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- /*
- * exception.c
- *
- * Copyright (C) 2017 Aleksandar Andrejevic <theflash@sdf.lonestar.org>
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License as
- * published by the Free Software Foundation, either version 3 of the
- * License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU Affero General Public License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
- #include <common.h>
- #include <exception.h>
- #include <syscalls.h>
- #include <process.h>
- #include <video.h>
- #include <vm86.h>
- #include <heap.h>
- #include <cpu.h>
- static const char *exception_names[] = {
- "Breakpoint",
- "Arithmetic Error",
- "Assertion Failure",
- "Bad Operation",
- "Memory Access Fault",
- };
- static void raise_exception_internal(thread_t *thread, processor_mode_t mode, exception_info_t *info, registers_t *exception_regs)
- {
- if (mode == USER_MODE)
- {
- bool_t current = (thread == get_current_thread());
- thread->user_exception_info = *info;
- registers_t *regs = (current || (thread->in_kernel > 0)) ? thread->last_context : &thread->state.regs;
- if (thread->user_handler.eip)
- {
- *regs = thread->user_handler;
- regs->eax = 1;
- regs->error_code = 0;
- ASSERT((regs->cs & 0xFFFC) == 0 || SEGMENT_RPL(regs->cs) == 3);
- ASSERT((regs->data_selector & 0xFFFC) == 0 || SEGMENT_RPL(regs->data_selector) == 3);
- if (current || (thread->in_kernel > 0))
- {
- registers_ext_t *regs_ext = (registers_ext_t*)regs;
- regs_ext->esp3 = regs->esp;
- }
- }
- else
- {
- dword_t exit_code = 1; // TODO: Perhaps something more meaningful
- process_t *proc = thread->owner_process;
- reference(&proc->header);
- terminate_process(proc, exit_code);
- dereference(&proc->header);
- }
- }
- else
- {
- ASSERT(thread == get_current_thread());
- thread->kernel_exception_info = *info;
- if (thread->kernel_handler.eip)
- {
- thread->kernel_handler.eax = 1;
- memcpy(exception_regs, &thread->kernel_handler, sizeof(registers_t));
- }
- else
- {
- KERNEL_CRASH_WITH_REGS(exception_names[info->number], exception_regs);
- }
- }
- }
- static void exception_handler(registers_t *regs, byte_t int_num)
- {
- exception_info_t info;
- processor_mode_t previous_mode = SEGMENT_RPL(regs->cs) == 0 ? KERNEL_MODE : USER_MODE;
- void *faulting_address;
- info.state = *regs;
- memset(info.parameters, 0, sizeof(info.parameters));
- switch (int_num)
- {
- case CPU_EXCEPTION_DE:
- case CPU_EXCEPTION_MF:
- info.number = EXCEPTION_ARITHMETIC;
- break;
- case CPU_EXCEPTION_DB:
- case CPU_EXCEPTION_BP:
- info.number = EXCEPTION_BREAKPOINT;
- break;
- case CPU_EXCEPTION_NMI:
- case CPU_EXCEPTION_MC:
- return;
- case CPU_EXCEPTION_OF:
- case CPU_EXCEPTION_BR:
- case CPU_EXCEPTION_AC:
- info.number = EXCEPTION_ASSERTION;
- break;
- case CPU_EXCEPTION_NM:
- if (cpu_fpu_present)
- {
- thread_lazy_fpu();
- return;
- }
- else
- {
- info.number = EXCEPTION_BAD_OPERATION;
- }
- break;
- case CPU_EXCEPTION_DF:
- KERNEL_CRASH_WITH_REGS("Double Fault", regs);
- return;
- case CPU_EXCEPTION_GP:
- if (regs->eflags & CPU_STATUS_FLAG_VM)
- {
- vm86_handler((registers_ext_vm86_t*)regs);
- return;
- }
- case CPU_EXCEPTION_UD:
- case CPU_EXCEPTION_TS:
- case CPU_EXCEPTION_NP:
- case CPU_EXCEPTION_SS:
- info.number = EXCEPTION_BAD_OPERATION;
