Line data    Source code

       1            0 : /*
       2              :  * Copyright (c) 2018 Intel Corporation.
       3              :  *
       4              :  * SPDX-License-Identifier: Apache-2.0
       5              :  */
       6              : 
       7              : #ifndef ZEPHYR_INCLUDE_EXC_HANDLE_H_
       8              : #define ZEPHYR_INCLUDE_EXC_HANDLE_H_
       9              : 
      10              : /*
      11              :  * This is used by some architectures to define code ranges which may
      12              :  * perform operations that could generate a CPU exception that should not
      13              :  * be fatal. Instead, the exception should return but set the program
      14              :  * counter to a 'fixup' memory address which will gracefully error out.
      15              :  *
      16              :  * For example, in the case where user mode passes in a C string via
      17              :  * system call, the length of that string needs to be measured. A specially
      18              :  * written assembly language version of strlen (arch_user_string_len)
      19              :  * defines start and end symbols where the memory in the string is examined;
      20              :  * if this generates a fault, jumping to the fixup symbol within the same
      21              :  * function will return an error result to the caller.
      22              :  *
      23              :  * To ensure precise control of the state of registers and the stack pointer,
      24              :  * these functions need to be written in assembly.
      25              :  *
      26              :  * The arch-specific fault handling code will define an array of these
      27              :  * z_exc_handle structures and return from the exception with the PC updated
      28              :  * to the fixup address if a match is found.
      29              :  */
      30              : 
      31              : struct z_exc_handle {
      32              :         void *start;
      33              :         void *end;
      34              :         void *fixup;
      35              : };
      36              : 
      37              : #define Z_EXC_HANDLE(name) \
      38              :         { name ## _fault_start, name ## _fault_end, name ## _fixup }
      39              : 
      40              : #define Z_EXC_DECLARE(name)          \
      41              :         void name ## _fault_start(void); \
      42              :         void name ## _fault_end(void);   \
      43              :         void name ## _fixup(void)
      44              : 
      45              : #endif /* ZEPHYR_INCLUDE_EXC_HANDLE_H_ */