[ Upstream commit 8c721c53dd ]
The recent support of low latency playback in USB-audio driver made
the snd_usb_queue_pending_output_urbs() function to be called via PCM
ack ops. In the new code path, the function is performed already in
the PCM stream lock. The problem is that, when an XRUN is detected,
the function calls snd_pcm_xrun() to notify, but snd_pcm_xrun() is
supposed to be called only outside the stream lock. As a result, it
leads to a deadlock of PCM stream locking.
For avoiding such a recursive locking, this patch adds an additional
check to the code paths in PCM core that call the ack callback; now it
checks the error code from the callback, and if it's -EPIPE, the XRUN
is handled in the PCM core side gracefully. Along with it, the
USB-audio driver code is changed to follow that, i.e. -EPIPE is
returned instead of the explicit snd_pcm_xrun() call when the function
is performed already in the stream lock.
Fixes: d5f871f89e ("ALSA: usb-audio: Improved lowlatency playback support")
Reported-and-tested-by: John Keeping <john@metanate.com>
Link: https://lore.kernel.org/r/20230317195128.3911155-1-john@metanate.com
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Reviewed-by; Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20230320142838.494-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 56b88b5056 upstream.
Takes rwsem lock inside snd_ctl_elem_read instead of snd_ctl_elem_read_user
like it was done for write in commit 1fa4445f9a ("ALSA: control - introduce
snd_ctl_notify_one() helper"). Doing this way we are also fixing the following
locking issue happening in the compat path which can be easily triggered and
turned into an use-after-free.
64-bits:
snd_ctl_ioctl
snd_ctl_elem_read_user
[takes controls_rwsem]
snd_ctl_elem_read [lock properly held, all good]
[drops controls_rwsem]
32-bits:
snd_ctl_ioctl_compat
snd_ctl_elem_write_read_compat
ctl_elem_write_read
snd_ctl_elem_read [missing lock, not good]
CVE-2023-0266 was assigned for this issue.
Cc: stable@kernel.org # 5.13+
Signed-off-by: Clement Lecigne <clecigne@google.com>
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20230113120745.25464-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 05530ef7cf ]
With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG),
indirect call targets are validated against the expected function
pointer prototype to make sure the call target is valid to help mitigate
ROP attacks. If they are not identical, there is a failure at run time,
which manifests as either a kernel panic or thread getting killed.
seq_copy_in_user() and seq_copy_in_kernel() did not have prototypes
matching snd_seq_dump_func_t. Adjust this and remove the casts. There
are not resulting binary output differences.
This was found as a result of Clang's new -Wcast-function-type-strict
flag, which is more sensitive than the simpler -Wcast-function-type,
which only checks for type width mismatches.
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/202211041527.HD8TLSE1-lkp@intel.com
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: alsa-devel@alsa-project.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221118232346.never.380-kees@kernel.org
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 97d917879d upstream.
We took sound_oss_mutex around the calls of unregister_sound_special()
at unregistering OSS devices. This may, however, lead to a deadlock,
because we manage the card release via the card's device object, and
the release may happen at unregister_sound_special() call -- which
will take sound_oss_mutex again in turn.
Although the deadlock might be fixed by relaxing the rawmidi mutex in
the previous commit, it's safer to move unregister_sound_special()
calls themselves out of the sound_oss_mutex, too. The call is
race-safe as the function has a spinlock protection by itself.
Link: https://lore.kernel.org/r/CAB7eexJP7w1B0mVgDF0dQ+gWor7UdkiwPczmL7pn91xx8xpzOA@mail.gmail.com
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20221011070147.7611-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit c3afa2a402 upstream.
During the code change to add the support for devres-managed card
instance, we put an explicit kfree(card) call at the error path in
snd_card_new(). This is needed for the early error path before the
card is initialized with the device, but is rather superfluous and
causes a double-free at the error path after the card instance is
initialized, as the destructor of the card object already contains a
kfree() call.
This patch fixes the double-free situation by removing the superfluous
kfree(). Meanwhile we need to call kfree() explicitly for the early
error path, so it's added there instead.
Fixes: e8ad415b7a ("ALSA: core: Add managed card creation")
Reported-by: Rondreis <linhaoguo86@gmail.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/CAB7eexL1zBnB636hwS27d-LdPYZ_R1-5fJS_h=ZbCWYU=UPWJg@mail.gmail.com
Link: https://lore.kernel.org/r/20220919123516.28222-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 4a971e84a7 ]
For avoiding the potential deadlock via kill_fasync() call, use the
new fasync helpers to defer the invocation from the control API. Note
that it's merely a workaround.
