Integrates object core statistics framework into the following
kernel objects:
sys_mem_blocks, k_mem_slab
threads, _cpu, z_kernel
Signed-off-by: Peter Mitsis <peter.mitsis@intel.com>
This internal kernel API is misplaced in a public kernel header. Just
make it available to the code using it in the kernel.
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
The _EXPIRED macro is no longer necessary. It is a relic of an older
timeout processing algorithm from several years ago.
Signed-off-by: Peter Mitsis <peter.mitsis@intel.com>
This is a private kernel header with private kernel APIs, it should not
be exposed in the public zephyr include directory.
Once sample remains to be fixed (metairq_dispatch), which currently uses
private APIs from that header, it should not be the case.
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
This header does not expose any public APIs, so move it under
kernel/include and change files including it.
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
While the LOCKED pattern is universally useful it can be misused. This
change therefore exposes the LOCKED pattern with extensive usage
documentation to reduce the risk of abuse or unintended deadlock.
Signed-off-by: Florian Grandel <fgrandel@code-for-humans.de>
Device dependencies are not always required, so make them optional via
CONFIG_DEVICE_DEPS. When enabled, the gen_device_deps script will run so
that dependencies are collected and part of the final image. Related
APIs will be also made available. Since device dependencies are used in
just a few places (power domains), disable the feature by default. When
not enabled, a second linking pass will not be required.
Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>
Rename struct device `handles` member to `deps`, in line with previous
renamings in the device API.
Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>
The switch_handle field in the thread struct is used as an atomic flag
between CPUs in SMP, and has been known for a long time to technically
require memory barriers for correct operation. We have an API for
that now, so put them in:
* The code immediately before arch_switch() needs a write barrier to
ensure that thread state written by the scheduler is seen to happen
before the outgoing thread is flagged with a valid switch handle.
* The loop in z_sched_switch_spin() needs a read barrier at the end,
to make sure the calling context doesn't load state from before the
other CPU stored the switch handle.
Also, that same spot in switch_spin was spinning with interrupts held,
which means it needs a call to arch_spin_relax() to avoid a FPU state
deadlock on some architectures.
Signed-off-by: Andy Ross <andyross@google.com>
This trick turns out also to be needed by the abort/join code.
Promote it to a more formal-looking internal API and clean up the
documentation to (hopefully) clarify the exact behavior and better
explain the need.
This is one of the more... enchanted bits of the scheduler, and while
the trick is IMHO pretty clean, it remains a big SMP footgun.
Signed-off-by: Andy Ross <andyross@google.com>
z_page_frame can't be packed on Xtensa due memory alignment
constraints. When this is struct is packed it is 5 bytes long it will
cause an memory alignment problem on Xtensa.
Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>
Removes unused absolute symbols that are defined via the
GEN_ABSOLUTE_SYM() macro in the kernel directory.
Signed-off-by: Peter Mitsis <peter.mitsis@intel.com>
Rework the fragile and ad-hoc computation of timeslice expirations
into per-CPU struct _timeout objects with regular callbacks. The
expiration callbacks themselves simply set a per-cpu flag (they might
run on any CPU), which gets checked at the end of the timer ISR on
every CPU.
This simplifies logic and removes a bunch of code. It also fixes at
least three bugs:
1. As @npitre discovered: On SMP, the number of ticks announced on any
given CPU is going to be a subset of all expired ticks. This broke
the accounting of timeslice ticks, and effectively meant that
timeslicing only worked on SMP on systems where one CPU could hog all
the announcements, and only on that CPU.
2. The bootstrap path to arm the timer driver after setting the first
timeout in an empty list couldn't take into account
sys_clock_elapsed() ticks, as it didn't know whether it was being
called underneath an existing announce loop. Now this code is no
longer responsible for knowing anything about time slicing at all.
3. Also on SMP, there was a case where two CPUs timeslicing
simultaneously could stomp on each others' timeouts in
z_set_timeout_expiry(), as neither had a way of knowing what the
other's state was. CPUs could miss their own expiration and have to
wait for the slice expiration on the other CPU. Now, timeouts are
global objects with simple expiration times, and there's no need for
that function at all.
