionos.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
As the ring buffer recording requires cmpxchg() to work, if the
architecture does not support cmpxchg in NMI, then do not do any recording
within an NMI.
Link: https://lore.kernel.org/linux-trace-kernel/20231213175403.6fc18540@gandalf.local.home
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
The rb_time_cmpxchg() on 32-bit architectures requires setting three
32-bit words to represent the 64-bit timestamp, with some salt for
synchronization. Those are: msb, top, and bottom
The issue is, the rb_time_cmpxchg() did not properly salt the msb portion,
and the msb that was written was stale.
Link: https://lore.kernel.org/linux-trace-kernel/20231215084114.20899342@rorschach.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes: f03f2abce4f39 ("ring-buffer: Have 32 bit time stamps use all 64 bits")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
The following race can cause rb_time_read() to observe a corrupted time
stamp:
rb_time_cmpxchg()
[...]
if (!rb_time_read_cmpxchg(&t->msb, msb, msb2))
return false;
if (!rb_time_read_cmpxchg(&t->top, top, top2))
return false;
<interrupted before updating bottom>
__rb_time_read()
[...]
do {
c = local_read(&t->cnt);
top = local_read(&t->top);
bottom = local_read(&t->bottom);
msb = local_read(&t->msb);
} while (c != local_read(&t->cnt));
*cnt = rb_time_cnt(top);
/* If top and msb counts don't match, this interrupted a write */
if (*cnt != rb_time_cnt(msb))
return false;
^ this check fails to catch that "bottom" is still not updated.
So the old "bottom" value is returned, which is wrong.
Fix this by checking that all three of msb, top, and bottom 2-bit cnt
values match.
The reason to favor checking all three fields over requiring a specific
update order for both rb_time_set() and rb_time_cmpxchg() is because
checking all three fields is more robust to handle partial failures of
rb_time_cmpxchg() when interrupted by nested rb_time_set().
Link: https://lore.kernel.org/lkml/20231211201324.652870-1-mathieu.desnoyers@efficios.com/
Link: https://lore.kernel.org/linux-trace-kernel/20231212193049.680122-1-mathieu.desnoyers@efficios.com
Fixes: f458a1453424e ("ring-buffer: Test last update in 32bit version of __rb_time_read()")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Mathieu Desnoyers pointed out an issue in the rb_time_cmpxchg() for 32 bit
architectures. That is:
static bool rb_time_cmpxchg(rb_time_t *t, u64 expect, u64 set)
{
unsigned long cnt, top, bottom, msb;
unsigned long cnt2, top2, bottom2, msb2;
u64 val;
/* The cmpxchg always fails if it interrupted an update */
if (!__rb_time_read(t, &val, &cnt2))
return false;
if (val != expect)
return false;
<<<< interrupted here!
cnt = local_read(&t->cnt);
The problem is that the synchronization counter in the rb_time_t is read
*after* the value of the timestamp is read. That means if an interrupt
were to come in between the value being read and the counter being read,
it can change the value and the counter and the interrupted process would
be clueless about it!
The counter needs to be read first and then the value. That way it is easy
to tell if the value is stale or not. If the counter hasn't been updated,
then the value is still good.
Link: https://lore.kernel.org/linux-trace-kernel/20231211201324.652870-1-mathieu.desnoyers@efficios.com/
Link: https://lore.kernel.org/linux-trace-kernel/20231212115301.7a9c9a64@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Fixes: 10464b4aa605e ("ring-buffer: Add rb_time_t 64 bit operations for speeding up 32 bit")
Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
When filtering is enabled, a temporary buffer is created to place the
content of the trace event output so that the filter logic can decide
from the trace event output if the trace event should be filtered out or
not. If it is to be filtered out, the content in the temporary buffer is
simply discarded, otherwise it is written into the trace buffer.
But if an interrupt were to come in while a previous event was using that
temporary buffer, the event written by the interrupt would actually go
into the ring buffer itself to prevent corrupting the data on the
temporary buffer. If the event is to be filtered out, the event in the
ring buffer is discarded, or if it fails to discard because another event
were to have already come in, it is turned into padding.
