tjh.dev
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
code
Clone this repository
https://tangled.org/tjh.dev/kernel
git@gordian.tjh.dev:tjh.dev/kernel
For self-hosted knots, clone URLs may differ based on your setup.
Pull irq fix from Thomas Gleixner:
"A single fix for a regression caused by the recent PCI/MSI rework
which resulted in a recursive locking problem in the VMD driver.
The cure is to cache the relevant information upfront instead of
retrieving it at runtime"
* tag 'irq-urgent-2022-02-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
PCI: vmd: Prevent recursive locking on interrupt allocation
Pull dma-mapping fix from Christoph Hellwig:
- fix a swiotlb info leak (Halil Pasic)
* tag 'dma-mapping-5.17-1' of git://git.infradead.org/users/hch/dma-mapping:
swiotlb: fix info leak with DMA_FROM_DEVICE
Tejas reported the following recursive locking issue:
swapper/0/1 is trying to acquire lock:
ffff8881074fd0a0 (&md->mutex){+.+.}-{3:3}, at: msi_get_virq+0x30/0xc0
but task is already holding lock:
ffff8881017cd6a0 (&md->mutex){+.+.}-{3:3}, at: __pci_enable_msi_range+0xf2/0x290
stack backtrace:
__mutex_lock+0x9d/0x920
msi_get_virq+0x30/0xc0
pci_irq_vector+0x26/0x30
vmd_msi_init+0xcc/0x210
msi_domain_alloc+0xbf/0x150
msi_domain_alloc_irqs_descs_locked+0x3e/0xb0
__pci_enable_msi_range+0x155/0x290
pci_alloc_irq_vectors_affinity+0xba/0x100
pcie_port_device_register+0x307/0x550
pcie_portdrv_probe+0x3c/0xd0
pci_device_probe+0x95/0x110
This is caused by the VMD MSI code which does a lookup of the Linux
interrupt number for an VMD managed MSI[X] vector. The lookup function
tries to acquire the already held mutex.
Avoid that by caching the Linux interrupt number at initialization time
instead of looking it up over and over.
Fixes: 82ff8e6b78fc ("PCI/MSI: Use msi_get_virq() in pci_get_vector()")
Reported-by: "Surendrakumar Upadhyay, TejaskumarX" <tejaskumarx.surendrakumar.upadhyay@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: "Surendrakumar Upadhyay, TejaskumarX" <tejaskumarx.surendrakumar.upadhyay@intel.com>
Cc: linux-pci@vger.kernel.org
Link: https://lore.kernel.org/r/87a6euub2a.ffs@tglx
Pull pin control fixes from Linus Walleij:
- Fix some drive strength and pull-up code in the K210 driver.
- Add the Alder Lake-M ACPI ID so it starts to work properly.
- Use a static name for the StarFive GPIO irq_chip, forestalling an
upcoming fixes series from Marc Zyngier.
- Fix an ages old bug in the Tegra 186 driver where we were indexing at
random into struct and being lucky getting the right member.
* tag 'pinctrl-v5-17-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
gpio: tegra186: Fix chip_data type confusion
pinctrl: starfive: Use a static name for the GPIO irq_chip
pinctrl: tigerlake: Revert "Add Alder Lake-M ACPI ID"
pinctrl: k210: Fix bias-pull-up
pinctrl: fix loop in k210_pinconf_get_drive()
The problem I'm addressing was discovered by the LTP test covering
cve-2018-1000204.
A short description of what happens follows:
1) The test case issues a command code 00 (TEST UNIT READY) via the SG_IO
interface with: dxfer_len == 524288, dxdfer_dir == SG_DXFER_FROM_DEV
and a corresponding dxferp. The peculiar thing about this is that TUR
is not reading from the device.
2) In sg_start_req() the invocation of blk_rq_map_user() effectively
bounces the user-space buffer. As if the device was to transfer into
it. Since commit a45b599ad808 ("scsi: sg: allocate with __GFP_ZERO in
sg_build_indirect()") we make sure this first bounce buffer is
allocated with GFP_ZERO.
3) For the rest of the story we keep ignoring that we have a TUR, so the
device won't touch the buffer we prepare as if the we had a
DMA_FROM_DEVICE type of situation. My setup uses a virtio-scsi device
and the buffer allocated by SG is mapped by the function
virtqueue_add_split() which uses DMA_FROM_DEVICE for the "in" sgs (here
scatter-gather and not scsi generics). This mapping involves bouncing
via the swiotlb (we need swiotlb to do virtio in protected guest like
s390 Secure Execution, or AMD SEV).