Signed-off-by: Andy Ross <andyross@google.com>
Some of the offset symbols that are derived from the macro
GEN_OFFSET_SYM() are not used anywhere in the Zephyr codebase.
Remove them as part of a cleanup effort.
Instances of an associated GEN_OFFSET_SYM() have also been
removed when the resulting macro is no longer referenced.
Signed-off-by: Peter Mitsis <peter.mitsis@intel.com>
Some of the offset symbols generated via the macro GEN_OFFSET_SYM()
are not used anywhere in the Zephyr codebase. Remove them as part of
a cleanup effort.
Signed-off-by: Peter Mitsis <peter.mitsis@intel.com>
Adds a routine to safely walk a specified wait queue and invoke a
custom callback function on each waiting thread.
Signed-off-by: Peter Mitsis <peter.mitsis@intel.com>
The interrupt stack is used as the system stack during kernel
initialization while IRQs are not yet enabled. The sp register is
set to z_interrupt_stacks + CONFIG_ISR_STACK_SIZE.
CONFIG_ISR_STACK_SIZE only represents the desired usable stack size.
This does not take into account the added guard area. Result is a stack
whose pointer is much closer to the trigger zone than expected when
CONFIG_PMP_STACK_GUARD=y, and the SMP configuration in particular pushes
it over the edge during many CI test cases.
Worse: during early init we're not quite ready to handle exceptions
yet and complete havoc ensues with no meaningful debugging output.
Make sure the early assembly code locates the actual top of the stack
by generating a constant with its true size.
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Fixes#46324
Set dummy_thread->base.slice_ticks to 0 when
CONFIG_TIMESLICE_PER_THREAD is set. To avoid
_current_cpu->slice_ticks be a big number.
Signed-off-by: Hu Zhenyu <zhenyu.hu@intel.com>
MISRA C:2012 Rule 14.4 (The controlling expression of an if statement
and the controlling expression of an iteration-statement shall have
essentially Boolean type.)
Use `bool' instead of `int' to represent Boolean values.
Use `do { ... } while (false)' instead of `do { ... } while (0)'.
Use comparisons with zero instead of implicitly testing integers.
This commit is a subset of the original commit:
5d02614e34a86b549c7707d3d9f0984bc3a5f22a
Signed-off-by: Simon Hein <SHein@baumer.com>
This commit updates all deprecated `K_KERNEL_PINNED_STACK_ARRAY_EXTERN`
macro usages to use the `K_KERNEL_PINNED_STACK_ARRAY_DECLARE` macro
instead.
Signed-off-by: Stephanos Ioannidis <root@stephanos.io>
In order to bring consistency in-tree, migrate all kernel code to the
new prefix <zephyr/...>. Note that the conversion has been scripted,
refer to zephyrproject-rtos#45388 for more details.
Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>
This adds lazy floating point context switching. On svc/irq entrance,
the VFP is disabled and a pointer to the exception stack frame is saved
away. If the esf pointer is still valid on exception exit, then no
other context used the VFP so the context is still valid and nothing
needs to be restored. If the esf pointer is NULL on exception exit,
then some other context used the VFP and the floating point context is
restored from the esf.
The undefined instruction handler is responsible for saving away the
floating point context if needed. If the handler is in the first
irq/svc context and the current thread uses the VFP, then the float
context needs to be saved. Also, if the handler is in a nested context
and the previous context was using the FVP, save the float context.
Signed-off-by: Bradley Bolen <bbolen@lexmark.com>
Instead of resizing all devices handles, we just resize devices that are
power domains. This means that a power domain has to be declared as
compatbile with "power-domain" in device tree node.
Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>
Zephyr's timeslice implementation has always been somewhat primitive.
You get a global timeslice that applies broadly to the whole bottom of
the priority space, with no ability (beyond that one priority
threshold) to tune it to work on certain threads, etc...