The update to the write_stamp in the rb_try_to_discard() happens after a
fix was made to force the next event after the discard to use an absolute
timestamp by setting the before_stamp to zero so it does not match the
write_stamp (which causes an event to use the absolute timestamp).
But there's an effort in rb_try_to_discard() to put back the write_stamp
to what it was before the event was added. But this is useless and
wasteful because nothing is going to be using that write_stamp for
calculations as it still will not match the before_stamp.
Remove this useless update, and in doing so, we remove another
cmpxchg64()!
Also update the comments to reflect this change as well as remove some
extra white space in another comment.
Link: https://lore.kernel.org/linux-trace-kernel/20231215081810.1f4f38fe@rorschach.local.home
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Vincent Donnefort <vdonnefort@google.com>
Fixes: b2dd797543cf ("ring-buffer: Force absolute timestamp on discard of event")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
If an update to an event is interrupted by another event between the time
the initial event allocated its buffer and where it wrote to the
write_stamp, the code try to reset the write stamp back to the what it had
just overwritten. It knows that it was overwritten via checking the
before_stamp, and if it didn't match what it wrote to the before_stamp
before it allocated its space, it knows it was overwritten.
To put back the write_stamp, it uses the before_stamp it read. The problem
here is that by writing the before_stamp to the write_stamp it makes the
two equal again, which means that the write_stamp can be considered valid
as the last timestamp written to the ring buffer. But this is not
necessarily true. The event that interrupted the event could have been
interrupted in a way that it was interrupted as well, and can end up
leaving with an invalid write_stamp. But if this happens and returns to
this context that uses the before_stamp to update the write_stamp again,
it can possibly incorrectly make it valid, causing later events to have in
correct time stamps.
As it is OK to leave this function with an invalid write_stamp (one that
doesn't match the before_stamp), there's no reason to try to make it valid
again in this case. If this race happens, then just leave with the invalid
write_stamp and the next event to come along will just add a absolute
timestamp and validate everything again.
Bonus points: This gets rid of another cmpxchg64!
Link: https://lore.kernel.org/linux-trace-kernel/20231214222921.193037a7@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Vincent Donnefort <vdonnefort@google.com>
Fixes: a389d86f7fd09 ("ring-buffer: Have nested events still record running time stamp")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
An S4 (suspend to disk) test on the LoongArch 3A6000 platform sometimes
fails with the following error messaged in the dmesg log:
Invalid LZO compressed length
That happens because when compressing/decompressing the image, the
synchronization between the control thread and the compress/decompress/crc
thread is based on a relaxed ordering interface, which is unreliable, and the
following situation may occur:
CPU 0 CPU 1
save_image_lzo lzo_compress_threadfn
atomic_set(&d->stop, 1);
atomic_read(&data[thr].stop)
data[thr].cmp = data[thr].cmp_len;
WRITE data[thr].cmp_len
Then CPU0 gets a stale cmp_len and writes it to disk. During resume from S4,
wrong cmp_len is loaded.
To maintain data consistency between the two threads, use the acquire/release
variants of atomic set and read operations.
Fixes: 081a9d043c98 ("PM / Hibernate: Improve performance of LZO/plain hibernation, checksum image")
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Hongchen Zhang <zhanghongchen@loongson.cn>
Co-developed-by: Weihao Li <liweihao@loongson.cn>
Signed-off-by: Weihao Li <liweihao@loongson.cn>
[ rjw: Subject rewrite and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Wakeup events that occur in the hibernation process's
hibernation_platform_enter() cannot wake up the system. Although the
current hibernation framework will execute part of the recovery process
after a wakeup event occurs, it ultimately performs a shutdown operation
because the system does not check the return value of
hibernation_platform_enter(). In short, if a wakeup event occurs before
putting the system into the final low-power state, it will be missed.
To solve this problem, check the return value of
hibernation_platform_enter(). When it returns -EAGAIN or -EBUSY (indicate
the occurrence of a wakeup event), execute the hibernation recovery
process, discard the previously saved image, and ultimately return to the
working state.
