rework var-names for clarity, regularity
rename variables
  - n to mod_sites - it counts sites-per-module
  - entries to i - display only
  - iter_start to iter_mod_start - marks start of each module's subrange
  - modct to mod_ct - stylistic

new iterator var:
  - site - cursor parallel to iter
    1st step towards 'demotion' of iter->site, for removal later

treat vars as iters:
  - drop init at top
    init just above for-loop, in a textual block
Acked-by: Jason Baron <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-11-jim.cromie@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This exported fn is unused, and will not be needed. Lets dump it.

The export was added to let drm control pr_debugs, as part of using
them to avoid drm_debug_enabled overheads.  But its better to just
implement the drm.debug bitmap interface, then its available for
everyone.

Fixes: a2d375ed ("dyndbg: refine export, rename to dynamic_debug_exec_queries()")
Fixes: 4c0d7782 ("dyndbg: export ddebug_exec_queries")
Acked-by: Jason Baron <jbaron@akamai.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-10-jim.cromie@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Provide a simple module to allow testing DYNAMIC_DEBUG behavior.  It
calls do_prints() from module-init, and with a sysfs-node.

  dmesg -C
  dmesg -w &
  modprobe test_dynamic_debug dyndbg=+p
  echo 1 > /sys/module/dynamic_debug/parameters/verbose

  cat /sys/module/test_dynamic_debug/parameters/do_prints
  echo module test_dynamic_debug +mftl > /proc/dynamic_debug/control
  echo junk > /sys/module/test_dynamic_debug/parameters/do_prints
Acked-by: Jason Baron <jbaron@akamai.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-9-jim.cromie@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

dyndbg's control-parser: ddebug_parse_query(), requires that search
terms: module, func, file, lineno, are used only once in a query; a
thing cannot be named both foo and bar.

The cited commit added an overriding module modname, taken from the
module loader, which is authoritative.  So it set query.module 1st,
which disallowed its use in the query-string.

But now, its useful to allow a module-load to enable classes across a
whole (or part of) a subsystem at once.

  # enable (dynamic-debug in) drm only
  modprobe drm dyndbg="class DRM_UT_CORE +p"

  # get drm_helper too
  modprobe drm dyndbg="class DRM_UT_CORE module drm* +p"

  # get everything that knows DRM_UT_CORE
  modprobe drm dyndbg="class DRM_UT_CORE module * +p"

  # also for boot-args:
  drm.dyndbg="class DRM_UT_CORE module * +p"

So convert the override into a default, by filling it only when/after
the query-string omitted the module.

NB: the query class FOO handling is forthcoming.

Fixes: 8e59b5cf dynamic_debug: add modname arg to exec_query callchain
Acked-by: Jason Baron <jbaron@akamai.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-8-jim.cromie@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

`cat control` currently does octal escape, so '\n' becomes "\012".
Change this to display as "\n" instead, which reads much cleaner.

   :#> head -n7 /proc/dynamic_debug/control
   # filename:lineno [module]function flags format
   init/main.c:1179 [main]initcall_blacklist =_ "blacklisting initcall %s\n"
   init/main.c:1218 [main]initcall_blacklisted =_ "initcall %s blacklisted\n"
   init/main.c:1424 [main]run_init_process =_ "  with arguments:\n"
   init/main.c:1426 [main]run_init_process =_ "    %s\n"
   init/main.c:1427 [main]run_init_process =_ "  with environment:\n"
   init/main.c:1429 [main]run_init_process =_ "    %s\n"
Acked-by: Jason Baron <jbaron@akamai.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-7-jim.cromie@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Walk the module's vector of callsites backwards; ie N..0.  This
"corrects" the backwards appearance of a module's prdbg vector when
walked 0..N.  I think this is due to linker mechanics, which I'm
inclined to treat as immutable, and the order is fixable in display.

No functional changes.

