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Userspace libraries, e.g. glibc's dprintf(), perform a SEEK_CUR operation
over any file descriptor requested to make sure the current position isn't
pointing to junk due to previous manipulation of that same fd. And whenever
that fd doesn't have support for such operation, the userspace code expects
-ESPIPE to be returned.
However, when the fd in question references the /dev/kmsg interface, the
current kernel code state returns -EINVAL instead, causing an unexpected
behavior in userspace: in the case of glibc, when -ESPIPE is returned it
gets ignored and the call completes successfully, while returning -EINVAL
forces dprintf to fail without performing any action over that fd:
if (_IO_SEEKOFF (fp, (off64_t)0, _IO_seek_cur, _IOS_INPUT|_IOS_OUTPUT) ==
_IO_pos_BAD && errno != ESPIPE)
return NULL;
With this patch we make sure to return the correct value when SEEK_CUR is
requested over kmsg and also add some kernel doc information to formalize
this behavior.
Link: https://lore.kernel.org/r/20200317103344.574277-1-bmeneg@redhat.com
Cc: linux-kernel@vger.kernel.org
Cc: rostedt@goodmis.org,
Cc: David.Laight@ACULAB.COM
Signed-off-by: Bruno Meneguele <bmeneg@redhat.com>
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
There is a typo in comment, fix it.
Signed-off-by: Ethon Paul <ethp@qq.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
In some cases we need to have an IRQ domain created out of software node.
One of such cases is DesignWare GPIO driver when it's instantiated from
half-baked ACPI table (alas, we can't fix it for devices which are few years
on market) and thus using software nodes to quirk this. But the driver
is using IRQ domains based on per GPIO port firmware nodes, which are in
the above case software ones. This brings a warning message to be printed
[ 73.957183] irq: Invalid fwnode type for irqdomain
and creates an anonymous IRQ domain without a debugfs entry.
Allowing software nodes to be valid for IRQ domains rids us of the warning
and debugs gets correctly populated.
% ls -1 /sys/kernel/debug/irq/domains/
...
intel-quark-dw-apb-gpio:portA
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
[maz: refactored commit message]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200520164927.39090-3-andriy.shevchenko@linux.intel.com
Now that __irq_domain_add() is able to better deals with generic
fwnodes, there is no need to special-case ACPI anymore.
Get rid of the special treatment for ACPI.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200520164927.39090-2-andriy.shevchenko@linux.intel.com
__irq_domain_add() relies in some places on the fact that the fwnode
can be only of type OF. This prevents refactoring of the code to support
other types of fwnode. Make it less OF-dependent by switching it
to use the fwnode directly where it makes sense.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200520164927.39090-1-andriy.shevchenko@linux.intel.com
As discussed in [0], it's dangerous to allow mapping BPF map, that's meant to
be frozen and is read-only on BPF program side, because that allows user-space
to actually store a writable view to the page even after it is frozen. This is
exacerbated by BPF verifier making a strong assumption that contents of such
frozen map will remain unchanged. To prevent this, disallow mapping
BPF_F_RDONLY_PROG mmap()'able BPF maps as writable, ever.
[0] https://lore.kernel.org/bpf/CAEf4BzYGWYhXdp6BJ7_=9OQPJxQpgug080MMjdSB72i9R+5c6g@mail.gmail.com/
Fixes: fc9702273e2e ("bpf: Add mmap() support for BPF_MAP_TYPE_ARRAY")
Suggested-by: Jann Horn <jannh@google.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Jann Horn <jannh@google.com>
Link: https://lore.kernel.org/bpf/20200519053824.1089415-1-andriin@fb.com
Some table unregister actions seem to be initiated by the kernel to
garbage collect unused tables that are not initiated by any userspace
actions. It was found to be necessary to add the subject credentials to
cover this case to reveal the source of these actions. A sample record:
The uid, auid, tty, ses and exe fields have not been included since they
are in the SYSCALL record and contain nothing useful in the non-user
context.