Signed-off-by: Chris Feng <chris.feng@mediatek.com>
[ rjw: Rephrase the message printed when going back to the working state ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
When lockdep is enabled, the for_each_sibling_event(sibling, event)
macro checks that event->ctx->mutex is held. When creating a new group
leader event, we call perf_event_validate_size() on a partially
initialized event where event->ctx is NULL, and so when
for_each_sibling_event() attempts to check event->ctx->mutex, we get a
splat, as reported by Lucas De Marchi:
WARNING: CPU: 8 PID: 1471 at kernel/events/core.c:1950 __do_sys_perf_event_open+0xf37/0x1080
This only happens for a new event which is its own group_leader, and in
this case there cannot be any sibling events. Thus it's safe to skip the
check for siblings, which avoids having to make invasive and ugly
changes to for_each_sibling_event().
Avoid the splat by bailing out early when the new event is its own
group_leader.
Fixes: 382c27f4ed28f803 ("perf: Fix perf_event_validate_size()")
Closes: https://lore.kernel.org/lkml/20231214000620.3081018-1-lucas.demarchi@intel.com/
Closes: https://lore.kernel.org/lkml/ZXpm6gQ%2Fd59jGsuW@xpf.sh.intel.com/
Reported-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reported-by: Pengfei Xu <pengfei.xu@intel.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20231215112450.3972309-1-mark.rutland@arm.com
Reproduced with below sequence:
dma_declare_coherent_memory()->dma_release_coherent_memory()
->dma_declare_coherent_memory()->"return -EBUSY" error
It will return -EBUSY from the dma_assign_coherent_memory()
in dma_declare_coherent_memory(), the reason is that dev->dma_mem
pointer has not been set to NULL after it's freed.
Fixes: cf65a0f6f6ff ("dma-mapping: move all DMA mapping code to kernel/dma")
Signed-off-by: Joakim Zhang <joakim.zhang@cixtech.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
If multiple areas and multiple IO TLB pools exist, first iterate the
current CPU specific area in all pools. Then move to the next area index.
This is best illustrated by a diagram:
area 0 | area 1 | ... | area M |
pool 0 A B C
pool 1 D E
...
pool N F G H
Currently, each pool is searched before moving on to the next pool,
i.e. the search order is A, B ... C, D, E ... F, G ... H. With this patch,
each area is searched in all pools before moving on to the next area,
i.e. the search order is A, D ... F, B, E ... G ... C ... H.
Note that preemption is not disabled, and raw_smp_processor_id() may not
return a stable result, but it is called only once to determine the initial
area index. The search will iterate over all areas eventually, even if the
current task is preempted.
Next, some pools may have less (but not more) areas than default_nareas.
Skip such pools if the distance from the initial area index is greater than
pool->nareas. This logic ensures that for every pool the search starts in
the initial CPU's own area and never tries any area twice.
To verify performance impact, I booted the kernel with a minimum pool
size ("swiotlb=512,4,force"), so multiple pools get allocated, and I ran
these benchmarks:
- small: single-threaded I/O of 4 KiB blocks,
- big: single-threaded I/O of 64 KiB blocks,
- 4way: 4-way parallel I/O of 4 KiB blocks.
The "var" column in the tables below is the coefficient of variance over 5
runs of the test, the "diff" column is the relative difference against base
in read-write I/O bandwidth (MiB/s).
Tested on an x86 VM against a QEMU virtio SATA driver backed by a RAM-based
block device on the host:
base patched
var var diff
small 0.69% 0.62% +25.4%
big 2.14% 2.27% +25.7%
4way 2.65% 1.70% +23.6%
Tested on a Raspberry Pi against a class-10 A1 microSD card:
base patched
var var diff
small 0.53% 1.96% -0.3%
big 0.02% 0.57% +0.8%
4way 6.17% 0.40% +0.3%
These results confirm that there is significant performance boost in the
software IO TLB slot allocation itself. Where performance is dominated by
actual hardware, there is no measurable change.