Combined with previous commit, which reversed tables-list, we get:

  :#> head -n7 /proc/dynamic_debug/control
  # filename:lineno [module]function flags format
  init/main.c:1179 [main]initcall_blacklist =_ "blacklisting initcall %s\012"
  init/main.c:1218 [main]initcall_blacklisted =_ "initcall %s blacklisted\012"
  init/main.c:1424 [main]run_init_process =_ "  with arguments:\012"
  init/main.c:1426 [main]run_init_process =_ "    %s\012"
  init/main.c:1427 [main]run_init_process =_ "  with environment:\012"
  init/main.c:1429 [main]run_init_process =_ "    %s\012"
Acked-by: Jason Baron <jbaron@akamai.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-6-jim.cromie@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

/proc/dynamic_debug/control walks the prdbg catalog in "reverse",
fix this by adding new ddebug_tables to tail of list.

This puts init/main.c entries 1st, which looks more than coincidental.

no functional changes.
Acked-by: Jason Baron <jbaron@akamai.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-5-jim.cromie@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

print "old => new" flag values to the info("change") message.

no functional change.
Acked-by: Jason Baron <jbaron@akamai.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-4-jim.cromie@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

For CONFIG_DYNAMIC_DEBUG=N, the ddebug_dyndbg_module_param_cb()
stub-fn is too permissive:

bash-5.1# modprobe drm JUNKdyndbg
bash-5.1# modprobe drm dyndbgJUNK
[   42.933220] dyndbg param is supported only in CONFIG_DYNAMIC_DEBUG builds
[   42.937484] ACPI: bus type drm_connector registered

This caused no ill effects, because unknown parameters are either
ignored by default with an "unknown parameter" warning, or ignored
because dyndbg allows its no-effect use on non-dyndbg builds.

But since the code has an explicit feedback message, it should be
issued accurately.  Fix with strcmp for exact param-name match.

Fixes: b48420c1 dynamic_debug: make dynamic-debug work for module initialization
Reported-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Jason Baron <jbaron@akamai.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-3-jim.cromie@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

In https://lore.kernel.org/lkml/20211209150910.GA23668@axis.com/

Vincent's patch commented on, and worked around, a bug toggling
static_branch's, when a 2nd PRINTK-ish flag was added.  The bug
results in a premature static_branch_disable when the 1st of 2 flags
was disabled.

The cited commit computed newflags, but then in the JUMP_LABEL block,
failed to use that result, instead using just one of the terms in it.
Using newflags instead made the code work properly.

This is Vincents test-case, reduced.  It needs the 2nd flag to
demonstrate the bug, but it's explanatory here.

pt_test() {
    echo 5 > /sys/module/dynamic_debug/verbose

    site="module tcp" # just one callsite
    echo " $site =_ " > /proc/dynamic_debug/control # clear it

    # A B ~A ~B
    for flg in +T +p "-T #broke here" -p; do
	echo " $site $flg " > /proc/dynamic_debug/control
    done;

    # A B ~B ~A
    for flg in +T +p "-p #broke here" -T; do
	echo " $site $flg " > /proc/dynamic_debug/control
    done
}
pt_test

Fixes: 84da83a6 dyndbg: combine flags & mask into a struct, simplify with it
CC: vincent.whitchurch@axis.com
Acked-by: Jason Baron <jbaron@akamai.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-2-jim.cromie@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

If the gfp flag used for the memory allocation already has __GFP_ZERO,
then there is no need to explicitly clear the "struct devres_node". It is
already zeroed.

This saves a few cycles when using devm_zalloc() and co.

In the case of devres_alloc() (which calls __devres_alloc_node()), the
compiler could remove the test and the memset() because it should be able
to see that the __GFP_ZERO flag is set.
So this would make the code both faster and smaller.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/d255bd871484e63cdd628e819f929e2df59afb02.1658352383.git.christophe.jaillet@wanadoo.frSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

If we're going to log the failure, we might as well log the return code
too.
Signed-off-by: Brian Norris <briannorris@chromium.org>
Link: https://lore.kernel.org/r/20220824165213.1.Ifdb98af3d0c23708a11d8d5ae5697bdb7e96a3cc@changeidSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Use IS_ERR_OR_NULL() helper in class_unregister() to simplify code.
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20220822061922.3884113-1-yangyingliang@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Follow the advice of the below link and prefer 'strscpy' in this
subsystem. Conversion is 1:1 because the return value is not used.
Generated by a coccinelle script.

Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20220818205956.6528-1-wsa+renesas@sang-engineering.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Add cgroup_file_show() which allows toggling visibility of a cgroup file
using the new kernfs_show(). This will be used to hide psi interface files
on cgroups where it's disabled.

Cc: Chengming Zhou <zhouchengming@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220828050440.734579-10-tj@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Currently, kernfs nodes can be created hidden and activated later by calling
kernfs_activate() to allow creation of multiple nodes to succeed or fail as
a unit. This is an one-way one-time-only transition. This patch introduces
kernfs_show() which can toggle visibility dynamically.

As the currently proposed use - toggling the cgroup pressure files - only
requires operating on leaf nodes, for the sake of simplicity, restrict it as
such for now.

Hiding uses the same mechanism as deactivation and likewise guarantees that
there are no in-flight operations on completion. KERNFS_ACTIVATED and
KERNFS_HIDDEN are used to manage the interactions between activations and
show/hide operations. A node is visible iff both activated & !hidden.

Cc: Chengming Zhou <zhouchengming@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220828050440.734579-9-tj@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Factor out kernfs_activate_one() from kernfs_activate() and reorder
operations so that KERNFS_ACTIVATED now simply indicates whether activation
was attempted on the node ignoring whether activation took place. As the
flag doesn't have a reader, the refactoring and reordering shouldn't cause
any behavior difference.
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220828050440.734579-8-tj@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

KERNFS_ACTIVATED tracks whether a given node has ever been activated. As a
node was only deactivated on removal, this was used for

 1. Drain optimization (removed by the previous patch).
 2. To hide !activated nodes
 3. To avoid double activations
 4. Reject adding children to a node being removed
 5. Skip activaing a node which is being removed.

We want to decouple deactivation from removal so that nodes can be
deactivated and hidden dynamically, which makes KERNFS_ACTIVATED useless for
all of the above purposes.

#1 is already gone. #2 and #3 can instead test whether the node is currently
active. A new flag KERNFS_REMOVING is added to explicitly mark nodes which
are being removed for #4 and #5.

While this leaves KERNFS_ACTIVATED with no users, leave it be as it will be
used in a following patch.

Cc: Chengming Zhou <zhouchengming@bytedance.com>
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220828050440.734579-7-tj@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

__kernfs_remove() was skipping draining based on KERNFS_ACTIVATED - whether
the node has ever been activated since creation. Instead, update it to
always call kernfs_drain() which now drains or skips based on the precise
drain conditions. This ensures that the nodes will be deactivated and
drained regardless of their states.

This doesn't make meaningful difference now but will enable deactivating and
draining nodes dynamically by making removals safe when racing those
operations.

While at it, drop / update comments.

v2: Fix the inverted test on kernfs_should_drain_open_files() noted by
    Chengming. This was fixed by the next unrelated patch in the previous
    posting.

Cc: Chengming Zhou <zhouchengming@bytedance.com>
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220828050440.734579-6-tj@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Track the number of mmapped files and files that need to be released and
skip kernfs_drain_open_file() if both are zero, which are the precise
conditions which require draining open_files. The early exit test is
factored into kernfs_should_drain_open_files() which is now tested by
kernfs_drain_open_files()'s caller - kernfs_drain().

This isn't a meaningful optimization on its own but will enable future
stand-alone kernfs_deactivate() implementation.

v2: Chengming noticed that on->nr_to_release was leaking after ->open()
    failure. Fix it by telling kernfs_unlink_open_file() that it's called
    from the ->open() fail path and should dec the counter. Use kzalloc() to
    allocate kernfs_open_node so that the tracking fields are correctly
    initialized.

Cc: Chengming Zhou <zhouchengming@bytedance.com>
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220828050440.734579-5-tj@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Factor out commont part. This is cleaner and should help with future
changes. No functional changes.
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220828050440.734579-4-tj@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

These are unnecessary and unconventional. Remove them. Also move variable
declaration into the block that it's used. No functional changes.