This adds an (optionally configurable) API that allows timeslicing to
be controlled on a per-thread basis: any thread at any priority can be
set to timeslice, for a configurable per-thread slice time, and at the
end of its slice a callback can be provided that can take action.
This allows the application to implement things like responsiveness
heuristics, "fair" scheduling algorithms, etc... without requiring
that facility in the core kernel.
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
Zeroing the BSS and copying data to RAM with regular memset/memcpy may
cause problems when those functions are assuming a fully initialized
system for their optimizations to work e.g. some instructions require
an active MMU, but turning the MMU on needs the .bss section to be
cleared first, etc.
Commit c5b898743a ("aarch64: Fix alignment fault on z_bss_zero()")
provides a detailed explanation of such a case.
Replacing z_bss_zero() with an architecture specific one is problematic
as the former may see new sections added to it that would be missed by
the later. The same reasoning goes for z_data_copy().
Let's make maintenance much easier by providing weak versions of
memset/memcpy that can be overridden by architecture-specific safe
versions when needed.
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Extracting stack usage calculation from k_thread_stack_space_get to
z_stack_space_get so it can be used also for interrupt stack.
Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>
There is no need to use conditional compilation for the function
prototypes in the kernel architecture header file. So remove it.
Added bouns is that these functions can appear in documentation
without explicitly enabled in pre-defines during doc build.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
Extends the CPU usage runtime stats to track current, total, peak
and average usage (as bounded by the scheduling of the idle thread).
This permits a developer to obtain more system information if desired
to tune the system.
Signed-off-by: Peter Mitsis <peter.mitsis@intel.com>
This commit does two things to the z_sched_thread_usage(). First,
it updates the API so that it accepts a pointer to the runtime
stats instead of simply returning the usage cycles. This gives it
the flexibility to retrieve additional statistics in the future.
Second, the runtime stats are only updated if the specified thread
is the current thread running on the current core.
Signed-off-by: Peter Mitsis <peter.mitsis@intel.com>
The resource pool of the short-lived dummy thread "stub" may be
inherited by other threads created during system initialization. This
commit initializes this resource pool to NULL or the system pool to
ensure that a well-defined resource pool propagates to other threads
that inherit it from the dummy thread.
Fixes#41482.
Signed-off-by: Berend Ozceri <berend@recogni.com>
Storing the state where this is the first GDB break can be done
in the main GDB stub code. There is no need to store the state
in architecture layer.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
Remove LOG_MINIMAL kconfig option which was confusing
since LOG_MODE_MINIMAL existed. LOG_MINIMAL was used to
force minimal mode but because of invalid dependencies
it was leading to issues.
Refactored code to use LOG_MODE_MINIMAL everywhere and
renamed LOG_MINIMAL to LOG_DEFAULT_MINIMAL which has impact
on defualt logging mode (which still can be later changed
in conf file or in menuconfig).
Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>
Clean up RUNTIME_STATS to separate the API from the individual data
backends. Use the SCHED_THREAD_USAGE tracking instead of the original
for execution_cycles. Move the kconfig for that into the runtime
stats menu, since it's part of the family now.
Also remove a lot of needless #if's around the declarations. Unused
structs and uncalled functions don't need to be explicitly hidden. An
attempt to access a non-existent field (e.g. "execution_cycles" if
that isn't configured) provides all the build time validation we need.
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
This is an alternate backend that does what THREAD_RUNTIME_STATS is
doing currently, but with a few advantages:
* Correctly synchronized: you can't race against a running thread
(potentially on another CPU!) while querying its usage.
* Realtime results: you get the right answer always, up to timer
precision, even if a thread has been running for a while
uninterrupted and hasn't updated its total.
* Portable, no need for per-architecture code at all for the simple
case. (It leverages the USE_SWITCH layer to do this, so won't work
on older architectures)
* Faster/smaller: minimizes use of 64 bit math; lower overhead in
thread struct (keeps the scratch "started" time in the CPU struct
instead). One 64 bit counter per thread and a 32 bit scratch
register in the CPU struct.
* Standalone. It's a core (but optional) scheduler feature, no
dependence on para-kernel configuration like the tracing
infrastructure.
