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[/] [ao486/] [trunk/] [bochs486/] [cpu/] [ret_far.cc] - Blame information for rev 2

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1 2 alfik 
////////////////////////////////////////////////////////////////////////
2 
// $Id: ret_far.cc 11106 2012-03-25 11:54:32Z sshwarts $
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/////////////////////////////////////////////////////////////////////////
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//
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//   Copyright (c) 2005-2012 Stanislav Shwartsman
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//          Written by Stanislav Shwartsman [sshwarts at sourceforge net]
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//
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//  This library is free software; you can redistribute it and/or
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//  modify it under the terms of the GNU Lesser General Public
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//  License as published by the Free Software Foundation; either
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//  version 2 of the License, or (at your option) any later version.
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//
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//  This library is distributed in the hope that it will be useful,
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//  but WITHOUT ANY WARRANTY; without even the implied warranty of
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//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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//  Lesser General Public License for more details.
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//
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//  You should have received a copy of the GNU Lesser General Public
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//  License along with this library; if not, write to the Free Software
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//  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA B 02110-1301 USA
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//
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////////////////////////////////////////////////////////////////////////
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24 
#define NEED_CPU_REG_SHORTCUTS 1
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#include "bochs.h"
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#include "cpu.h"
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#define LOG_THIS BX_CPU_THIS_PTR
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29 
  void BX_CPP_AttrRegparmN(2)
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BX_CPU_C::return_protected(bxInstruction_c *i, Bit16u pop_bytes)
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{
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  Bit16u raw_cs_selector, raw_ss_selector;
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  bx_selector_t cs_selector, ss_selector;
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  bx_descriptor_t cs_descriptor, ss_descriptor;
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  Bit32u stack_param_offset;
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  bx_address return_RIP, return_RSP, temp_RSP;
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  Bit32u dword1, dword2;
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  /* + 6+N*2: SS      | +12+N*4:     SS | +24+N*8      SS */
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  /* + 4+N*2: SP      | + 8+N*4:    ESP | +16+N*8     RSP */
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  /*          parm N  | +        parm N | +        parm N */
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  /*          parm 3  | +        parm 3 | +        parm 3 */
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  /*          parm 2  | +        parm 2 | +        parm 2 */
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  /* + 4:     parm 1  | + 8:     parm 1 | +16:     parm 1 */
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  /* + 2:     CS      | + 4:         CS | + 8:         CS */
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  /* + 0:     IP      | + 0:        EIP | + 0:        RIP */
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#if BX_SUPPORT_X86_64
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  if (long64_mode()) temp_RSP = RSP;
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  else
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#endif
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  {
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    if (BX_CPU_THIS_PTR sregs[BX_SEG_REG_SS].cache.u.segment.d_b) temp_RSP = ESP;
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    else temp_RSP = SP;
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  }
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#if BX_SUPPORT_X86_64
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  if (i->os64L()) {
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    raw_cs_selector = (Bit16u) stack_read_qword(temp_RSP + 8);
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    return_RIP      =          stack_read_qword(temp_RSP);
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    stack_param_offset = 16;
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  }
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  else
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#endif
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  if (i->os32L()) {
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    raw_cs_selector = (Bit16u) stack_read_dword(temp_RSP + 4);
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    return_RIP      =          stack_read_dword(temp_RSP);
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    stack_param_offset = 8;
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  }
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  else {
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    raw_cs_selector = stack_read_word(temp_RSP + 2);
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    return_RIP      = stack_read_word(temp_RSP);
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    stack_param_offset = 4;
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  }
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  // selector must be non-null else #GP(0)
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  if ((raw_cs_selector & 0xfffc) == 0) {
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    BX_ERROR(("return_protected: CS selector null"));
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    exception(BX_GP_EXCEPTION, 0);
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  }
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  parse_selector(raw_cs_selector, &cs_selector);
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  // selector index must be within its descriptor table limits,
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  // else #GP(selector)
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  fetch_raw_descriptor(&cs_selector, &dword1, &dword2, BX_GP_EXCEPTION);
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  // descriptor AR byte must indicate code segment, else #GP(selector)
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  parse_descriptor(dword1, dword2, &cs_descriptor);
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  // return selector RPL must be >= CPL, else #GP(return selector)
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  if (cs_selector.rpl < CPL) {
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    BX_ERROR(("return_protected: CS.rpl < CPL"));
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    exception(BX_GP_EXCEPTION, raw_cs_selector & 0xfffc);
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  }
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  // check code-segment descriptor
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  check_cs(&cs_descriptor, raw_cs_selector, 0, cs_selector.rpl);
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  // if return selector RPL == CPL then
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  // RETURN TO SAME PRIVILEGE LEVEL
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  if (cs_selector.rpl == CPL)
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  {
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    BX_DEBUG(("return_protected: return to SAME PRIVILEGE LEVEL"));
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    branch_far64(&cs_selector, &cs_descriptor, return_RIP, CPL);
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#if BX_SUPPORT_X86_64
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    if (long64_mode())
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      RSP += stack_param_offset + pop_bytes;
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    else
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#endif
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    {
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      if (BX_CPU_THIS_PTR sregs[BX_SEG_REG_SS].cache.u.segment.d_b)
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        RSP = ESP + stack_param_offset + pop_bytes;
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      else
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         SP += stack_param_offset + pop_bytes;
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    }
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  }
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  /* RETURN TO OUTER PRIVILEGE LEVEL */
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  else {
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    /* + 6+N*2: SS      | +12+N*4:     SS | +24+N*8      SS */
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    /* + 4+N*2: SP      | + 8+N*4:    ESP | +16+N*8     RSP */
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    /*          parm N  | +        parm N | +        parm N */
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    /*          parm 3  | +        parm 3 | +        parm 3 */
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    /*          parm 2  | +        parm 2 | +        parm 2 */
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    /* + 4:     parm 1  | + 8:     parm 1 | +16:     parm 1 */
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    /* + 2:     CS      | + 4:         CS | + 8:         CS */
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    /* + 0:     IP      | + 0:        EIP | + 0:        RIP */
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    BX_DEBUG(("return_protected: return to OUTER PRIVILEGE LEVEL"));
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#if BX_SUPPORT_X86_64
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    if (i->os64L()) {
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      raw_ss_selector = stack_read_word(temp_RSP + 24 + pop_bytes);
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      return_RSP      = stack_read_qword(temp_RSP + 16 + pop_bytes);
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    }
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    else
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#endif
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    if (i->os32L()) {
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      raw_ss_selector = stack_read_word(temp_RSP + 12 + pop_bytes);
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      return_RSP      = stack_read_dword(temp_RSP + 8 + pop_bytes);
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    }
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    else {
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      raw_ss_selector = stack_read_word(temp_RSP + 6 + pop_bytes);
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      return_RSP      = stack_read_word(temp_RSP + 4 + pop_bytes);
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    }
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    /* selector index must be within its descriptor table limits,
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     * else #GP(selector) */
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    parse_selector(raw_ss_selector, &ss_selector);
152 
 