Cc: Imran Khan <imran.f.khan@oracle.com>
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220828050440.734579-3-tj@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

kernfs_node->attr.open is an RCU pointer to kernfs_open_node. However, RCU
dereference is currently only used in kernfs_notify(). Everywhere else,
either we're holding the lock which protects it or know that the
kernfs_open_node is pinned becaused we have a pointer to a kernfs_open_file
which is hanging off of it.

kernfs_deref_open_node() is used for the latter case - accessing
kernfs_open_node from kernfs_open_file. The lifetime and visibility rules
are simple and clear here. To someone who can access a kernfs_open_file, its
kernfs_open_node is pinned and visible through of->kn->attr.open.

Replace kernfs_deref_open_node() which simpler of_on(). The former takes
both @kn and @of and RCU deref @kn->attr.open while sanity checking with
@of. The latter takes @of and uses protected deref on of->kn->attr.open.

As the return value can't be NULL, remove the error handling in the callers
too.

This shouldn't cause any functional changes.

Cc: Imran Khan <imran.f.khan@oracle.com>
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220828050440.734579-2-tj@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

devm_ioremap_np has never been used anywhere since it was added in early
2021, so remove it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220822061424.151819-1-hch@lst.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull irq fixes from Ingo Molnar:
 "Misc irqchip fixes: LoongArch driver fixes and a Hyper-V IOMMU fix"

* tag 'irq-urgent-2022-08-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/loongson-liointc: Fix an error handling path in liointc_init()
  irqchip/loongarch: Fix irq_domain_alloc_fwnode() abuse
  irqchip/loongson-pch-pic: Move find_pch_pic() into CONFIG_ACPI
  irqchip/loongson-eiointc: Fix a build warning
  irqchip/loongson-eiointc: Fix irq affinity setting
  iommu/hyper-v: Use helper instead of directly accessing affinity

Pull x86 kprobes fix from Ingo Molnar:
 "Fix a kprobes bug in JNG/JNLE emulation when a kprobe is installed at
  such instructions, possibly resulting in incorrect execution (the
  wrong branch taken)"

* tag 'perf-urgent-2022-08-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/kprobes: Fix JNG/JNLE emulation

Pull tracing fixes from Steven Rostedt:
 "Various fixes for tracing:

   - Fix a return value of traceprobe_parse_event_name()

   - Fix NULL pointer dereference from failed ftrace enabling

   - Fix NULL pointer dereference when asking for registers from eprobes

   - Make eprobes consistent with kprobes/uprobes, filters and
     histograms"

* tag 'trace-v6.0-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Have filter accept "common_cpu" to be consistent
  tracing/probes: Have kprobes and uprobes use $COMM too
  tracing/eprobes: Have event probes be consistent with kprobes and uprobes
  tracing/eprobes: Fix reading of string fields
  tracing/eprobes: Do not hardcode $comm as a string
  tracing/eprobes: Do not allow eprobes to use $stack, or % for regs
  ftrace: Fix NULL pointer dereference in is_ftrace_trampoline when ftrace is dead
  tracing/perf: Fix double put of trace event when init fails
  tracing: React to error return from traceprobe_parse_event_name()

Make filtering consistent with histograms. As "cpu" can be a field of an
event, allow for "common_cpu" to keep it from being confused with the
"cpu" field of the event.

Link: https://lkml.kernel.org/r/20220820134401.513062765@goodmis.org
Link: https://lore.kernel.org/all/20220820220920.e42fa32b70505b1904f0a0ad@kernel.org/

Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Fixes: 1e3bac71 ("tracing/histogram: Rename "cpu" to "common_cpu"")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Both $comm and $COMM can be used to get current->comm in eprobes and the
filtering and histogram logic. Make kprobes and uprobes consistent in this
regard and allow both $comm and $COMM as well. Currently kprobes and
uprobes only handle $comm, which is inconsistent with the other utilities,
and can be confusing to users.

Link: https://lkml.kernel.org/r/20220820134401.317014913@goodmis.org
Link: https://lore.kernel.org/all/20220820220442.776e1ddaf8836e82edb34d01@kernel.org/

Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Fixes: 53305928 ("tracing: probeevent: Introduce new argument fetching code")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Currently, if a symbol "@" is attempted to be used with an event probe
(eprobes), it will cause a NULL pointer dereference crash.