* More precise: allows architectures to optionally call a trivial
zero-argument/no-result cdecl function out of interrupt entry to
avoid accounting for ISR runtime in thread totals. No configuration
needed here, if it's called then you get proper ISR accounting, and
if not you don't.
For right now, pending unification, it's added side-by-side with the
older API and left as a z_*() internal symbol.
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
Instead of returning PM_STATE_ACTIVE for when the cpu didn't enter a
low power state and a different state when it entered, but has
already left the state and is active again, it changes
pm_system_suspend to return true when the cpu has entered a low power
state and false otherwise.
Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>
There was a brief (but seen in practice on real apps on real
hardware!) race with the switch-based z_swap() implementation. The
thread return value was being initialized to -EAGAIN after the
enclosing lock had been released. But that lock is supposed to be
atomic with the thread suspend.
This opened a window for another racing thread to come by and "wake
up" our pending thread (which is fine on its own), set its return
value (e.g. to 0 for success) and then have that value clobbered by
the thread continuing to suspend itself outside the lock.
Melodramatic aside: I continue to hate this
arch_thread_return_value_set() API; it needs to die. At best it's a
mild optimization on a handful of architectures (e.g. x86 implements
it by writing to the EAX register save slot in the context block).
Asynchronous APIs are almost always worse than synchronous ones, and
in this case it's an async operation that races against literal
context switch code that can't use traditional locking strategies.
Fixes#39575
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
Some SMP applications have threading designs where every thread
created is always assigned to a specific CPU, and never want to
schedule them symmetrically across CPUs under any circumstance.
In this situation, it's possible to optimize the run queue design a
bit to put a separate queue in each CPU struct instead of having a
single global one. This is probably good for a few cycles per
scheduling event (maybe a bit more on architectures where cache
locality can be exploited) in circumstances where there is more than
one runnable thread. It's a mild optimization, but a basically simple
one.
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
Some architectures already returns -ENOTSUP when these functions
are called. So add this return value to the API doc.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
Add a SOC API to allow for application control over deep idle power
states. Note that the hardware idle entry happens out of the WAITI
instruction, so the application has to be responsibile for ensuring
the CPU to be halted actually reaches idle deterministically. Lots of
warnings in the docs to this effect.
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
During boot process, the boot sections need to be pinned in
memory to prevent them from being paged out (to avoid
pages being paged out and immediately paged in again).
Once the boot process is completed (just before calling main()),
the boot sections can be unpinned so the memory can be
used for demand paging for paging in data pages.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
z_smp_init() is only available if CONFIG_SMP is defined,
smp_timer_init() also depends on two Kconfig parameters. Also make it
conditional in cavs_timer.c. Also clarify some SMP-related comments
there.
Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
The z_interrupt_stacks was declared extern in the kernel internal
header file using the same macro which defines the same stack
array but with an added "extern" in front. This macro adds
alignment and section attribute which are actually not the same
as the actual stack array defined in kernel/init.c. The section
name used in the section attribute contains the file name where
the stack array is defined or extern declared. So the same
symbol, in this case z_interrupt_stacks, has different
attributes in two places, and GCC 11 starts to complain about
this. So use the newly introduced macro to extern declare
the stack array without adding/replacing any symbol attributes.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
These functions are those that need be implemented by backing
store outside kernel. Promote them from z_* so these can be
included in documentation.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
These functions and data structures are those that need
to be implemented by eviction algorithm and application
outside kernel. Promote them from z_* so these can be
included in documentation.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
The scheduler has historically had an API where an application can
inform the kernel that it will never create a thread that can be
preempted, and the kernel and architecture layer would use that as an
optimization hint to eliminate some code paths.
Those optimizations have dwindled to almost nothing at this point, and
they're now objectively a smaller impact than the special casing that
was required to handle the idle thread (which, obviously, must always
be preemptible).
Fix this by eliminating the idea of "cooperative only" and ensuring
that there will always be at least one preemptible priority with value
>=0. CONFIG_NUM_PREEMPT_PRIORITIES now specifies the number of
user-accessible priorities other than the idle thread.
