Linux kernel
============
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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 reStructuredText 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.
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Pull more clocksource updates from Thomas Gleixner:
"A set of updates for clocksource and clockevent drivers:
- A fix for the prescaler of the ARM global timer where the prescaler
mask define only covered 4 bits while it is actully 8 bits wide.
This obviously restricted the possible range of prescaler
adjustments
- A fix for the RISC-V timer which prevents a timer interrupt being
raised while the timer is initialized
- A set of device tree updates to support new system on chips in
various drivers
- Kernel-doc and other cleanups all over the place"
* tag 'timers-core-2024-03-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
clocksource/drivers/timer-riscv: Clear timer interrupt on timer initialization
dt-bindings: timer: Add support for cadence TTC PWM
clocksource/drivers/arm_global_timer: Simplify prescaler register access
clocksource/drivers/arm_global_timer: Guard against division by zero
clocksource/drivers/arm_global_timer: Make gt_target_rate unsigned long
dt-bindings: timer: add Ralink SoCs system tick counter
clocksource: arm_global_timer: fix non-kernel-doc comment
clocksource/drivers/arm_global_timer: Remove stray tab
clocksource/drivers/arm_global_timer: Fix maximum prescaler value
clocksource/drivers/imx-sysctr: Add i.MX95 support
clocksource/drivers/imx-sysctr: Drop use global variables
dt-bindings: timer: nxp,sysctr-timer: support i.MX95
dt-bindings: timer: renesas: ostm: Document RZ/Five SoC
dt-bindings: timer: renesas,tmu: Document input capture interrupt
clocksource/drivers/ti-32K: Fix misuse of "/**" comment
clocksource/drivers/stm32: Fix all kernel-doc warnings
dt-bindings: timer: exynos4210-mct: Add google,gs101-mct compatible
clocksource/drivers/imx: Fix -Wunused-but-set-variable warning
Pull irq fixes from Thomas Gleixner:
"A series of fixes for the Renesas RZG21 interrupt chip driver to
prevent spurious and misrouted interrupts.
- Ensure that posted writes are flushed in the eoi() callback
- Ensure that interrupts are masked at the chip level when the
trigger type is changed
- Clear the interrupt status register when setting up edge type
trigger modes
- Ensure that the trigger type and routing information is set before
the interrupt is enabled"
* tag 'irq-urgent-2024-03-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
irqchip/renesas-rzg2l: Do not set TIEN and TINT source at the same time
irqchip/renesas-rzg2l: Prevent spurious interrupts when setting trigger type
irqchip/renesas-rzg2l: Rename rzg2l_irq_eoi()
irqchip/renesas-rzg2l: Rename rzg2l_tint_eoi()
irqchip/renesas-rzg2l: Flush posted write in irq_eoi()
Pull clocksource/event driver updates from Daniel Lezcano:
- Fix -Wunused-but-set-variable warning for the iMX GPT timer (Daniel
Lezcano)
- Add Pixel6 compatible string for Exynos 4210 MCT timer (Peter Griffin)
- Fix all kernel-doc warnings and misuse of comment format (Randy
Dunlap)
- Document in the DT bindings the interrupt used for input capture
interrupt and udpate the example to match the reality (Geert
Uytterhoeven)
- Document RZ/Five SoC DT bindings (Lad Prabhakar)
- Add DT bindings support for the i.MX95, reorganize the driver to
move globale variables to a timer private structure and introduce
the i.MX95 timer support (Peng Fan)
- Fix prescalar value to conform to the ARM global timer
documentation. Fix data types and comparison, guard the divide by
zero code section and use the available macros for bit manipulation
(Martin Blumenstingl)
- Add Ralink SoCs system tick counter (Sergio Paracuellos)
- Add support for cadence TTC PWM (Mubin Sayyed)
- Clear timer interrupt on timer initialization to prevent the
interrupt to fire during setup (Ley Foon Tan)
Link: https://lore.kernel.org/r/5552010a-1ce2-46a1-a740-a69f2e9a2cf2@linaro.org
Pull core entry fix from Thomas Gleixner:
"A single fix for the generic entry code:
The trace_sys_enter() tracepoint can modify the syscall number via
kprobes or BPF in pt_regs, but that requires that the syscall number
is re-evaluted from pt_regs after the tracepoint.
A seccomp fix in that area removed the re-evaluation so the change
does not take effect as the code just uses the locally cached number.
Restore the original behaviour by re-evaluating the syscall number
after the tracepoint"
* tag 'core-entry-2024-03-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
entry: Respect changes to system call number by trace_sys_enter()
As per the hardware team, TIEN and TINT source should not set at the same
time due to a possible hardware race leading to spurious IRQ.