Both kprobes and uprobes can reference data other than the main registers.
Such as immediate address, symbols and the current task name. Have eprobes
do the same thing.

For "comm", if "comm" is used and the event being attached to does not
have the "comm" field, then make it the "$comm" that kprobes has. This is
consistent to the way histograms and filters work.

Link: https://lkml.kernel.org/r/20220820134401.136924220@goodmis.org

Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Fixes: 7491e2c4 ("tracing: Add a probe that attaches to trace events")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Currently when an event probe (eprobe) hooks to a string field, it does
not display it as a string, but instead as a number. This makes the field
rather useless. Handle the different kinds of strings, dynamic, static,
relational/dynamic etc.

Now when a string field is used, the ":string" type can be used to display
it:

  echo "e:sw sched/sched_switch comm=$next_comm:string" > dynamic_events

Link: https://lkml.kernel.org/r/20220820134400.959640191@goodmis.org

Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Fixes: 7491e2c4 ("tracing: Add a probe that attaches to trace events")
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

The variable $comm is hard coded as a string, which is true for both
kprobes and uprobes, but for event probes (eprobes) it is a field name. In
most cases the "comm" field would be a string, but there's no guarantee of
that fact.

Do not assume that comm is a string. Not to mention, it currently forces
comm fields to fault, as string processing for event probes is currently
broken.

Link: https://lkml.kernel.org/r/20220820134400.756152112@goodmis.org

Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Fixes: 7491e2c4 ("tracing: Add a probe that attaches to trace events")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

While playing with event probes (eprobes), I tried to see what would
happen if I attempted to retrieve the instruction pointer (%rip) knowing
that event probes do not use pt_regs. The result was:

 BUG: kernel NULL pointer dereference, address: 0000000000000024
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 0 P4D 0
 Oops: 0000 [#1] PREEMPT SMP PTI
 CPU: 1 PID: 1847 Comm: trace-cmd Not tainted 5.19.0-rc5-test+ #309
 Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01
v03.03 07/14/2016
 RIP: 0010:get_event_field.isra.0+0x0/0x50
 Code: ff 48 c7 c7 c0 8f 74 a1 e8 3d 8b f5 ff e8 88 09 f6 ff 4c 89 e7 e8
50 6a 13 00 48 89 ef 5b 5d 41 5c 41 5d e9 42 6a 13 00 66 90 <48> 63 47 24
8b 57 2c 48 01 c6 8b 47 28 83 f8 02 74 0e 83 f8 04 74
 RSP: 0018:ffff916c394bbaf0 EFLAGS: 00010086
 RAX: ffff916c854041d8 RBX: ffff916c8d9fbf50 RCX: ffff916c255d2000
 RDX: 0000000000000000 RSI: ffff916c255d2008 RDI: 0000000000000000
 RBP: 0000000000000000 R08: ffff916c3a2a0c08 R09: ffff916c394bbda8
 R10: 0000000000000000 R11: 0000000000000000 R12: ffff916c854041d8
 R13: ffff916c854041b0 R14: 0000000000000000 R15: 0000000000000000
 FS:  0000000000000000(0000) GS:ffff916c9ea40000(0000)
knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 0000000000000024 CR3: 000000011b60a002 CR4: 00000000001706e0
 Call Trace:
  <TASK>
  get_eprobe_size+0xb4/0x640
  ? __mod_node_page_state+0x72/0xc0
  __eprobe_trace_func+0x59/0x1a0
  ? __mod_lruvec_page_state+0xaa/0x1b0
  ? page_remove_file_rmap+0x14/0x230
  ? page_remove_rmap+0xda/0x170
  event_triggers_call+0x52/0xe0
  trace_event_buffer_commit+0x18f/0x240
  trace_event_raw_event_sched_wakeup_template+0x7a/0xb0
  try_to_wake_up+0x260/0x4c0
  __wake_up_common+0x80/0x180
  __wake_up_common_lock+0x7c/0xc0
  do_notify_parent+0x1c9/0x2a0
  exit_notify+0x1a9/0x220
  do_exit+0x2ba/0x450
  do_group_exit+0x2d/0x90
  __x64_sys_exit_group+0x14/0x20
  do_syscall_64+0x3b/0x90
  entry_SYSCALL_64_after_hwframe+0x46/0xb0

Obviously this is not the desired result.