Here are two sample orphaned records:
type=NETFILTER_CFG msg=audit(2020-05-20 12:14:36.505:5) : table=filter family=ipv4 entries=0 op=register pid=1 subj=kernel comm=swapper/0
type=NETFILTER_CFG msg=audit(2020-05-20 12:15:27.701:301) : table=nat family=bridge entries=0 op=unregister pid=30 subj=system_u:system_r:kernel_t:s0 comm=kworker/u4:1
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
It is almost possible to use the result of prepare_exec_creds with no
modifications during exec. Update prepare_exec_creds to initialize
the suid and the fsuid to the euid, and the sgid and the fsgid to the
egid. This is all that is needed to handle the common case of exec
when nothing special like a setuid exec is happening.
That this preserves the existing behavior of exec can be verified
by examing bprm_fill_uid and cap_bprm_set_creds.
This change makes it clear that the later parts of exec that
update bprm->cred are just need to handle special cases such
as setuid exec and change of domains.
Link: https://lkml.kernel.org/r/871rng22dm.fsf_-_@x220.int.ebiederm.org
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
And replace the arcane return value convention with a simple bool
where true means success and false means failure.
[AV: braino fix folded in]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
tracing_pipe_buf_ops has identical ops to default_pipe_buf_ops, so use
that instead.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Merge our uaccess-ppc topic branch. It is based on the uaccess topic
branch that we're sharing with Viro.
This includes the addition of user_[read|write]_access_begin(), as
well as some powerpc specific changes to our uaccess routines that
would conflict badly if merged separately.
Elsewhere in the file, the function trace_kprobe_has_same_kprobe uses
a trace_probe_event.probes object as the second argument of
list_for_each_entry, ie as a list head, while the list_for_each_entry
iterates over the list fields of the trace_probe structures, making
them the list elements. So, exchange the arguments on the list_add
call to put the list head in the second argument.
Since both list_head structures were just initialized, this problem
did not cause any loss of information.
Link: https://lkml.kernel.org/r/1588879808-24488-1-git-send-email-Julia.Lawall@inria.fr
Fixes: 60d53e2c3b75 ("tracing/probe: Split trace_event related data from trace_probe")
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
When an anomaly is detected in the function call modification
code, ftrace_bug() is called to disable function tracing as well
as give some warn and information that may help debug the problem.
But currently, we call FTRACE_WARN_ON_ONCE() first in ftrace_bug(),
so when panic_on_warn is set, we can't see the debugging information
here. Call FTRACE_WARN_ON_ONCE() at the end of ftrace_bug() to ensure
that the debugging information is displayed first.
after this patch, the dmesg looks like:
------------[ ftrace bug ]------------
ftrace failed to modify
[<ffff800010081004>] bcm2835_handle_irq+0x4/0x58
actual: 1f:20:03:d5
Setting ftrace call site to call ftrace function
ftrace record flags: 80000001
(1)
expected tramp: ffff80001009d6f0
------------[ cut here ]------------
WARNING: CPU: 2 PID: 1635 at kernel/trace/ftrace.c:2078 ftrace_bug+0x204/0x238
Kernel panic - not syncing: panic_on_warn set ...
CPU: 2 PID: 1635 Comm: sh Not tainted 5.7.0-rc5-00033-gb922183867f5 #14
Hardware name: linux,dummy-virt (DT)
Call trace:
dump_backtrace+0x0/0x1b0
show_stack+0x20/0x30
dump_stack+0xc0/0x10c
panic+0x16c/0x368
__warn+0x120/0x160
report_bug+0xc8/0x160
bug_handler+0x28/0x98
brk_handler+0x70/0xd0
do_debug_exception+0xcc/0x1ac
el1_sync_handler+0xe4/0x120
el1_sync+0x7c/0x100
ftrace_bug+0x204/0x238
Link: https://lkml.kernel.org/r/20200515100828.7091-1-cj.chengjian@huawei.com
Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200507185804.GA15036@embeddedor
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200511201227.GA14041@embeddedor
When users write some huge number into cpu.cfs_quota_us or
cpu.rt_runtime_us, overflow might happen during to_ratio() shifts of
schedulable checks.
to_ratio() could be altered to avoid unnecessary internal overflow, but
min_cfs_quota_period is less than 1 << BW_SHIFT, so a cutoff would still
be needed. Set a cap MAX_BW for cfs_quota_us and rt_runtime_us to
prevent overflow.
