This is a runtime counterpart to K_THREAD_ACCESS_GRANT().
This function takes a thread and a NULL-terminated list of kernel
objects and runs k_object_access_grant() on each of them.
This function doesn't require any special permissions and doesn't
need to become a system call.
__attribute__((sentinel)) added to warn users if they omit the
required NULL termination.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
It's possible to declare static threads that start up as K_USER,
but these threads can't do much since they start with permissions on
no kernel objects other than their own thread object.
Rather than do some run-time synchronization to have some other thread
grant the necessary permissions, we introduce macros
to conveniently assign object permissions to these threads when they
are brought up at boot by the kernel. The tables generated here
are constant and live in ROM when possible.
Example usage:
K_THREAD_DEFINE(my_thread, STACK_SIZE, my_thread_entry,
NULL, NULL, NULL, 0, K_USER, K_NO_WAIT);
K_THREAD_ACCESS_GRANT(my_thread, &my_sem, &my_mutex, &my_pipe);
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
Currently this is defined as a k_thread_stack_t pointer.
However this isn't correct, stacks are defined as arrays. Extern
references to k_thread_stack_t doesn't work properly as the compiler
treats it as a pointer to the stack array and not the array itself.
Declaring as an unsized array of k_thread_stack_t doesn't work
well either. The least amount of confusion is to leave out the
pointer/array status completely, use pointers for function prototypes,
and define K_THREAD_STACK_EXTERN() to properly create an extern
reference.
The definitions for all functions and struct that use
k_thread_stack_t need to be updated, but code that uses them should
be unchanged.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
User threads can only create other nonessential user threads
of equal or lower priority and must have access to the entire
stack area.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
We need to track permission on stack memory regions like we do
with other kernel objects. We want stacks to live in a memory
area that is outside the scope of memory domain permission
management. We need to be able track what stacks are in use,
and what stacks may be used by user threads trying to call
k_thread_create().
Some special handling is needed because thread stacks appear as
variously-sized arrays of struct _k_thread_stack_element which is
just a char. We need the entire array to be considered an object,
but also properly handle arrays of stacks.
Validation of stacks also requires that the bounds of the stack
are not exceeded. Various approaches were considered. Storing
the size in some header region of the stack itself would not allow
the stack to live in 'noinit'. Having a stack object be a data
structure that points to the stack buffer would confound our
current APIs for declaring stacks as arrays or struct members.
In the end, the struct _k_object was extended to store this size.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
This is too powerful for user mode, the other access APIs
require explicit permissions on the threads that are being
granted access.
The API is no longer exposed as a system call and hence will
only be usable by supervisor threads.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
It's currently too easy to run out of thread IDs as they
are never re-used on thread exit.
Now the kernel maintains a bitfield of in-use thread IDs,
updated on thread creation and termination. When a thread
exits, the permission bitfield for all kernel objects is
updated to revoke access for that retired thread ID, so that
a new thread re-using that ID will not gain access to objects
that it should not have.
Because of these runtime updates, setting the permission
bitmap for an object to all ones for a "public" object doesn't
work properly any more; a flag is now set for this instead.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
Fixes issues where these were getting sign-extended when
dumped out, resulting in (for example) "ffffffff" being
printed when it ought to be "ff".
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
Does the opposite of k_object_access_grant(); the provided thread will
lose access to that kernel object.
If invoked from userspace the caller must hace sufficient access
to that object and permission on the thread being revoked access.
Fix documentation for k_object_access_grant() API to reflect that
permission on the thread parameter is needed as well.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
By default, threads are created only having access to their own thread
object and nothing else. This new flag to k_thread_create() gives the
thread access to all objects that the parent had at the time it was
created, with the exception of the parent thread itself.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
- Dumping error messages split from _k_object_validate(), to avoid spam
in test cases that are expected to have failure result.
- _k_object_find() prototype moved to syscall_handler.h
- Clean up k_object_access() implementation to avoid double object
lookup and use single validation function
- Added comments, minor whitespace changes
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
This API only gets used inside system call handlers and a specific test
case dedicated to it. Move definition to the private kernel header along
with the rest of the defines for system call handlers.