Move the testing for TPARG_FL_TPOINT which is only used for event probes
to the top of the "$" variable check, as all the other variables are not
used for event probes. Also add a check in the register parsing "%" to
fail if an event probe is used.

Link: https://lkml.kernel.org/r/20220820134400.564426983@goodmis.org

Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Fixes: 7491e2c4 ("tracing: Add a probe that attaches to trace events")
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

ftrace_startup does not remove ops from ftrace_ops_list when
ftrace_startup_enable fails:

register_ftrace_function
  ftrace_startup
    __register_ftrace_function
      ...
      add_ftrace_ops(&ftrace_ops_list, ops)
      ...
    ...
    ftrace_startup_enable // if ftrace failed to modify, ftrace_disabled is set to 1
    ...
  return 0 // ops is in the ftrace_ops_list.

When ftrace_disabled = 1, unregister_ftrace_function simply returns without doing anything:
unregister_ftrace_function
  ftrace_shutdown
    if (unlikely(ftrace_disabled))
            return -ENODEV;  // return here, __unregister_ftrace_function is not executed,
                             // as a result, ops is still in the ftrace_ops_list
    __unregister_ftrace_function
    ...

If ops is dynamically allocated, it will be free later, in this case,
is_ftrace_trampoline accesses NULL pointer:

is_ftrace_trampoline
  ftrace_ops_trampoline
    do_for_each_ftrace_op(op, ftrace_ops_list) // OOPS! op may be NULL!

Syzkaller reports as follows:
[ 1203.506103] BUG: kernel NULL pointer dereference, address: 000000000000010b
[ 1203.508039] #PF: supervisor read access in kernel mode
[ 1203.508798] #PF: error_code(0x0000) - not-present page
[ 1203.509558] PGD 800000011660b067 P4D 800000011660b067 PUD 130fb8067 PMD 0
[ 1203.510560] Oops: 0000 [#1] SMP KASAN PTI
[ 1203.511189] CPU: 6 PID: 29532 Comm: syz-executor.2 Tainted: G    B   W         5.10.0 #8
[ 1203.512324] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
[ 1203.513895] RIP: 0010:is_ftrace_trampoline+0x26/0xb0
[ 1203.514644] Code: ff eb d3 90 41 55 41 54 49 89 fc 55 53 e8 f2 00 fd ff 48 8b 1d 3b 35 5d 03 e8 e6 00 fd ff 48 8d bb 90 00 00 00 e8 2a 81 26 00 <48> 8b ab 90 00 00 00 48 85 ed 74 1d e8 c9 00 fd ff 48 8d bb 98 00
[ 1203.518838] RSP: 0018:ffffc900012cf960 EFLAGS: 00010246
[ 1203.520092] RAX: 0000000000000000 RBX: 000000000000007b RCX: ffffffff8a331866
[ 1203.521469] RDX: 0000000000000000 RSI: 0000000000000008 RDI: 000000000000010b
[ 1203.522583] RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8df18b07
[ 1203.523550] R10: fffffbfff1be3160 R11: 0000000000000001 R12: 0000000000478399
[ 1203.524596] R13: 0000000000000000 R14: ffff888145088000 R15: 0000000000000008
[ 1203.525634] FS:  00007f429f5f4700(0000) GS:ffff8881daf00000(0000) knlGS:0000000000000000
[ 1203.526801] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1203.527626] CR2: 000000000000010b CR3: 0000000170e1e001 CR4: 00000000003706e0
[ 1203.528611] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 1203.529605] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Therefore, when ftrace_startup_enable fails, we need to rollback registration
process and remove ops from ftrace_ops_list.