Signed-off-by: Huaixin Chang <changhuaixin@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ben Segall <bsegall@google.com>
Link: https://lkml.kernel.org/r/20200425105248.60093-1-changhuaixin@linux.alibaba.com
The user_mode(task_pt_regs(tsk)) always return true for
user thread, and false for kernel thread. So it means that
the cpuacct.usage_sys is the time that kernel thread uses
not the time that thread uses in the kernel mode. We can
try get_irq_regs() first, if it is NULL, then we can fall
back to task_pt_regs().
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200420070453.76815-1-songmuchun@bytedance.com
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200507192141.GA16183@embeddedor
update_tg_cfs_*() propagate the impact of the attach/detach of an entity
down into the cfs_rq hierarchy and must keep the sync with the current pelt
window.
Even if we can't sync child cfs_rq and its group se, we can sync the group
se and its parent cfs_rq with current position in the PELT window. In fact,
we must keep them sync in order to stay also synced with others entities
and group entities that are already attached to the cfs_rq.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200506155301.14288-1-vincent.guittot@linaro.org
The cpuacct_charge() and cpuacct_account_field() are called with
rq->lock held, and this means preemption(and IRQs) are indeed
disabled, so it is safe to use __this_cpu_*() to allow for better
code-generation.
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200507031039.32615-1-songmuchun@bytedance.com
enqueue_task_fair jumps to enqueue_throttle label when cfs_rq_of(se) is
throttled which means that se can't be NULL in such case and we can move
the label after the if (!se) statement. Futhermore, the latter can be
removed because se is always NULL when reaching this point.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Link: https://lkml.kernel.org/r/20200513135502.4672-1-vincent.guittot@linaro.org
Although not exactly identical, unthrottle_cfs_rq() and enqueue_task_fair()
are quite close and follow the same sequence for enqueuing an entity in the
cfs hierarchy. Modify unthrottle_cfs_rq() to use the same pattern as
enqueue_task_fair(). This fixes a problem already faced with the latter and
add an optimization in the last for_each_sched_entity loop.
Fixes: fe61468b2cb (sched/fair: Fix enqueue_task_fair warning)
Reported-by Tao Zhou <zohooouoto@zoho.com.cn>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Reviewed-by: Ben Segall <bsegall@google.com>
Link: https://lkml.kernel.org/r/20200513135528.4742-1-vincent.guittot@linaro.org
The intention of commit 96e74ebf8d59 ("sched/debug: Add task uclamp
values to SCHED_DEBUG procfs") was to print requested and effective
task uclamp values. The requested values printed are read from p->uclamp,
which holds the last effective values. Fix this by printing the values
from p->uclamp_req.
Fixes: 96e74ebf8d59 ("sched/debug: Add task uclamp values to SCHED_DEBUG procfs")
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/1589115401-26391-1-git-send-email-pkondeti@codeaurora.org
sched/fair: Fix enqueue_task_fair warning some more
The recent patch, fe61468b2cb (sched/fair: Fix enqueue_task_fair warning)
did not fully resolve the issues with the rq->tmp_alone_branch !=
&rq->leaf_cfs_rq_list warning in enqueue_task_fair. There is a case where
the first for_each_sched_entity loop exits due to on_rq, having incompletely
updated the list. In this case the second for_each_sched_entity loop can
further modify se. The later code to fix up the list management fails to do
what is needed because se does not point to the sched_entity which broke out
of the first loop. The list is not fixed up because the throttled parent was
already added back to the list by a task enqueue in a parallel child hierarchy.
Address this by calling list_add_leaf_cfs_rq if there are throttled parents
while doing the second for_each_sched_entity loop.
Fixes: fe61468b2cb ("sched/fair: Fix enqueue_task_fair warning")
Suggested-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Phil Auld <pauld@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20200512135222.GC2201@lorien.usersys.redhat.com
As stated in 983695fa6765 ("bpf: fix unconnected udp hooks"), the objective
for the existing cgroup connect/sendmsg/recvmsg/bind BPF hooks is to be
transparent to applications. In Cilium we make use of these hooks [0] in
order to enable E-W load balancing for existing Kubernetes service types
for all Cilium managed nodes in the cluster. Those backends can be local
or remote. The main advantage of this approach is that it operates as close
as possible to the socket, and therefore allows to avoid packet-based NAT
given in connect/sendmsg/recvmsg hooks we only need to xlate sock addresses.