The only remaining workaround is that some older architectures (and
also SPARC) use the CONFIG_PREEMPT_ENABLED=n state as a hint to skip
thread switching on interrupt exit. So detect exactly those platforms
and implement a minimal workaround in the idle loop (basically "just
call swap()") instead, with a big explanation.
Note that this also fixes a bug in one of the philosophers samples,
where it would ask for 6 cooperative priorities but then use values -7
through -2. It was assuming the kernel would magically create a
cooperative priority for its idle thread, which wasn't correct even
before.
Fixes#34584
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
Our z_swap() API takes a key returned from arch_irq_lock() and
releases it atomically with the context switch. Make sure that the
action of the unlocking is to unmask interrupts globally. If
interrupts would still be masked then that means there is an OUTER
interrupt lock still held, and the code that locked it surely doesn't
expect the thread to be suspended and interrupts unmasked while it's
held!
Unfortunately, this kind of mistake is very easy to make. We should
catch that with a simple assertion. This is essentially a crude
Zephyr equivalent of the extremely common "BUG: scheduling while
atomic" error in Linux drivers (just google it).
The one exception made is the circumstance where a thread has already
aborted itself. At that stage, whatever upthread lock state might
have existed will have already been messed up, so there's no value in
our asserting here. We can't catch all bugs, and this can actually
happen in error handling and/or test frameworks.
Fixes#33319
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
This adds the necessary bits for linker scripts and source code
to specify which symbols need to be pinned in memory. This is
needed for demand paging as some functions and data must reside
in memory all the time and cannot be paged out (e.g. paging,
scheduler, and interrupt routines for functionality).
This is up to the arch/SoC/board to define the sections in
their linker scripts as the pinned section may need special
alignment which cannot be done in common script snippets.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
This adds the necessary bits for linker scripts and source code
to specify which symbols are needed for boot process so they
can be grouped together.
One use of this is to group boot related code and data so these
won't interval with other kernel and application for better
caching.
This is a must for demand paging as some functions and data
must be available during the boot process and before the memory
manager is initialized. During this time, paging cannot be used
so symbols linked in virtual memory space are unavailable.
This is up to the arch/SoC/board to define the sections in
their linker scripts as section may need special alignment
which cannot be done in common script snippets.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
This adds a new function prototype for arch_page_phys_get()
which will be used to translate mapped virtual addresses back
to physical memory addresses. This is needed for the future
k_mem_unmap() function which requires this to find
the corresponding page frame. It is faster to look through
the page tables instead of doing linear search of the page
frame array.
A weak function is provided in case arch_page_phys_get()
is not implemented at the arch level. This simply goes
through all the page frame and find the one which has
mapped to the virtual address.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
Remove the config BOOT_TIME_MEASUREMENT and corresponding #ifdef'd code
throughout (kernel/init.c, idle.c, core/common.S , reset.S, ... ) which
hold the extern hooks for z_timestamp_main and z_timestamp_idle in the
removed boot_time test suite.
Signed-off-by: Jennifer Williams <jennifer.m.williams@intel.com>
Due to the use of gperf to generate hash table for kobjects,
the addresses of these kobjects cannot change during the last
few phases of linking (especially between zephyr_prebuilt.elf
and zephyr.elf). Because of this, the gperf generated data
needs to be placed at the end of memory to avoid pushing symbols
around in memory. This prevents moving these generated blocks
to earlier sections, for example, pinned data section needed
for demand paging. So create placeholders for use in
intermediate linking to reserve space for these generated blocks.
Due to uncertainty on the size of these blocks, more space is
being reserved which could result in wasted space. Though, this
retains the use of hash table for faster lookup.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
Add the ability to define architecture specific structures, notably
the ability to extend struct _cpu with per-CPU arch-specific stuff that
can be accessed with _current_cpu->arch.* similarly to _current->arch.*
for per-thead architecture data.