Another note: although we haven't received reports about the deadlock
with the control API, the deadlock is still potentially possible, and
it's better to align the behavior with other core APIs (PCM and
timer); so let's move altogether.
Link: https://lore.kernel.org/r/20220728125945.29533-5-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit ef34a0ae7a ]
Currently the call of kill_fasync() from an interrupt handler might
lead to potential spin deadlocks, as spotted by syzkaller.
Unfortunately, it's not so trivial to fix this lock chain as it's
involved with the tasklist_lock that is touched in allover places.
As a temporary workaround, this patch provides the way to defer the
async signal notification in a work. The new helper functions,
snd_fasync_helper() and snd_kill_faync() are replacements for
fasync_helper() and kill_fasync(), respectively. In addition,
snd_fasync_free() needs to be called at the destructor of the relevant
file object.
Link: https://lore.kernel.org/r/20220728125945.29533-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 011b559be8 ]
Pointer substream is being dereferenced on the assignment of pointer card
before substream is being null checked with the macro PCM_RUNTIME_CHECK.
Although PCM_RUNTIME_CHECK calls BUG_ON, it still is useful to perform the
the pointer check before card is assigned.
Fixes: d4cfb30fce ("ALSA: pcm: Set per-card upper limit of PCM buffer allocations")
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://lore.kernel.org/r/20220424205945.1372247-1-colin.i.king@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit fee2b871d8 upstream.
This is a small helper function to handle the error path more easily
when an error happens during the probe for the device with the
device-managed card. Since devres releases in the reverser order of
the creations, usually snd_card_free() gets called at the last in the
probe error path unless it already reached snd_card_register() calls.
Due to this nature, when a driver expects the resource releases in
card->private_free, this might be called too lately.
As a workaround, one should call the probe like:
static int __some_probe(...) { // do real probe.... }
static int some_probe(...)
{
return snd_card_free_on_error(dev, __some_probe(dev, ...));
}
so that the snd_card_free() is called explicitly at the beginning of
the error path from the probe.
This function will be used in the upcoming fixes to address the
regressions by devres usages.
Fixes: e8ad415b7a ("ALSA: core: Add managed card creation")
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220412093141.8008-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit bc55cfd571 upstream.
syzbot caught a potential deadlock between the PCM
runtime->buffer_mutex and the mm->mmap_lock. It was brought by the
recent fix to cover the racy read/write and other ioctls, and in that
commit, I overlooked a (hopefully only) corner case that may take the
revert lock, namely, the OSS mmap. The OSS mmap operation
exceptionally allows to re-configure the parameters inside the OSS
mmap syscall, where mm->mmap_mutex is already held. Meanwhile, the
copy_from/to_user calls at read/write operations also take the
mm->mmap_lock internally, hence it may lead to a AB/BA deadlock.
A similar problem was already seen in the past and we fixed it with a
refcount (in commit b248371628). The former fix covered only the
call paths with OSS read/write and OSS ioctls, while we need to cover
the concurrent access via both ALSA and OSS APIs now.
This patch addresses the problem above by replacing the buffer_mutex
lock in the read/write operations with a refcount similar as we've
used for OSS. The new field, runtime->buffer_accessing, keeps the
number of concurrent read/write operations. Unlike the former
buffer_mutex protection, this protects only around the
copy_from/to_user() calls; the other codes are basically protected by
the PCM stream lock. The refcount can be a negative, meaning blocked
by the ioctls. If a negative value is seen, the read/write aborts
with -EBUSY. In the ioctl side, OTOH, they check this refcount, too,
and set to a negative value for blocking unless it's already being
accessed.
Reported-by: syzbot+6e5c88838328e99c7e1c@syzkaller.appspotmail.com
Fixes: dca947d4d2 ("ALSA: pcm: Fix races among concurrent read/write and buffer changes")
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/000000000000381a0d05db622a81@google.com
Link: https://lore.kernel.org/r/20220330120903.4738-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 3c3201f8c7 upstream.
Like the previous fixes to hw_params and hw_free ioctl races, we need
to paper over the concurrent prepare ioctl calls against hw_params and
hw_free, too.