This also allows to expose NodePort services on loopback addresses in the
host namespace, for example. As another advantage, this also efficiently
blocks bind requests for applications in the host namespace for exposed
ports. However, one missing item is that we also need to perform reverse
xlation for inet{,6}_getname() hooks such that we can return the service
IP/port tuple back to the application instead of the remote peer address.
The vast majority of applications does not bother about getpeername(), but
in a few occasions we've seen breakage when validating the peer's address
since it returns unexpectedly the backend tuple instead of the service one.
Therefore, this trivial patch allows to customise and adds a getpeername()
as well as getsockname() BPF cgroup hook for both IPv4 and IPv6 in order
to address this situation.
Simple example:
# ./cilium/cilium service list
ID Frontend Service Type Backend
1 1.2.3.4:80 ClusterIP 1 => 10.0.0.10:80
Before; curl's verbose output example, no getpeername() reverse xlation:
# curl --verbose 1.2.3.4
* Rebuilt URL to: 1.2.3.4/
* Trying 1.2.3.4...
* TCP_NODELAY set
* Connected to 1.2.3.4 (10.0.0.10) port 80 (#0)
> GET / HTTP/1.1
> Host: 1.2.3.4
> User-Agent: curl/7.58.0
> Accept: */*
[...]
After; with getpeername() reverse xlation:
# curl --verbose 1.2.3.4
* Rebuilt URL to: 1.2.3.4/
* Trying 1.2.3.4...
* TCP_NODELAY set
* Connected to 1.2.3.4 (1.2.3.4) port 80 (#0)
> GET / HTTP/1.1
> Host: 1.2.3.4
> User-Agent: curl/7.58.0
> Accept: */*
[...]
Originally, I had both under a BPF_CGROUP_INET{4,6}_GETNAME type and exposed
peer to the context similar as in inet{,6}_getname() fashion, but API-wise
this is suboptimal as it always enforces programs having to test for ctx->peer
which can easily be missed, hence BPF_CGROUP_INET{4,6}_GET{PEER,SOCK}NAME split.
Similarly, the checked return code is on tnum_range(1, 1), but if a use case
comes up in future, it can easily be changed to return an error code instead.
Helper and ctx member access is the same as with connect/sendmsg/etc hooks.
[0] https://github.com/cilium/cilium/blob/master/bpf/bpf_sock.c
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Andrey Ignatov <rdna@fb.com>
Link: https://lore.kernel.org/bpf/61a479d759b2482ae3efb45546490bacd796a220.1589841594.git.daniel@iogearbox.net
Make it possible to reduce the attack surface in case the snapshot
device is not to be used from userspace.
Signed-off-by: Domenico Andreoli <domenico.andreoli@linux.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Hibernation concurrency handling is currently delegated to user.c,
where it's also used for regulating the access to the snapshot device.
In the prospective of making user.c a separate configuration option,
such mutual exclusion is brought into hibernate.c and made available
through accessor helpers hereby introduced.
Signed-off-by: Domenico Andreoli <domenico.andreoli@linux.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Add handling for loss of notifications by having read() insert a
loss-notification message after it has read the pipe buffer that was last
in the ring when the loss occurred.
Lossage can come about either by running out of notification descriptors or
by running out of space in the pipe ring.
Signed-off-by: David Howells <dhowells@redhat.com>
Allow a buffer to be marked such that read() must return the entire buffer
in one go or return ENOBUFS. Multiple buffers can be amalgamated into a
single read, but a short read will occur if the next "whole" buffer won't
fit.
This is useful for watch queue notifications to make sure we don't split a
notification across multiple reads, especially given that we need to
fabricate an overrun record under some circumstances - and that isn't in
the buffers.