This is opt-in for architectures that want to benefit from this,
otherwise empty defaults are provided. A placeholder for ARM64 is
included to show the pattern.
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Currently _curr_cpu is only used by the get_cpu macro to quickly access
the cpu struct. This is not really necessary because we can access to
the struct by directly referencing &(_kernel.cpus[cpu_num]) in assembly
Signed-off-by: Carlo Caione <ccaione@baylibre.com>
This adds the bits to record execution time of eviction selection,
and backing store page-in/page-out in histograms.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
Add a 'U' suffix to values when computing and comparing against
unsigned variables and other related fixes of the same MISRA rule (10.4)
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
The identifiers used in the declaration and definition of a function
shall be identical [MISRAC2012-RULE_8_3-b]
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
This patch introduce new API to enable FPU of thread. This is pair of
existed k_float_disable() API. And also add empty arch_float_enable()
into each architectures that have arch_float_disable(). The arc and
riscv already implemented arch_float_enable() so I do not touch
these implementations.
Motivation: Current Zephyr implementation does not allow to use FPU
on main and other system threads like as work queue. Users need to
create an other thread with K_FP_REGS for floating point programs.
Users can use FPU more easily if they can enable FPU on running
threads.
Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
The internal function z_smp_reacquire_global_lock() has not used by
anywhere inside zephyr code, so remove it.
Fixes#33273.
Signed-off-by: Enjia Mai <enjiax.mai@intel.com>
Commit 6b84ab3830 ("kernel/sched: Adjust locking in z_swap()") moved
the call to arch_cohere_stacks() out of the scheduler lock while doing
some reorgnizing. On further reflection, this is incorrect. When
done outside the lock, the two arch_cohere_stacks() calls will race
against each other.
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
pm_system_suspend is called only from the idle thread and should
not be exported as a public API.
Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>
Due to the recent changes to scheduler z_find_first_thread_to_unpend
& z_remove_thread_from_ready_q are not used anymore. So removing the
dead code.
fixes: #32691
Signed-off-by: Spoorthy Priya Yerabolu <spoorthy.priya.yerabolu@intel.com>
These functions are a subset of proposed public APIs to clean up
several issues related to safely handling waking of threads. They
have been made private as they interface may change, but their use
will simplify the reimplementation of the k_work functionality.
See: https://github.com/zephyrproject-rtos/zephyr/pull/29668
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>
`z_is_t1_higher_prio_than_t2` was being called twice in both the
context-switch fastpath and in `z_priq_rb_lessthan`, just to
dealing with priority ties. In addition, the API was error-prone
(and too much in the fastpath to be able to assert its invarients)
- see also #32710 for a previous example of this API breaking
and returning a>b but also b>a.
Replacing this with a direct 3-way comparison `z_cmp_t1_prio_with_t2`
sidesteps most of these issues. There is still a concern that
`sgn(z_cmp_t1_prio_with_t2(a,b)) != -sgn(z_cmp_t1_prio_with_t2(b,a))`
but I don't see any way to alleviate this aside from adding an
assert to the fastpath.
Signed-off-by: James Harris <james.harris@intel.com>
Add a newer, much smaller and simpler implementation of abort and
join. No need to involve the idle thread. No need for a special code
path for self-abort. Joining a thread and waiting for an aborting one
to terminate elsewhere share an implementation. All work in both
calls happens under a single locked path with no unexpected
synchronization points.
This fixes a bug with the current implementation where the action of
z_sched_single_abort() was nonatomic, releasing the lock internally at
a point where the thread to be aborted could self-abort and confuse
the state such that it failed to abort at all.
Note that the arm32 and native_posix architectures, which have their
own thread abort implementations, now see a much simplified
"z_thread_abort()" internal API.
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
Swap was originally written to use the scheduler lock just to select a
new thread, but it would be nice to be able to rely on scheduler
atomicity later in the process (in particular it would be nice if the
assignment to cpu.current could be seen atomically). Rework the code
a bit so that swap takes the lock itself and holds it until just
before the call to arch_switch().