4) When the SCSI TUR is done, we first copy back the content of the second
(that is swiotlb) bounce buffer (which most likely contains some
previous IO data), to the first bounce buffer, which contains all
zeros. Then we copy back the content of the first bounce buffer to
the user-space buffer.
5) The test case detects that the buffer, which it zero-initialized,
ain't all zeros and fails.
One can argue that this is an swiotlb problem, because without swiotlb
we leak all zeros, and the swiotlb should be transparent in a sense that
it does not affect the outcome (if all other participants are well
behaved).
Copying the content of the original buffer into the swiotlb buffer is
the only way I can think of to make swiotlb transparent in such
scenarios. So let's do just that if in doubt, but allow the driver
to tell us that the whole mapped buffer is going to be overwritten,
in which case we can preserve the old behavior and avoid the performance
impact of the extra bounce.
Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Pull tracing fixes from Steven Rostedt:
- rtla (Real-Time Linux Analysis tool):
- fix typo in man page
- Update API -e to -E before it is released
- Error message fix and memory leak fix
- Partially uninline trace event soft disable to shrink text
- Fix function graph start up test
- Have triggers affect the trace instance they are in and not top level
- Have osnoise sleep in the units it says it uses
- Remove unused ftrace stub function
- Remove event probe redundant info from event in the buffer
- Fix group ownership setting in tracefs
- Ensure trace buffer is minimum size to prevent crashes
* tag 'trace-v5.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
rtla/osnoise: Fix error message when failing to enable trace instance
rtla/osnoise: Free params at the exit
rtla/hist: Make -E the short version of --entries
tracing: Fix selftest config check for function graph start up test
tracefs: Set the group ownership in apply_options() not parse_options()
tracing/osnoise: Make osnoise_main to sleep for microseconds
ftrace: Remove unused ftrace_startup_enable() stub
tracing: Ensure trace buffer is at least 4096 bytes large
tracing: Uninline trace_trigger_soft_disabled() partly
eprobes: Remove redundant event type information
tracing: Have traceon and traceoff trigger honor the instance
tracing: Dump stacktrace trigger to the corresponding instance
rtla: Fix systme -> system typo on man page
intel-pinctrl for v5.17-5
* Revert misplaced ID
The following is an automated git shortlog grouped by driver:
tigerlake:
- Revert "Add Alder Lake-M ACPI ID"
Pull locking fix from Borislav Petkov:
"Fix a NULL ptr dereference when dumping lockdep chains through
/proc/lockdep_chains"
* tag 'locking_urgent_for_v5.17_rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
lockdep: Correct lock_classes index mapping
Pull memblock fix from Mike Rapoport:
"Use kfree() to release kmalloced memblock regions
memblock.{reserved,memory}.regions may be allocated using kmalloc()
in memblock_double_array(). Use kfree() to release these kmalloced
regions"
* tag 'fixes-2022-02-26' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock:
memblock: use kfree() to release kmalloced memblock regions
When a trace instance creation fails, tools are printing:
Could not enable -> osnoiser <- tracer for tracing
Print the actual (and correct) name of the tracer it fails to enable.
Link: https://lkml.kernel.org/r/53ef0582605af91eca14b19dba9fc9febb95d4f9.1645206561.git.bristot@kernel.org
Fixes: b1696371d865 ("rtla: Helper functions for rtla")
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
The tegra186 GPIO driver makes the assumption that the pointer
returned by irq_data_get_irq_chip_data() is a pointer to a
tegra_gpio structure. Unfortunately, it is actually a pointer
to the inner gpio_chip structure, as mandated by the gpiolib
infrastructure. Nice try.
The saving grace is that the gpio_chip is the first member of
tegra_gpio, so the bug has gone undetected since... forever.
Fix it by performing a container_of() on the pointer. This results
in no additional code, and makes it possible to understand how
the whole thing works.
Fixes: 5b2b135a87fc ("gpio: Add Tegra186 support")
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: Thierry Reding <treding@nvidia.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Link: https://lore.kernel.org/r/20220211093904.1112679-1-maz@kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
README