Signed-off-by: David Howells <dhowells@redhat.com>
Make it possible to have a general notification queue built on top of a
standard pipe. Notifications are 'spliced' into the pipe and then read
out. splice(), vmsplice() and sendfile() are forbidden on pipes used for
notifications as post_one_notification() cannot take pipe->mutex. This
means that notifications could be posted in between individual pipe
buffers, making iov_iter_revert() difficult to effect.
The way the notification queue is used is:
(1) An application opens a pipe with a special flag and indicates the
number of messages it wishes to be able to queue at once (this can
only be set once):
pipe2(fds, O_NOTIFICATION_PIPE);
ioctl(fds[0], IOC_WATCH_QUEUE_SET_SIZE, queue_depth);
(2) The application then uses poll() and read() as normal to extract data
from the pipe. read() will return multiple notifications if the
buffer is big enough, but it will not split a notification across
buffers - rather it will return a short read or EMSGSIZE.
Notification messages include a length in the header so that the
caller can split them up.
Each message has a header that describes it:
struct watch_notification {
__u32 type:24;
__u32 subtype:8;
__u32 info;
};
The type indicates the source (eg. mount tree changes, superblock events,
keyring changes, block layer events) and the subtype indicates the event
type (eg. mount, unmount; EIO, EDQUOT; link, unlink). The info field
indicates a number of things, including the entry length, an ID assigned to
a watchpoint contributing to this buffer and type-specific flags.
Supplementary data, such as the key ID that generated an event, can be
attached in additional slots. The maximum message size is 127 bytes.
Messages may not be padded or aligned, so there is no guarantee, for
example, that the notification type will be on a 4-byte bounary.
Signed-off-by: David Howells <dhowells@redhat.com>
Instrumentation is forbidden in the .noinstr.text section. Make kprobes
respect this.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lkml.kernel.org/r/20200505134100.179862032@linutronix.de
Same as rcu_is_watching() but without the preempt_disable/enable() pair
inside the function. It is merked noinstr so it ends up in the
non-instrumentable text section.
This is useful for non-preemptible code especially in the low level entry
section. Using rcu_is_watching() there results in a call to the
preempt_schedule_notrace() thunk which triggers noinstr section warnings in
objtool.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200512213810.518709291@linutronix.de
Interrupts and exceptions invoke rcu_irq_enter() on entry and need to
invoke rcu_irq_exit() before they either return to the interrupted code or
invoke the scheduler due to preemption.
The general assumption is that RCU idle code has to have preemption
disabled so that a return from interrupt cannot schedule. So the return
from interrupt code invokes rcu_irq_exit() and preempt_schedule_irq().
If there is any imbalance in the rcu_irq/nmi* invocations or RCU idle code
had preemption enabled then this goes unnoticed until the CPU goes idle or
some other RCU check is executed.
Provide rcu_irq_exit_preempt() which can be invoked from the
interrupt/exception return code in case that preemption is enabled. It
invokes rcu_irq_exit() and contains a few sanity checks in case that
CONFIG_PROVE_RCU is enabled to catch such issues directly.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200505134904.364456424@linutronix.de
The rcu_nmi_enter_common() and rcu_nmi_exit_common() functions take an
"irq" parameter that indicates whether these functions have been invoked from
an irq handler (irq==true) or an NMI handler (irq==false).
However, recent changes have applied notrace to a few critical functions
such that rcu_nmi_enter_common() and rcu_nmi_exit_common() many now rely on
in_nmi(). Note that in_nmi() works no differently than before, but rather
that tracing is now prohibited in code regions where in_nmi() would
incorrectly report NMI state.
Therefore remove the "irq" parameter and inline rcu_nmi_enter_common() and
rcu_nmi_exit_common() into rcu_nmi_enter() and rcu_nmi_exit(),
respectively.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Link: https://lkml.kernel.org/r/20200505134101.617130349@linutronix.de
These functions are invoked from context tracking and other places in the
low level entry code. Move them into the .noinstr.text section to exclude
them from instrumentation.