Note that the local interrupt mask has always been required to be held
across the swap, so extending the lock here has no effect on latency
at all on uniprocessor setups, and even on SMP only affects average
latency and not worst case.
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
Remove duplication in the code by moving macro LOCKED() to the correct
kernel_internal.h header.
Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
This adds a new kconfig CONFIG_SRAM_OFFSET to specify the offset
from beginning of SRAM where the kernel begins. On x86 and
PC compatible platforms, the first 1MB of RAM is reserved and
Zephyr should not link anything there. However, this 1MB still
needs to be mapped by the MMU to access various platform related
information. CONFIG_SRAM_OFFSET serves similar function as
CONFIG_KERNEL_VM_OFFSET and is needed for proper phys/virt
address translations.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
The Z_BOOT_VIRT_TO_PHYS() and Z_BOOT_PHYS_TO_VIRT() address
translation macros are flipped in their calculations.
The calculation is supposed to be:
virt = phys + ((KERNEL_VM_BASE + KERNEL_VM_OFFSET) -
SRAM_BASE_ADDRESS)
So fix the them.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
Following the idiom used for system calls, add script support to read
the initial application binary to identify which devices are defined,
and to use their offset in the device array as their unique handle
rather than the externally-defined ordinal from devicetree. The
device dependency arrays are updated to use these handles.
Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>
Initialize all device objects in a batch before invoking any code that
might try to reference data in them. This eliminates a race condition
enabled by the ability to resolve a device structure at build time,
and reference it from one device's initialization routine before the
device itself has been initialized.
While the device is pulled from the sys_init records rather than
static devices, all in-tree init_entry records that are associated
with devices are produced via Z_DEVICE_DEFINE(), so there should be no
static devices that would be missed by instead iterating over the
device records.
Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>
Some recent changes exposed some common "arch_switch() anti-patterns"
in various architectures. The documentation technically described
this all correctly, but probably wasn't as clear as it should have
been. Rewrite, making clear exactly what needs to happen and how the
fields should be interpreted.
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
It was possible with pathological timing (see below) for the scheduler
to pick a cycle of threads on each CPU and enter the context switch
path on all of them simultaneously.
Example:
* CPU0 is idle, CPU1 is running thread A
* CPU1 makes high priority thread B runnable
* CPU1 reaches a schedule point (or returns from an interrupt) and
decides to run thread B instead
* CPU0 simultaneously takes its IPI and returns, selecting thread A
Now both CPUs enter wait_for_switch() to spin, waiting for the context
switch code on the other thread to finish and mark the thread
runnable. So we have a deadlock, each CPU is spinning waiting for the
other!
Actually, in practice this seems not to happen on existing hardware
platforms, it's only exercisable in emulation. The reason is that the
hardware IPI time is much faster than the software paths required to
reach a schedule point or interrupt exit, so CPU1 always selects the
newly scheduled thread and no deadlock appears. I tried for a bit to
make this happen with a cycle of three threads, but it's complicated
to get right and I still couldn't get the timing to hit correctly. In
qemu, though, the IPI is implemented as a Unix signal sent to the
thread running the other CPU, which is far slower and opens the window
to see this happen.
The solution is simple enough: don't store the _current thread in the
run queue until we are on the tail end of the context switch path,
after wait_for_switch() and going to reach the end in guaranteed time.
Note that this requires changing a little logic to handle the yield
case: because we can no longer rely on _current's position in the run
queue to suppress it, we need to do the priority comparison directly
based on the existing "swap_ok" flag (which has always meant
"yielded", and maybe should be renamed).
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
The QUEUED state flag was managed separately from the run queue
insertion/deletion, and the logic (while AFAICT perfectly correct) was
tangled in a few places trying to keep them in sync. Put the
management of both behind a queue_thread()/dequeue_thread() API for
clarity. The ALWAYS_INLINE usage seems to be working to get the
compiler to condense the resulting multiple assignments. No behavior
change.
