diff options
Diffstat (limited to 'src/kernel/dev/v86.c')
| -rw-r--r-- | src/kernel/dev/v86.c | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/src/kernel/dev/v86.c b/src/kernel/dev/v86.c new file mode 100644 index 0000000..9498eaf --- /dev/null +++ b/src/kernel/dev/v86.c @@ -0,0 +1,208 @@ +#include <string.h> +#include <paging.h> + +#include <dev/v86.h> + +#define EFLAGS_VM 0x20000 +#define V86_VALID_FLAGS 0xDFF + +// ---- Ugly big static data + +STATIC_MUTEX(v86_mutex); + +v86_regs_t v86_regs; +bool v86_if; + +pagedir_t *v86_pagedir = 0; +void* v86_alloc_addr; + +bool v86_retval; +thread_t *v86_caller_thread = 0; + +pagedir_t *v86_prev_pagedir = 0; + +// ---- Setup code + +void v86_run_bios_int(void*); +void v86_ex_handler(registers_t *regs); +void v86_pf_handler(void*, registers_t *regs, void* addr); +void v86_asm_enter_v86(v86_regs_t*); + +bool v86_begin_session() { + mutex_lock(&v86_mutex); + + if (v86_pagedir == 0) { + v86_pagedir = create_pagedir(v86_pf_handler, 0); + if (v86_pagedir == 0) return false; + + v86_prev_pagedir = get_current_pagedir(); + switch_pagedir(v86_pagedir); + + for (void* addr = (void*)V86_ALLOC_ADDR; addr < (void*)V86_STACK_TOP; addr += PAGE_SIZE) { + pd_map_page(addr, (uint32_t)addr / PAGE_SIZE, true); + } + for (void* addr = (void*)V86_BIOS_BEGIN; addr < (void*)V86_BIOS_END; addr += PAGE_SIZE) { + pd_map_page(addr, (uint32_t)addr / PAGE_SIZE, true); + } + pd_map_page(0, 0, true); + } + + v86_alloc_addr = (void*)V86_ALLOC_ADDR; + + memset(&v86_regs, 0, sizeof(v86_regs)); + + return true; +} + +void v86_end_session() { + switch_pagedir(v86_prev_pagedir); + v86_prev_pagedir = 0; + v86_caller_thread = 0; + + mutex_unlock(&v86_mutex); +} + +void* v86_alloc(size_t size) { + void* addr = v86_alloc_addr; + + v86_alloc_addr += size; + + return addr; +} + +bool v86_bios_int(uint8_t int_no) { + v86_caller_thread = current_thread; + + uint32_t int_no_32 = int_no; + + thread_t *v86t = new_thread(v86_run_bios_int, (void*)int_no_32); + v86t->user_ex_handler = v86_ex_handler; + + int st = enter_critical(CL_NOSWITCH); + start_thread(v86t); + wait_on(current_thread); + exit_critical(st); + + return v86_retval; +} + +void v86_run_bios_int(void* x) { + switch_pagedir(v86_pagedir); + + uint32_t int_no = (uint32_t)x; + + uint16_t *ivt = (uint16_t*)0; + + v86_regs.cs = ivt[2 * int_no + 1]; + v86_regs.ip = ivt[2 * int_no]; + v86_regs.ss = ((V86_STACK_TOP - 0x10000) >> 4); + v86_regs.sp = 0; + + v86_if = true; + + v86_asm_enter_v86(&v86_regs); +} + +void v86_exit_thread(bool status) { + v86_retval = status; + + resume_on(v86_caller_thread); + exit(); +} + +bool v86_gpf_handler(registers_t *regs) { + uint8_t* ip = (uint8_t*)V86_LIN_OF_SEG_OFF(regs->cs, regs->eip); + uint16_t *stack = (uint16_t*)V86_LIN_OF_SEG_OFF(regs->ss, (regs->esp & 0xFFFF)); + uint32_t *stack32 = (uint32_t*)stack; + bool is_operand32 = false; // bool is_address32 = false; + + while (true) { + switch (ip[0]) { + case 0x66: // O32 + is_operand32 = true; + ip++; regs->eip = (uint16_t)(regs->eip + 1); + break; + case 0x67: // A32 + // is_address32 = true; + ip++; regs->eip = (uint16_t)(regs->eip + 1); + break; + case 0x9C: // PUSHF + if (is_operand32) { + regs->esp = ((regs->esp & 0xFFFF) - 4) & 0xFFFF; + stack32--; + *stack32 = regs->eflags & V86_VALID_FLAGS; + if (v86_if) + *stack32 |= EFLAGS_IF; + else + *stack32 &= ~EFLAGS_IF; + } else { + regs->esp = ((regs->esp & 0xFFFF) - 2) & 0xFFFF; + stack--; + *stack = regs->eflags; + if (v86_if) + *stack |= EFLAGS_IF; + else + *stack &= ~EFLAGS_IF; + } + regs->eip = (uint16_t)(regs->eip + 1); + return true; + case 0x9D: // POPF + if (is_operand32) { + regs->eflags = EFLAGS_IF | EFLAGS_VM | (stack32[0] & V86_VALID_FLAGS); + v86_if = (stack32[0] & EFLAGS_IF) != 0; + regs->esp = ((regs->esp & 0xFFFF) + 4) & 0xFFFF; + } else { + regs->eflags = EFLAGS_IF | EFLAGS_VM | stack[0]; + v86_if = (stack[0] & EFLAGS_IF) != 0; + regs->esp = ((regs->esp & 0xFFFF) + 2) & 0xFFFF; + } + regs->eip = (uint16_t)(regs->eip + 1); + return true; + case 0xCF: // IRET + v86_regs.ax = (uint16_t)regs->eax; + v86_regs.bx = (uint16_t)regs->ebx; + v86_regs.cx = (uint16_t)regs->ecx; + v86_regs.dx = (uint16_t)regs->edx; + v86_regs.di = (uint16_t)regs->edi; + v86_regs.si = (uint16_t)regs->esi; + + v86_exit_thread(true); + case 0xFA: // CLI + v86_if = false; + regs->eip = (uint16_t)(regs->eip + 1); + return true; + case 0xFB: // STI + v86_if = true; + regs->eip = (uint16_t)(regs->eip + 1); + return true; + default: + return false; + } + } +} + +void v86_ex_handler(registers_t *regs) { + if (regs->int_no == EX_GENERAL_PROTECTION) { + if (!v86_gpf_handler(regs)) v86_exit_thread(false); + } else { + v86_exit_thread(false); + } +} + +void v86_pf_handler(void* zero, registers_t *regs, void* addr) { + if (addr < (void*)V86_STACK_TOP) { + pd_map_page(addr, (uint32_t)addr / PAGE_SIZE, true); + } else { + dbg_printf("Unexpected V86 PF at 0x%p\n", addr); + + if (current_thread->user_ex_handler == v86_ex_handler) { + // we are in V86 thread + v86_exit_thread(false); + } else { + PANIC("V86 memory access exception."); + } + } +} + + +/* vim: set ts=4 sw=4 tw=0 noet :*/ |