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/*
* x86 segmentation related helpers (user-mode code):
* TSS, interrupts, system calls, jumps and call/task gates, descriptors
*
* Copyright (c) 2003 Fabrice Bellard
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "cpu.h"
#include "exec/helper-proto.h"
#include "exec/exec-all.h"
#include "exec/cpu_ldst.h"
#include "tcg/helper-tcg.h"
#include "tcg/seg_helper.h"
#ifdef TARGET_X86_64
void helper_syscall(CPUX86State *env, int next_eip_addend)
{
CPUState *cs = env_cpu(env);
cs->exception_index = EXCP_SYSCALL;
env->exception_is_int = 0;
env->exception_next_eip = env->eip + next_eip_addend;
cpu_loop_exit(cs);
}
#endif /* TARGET_X86_64 */
/*
* fake user mode interrupt. is_int is TRUE if coming from the int
* instruction. next_eip is the env->eip value AFTER the interrupt
* instruction. It is only relevant if is_int is TRUE or if intno
* is EXCP_SYSCALL.
*/
static void do_interrupt_user(CPUX86State *env, int intno, int is_int,
int error_code, target_ulong next_eip)
{
if (is_int) {
SegmentCache *dt;
target_ulong ptr;
int dpl, cpl, shift;
uint32_t e2;
dt = &env->idt;
if (env->hflags & HF_LMA_MASK) {
shift = 4;
} else {
shift = 3;
}
ptr = dt->base + (intno << shift);
e2 = cpu_ldl_kernel(env, ptr + 4);
dpl = (e2 >> DESC_DPL_SHIFT) & 3;
cpl = env->hflags & HF_CPL_MASK;
/* check privilege if software int */
if (dpl < cpl) {
raise_exception_err(env, EXCP0D_GPF, (intno << shift) + 2);
}
}
/* Since we emulate only user space, we cannot do more than
exiting the emulation with the suitable exception and error
code. So update EIP for INT 0x80 and EXCP_SYSCALL. */
if (is_int || intno == EXCP_SYSCALL) {
env->eip = next_eip;
}
}
void x86_cpu_do_interrupt(CPUState *cs)
{
X86CPU *cpu = X86_CPU(cs);
CPUX86State *env = &cpu->env;
/* if user mode only, we simulate a fake exception
which will be handled outside the cpu execution
loop */
do_interrupt_user(env, cs->exception_index,
env->exception_is_int,
env->error_code,
env->exception_next_eip);
/* successfully delivered */
env->old_exception = -1;
}
void cpu_x86_load_seg(CPUX86State *env, X86Seg seg_reg, int selector)
{
if (!(env->cr[0] & CR0_PE_MASK) || (env->eflags & VM_MASK)) {
int dpl = (env->eflags & VM_MASK) ? 3 : 0;
selector &= 0xffff;
cpu_x86_load_seg_cache(env, seg_reg, selector,
(selector << 4), 0xffff,
DESC_P_MASK | DESC_S_MASK | DESC_W_MASK |
DESC_A_MASK | (dpl << DESC_DPL_SHIFT));
} else {
helper_load_seg(env, seg_reg, selector);
}
}
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