error.h

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/*
 * Copyright (c) 2020 BayLibre, SAS
 *
 * SPDX-License-Identifier: Apache-2.0
 */
 
#ifndef ZEPHYR_INCLUDE_ARCH_RISCV_ERROR_H_
#define ZEPHYR_INCLUDE_ARCH_RISCV_ERROR_H_
 
#include <arch/riscv/syscall.h>
#include <arch/riscv/exp.h>
#include <stdbool.h>
 
#ifdef __cplusplus
extern "C" {
#endif
 
#ifdef CONFIG_USERSPACE
 
/*
 * Kernel features like canary (software stack guard) are built
 * with an argument to bypass the test before syscall (test if CPU
 * is running in user or kernel) and directly execute the function.
 * Then if this kind of code wishes to trigger a CPU exception,
 * the implemented syscall is useless because  the function is directly
 * called even if the CPU is running in user (which happens during
 * sanity check). To fix that, I bypass the generated test code by writing
 * the test myself to remove the bypass ability.
 */
 
#define ARCH_EXCEPT(reason_p)   do {                    \
                if (k_is_user_context()) {              \
                        arch_syscall_invoke1(reason_p,  \
                                K_SYSCALL_USER_FAULT);  \
                } else {                                \
                        compiler_barrier();             \
                        z_impl_user_fault(reason_p);    \
                }                                       \
                CODE_UNREACHABLE; /* LCOV_EXCL_LINE */  \
        } while (false)
#else
/*
 * Raise an illegal instruction exception so that mepc will hold expected value in
 * exception handler, and generated coredump can reconstruct the failing stack.
 * Store reason_p in register t6, marker in t5
 */
#define ARCH_EXCEPT_MARKER 0x00DEAD00
#define ARCH_EXCEPT(reason_p)   do {                    \
                __asm__ volatile("addi t5, %[marker], 0"        \
                        : : [marker] "r" (ARCH_EXCEPT_MARKER)); \
                __asm__ volatile("addi t6, %[reason], 0"        \
                        : : [reason] "r" (reason_p));   \
                __asm__ volatile("unimp");              \
        } while (false)
#endif
 
__syscall void user_fault(unsigned int reason);
 
#include <syscalls/error.h>
 
#ifdef __cplusplus
}
#endif
 
#endif /* ZEPHYR_INCLUDE_ARCH_RISCV_ERROR_H_ */