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
The "null out the switch handle and put it back" code in the swap
implementation is a holdover from some defensive coding (not wanting
to break the case where we picked our current thread), but it hides a
subtle SMP race: when that field goes NULL, another CPU that may have
selected that thread (which is to say, our current thread) as its next
to run will be spinning on that to detect when the field goes
non-NULL. So it will get the signal to move on when we revert the
value, when clearly we are still running on the stack!
In practice this was found on x86 which poisons the switch context
such that it crashes instantly.
Instead, be firm about state and always set the switch handle of a
currently running thread to NULL immediately before it starts running:
right before entering arch_switch() and symmetrically on the interrupt
exit path.
Fixes#28105
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
The z_swap_unlocked() function used a dummy spinlock for simplicity.
But this runs afouls of checking for stack-resident spinlocks
(forbidden when KERNEL_COHERENCE is set). And it's executing needless
code to release the lock anyway. Replace with a compile time NULL,
which will improve performance, correctness and code size.
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
The two calls to unpend a thread from a wait queue were inexplicably*
unsynchronized, as James Harris discovered. Rework them to call the
lowest level primities so we can wrap the process inside the scheduler
lock.
Fixes#32136
* I took a brief look. What seems to have happened here is that these
were originally synchronized via an implicit from an outer caller
(remember the original Uniprocessor irq_lock() API is a recursive
lock), and they were mostly implemented in terms of middle-level
calls that were themselves locked. So those got ported over to the
newer spinlock but the outer wrapper layer got forgotten.
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
This lets the linker tell us what kind of alignment is required
for both tdata and tbss data when copying them into stack.
If they are not aligned as expected by the toolchain, generated
code would be accessing incorrect location for thread variables.
Fixes#32015
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
The linker script defines `z_mapped_size` as follows:
```
z_mapped_size = z_mapped_end - z_mapped_start;
```
This is done with the belief that precomputed values at link time will
make the code smaller and faster.
On Aarch64, symbol values are relocated and loaded relative to the PC
as those are normally meant to be memory addresses.
Now if you have e.g. `CONFIG_SRAM_BASE_ADDRESS=0x2000000000` then
`z_mapped_size` might still have a reasonable value, say 0x59334.
But, when interpreted as an address, that's very very far from the PC
whose value is in the neighborhood of 0x2000000000. That overflows the
4GB relocation range:
```
kernel/libkernel.a(mmu.c.obj): in function `z_mem_manage_init':
kernel/mmu.c:527:(.text.z_mem_manage_init+0x1c):
relocation truncated to fit: R_AARCH64_ADR_PREL_PG_HI21
```
The solution is to define `Z_KERNEL_VIRT_SIZE` in terms of
`z_mapped_end - z_mapped_start` at the source code level. Given this
is used within loops that already start with `z_mapped_start` anyway,
the compiler is smart enough to combine the two occurrences and
dispense with a size counter, making the code effectively
slightly better for all while avoiding the Aarch64 relocation
overflow:
```
text data bss dec hex filename
1216 8 294936 296160 484e0 mmu.c.obj.arm64.before
1212 8 294936 296156 484dc mmu.c.obj.arm64.after
1110 8 9244 10362 287a mmu.c.obj.x86-64.before
1106 8 9244 10358 2876 mmu.c.obj.x86-64.after
```
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Some arches like x86 need all memory mapped so that they can
fetch information placed arbitrarily by firmware, like ACPI
tables.
Ensure that if this is the case, the kernel won't accidentally
clobber it by thinking the relevant virtual memory is unused.
Otherwise this has no effect on page frame management.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
If we evict enough pages to completely fill the backing store,
through APIs like k_mem_map(), z_page_frame_evict(), or
z_mem_page_out(), this will produce a crash the next time we
try to handle a page fault.
The backing store now always reserves a free storage location
for actual page faults.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
Architecture layer hooks for demand paging. See
doxygen for these API definitions for more details.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
Page tables created at build time may not include the
gperf data at the very end of RAM. Ensure this is mapped
properly at runtime to work around this.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
Pre-allocation of paging structures is now required, such that
no allocations are ever needed when mapping memory.
Instantiation of new memory domains may still require allocations
unless a common page table is used.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