Currently on some scenarios hardware settings for TINT detection is not in
sync with TINT source as the enable/disable overrides source setting value
leading to hardware inconsistent state. For eg: consider the case GPIOINT0
is used as TINT interrupt and configuring GPIOINT5 as edge type. During
rzg2l_irq_set_type(), TINT source for GPIOINT5 is set. On disable(),
clearing of the entire bytes of TINT source selection for GPIOINT5 is same
as GPIOINT0 with TIEN disabled. Apart from this during enable(), the
setting of GPIOINT5 with TIEN results in spurious IRQ as due to a HW race,
it is possible that IP can use the TIEN with previous source value
(GPIOINT0).
So, just update TIEN during enable/disable as TINT source is already set
during rzg2l_irq_set_type(). This will make the consistent hardware
settings for detection method tied with TINT source and allows to simplify
the code.
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
When a CPU is the last active in the hierarchy and it tries to enter
into idle, the quick check looking up the next event towards cpuidle
heuristics may report a too late expiry, such as in the following
scenario:
[GRP1:0]
migrator = NONE
active = NONE
nextevt = T0:0, T0:1
/ \
[GRP0:0] [GRP0:1]
migrator = NONE migrator = NONE
active = NONE active = NONE
nextevt = T0, T1 nextevt = T2
/ \ / \
0 1 2 3
idle idle idle idle
0) The whole system is idle, and CPU 0 was the last migrator. CPU 0 has
a timer (T0), CPU 1 has a timer (T1) and CPU 2 has a timer (T2). The
expire order is T0 < T1 < T2.
[GRP1:0]
migrator = GRP0:0
active = GRP0:0
nextevt = T0:0(i), T0:1
/ \
[GRP0:0] [GRP0:1]
migrator = CPU0 migrator = NONE
active = CPU0 active = NONE
nextevt = T0(i), T1 nextevt = T2
/ \ / \
0 1 2 3
active idle idle idle
1) CPU 0 becomes active. The (i) means a now ignored timer.
[GRP1:0]
migrator = GRP0:0
active = GRP0:0
nextevt = T0:1
/ \
[GRP0:0] [GRP0:1]
migrator = CPU0 migrator = NONE
active = CPU0 active = NONE
nextevt = T1 nextevt = T2
/ \ / \
0 1 2 3
active idle idle idle
2) CPU 0 handles remote. No timer actually expired but ignored timers
have been cleaned out and their sibling's timers haven't been
propagated. As a result the top level's next event is T2 and not T1.
3) CPU 0 tries to enter idle without any global timer enqueued and calls
tmigr_quick_check(). The expiry of T2 is returned instead of the
expiry of T1.
When the quick check returns an expiry that is too late, the cpuidle
governor may pick up a C-state that is too deep. This may be result into
undesired CPU wake up latency if the next timer is actually close enough.
Fix this with assuming that expiries aren't sorted top-down while
performing the quick check. Pick up instead the earliest encountered one
while walking up the hierarchy.
7ee988770326 ("timers: Implement the hierarchical pull model")
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240305002822.18130-1-frederic@kernel.org
In the RISC-V specification, the stimecmp register doesn't have a default
value. To prevent the timer interrupt from being triggered during timer
initialization, clear the timer interrupt by writing stimecmp with a
maximum value.
Fixes: 9f7a8ff6391f ("RISC-V: Prefer sstc extension if available")
Cc: <stable@vger.kernel.org>
Signed-off-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
Reviewed-by: Samuel Holland <samuel.holland@sifive.com>
Tested-by: Samuel Holland <samuel.holland@sifive.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20240306172330.255844-1-leyfoon.tan@starfivetech.com
Pull more powerpc updates from Michael Ellerman:
- Handle errors in mark_rodata_ro() and mark_initmem_nx()
- Make struct crash_mem available without CONFIG_CRASH_DUMP
Thanks to Christophe Leroy and Hari Bathini.
* tag 'powerpc-6.9-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
powerpc/kdump: Split KEXEC_CORE and CRASH_DUMP dependency
powerpc/kexec: split CONFIG_KEXEC_FILE and CONFIG_CRASH_DUMP
kexec/kdump: make struct crash_mem available without CONFIG_CRASH_DUMP
powerpc: Handle error in mark_rodata_ro() and mark_initmem_nx()
When a probe is registered at the trace_sys_enter() tracepoint, and that
probe changes the system call number, the old system call still gets
executed. This worked correctly until commit b6ec41346103 ("core/entry:
Report syscall correctly for trace and audit"), which removed the
re-evaluation of the syscall number after the trace point.