This patch implements the locking with the existing
runtime->buffer_mutex for prepare ioctls. Unlike the previous case
for snd_pcm_hw_hw_params() and snd_pcm_hw_free(), snd_pcm_prepare() is
performed to the linked streams, hence the lock can't be applied
simply on the top. For tracking the lock in each linked substream, we
modify snd_pcm_action_group() slightly and apply the buffer_mutex for
the case stream_lock=false (formerly there was no lock applied)
there.
Cc: <stable@vger.kernel.org>
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20220322170720.3529-4-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit dca947d4d2 upstream.
In the current PCM design, the read/write syscalls (as well as the
equivalent ioctls) are allowed before the PCM stream is running, that
is, at PCM PREPARED state. Meanwhile, we also allow to re-issue
hw_params and hw_free ioctl calls at the PREPARED state that may
change or free the buffers, too. The problem is that there is no
protection against those mix-ups.
This patch applies the previously introduced runtime->buffer_mutex to
the read/write operations so that the concurrent hw_params or hw_free
call can no longer interfere during the operation. The mutex is
unlocked before scheduling, so we don't take it too long.
Cc: <stable@vger.kernel.org>
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20220322170720.3529-3-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 92ee3c60ec upstream.
Currently we have neither proper check nor protection against the
concurrent calls of PCM hw_params and hw_free ioctls, which may result
in a UAF. Since the existing PCM stream lock can't be used for
protecting the whole ioctl operations, we need a new mutex to protect
those racy calls.
This patch introduced a new mutex, runtime->buffer_mutex, and applies
it to both hw_params and hw_free ioctl code paths. Along with it, the
both functions are slightly modified (the mmap_count check is moved
into the state-check block) for code simplicity.
Reported-by: Hu Jiahui <kirin.say@gmail.com>
Cc: <stable@vger.kernel.org>
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20220322170720.3529-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit efb6402c3c upstream.
We've got syzbot reports hitting INT_MAX overflow at vmalloc()
allocation that is called from snd_pcm_plug_alloc(). Although we
apply the restrictions to input parameters, it's based only on the
hw_params of the underlying PCM device. Since the PCM OSS layer
allocates a temporary buffer for the data conversion, the size may
become unexpectedly large when more channels or higher rates is given;
in the reported case, it went over INT_MAX, hence it hits WARN_ON().
This patch is an attempt to avoid such an overflow and an allocation
for too large buffers. First off, it adds the limit of 1MB as the
upper bound for period bytes. This must be large enough for all use
cases, and we really don't want to handle a larger temporary buffer
than this size. The size check is performed at two places, where the
original period bytes is calculated and where the plugin buffer size
is calculated.
In addition, the driver uses array_size() and array3_size() for
multiplications to catch overflows for the converted period size and
buffer bytes.
Reported-by: syzbot+72732c532ac1454eeee9@syzkaller.appspotmail.com
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/00000000000085b1b305da5a66f3@google.com
Link: https://lore.kernel.org/r/20220318082036.29699-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 6fadb494a6 ]
Currently ALSA sequencer core tries to process the queued events as
much as possible when they become dispatchable. If applications try
to queue too massive events to be processed at the very same timing,
the sequencer core would still try to process such all events, either
in the interrupt context or via some notifier; in either away, it
might be a cause of RCU stall or such problems.
As a potential workaround for those problems, this patch adds the
upper limit of the amount of events to be processed. The remaining
events are processed in the next batch, so they won't be lost.
For the time being, it's limited up to 1000 events per queue, which
should be high enough for any normal usages.
Reported-by: Zqiang <qiang.zhang1211@gmail.com>
Reported-by: syzbot+bb950e68b400ab4f65f8@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20211102033222.3849-1-qiang.zhang1211@gmail.com
Link: https://lore.kernel.org/r/20211207165146.2888-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit b6409dd6bd upstream.
When control_compat.c:copy_ctl_value_to_user() is used, by
ctl_elem_read_user() & ctl_elem_write_user(), it must also copy back the
snd_ctl_elem_id value that may have been updated (filled in) by the call
to snd_ctl_elem_read/snd_ctl_elem_write().
This matches the functionality provided by snd_ctl_elem_read_user() and
snd_ctl_elem_write_user(), via snd_ctl_build_ioff().
Without this, and without making additional calls to snd_ctl_info()
which are unnecessary when using the non-compat calls, a userspace
application will not know the numid value for the element and
consequently will not be able to use the poll/read interface on the
control file to determine which elements have updates.