153 
    if ((raw_ss_selector & 0xfffc) == 0) {
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#if BX_SUPPORT_X86_64
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      if (long_mode()) {
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        if (! IS_LONG64_SEGMENT(cs_descriptor) || (cs_selector.rpl == 3)) {
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          BX_ERROR(("return_protected: SS selector null"));
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          exception(BX_GP_EXCEPTION, 0);
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        }
160 
      }
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      else // not in long or compatibility mode
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#endif
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      {
164 
        BX_ERROR(("return_protected: SS selector null"));
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        exception(BX_GP_EXCEPTION, 0);
166 
      }
167 
    }
168 
    else {
169 
      fetch_raw_descriptor(&ss_selector, &dword1, &dword2, BX_GP_EXCEPTION);
170 
      parse_descriptor(dword1, dword2, &ss_descriptor);
171 
 
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      /* selector RPL must = RPL of the return CS selector,
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       * else #GP(selector) */
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      if (ss_selector.rpl != cs_selector.rpl) {
175 
        BX_ERROR(("return_protected: ss.rpl != cs.rpl"));
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        exception(BX_GP_EXCEPTION, raw_ss_selector & 0xfffc);
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      }
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      /* descriptor AR byte must indicate a writable data segment,
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       * else #GP(selector) */
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      if (ss_descriptor.valid==0 || ss_descriptor.segment==0 ||
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           IS_CODE_SEGMENT(ss_descriptor.type) ||
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          !IS_DATA_SEGMENT_WRITEABLE(ss_descriptor.type))
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      {
185 
        BX_ERROR(("return_protected: SS.AR byte not writable data"));
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        exception(BX_GP_EXCEPTION, raw_ss_selector & 0xfffc);
187 
      }
188 
 
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      /* descriptor dpl must = RPL of the return CS selector,
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       * else #GP(selector) */
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      if (ss_descriptor.dpl != cs_selector.rpl) {
192 
        BX_ERROR(("return_protected: SS.dpl != cs.rpl"));
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        exception(BX_GP_EXCEPTION, raw_ss_selector & 0xfffc);
194 
      }
195 
 
196 
      /* segment must be present else #SS(selector) */
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      if (! IS_PRESENT(ss_descriptor)) {
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        BX_ERROR(("return_protected: ss.present == 0"));
199 
        exception(BX_SS_EXCEPTION, raw_ss_selector & 0xfffc);
200 
      }
201 
    }
202 
 
203 
    branch_far64(&cs_selector, &cs_descriptor, return_RIP, cs_selector.rpl);
204 
 
205 
    if ((raw_ss_selector & 0xfffc) != 0) {
206 
      // load SS:RSP from stack
207 
      // load the SS-cache with SS descriptor
208 
      load_ss(&ss_selector, &ss_descriptor, cs_selector.rpl);
209 
    }
210 
#if BX_SUPPORT_X86_64
211 
    else {
212 
      // we are in 64-bit mode (checked above)
213 
      load_null_selector(&BX_CPU_THIS_PTR sregs[BX_SEG_REG_SS], raw_ss_selector);
214 
    }
215 
 
216 
    if (long64_mode())
217 
      RSP = return_RSP + pop_bytes;
218 
    else
219 
#endif
220 
    {
221 
      if (ss_descriptor.u.segment.d_b)
222 
        RSP = (Bit32u)(return_RSP + pop_bytes);
223 
      else
224 
        SP  = (Bit16u)(return_RSP + pop_bytes);
225 
    }
226 
 
227 
    /* check ES, DS, FS, GS for validity */
228 
    validate_seg_regs();
229 
  }
230 
}

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