- break;
- case CPU_EXCEPTION_PF:
- faulting_address = (void*)cpu_read_faulting_address();
- if (memory_fault_handler(faulting_address, regs)) return;
- info.number = EXCEPTION_MEMORY_ACCESS;
- memcpy(info.parameters, &faulting_address, sizeof(faulting_address));
- break;
- default:
- KERNEL_CRASH_WITH_REGS("Unexpected CPU exception", regs);
- }
- thread_t *thread = get_current_thread();
- if (thread == NULL) KERNEL_CRASH_WITH_REGS(exception_names[info.number], regs);
- raise_exception_internal(thread, previous_mode, &info, regs);
- }
- sysret_t syscall_raise_exception(handle_t thread_handle, const exception_info_t *info)
- {
- exception_info_t safe_info;
- if (get_previous_mode() == USER_MODE)
- {
- if (!check_usermode(info, sizeof(exception_info_t))) return ERR_BADPTR;
- EH_TRY safe_info = *info;
- EH_CATCH EH_ESCAPE(return ERR_BADPTR);
- EH_DONE;
- }
- else
- {
- safe_info = *info;
- }
- thread_t *thread = NULL;
- if (thread_handle == INVALID_HANDLE)
- {
- thread = get_current_thread();
- reference(&thread->header);
- }
- else
- {
- if (!reference_by_handle(thread_handle, OBJECT_THREAD, (object_t**)&thread)) return ERR_INVALID;
- }
- raise_exception_internal(thread, USER_MODE, &safe_info, NULL);
- dereference(&thread->header);
- return ERR_SUCCESS;
- }
- sysret_t syscall_get_exception_info(exception_info_t *info)
- {
- thread_t *thread = get_current_thread();
- if (get_previous_mode() == USER_MODE)
- {
- if (!check_usermode(info, sizeof(exception_info_t))) return ERR_BADPTR;
- EH_TRY memcpy(info, &thread->user_exception_info, sizeof(exception_info_t));
- EH_CATCH EH_ESCAPE(return ERR_BADPTR);
- EH_DONE;
- }
- else
- {
- *info = thread->kernel_exception_info;
- }
- return ERR_SUCCESS;
- }
- void set_exception_handler(registers_t *regs, processor_mode_t mode, exception_handler_t *old_handler)
- {
- thread_t *thread = get_current_thread();
- if (mode == KERNEL_MODE)
- {
- *old_handler = thread->kernel_handler;
- thread->kernel_handler = *regs;
- }
- else
- {
- if (!check_usermode(old_handler, sizeof(exception_handler_t))) return;
- EH_TRY
- {
- *old_handler = thread->user_handler;
- thread->user_handler = *regs;
- }
- EH_DONE;
- }
- }
- sysret_t syscall_save_exception_handler(exception_handler_t *old_handler)
- {
- set_exception_handler(old_handler, USER_MODE, get_current_thread()->last_context);
- return 0;
- }
- sysret_t syscall_restore_exception_handler(const exception_handler_t *old_handler)
- {
- thread_t *thread = get_current_thread();
- if (get_previous_mode() == USER_MODE)
- {
- exception_handler_t safe_handler;
- if (!check_usermode(old_handler, sizeof(exception_handler_t))) return ERR_BADPTR;
- EH_TRY
- {
- safe_handler = *old_handler;
- }
- EH_CATCH
- {
- EH_ESCAPE(return ERR_BADPTR);
- }
- EH_DONE;
- if (((safe_handler.cs & 0xFFFC) != 0 && SEGMENT_RPL(safe_handler.cs) != 3)
- || ((safe_handler.data_selector & 0xFFFC) != 0
- && SEGMENT_RPL(safe_handler.data_selector) != 3))
- {
- return ERR_INVALID;
- }
- thread->user_handler = safe_handler;
- }
- else
- {
- thread->kernel_handler = *old_handler;
- }
- return ERR_SUCCESS;
- }
- void exceptions_init()
- {
- byte_t i;
- for (i = 0; i < CPU_EXCEPTION_MAX; i++) set_int_handler(i, exception_handler, FALSE, FALSE);
- }
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