Mark the places which are safe to invoke traceable functions with
instrumentation_begin/end() so objtool won't complain.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lkml.kernel.org/r/20200505134100.575356107@linutronix.de
SuperH is the last remaining user of arch_ftrace_nmi_{enter,exit}(),
remove it from the generic code and into the SuperH code.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: https://lkml.kernel.org/r/20200505134101.248881738@linutronix.de
These functions are called {early,late} in nmi_{enter,exit} and should
not be traced or probed. They are also puny, so 'inline' them.
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Link: https://lkml.kernel.org/r/20200505134101.048523500@linutronix.de
It happens early in nmi_enter(), no tracing, probing or other funnies
allowed. Specifically as nmi_enter() will be used in do_debug(), which
would cause recursive exceptions when kprobed.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Link: https://lkml.kernel.org/r/20200505134101.139720912@linutronix.de
There is plenty of space in the printk_context variable. Reserve one byte
there for the NMI context to be on the safe side.
It should never overflow. The BUG_ON(in_nmi() == NMI_MASK) in nmi_enter()
will trigger much earlier.
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Link: https://lkml.kernel.org/r/20200505134100.681374113@linutronix.de
Force inlining and prevent instrumentation of all sorts by marking the
functions which are invoked from low level entry code with 'noinstr'.
Split the irqflags tracking into two parts. One which does the heavy
lifting while RCU is watching and the final one which can be invoked after
RCU is turned off.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Link: https://lkml.kernel.org/r/20200505134100.484532537@linutronix.de
trace_hardirqs_on/off() is only partially safe vs. RCU idle. The tracer
core itself is safe, but the resulting tracepoints can be utilized by
e.g. BPF which is unsafe.
Provide variants which do not contain the lockdep invocation so the lockdep
and tracer invocations can be split at the call site and placed
properly. This is required because lockdep needs to be aware of the state
before switching away from RCU idle and after switching to RCU idle because
these transitions can take locks.
As these code pathes are going to be non-instrumentable the tracer can be
invoked after RCU is turned on and before the switch to RCU idle. So for
these new variants there is no need to invoke the rcuidle aware tracer
functions.
Name them so they match the lockdep counterparts.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200505134100.270771162@linutronix.de
syzbot found that
touch /proc/testfile
causes NULL pointer dereference at tomoyo_get_local_path()
because inode of the dentry is NULL.
Before c59f415a7cb6, Tomoyo received pid_ns from proc's s_fs_info
directly. Since proc_pid_ns() can only work with inode, using it in
the tomoyo_get_local_path() was wrong.
To avoid creating more functions for getting proc_ns, change the
argument type of the proc_pid_ns() function. Then, Tomoyo can use
the existing super_block to get pid_ns.
Link: https://lkml.kernel.org/r/0000000000002f0c7505a5b0e04c@google.com
Link: https://lkml.kernel.org/r/20200518180738.2939611-1-gladkov.alexey@gmail.com
Reported-by: syzbot+c1af344512918c61362c@syzkaller.appspotmail.com
Fixes: c59f415a7cb6 ("Use proc_pid_ns() to get pid_namespace from the proc superblock")
Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
ARM stores unwind information for .init.text in sections named
.ARM.extab.init.text and .ARM.exidx.init.text. Since those aren't
currently recognized as init sections, they're allocated along with the
core section, and relocation fails if the core and the init section are
allocated from different regions and can't reach other.
final section addresses:
...
0x7f800000 .init.text
..
0xcbb54078 .ARM.exidx.init.text
..
section 16 reloc 0 sym '': relocation 42 out of range (0xcbb54078 ->
0x7f800000)
Allow architectures to override the section name so that ARM can fix
this.
Acked-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
The break instruction in RISC-V does not have an immediate value field, so
the kernel cannot identify the purpose of each trap exception through the
opcode. This makes the existing identification schemes in other
architecture unsuitable for the RISC-V kernel. To solve this problem, this
patch adds kgdb_has_hit_break(), which can help RISC-V kernel identify
the KGDB trap exception.
Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
We want to enable kgdb to debug the early parts of the kernel.
Unfortunately kgdb normally is a client of the tty API in the kernel
and serial drivers don't register to the tty layer until fairly late
in the boot process.
Serial drivers do, however, commonly register a boot console. Let's
enable the kgdboc driver to work with boot consoles to provide early
debugging.