A non-userspace inline variant of this function is unnecessary and has
been deleted.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
To avoid making a system call for every character emitted, there is now
a small line buffer if userspace is enabled. The interface to the kernel
is a new system call which takes a sized buffer of console data.
If userspace is not enabled this works like before.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
These are removed as the APIs that use them are not suitable for
exporting to userspace.
- Kernel workqueues run in supervisor mode, so it would not be
appropriate to allow user threads to submit work to them. A future
enhancement may extend or introduce parallel API where the workqueue
threads may run in user mode (or leave as an exercise to the user).
- Kernel slabs store private bookkeeping data inside the
user-accessible slab buffers themselves. Alternate APIs are planned
here for managing slabs of kernel objects, implemented within the
runtime library and not the kernel.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
k_pipe_block_put() will be done in another patch, we need to design
handling for the k_mem_block object.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
These modify kernel object metadata and are intended to be callable from
user threads, need a privilege elevation for these to work.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
We want applications to be able to enable and disable userspace without
changing any code. k_thread_user_mode_enter() now just jumps into the
entry point if CONFIG_USERSPACE is disabled.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
This used to exist because in earlier versions of the system call
interfaces, an "extern" declaration of the system call implementation
function would precede the real inline version of the implementation.
The compiler would not like this and would throw "static declaration
of ‘foo’ follows non-static declaration". So alternate macros were
needed which declare the implementation function as 'static inline'
instead of extern.
However, currently the inline version of these system call
implementations appear first, the K_SYSCALL_DECLARE() macros appear in
the header generated by gen_syscalls.py, which is always included at the
end of the header file. The compiler does not complain if a
static inline function is succeeded by an extern prototype of the
same function. This lets us simplify the generated system call
macros and just use __syscall everywhere.
The disassembly of this was checked on x86 to ensure that for
kernel-only or CONFIG_USERSPACE=n scenarios, everything is still being
inlined as expected.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
Add the following application-facing memory domain APIs:
k_mem_domain_init() - to initialize a memory domain
k_mem_domain_destroy() - to destroy a memory domain
k_mem_domain_add_partition() - to add a partition into a domain
k_mem_domain_remove_partition() - to remove a partition from a domain
k_mem_domain_add_thread() - to add a thread into a domain
k_mem_domain_remove_thread() - to remove a thread from a domain
A memory domain would contain some number of memory partitions.
A memory partition is a memory region (might be RAM, peripheral
registers, flash...) with specific attributes (access permission,
e.g. privileged read/write, unprivileged read-only, execute never...).
Memory partitions would be defined by set of MPU regions or MMU tables
underneath.
A thread could only belong to a single memory domain any point in time
but a memory domain could contain multiple threads.
Threads in the same memory domain would have the same access permission
to the memory partitions belong to the memory domain.
The memory domain APIs are used by unprivileged threads to share data
to the threads in the same memory and protect sensitive data from
threads outside their domain. It is not only for improving the security
but also useful for debugging (unexpected access would cause exception).
Jira: ZEP-2281
Signed-off-by: Chunlin Han <chunlin.han@linaro.org>
Device drivers need to be treated like other kernel objects, with
thread-level permissions and validation of struct device pointers passed
in from userspace when making API calls.
However it's not sufficient to identify an object as a driver, we need
to know what subsystem it belongs to (if any) so that userspace cannot,
for example, make Ethernet driver API calls using a UART driver object.
Upon encountering a variable representing a device struct, we look at
the value of its driver_api member. If that corresponds to an instance
of a driver API struct belonging to a known subsystem, the proper
K_OBJ_DRIVER_* enumeration type will be associated with this device in
the generated gperf table.
If there is no API struct or it doesn't correspond to a known subsystem,
the device is omitted from the table; it's presumably used internally
by the kernel or is a singleton with specific APIs for it that do not
take a struct device parameter.
The list of kobjects and subsystems in the script is simplified since
the enumeration type name is strongly derived from the name of the data
structure.