Restore the original semantics by re-evaluating the system call number
after trace_sys_enter().
The performance impact of this re-evaluation is minimal because it only
takes place when a trace point is active, and compared to the actual trace
point overhead the read from a cache hot variable is negligible.
Fixes: b6ec41346103 ("core/entry: Report syscall correctly for trace and audit")
Signed-off-by: André Rösti <an.roesti@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240311211704.7262-1-an.roesti@gmail.com
RZ/G2L interrupt chips require that the interrupt is masked before changing
the NMI, IRQ, TINT interrupt settings. Aside of that, after setting an edge
trigger type it is required to clear the interrupt status register in order
to avoid spurious interrupts.
The current implementation fails to do either of that and therefore is
prone to generate spurious interrupts when setting the trigger type.
Address this by:
- Ensuring that the interrupt is masked at the chip level across the
update for the TINT chip
- Clearing the interrupt status register after updating the trigger mode
for edge type interrupts
[ tglx: Massaged changelog and reverted the spin_lock_irqsave() change as
the set_type() callback is always called with interrupts disabled. ]
Fixes: 3fed09559cd8 ("irqchip: Add RZ/G2L IA55 Interrupt Controller driver")
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
In configurations with CONFIG_TICK_ONESHOT but no CONFIG_NO_HZ or
CONFIG_HIGH_RES_TIMERS, tick_sched_timer_dying() is stubbed out,
but still defined as a global function as well:
kernel/time/tick-sched.c:1599:6: error: redefinition of 'tick_sched_timer_dying'
1599 | void tick_sched_timer_dying(int cpu)
| ^
kernel/time/tick-sched.h:111:20: note: previous definition is here
111 | static inline void tick_sched_timer_dying(int cpu) { }
| ^
This configuration only appears with ARM CONFIG_ARCH_BCM_MOBILE,
which should not actually select CONFIG_TICK_ONESHOT.
Adjust the #ifdef for the stub to match the condition for building the
tick-sched.c file for consistency with the definition and to avoid
the build regression.
Fixes: 3aedb7fcd88a ("tick/sched: Remove useless oneshot ifdeffery")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240228123850.3499024-1-arnd@kernel.org
Cadence TTC can act as PWM device, it will be supported through
separate PWM framework based driver. Decision to configure
specific TTC device as PWM or clocksource/clockevent would
be done based on presence of "#pwm-cells" property.
Also, interrupt property is not required for TTC PWM driver.
Update bindings to support TTC PWM configuration.
Signed-off-by: Mubin Sayyed <mubin.sayyed@amd.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20240226093333.2581092-1-mubin.sayyed@amd.com
Pull ARM updates from Russell King:
- remove a misuse of kernel-doc comment
- use "Call trace:" for backtraces like other architectures
- implement copy_from_kernel_nofault_allowed() to fix a LKDTM test
- add a "cut here" line for prefetch aborts
- remove unnecessary Kconfing entry for FRAME_POINTER
- remove iwmmxy support for PJ4/PJ4B cores
- use bitfield helpers in ptrace to improve readabililty
- check if folio is reserved before flushing
* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
ARM: 9359/1: flush: check if the folio is reserved for no-mapping addresses
ARM: 9354/1: ptrace: Use bitfield helpers
ARM: 9352/1: iwmmxt: Remove support for PJ4/PJ4B cores
ARM: 9353/1: remove unneeded entry for CONFIG_FRAME_POINTER
ARM: 9351/1: fault: Add "cut here" line for prefetch aborts
ARM: 9350/1: fault: Implement copy_from_kernel_nofault_allowed()
ARM: 9349/1: unwind: Add missing "Call trace:" line
ARM: 9334/1: mm: init: remove misuse of kernel-doc comment
Remove CONFIG_CRASH_DUMP dependency on CONFIG_KEXEC. CONFIG_KEXEC_CORE
was used at places where CONFIG_CRASH_DUMP or CONFIG_CRASH_RESERVE was
appropriate. Replace with appropriate #ifdefs to support CONFIG_KEXEC
and !CONFIG_CRASH_DUMP configuration option. Also, make CONFIG_FA_DUMP
dependent on CONFIG_CRASH_DUMP to avoid unmet dependencies for FA_DUMP
with !CONFIG_KEXEC_CORE configuration option.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240226103010.589537-4-hbathini@linux.ibm.com