This change co-opts the existing read() function pointer that's part
of "struct console". It's assumed that if a boot console (with the
flag CON_BOOT) has implemented read() that both the read() and write()
function are polling functions. That means they work without
interrupts and read() will return immediately (with 0 bytes read) if
there's nothing to read. This should be a safe assumption since it
appears that no current boot consoles implement read() right now and
there seems no reason to do so unless they wanted to support
"kgdboc_earlycon".
The normal/expected way to make all this work is to use
"kgdboc_earlycon" and "kgdboc" together. You should point them both
to the same physical serial connection. At boot time, as the system
transitions from the boot console to the normal console (and registers
a tty), kgdb will switch over.
One awkward part of all this, though, is that there can be a window
where the boot console goes away and we can't quite transtion over to
the main kgdboc that uses the tty layer. There are two main problems:
1. The act of registering the tty doesn't cause any call into kgdboc
so there is a window of time when the tty is there but kgdboc's
init code hasn't been called so we can't transition to it.
2. On some serial drivers the normal console inits (and replaces the
boot console) quite early in the system. Presumably these drivers
were coded up before earlycon worked as well as it does today and
probably they don't need to do this anymore, but it causes us
problems nontheless.
Problem #1 is not too big of a deal somewhat due to the luck of probe
ordering. kgdboc is last in the tty/serial/Makefile so its probe gets
right after all other tty devices. It's not fun to rely on this, but
it does work for the most part.
Problem #2 is a big deal, but only for some serial drivers. Other
serial drivers end up registering the console (which gets rid of the
boot console) and tty at nearly the same time.
The way we'll deal with the window when the system has stopped using
the boot console and the time when we're setup using the tty is to
keep using the boot console. This may sound surprising, but it has
been found to work well in practice. If it doesn't work, it shouldn't
be too hard for a given serial driver to make it keep working.
Specifically, it's expected that the read()/write() function provided
in the boot console should be the same (or nearly the same) as the
normal kgdb polling functions. That means continuing to use them
should work just fine. To make things even more likely to work work
we'll also trap the recently added exit() function in the boot console
we're using and delay any calls to it until we're all done with the
boot console.
NOTE: there could be ways to use all this in weird / unexpected ways.
If you do something like this, it's a bit of a buyer beware situation.
Specifically:
- If you specify only "kgdboc_earlycon" but not "kgdboc" then
(depending on your serial driver) things will probably work OK, but
you'll get a warning printed the first time you use kgdb after the
boot console is gone. You'd only be able to do this, of course, if
the serial driver you're running atop provided an early boot console.
- If your "kgdboc_earlycon" and "kgdboc" devices are not the same
device things should work OK, but it'll be your job to switch over
which device you're monitoring (including figuring out how to switch
over gdb in-flight if you're using it).
When trying to enable "kgdboc_earlycon" it should be noted that the
names that are registered through the boot console layer and the tty
layer are not the same for the same port. For example when debugging
on one board I'd need to pass "kgdboc_earlycon=qcom_geni
kgdboc=ttyMSM0" to enable things properly. Since digging up the boot
console name is a pain and there will rarely be more than one boot
console enabled, you can provide the "kgdboc_earlycon" parameter
without specifying the name of the boot console. In this case we'll
just pick the first boot that implements read() that we find.
This new "kgdboc_earlycon" parameter should be contrasted to the
existing "ekgdboc" parameter. While both provide a way to debug very
early, the usage and mechanisms are quite different. Specifically
"kgdboc_earlycon" is meant to be used in tandem with "kgdboc" and
there is a transition from one to the other. The "ekgdboc" parameter,
on the other hand, replaces the "kgdboc" parameter. It runs the same
logic as the "kgdboc" parameter but just relies on your TTY driver
being present super early. The only known usage of the old "ekgdboc"
parameter is documented as "ekgdboc=kbd earlyprintk=vga". It should
be noted that "kbd" has special treatment allowing it to init early as
a tty device.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Tested-by: Sumit Garg <sumit.garg@linaro.org>
Link: https://lore.kernel.org/r/20200507130644.v4.8.I8fba5961bf452ab92350654aa61957f23ecf0100@changeid
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