Signed-off-by: Petr Tesarik <petr.tesarik1@huawei-partners.com>
Reviewed-by: Mirsad Todorovac <mirsad.todorovac@alu.unizg.hr>
Signed-off-by: Christoph Hellwig <hch@lst.de>
A bus_dma_region necessarily stores both CPU and DMA base addresses for
a range, so there's no need to also store the difference between them.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Registering generic_kfunc_set with XDP programs enables some of the
newer BPF features inside XDP -- namely tree based data structures and
BPF exceptions.
The current motivation for this commit is to enable assertions inside
XDP bpf progs. Assertions are a standard and useful tool to encode
intent.
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/d07d4614b81ca6aada44fcb89bb6b618fb66e4ca.1702594357.git.dxu@dxuuu.xyz
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Besides already supported special "any" value and hex bit mask, support
string-based parsing of delegation masks based on exact enumerator
names. Utilize BTF information of `enum bpf_cmd`, `enum bpf_map_type`,
`enum bpf_prog_type`, and `enum bpf_attach_type` types to find supported
symbolic names (ignoring __MAX_xxx guard values and stripping repetitive
prefixes like BPF_ for cmd and attach types, BPF_MAP_TYPE_ for maps, and
BPF_PROG_TYPE_ for prog types). The case doesn't matter, but it is
normalized to lower case in mount option output. So "PROG_LOAD",
"prog_load", and "MAP_create" are all valid values to specify for
delegate_cmds options, "array" is among supported for map types, etc.
Besides supporting string values, we also support multiple values
specified at the same time, using colon (':') separator.
There are corresponding changes on bpf_show_options side to use known
values to print them in human-readable format, falling back to hex mask
printing, if there are any unrecognized bits. This shouldn't be
necessary when enum BTF information is present, but in general we should
always be able to fall back to this even if kernel was built without BTF.
As mentioned, emitted symbolic names are normalized to be all lower case.
Example below shows various ways to specify delegate_cmds options
through mount command and how mount options are printed back:
12/14 14:39:07.604
vmuser@archvm:~/local/linux/tools/testing/selftests/bpf
$ mount | rg token
$ sudo mkdir -p /sys/fs/bpf/token
$ sudo mount -t bpf bpffs /sys/fs/bpf/token \
-o delegate_cmds=prog_load:MAP_CREATE \
-o delegate_progs=kprobe \
-o delegate_attachs=xdp
$ mount | grep token
bpffs on /sys/fs/bpf/token type bpf (rw,relatime,delegate_cmds=map_create:prog_load,delegate_progs=kprobe,delegate_attachs=xdp)
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231214225016.1209867-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cross-merge networking fixes after downstream PR.
Conflicts:
drivers/net/ethernet/intel/iavf/iavf_ethtool.c
3a0b5a2929fd ("iavf: Introduce new state machines for flow director")
95260816b489 ("iavf: use iavf_schedule_aq_request() helper")
https://lore.kernel.org/all/84e12519-04dc-bd80-bc34-8cf50d7898ce@intel.com/
drivers/net/ethernet/broadcom/bnxt/bnxt.c
c13e268c0768 ("bnxt_en: Fix HWTSTAMP_FILTER_ALL packet timestamp logic")
c2f8063309da ("bnxt_en: Refactor RX VLAN acceleration logic.")
a7445d69809f ("bnxt_en: Add support for new RX and TPA_START completion types for P7")
1c7fd6ee2fe4 ("bnxt_en: Rename some macros for the P5 chips")
https://lore.kernel.org/all/20231211110022.27926ad9@canb.auug.org.au/
drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c
bd6781c18cb5 ("bnxt_en: Fix wrong return value check in bnxt_close_nic()")
84793a499578 ("bnxt_en: Skip nic close/open when configuring tstamp filters")
https://lore.kernel.org/all/20231214113041.3a0c003c@canb.auug.org.au/
drivers/net/ethernet/mellanox/mlx5/core/fw_reset.c
3d7a3f2612d7 ("net/mlx5: Nack sync reset request when HotPlug is enabled")
cecf44ea1a1f ("net/mlx5: Allow sync reset flow when BF MGT interface device is present")
https://lore.kernel.org/all/20231211110328.76c925af@canb.auug.org.au/
No adjacent changes.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