Link: https://lkml.kernel.org/r/20220818032659.56209-1-yangjihong1@huawei.comSuggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

If in perf_trace_event_init(), the perf_trace_event_open() fails, then it
will call perf_trace_event_unreg() which will not only unregister the perf
trace event, but will also call the put() function of the tp_event.

The problem here is that the trace_event_try_get_ref() is called by the
caller of perf_trace_event_init() and if perf_trace_event_init() returns a
failure, it will then call trace_event_put(). But since the
perf_trace_event_unreg() already called the trace_event_put() function, it
triggers a WARN_ON().

 WARNING: CPU: 1 PID: 30309 at kernel/trace/trace_dynevent.c:46 trace_event_dyn_put_ref+0x15/0x20

If perf_trace_event_reg() does not call the trace_event_try_get_ref() then
the perf_trace_event_unreg() should not be calling trace_event_put(). This
breaks symmetry and causes bugs like these.

Pull out the trace_event_put() from perf_trace_event_unreg() and call it
in the locations that perf_trace_event_unreg() is called. This not only
fixes this bug, but also brings back the proper symmetry of the reg/unreg
vs get/put logic.

Link: https://lore.kernel.org/all/cover.1660347763.git.kjlx@templeofstupid.com/
Link: https://lkml.kernel.org/r/20220816192817.43d5e17f@gandalf.local.home

Cc: stable@vger.kernel.org
Fixes: 1d18538e ("tracing: Have dynamic events have a ref counter")
Reported-by: Krister Johansen <kjlx@templeofstupid.com>
Reviewed-by: Krister Johansen <kjlx@templeofstupid.com>
Tested-by: Krister Johansen <kjlx@templeofstupid.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

The function traceprobe_parse_event_name() may set the first two function
arguments to a non-null value and still return -EINVAL to indicate an
unsuccessful completion of the function. Hence, it is not sufficient to
just check the result of the two function arguments for being not null,
but the return value also needs to be checked.

Commit 95c104c3 ("tracing: Auto generate event name when creating a
group of events") changed the error-return-value checking of the second
traceprobe_parse_event_name() invocation in __trace_eprobe_create() and
removed checking the return value to jump to the error handling case.

Reinstate using the return value in the error-return-value checking.

Link: https://lkml.kernel.org/r/20220811071734.20700-1-lukas.bulwahn@gmail.com

Fixes: 95c104c3 ("tracing: Auto generate event name when creating a group of events")
Acked-by: Linyu Yuan <quic_linyyuan@quicinc.com>
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Pull i2c fixes from Wolfram Sang:
 "A revert to fix a regression introduced this merge window and a fix
  for proper error handling in the remove path of the iMX driver"

* tag 'i2c-for-6.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: imx: Make sure to unregister adapter on remove()
  Revert "i2c: scmi: Replace open coded device_get_match_data()"

Pull cifs client fixes from Steve French:

 - memory leak fix

 - two small cleanups

 - trivial strlcpy removal

 - update missing entry for cifs headers in MAINTAINERS file

* tag '6.0-rc1-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: move from strlcpy with unused retval to strscpy
  cifs: Fix memory leak on the deferred close
  cifs: remove useless parameter 'is_fsctl' from SMB2_ioctl()
  cifs: remove unused server parameter from calc_smb_size()
  cifs: missing directory in MAINTAINERS file

GCC has supported asm goto since 4.5, and Clang has since version 9.0.0.
The minimum supported versions of these tools for the build according to
Documentation/process/changes.rst are 5.1 and 11.0.0 respectively.

Remove the feature detection script, Kconfig option, and clean up some
fallback code that is no longer supported.

The removed script was also testing for a GCC specific bug that was
fixed in the 4.7 release.

Also remove workarounds for bpftrace using clang older than 9.0.0, since
other BPF backend fixes are required at this point.

Link: https://lore.kernel.org/lkml/CAK7LNATSr=BXKfkdW8f-H5VT_w=xBpT2ZQcZ7rm6JfkdE+QnmA@mail.gmail.com/
Link: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48637Acked-by: Borislav Petkov <bp@suse.de>
Suggested-by: Masahiro Yamada <masahiroy@kernel.org>
Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>