| 1 | /* |
| 2 | * x86 segmentation related helpers (user-mode code): |
| 3 | * TSS, interrupts, system calls, jumps and call/task gates, descriptors |
| 4 | * |
| 5 | * Copyright (c) 2003 Fabrice Bellard |
| 6 | * |
| 7 | * This library is free software; you can redistribute it and/or |
| 8 | * modify it under the terms of the GNU Lesser General Public |
| 9 | * License as published by the Free Software Foundation; either |
| 10 | * version 2.1 of the License, or (at your option) any later version. |
| 11 | * |
| 12 | * This library is distributed in the hope that it will be useful, |
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 15 | * Lesser General Public License for more details. |
| 16 | * |
| 17 | * You should have received a copy of the GNU Lesser General Public |
| 18 | * License along with this library; if not, see <http://www.gnu.org/licenses/>. |
| 19 | */ |
| 20 | |
| 21 | #include "qemu/osdep.h" |
| 22 | #include "cpu.h" |
| 23 | #include "exec/helper-proto.h" |
| 24 | #include "accel/tcg/cpu-ldst.h" |
| 25 | #include "accel/tcg/cpu-loop.h" |
| 26 | #include "tcg/helper-tcg.h" |
| 27 | #include "tcg/seg_helper.h" |
| 28 | |
| 29 | void helper_syscall(CPUX86State *env, int next_eip_addend) |
| 30 | { |
| 31 | CPUState *cs = env_cpu(env); |
| 32 | |
| 33 | cs->exception_index = EXCP_SYSCALL; |
| 34 | env->exception_is_int = 0; |
| 35 | env->exception_next_eip = env->eip + next_eip_addend; |
| 36 | cpu_loop_exit(cs); |
| 37 | } |
| 38 | |
| 39 | /* |
| 40 | * fake user mode interrupt. is_int is TRUE if coming from the int |
| 41 | * instruction. next_eip is the env->eip value AFTER the interrupt |
| 42 | * instruction. It is only relevant if is_int is TRUE or if intno |
| 43 | * is EXCP_SYSCALL. |
| 44 | */ |
| 45 | static void do_interrupt_user(CPUX86State *env, int intno, int is_int, |
| 46 | int error_code, target_ulong next_eip) |
| 47 | { |
| 48 | if (is_int) { |
| 49 | SegmentCache *dt; |
| 50 | target_ulong ptr; |
| 51 | int dpl, cpl, shift; |
| 52 | uint32_t e2; |
| 53 | |
| 54 | dt = &env->idt; |
| 55 | if (env->hflags & HF_LMA_MASK) { |
| 56 | shift = 4; |
| 57 | } else { |
| 58 | shift = 3; |
| 59 | } |
| 60 | ptr = dt->base + (intno << shift); |
| 61 | e2 = cpu_ldl_kernel(env, ptr + 4); |
| 62 | |
| 63 | dpl = (e2 >> DESC_DPL_SHIFT) & 3; |
| 64 | cpl = env->hflags & HF_CPL_MASK; |
| 65 | /* check privilege if software int */ |
| 66 | if (dpl < cpl) { |
| 67 | raise_exception_err(env, EXCP0D_GPF, intno * 8 + 2); |
| 68 | } |
| 69 | } |
| 70 | |
| 71 | /* Since we emulate only user space, we cannot do more than |
| 72 | exiting the emulation with the suitable exception and error |
| 73 | code. So update EIP for INT 0x80 and EXCP_SYSCALL. */ |
| 74 | if (is_int || intno == EXCP_SYSCALL) { |
| 75 | env->eip = next_eip; |
| 76 | } |
| 77 | } |
| 78 | |
| 79 | void x86_cpu_do_interrupt(CPUState *cs) |
| 80 | { |
| 81 | X86CPU *cpu = X86_CPU(cs); |
| 82 | CPUX86State *env = &cpu->env; |
| 83 | |
| 84 | /* if user mode only, we simulate a fake exception |
| 85 | which will be handled outside the cpu execution |
| 86 | loop */ |
| 87 | do_interrupt_user(env, cs->exception_index, |
| 88 | env->exception_is_int, |
| 89 | env->error_code, |
| 90 | env->exception_next_eip); |
| 91 | /* successfully delivered */ |
| 92 | env->old_exception = -1; |
| 93 | } |
| 94 | |
| 95 | void cpu_x86_load_seg(CPUX86State *env, X86Seg seg_reg, int selector) |
| 96 | { |
| 97 | if (!(env->cr[0] & CR0_PE_MASK) || (env->eflags & VM_MASK)) { |
| 98 | int dpl = (env->eflags & VM_MASK) ? 3 : 0; |
| 99 | selector &= 0xffff; |
| 100 | cpu_x86_load_seg_cache(env, seg_reg, selector, |
| 101 | (selector << 4), 0xffff, |
| 102 | DESC_P_MASK | DESC_S_MASK | DESC_W_MASK | |
| 103 | DESC_A_MASK | (dpl << DESC_DPL_SHIFT)); |
| 104 | } else { |
| 105 | helper_load_seg(env, seg_reg, selector); |
| 106 | } |
| 107 | } |