Signed-off-by: Alan Young <consult.awy@gmail.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20211202150607.543389-1-consult.awy@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 3c05f1477e ]
On m68k, compiling drivers under SND_ISA causes build errors:
../sound/core/isadma.c: In function 'snd_dma_program':
../sound/core/isadma.c:33:17: error: implicit declaration of function 'claim_dma_lock' [-Werror=implicit-function-declaration]
33 | flags = claim_dma_lock();
| ^~~~~~~~~~~~~~
../sound/core/isadma.c:41:9: error: implicit declaration of function 'release_dma_lock' [-Werror=implicit-function-declaration]
41 | release_dma_lock(flags);
| ^~~~~~~~~~~~~~~~
../sound/isa/sb/sb16_main.c: In function 'snd_sb16_playback_prepare':
../sound/isa/sb/sb16_main.c:253:72: error: 'DMA_AUTOINIT' undeclared (first use in this function)
253 | snd_dma_program(dma, runtime->dma_addr, size, DMA_MODE_WRITE | DMA_AUTOINIT);
| ^~~~~~~~~~~~
../sound/isa/sb/sb16_main.c:253:72: note: each undeclared identifier is reported only once for each function it appears in
../sound/isa/sb/sb16_main.c: In function 'snd_sb16_capture_prepare':
../sound/isa/sb/sb16_main.c:322:71: error: 'DMA_AUTOINIT' undeclared (first use in this function)
322 | snd_dma_program(dma, runtime->dma_addr, size, DMA_MODE_READ | DMA_AUTOINIT);
| ^~~~~~~~~~~~
and more...
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: alsa-devel@alsa-project.org
Cc: linux-m68k@lists.linux-m68k.org
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/20211016062602.3588-1-rdunlap@infradead.org
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit dce9446192 ]
Although we've covered all calls with NULL dma buffer pointer, so far,
there may be still some else in the wild. For catching such a case
more easily, add a WARN_ON_ONCE() in snd_dma_get_ops().
Fixes: 37af81c599 ("ALSA: core: Abstract memory alloc helpers")
Link: https://lore.kernel.org/r/20211105102103.28148-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit c0317c0e87 upstream.
When the timer instance was add into ack_list but was not currently in
process, the user could stop it via snd_timer_stop1() without delete it
from the ack_list. Then the user could free the timer instance and when
it was actually processed UAF occurred.
This issue could be reproduced via testcase snd_timer01 in ltp - running
several instances of that testcase at the same time.
What I actually met was that the ack_list of the timer broken and the
kernel went into deadloop with irqoff. That could be detected by
hardlockup detector on board or when we run it on qemu, we could use gdb
to dump the ack_list when the console has no response.
To fix this issue, we delete the timer instance from ack_list and
active_list unconditionally in snd_timer_stop1().
Signed-off-by: Wang Wensheng <wangwensheng4@huawei.com>
Suggested-by: Takashi Iwai <tiwai@suse.de>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20211103033517.80531-1-wangwensheng4@huawei.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Michael Forney reported an incorrect padding type that was defined in
the commit 80fe7430c7 ("ALSA: add new 32-bit layout for
snd_pcm_mmap_status/control") for PCM control mmap data.
His analysis is correct, and this caused the misplacements of PCM
control data on 32bit arch and 32bit compat mode.
The bug is that the __pad2 definition in __snd_pcm_mmap_control64
struct was wrongly with __pad_before_uframe, which should have been
__pad_after_uframe instead. This struct is used in SYNC_PTR ioctl and
control mmap. Basically this bug leads to two problems:
- The offset of avail_min field becomes wrong, it's placed right after
appl_ptr without padding on little-endian
- When appl_ptr and avail_min are read as 64bit values in kernel side,
the values become either zero or corrupted (mixed up)
One good news is that, because both user-space and kernel
misunderstand the wrong offset, at least, 32bit application running on
32bit kernel works as is. Also, 64bit applications are unaffected
because the padding size is zero. The remaining problem is the 32bit
compat mode; as mentioned in the above, avail_min is placed right
after appl_ptr on little-endian archs, 64bit kernel reads bogus values
for appl_ptr updates, which may lead to streaming bugs like jumping,
XRUN or whatever unexpected.
(However, we haven't heard any serious bug reports due to this over
years, so practically seen, it's fairly safe to assume that the impact
by this bug is limited.)