A device object is marked as initialized after its init function has
been run at boot.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
To define a system call, it's now sufficient to simply tag the inline
prototype with "__syscall" or "__syscall_inline" and include a special
generated header at the end of the header file.
The system call dispatch table and enumeration of system call IDs is now
automatically generated.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
- syscall.h now contains those APIs needed to support invoking calls
from user code. Some stuff moved out of main kernel.h.
- syscall_handler.h now contains directives useful for implementing
system call handler functions. This header is not pulled in by
kernel.h and is intended to be used by C files implementing kernel
system calls and driver subsystem APIs.
- syscall_list.h now contains the #defines for system call IDs. This
list is expected to grow quite large so it is put in its own header.
This is now an enumerated type instead of defines to make things
easier as we introduce system calls over the new few months. In the
fullness of time when we desire to have a fixed userspace/kernel ABI,
this can always be converted to defines.
Some new code added:
- _SYSCALL_MEMORY() macro added to check memory regions passed up from
userspace in handler functions
- _syscall_invoke{7...10}() inline functions declare for invoking system
calls with more than 6 arguments. 10 was chosen as the limit as that
corresponds to the largest arg list we currently have
which is for k_thread_create()
Other changes
- auto-generated K_SYSCALL_DECLARE* macros documented
- _k_syscall_table in userspace.c is not a placeholder. There's no
strong need to generate it and doing so would require the introduction
of a third build phase.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
A quick look at "man syscall" shows that in Linux, all architectures
support at least 6 argument system calls, with a few supporting 7. We
can at least do 6 in Zephyr.
x86 port modified to use EBP register to carry the 6th system call
argument.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
Now creating a thread will assign it a unique, monotonically increasing
id which is used to reference the permission bitfield in the kernel
object metadata.
Stub functions in userspace.c now implemented.
_new_thread is now wrapped in a common function with pre- and post-
architecture thread initialization tasks.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
In various places, a private _thread_entry_t, or the full prototype
were being used. Be consistent and use the same typedef everywhere.
Signen-off-by: Andrew Boie <andrew.p.boie@intel.com>
The generated struct k_thread could end up in the wrong memory space
if CONFIG_APPLICATION_MEMORY is enabled.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
It's now possible to instantiate a thread object, but delay its
execution indefinitely. This was already supported with K_THREAD_DEFINE.
A new API, k_thread_start(), now exists to start threads that are in
this state.
The intended use-case is to initialize a thread with K_USER, then grant
it various access permissions, and only then start it.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
All system calls made from userspace which involve pointers to kernel
objects (including device drivers) will need to have those pointers
validated; userspace should never be able to crash the kernel by passing
it garbage.
The actual validation with _k_object_validate() will be in the system
call receiver code, which doesn't exist yet.
- CONFIG_USERSPACE introduced. We are somewhat far away from having an
end-to-end implementation, but at least need a Kconfig symbol to
guard the incoming code with. Formal documentation doesn't exist yet
either, but will appear later down the road once the implementation is
mostly finalized.
- In the memory region for RAM, the data section has been moved last,
past bss and noinit. This ensures that inserting generated tables
with addresses of kernel objects does not change the addresses of
those objects (which would make the table invalid)
- The DWARF debug information in the generated ELF binary is parsed to
fetch the locations of all kernel objects and pass this to gperf to
create a perfect hash table of their memory addresses.
- The generated gperf code doesn't know that we are exclusively working
with memory addresses and uses memory inefficently. A post-processing
script process_gperf.py adjusts the generated code before it is
compiled to work with pointer values directly and not strings
containing them.
- _k_object_init() calls inserted into the init functions for the set of
kernel object types we are going to support so far
Issue: ZEP-2187
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
This is necessary in order for k_queue_get to work properly since that
is used with buffer pools which might be used by multiple threads asking
for buffers.
Jira: ZEP-2553
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
This has been a limitation caused by k_fifo which could only remove
items from the beggining, but with the change to use k_queue in
k_work_q it is now possible to remove items from any position with
use of k_queue_remove.
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
This makes use of POLL_EVENT in case k_poll is enabled which is
preferable over wait_q as that allows objects to be removed for the
data_q at any time.
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
