46 lines
1.5 KiB
C
46 lines
1.5 KiB
C
/*
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* Copyright (c) 2018 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_EXC_HANDLE_H_
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#define _ZEPHYR_EXC_HANDLE_H_
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/*
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* This is used by some architectures to define code ranges which may
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* perform operations that could generate a CPU exception that should not
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* be fatal. Instead, the exception should return but set the program
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* counter to a 'fixup' memory address which will gracefully error out.
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*
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* For example, in the case where user mode passes in a C string via
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* system call, the length of that string needs to be measured. A specially
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* written assembly language version of strlen (z_arch_user_string_len)
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* defines start and end symbols where the memory in the string is examined;
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* if this generates a fault, jumping to the fixup symbol within the same
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* function will return an error result to the caller.
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*
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* To ensure precise control of the state of registers and the stack pointer,
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* these functions need to be written in assembly.
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*
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* The arch-specific fault handling code will define an array of these
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* z_exc_handle structures and return from the exception with the PC updated
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* to the fixup address if a match is found.
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*/
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struct z_exc_handle {
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void *start;
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void *end;
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void *fixup;
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};
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#define Z_EXC_HANDLE(name) \
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{ &name ## _fault_start, &name ## _fault_end, &name ## _fixup }
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#define Z_EXC_DECLARE(name) \
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extern void (*name ## _fault_start)(void); \
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extern void (*name ## _fault_end)(void); \
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extern void (*name ## _fixup)(void)
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#endif /* _ZEPHYR_EXC_HANDLE_H_ */
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