Ideally speaking, we should correct the wrong mmap status control
definition. But this would cause again incompatibility with the
existing binaries, and fixing it (e.g. by renumbering ioctls) would be
really messy.
So, as of this patch, we only correct the behavior of 32bit compat
mode and keep the rest as is. Namely, the SYNC_PTR ioctl is now
handled differently in compat mode to read/write the 32bit values at
the right offsets. The control mmap of 32bit apps on 64bit kernels
has been already disabled (which is likely rather an overlook, but
this worked fine at this time :), so covering SYNC_PTR ioctl should
suffice as a fallback.
Fixes: 80fe7430c7 ("ALSA: add new 32-bit layout for snd_pcm_mmap_status/control")
Reported-by: Michael Forney <mforney@mforney.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Cc: <stable@vger.kernel.org>
Cc: Rich Felker <dalias@libc.org>
Link: https://lore.kernel.org/r/29QBMJU8DE71E.2YZSH8IHT5HMH@mforney.org
Link: https://lore.kernel.org/r/20211010075546.23220-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
John Keeping reported and posted a patch for a potential UAF in
rawmidi sequencer destruction: the snd_rawmidi_dev_seq_free() may be
called after the associated rawmidi object got already freed.
After a deeper look, it turned out that the bug is rather the
incorrect private_free call order for a snd_seq_device. The
snd_seq_device private_free gets called at the release callback of the
sequencer device object, while this was rather expected to be executed
at the snd_device call chains that runs at the beginning of the whole
card-free procedure. It's been broken since the rewrite of
sequencer-device binding (although it hasn't surfaced because the
sequencer device release happens usually right along with the card
device release).
This patch corrects the private_free call to be done in the right
place, at snd_seq_device_dev_free().
Fixes: 7c37ae5c62 ("ALSA: seq: Rewrite sequencer device binding with standard bus")
Reported-and-tested-by: John Keeping <john@metanate.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210930114114.8645-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Pull Kbuild updates from Masahiro Yamada:
- Add -s option (strict mode) to merge_config.sh to make it fail when
any symbol is redefined.
- Show a warning if a different compiler is used for building external
modules.
- Infer --target from ARCH for CC=clang to let you cross-compile the
kernel without CROSS_COMPILE.
- Make the integrated assembler default (LLVM_IAS=1) for CC=clang.
- Add <linux/stdarg.h> to the kernel source instead of borrowing
<stdarg.h> from the compiler.
- Add Nick Desaulniers as a Kbuild reviewer.
- Drop stale cc-option tests.
- Fix the combination of CONFIG_TRIM_UNUSED_KSYMS and CONFIG_LTO_CLANG
to handle symbols in inline assembly.
- Show a warning if 'FORCE' is missing for if_changed rules.
- Various cleanups
* tag 'kbuild-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (39 commits)
kbuild: redo fake deps at include/ksym/*.h
kbuild: clean up objtool_args slightly
modpost: get the *.mod file path more simply
checkkconfigsymbols.py: Fix the '--ignore' option
kbuild: merge vmlinux_link() between ARCH=um and other architectures
kbuild: do not remove 'linux' link in scripts/link-vmlinux.sh
kbuild: merge vmlinux_link() between the ordinary link and Clang LTO
kbuild: remove stale *.symversions
kbuild: remove unused quiet_cmd_update_lto_symversions
gen_compile_commands: extract compiler command from a series of commands
x86: remove cc-option-yn test for -mtune=
arc: replace cc-option-yn uses with cc-option
s390: replace cc-option-yn uses with cc-option
ia64: move core-y in arch/ia64/Makefile to arch/ia64/Kbuild
sparc: move the install rule to arch/sparc/Makefile
security: remove unneeded subdir-$(CONFIG_...)
kbuild: sh: remove unused install script
kbuild: Fix 'no symbols' warning when CONFIG_TRIM_UNUSD_KSYMS=y
kbuild: Switch to 'f' variants of integrated assembler flag
kbuild: Shuffle blank line to improve comment meaning
...
Takashi Iwai
Jaroslav Kysela
Clement Lecigne
Kees Cook
Andreas Pape
Amadeusz Sławiński
Colin Ian King
Fabio M. De Francesco
Bixuan Cui
Xiaoke Wang
Alan Young
Randy Dunlap
Wang Wensheng
Pavel Skripkin
Linus Torvalds