13ca6fe284
- 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>
91 lines
2.9 KiB
C
91 lines
2.9 KiB
C
/*
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* Copyright (c) 2017, Intel Corporation
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*
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* SPDX-License-Identifier: Apache 2.0
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*/
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#ifndef _ZEPHYR_SYSCALL_HANDLER_H_
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#define _ZEPHYR_SYSCALL_HANDLER_H_
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#ifdef CONFIG_USERSPACE
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#ifndef _ASMLANGUAGE
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#include <kernel.h>
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#include <misc/printk.h>
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#include <nano_internal.h>
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extern const _k_syscall_handler_t _k_syscall_table[K_SYSCALL_LIMIT];
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/**
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* @brief Runtime expression check for system call arguments
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*
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* Used in handler functions to perform various runtime checks on arguments,
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* and generate a kernel oops if anything is not expected
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*
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* @param expr Boolean expression to verify, a false result will trigger an
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* oops
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* @param ssf Syscall stack frame argument passed to the handler function
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*/
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#define _SYSCALL_VERIFY(expr, ssf) \
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do { \
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if (!(expr)) { \
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printk("FATAL: syscall failed check: " #expr "\n"); \
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_arch_syscall_oops(ssf); \
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} \
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} while (0)
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/**
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* @brief Runtime check that a user thread has proper access to a memory area
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*
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* Checks that the particular memory area is readable or writable by the
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* currently running thread if the CPU was in user mode, and generates a kernel
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* oops if it wasn't. Prevents userspace from getting the kernel to read or
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* modify memory the thread does not have access to, or passing in garbage
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* pointers that would crash/pagefault the kernel if accessed.
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*
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* @param ptr Memory area to examine
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* @param size Size of the memory area
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* @param write If the thread should be able to write to this memory, not just
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* read it
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* @param ssf Syscall stack frame argument passed to the handler function
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*/
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#define _SYSCALL_MEMORY(ptr, size, write, ssf) \
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_SYSCALL_VERIFY(!_arch_buffer_validate(ptr, size, write), ssf)
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/**
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* @brief Runtime check that a pointer is a kernel object of expected type
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*
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* Passes along arguments to _k_object_validate() and triggers a kernel oops
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* if the object wasn't valid or had incorrect permissions.
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*
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* @param ptr Untrusted kernel object pointer
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* @param type Expected kernel object type
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* @param init Whether this is an init function handler
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* @param ssf Syscall stack frame argument passed to the handler function
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*/
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#define _SYSCALL_IS_OBJ(ptr, type, init, ssf) \
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_SYSCALL_VERIFY(!_k_object_validate((void *)ptr, type, init), ssf)
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/* Convenience macros for handler implementations */
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#define _SYSCALL_ARG0 ARG_UNUSED(arg1); ARG_UNUSED(arg2); ARG_UNUSED(arg3); \
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ARG_UNUSED(arg4); ARH_UNUSED(arg5); ARG_UNUSED(arg6)
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#define _SYSCALL_ARG1 ARG_UNUSED(arg2); ARG_UNUSED(arg3); ARG_UNUSED(arg4); \
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ARG_UNUSED(arg5); ARG_UNUSED(arg6)
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#define _SYSCALL_ARG2 ARG_UNUSED(arg3); ARG_UNUSED(arg4); ARG_UNUSED(arg5); \
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ARG_UNUSED(arg6)
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#define _SYSCALL_ARG3 ARG_UNUSED(arg4); ARG_UNUSED(arg5); ARG_UNUSED(arg6)
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#define _SYSCALL_ARG4 ARG_UNUSED(arg5); ARG_UNUSED(arg6)
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#define _SYSCALL_ARG5 ARG_UNUSED(arg6)
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#endif /* _ASMLANGUAGE */
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#endif /* CONFIG_USERSPACE */
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#endif /* _ZEPHYR_SYSCALL_H_ */
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