src/libcaptive/ps/signal.c

   1 /* $Id$
   2  * UNIX signal handling for processor emulation for support of ntoskrnl of libcaptive
   3  * Copyright (C) 2002 Jan Kratochvil <project-captive@jankratochvil.net>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; exactly version 2 of June 1991 is required
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  17  */
  18
  19
  20 #define _GNU_SOURCE 1   /* for sys/ucontext.h for REG_* */
  21
  22 #include "config.h"
  23
  24 #include "captive/signal.h"     /* self */
  25 #include <glib/gtypes.h>
  26 #include <glib/gmessages.h>
  27 #include <signal.h>
  28 #include "captive/macros.h"
  29 #include <sys/ucontext.h>       /* for struct ucontext */
  30 #include "captive/mm.h" /* for captive_mmap_map_get() */
  31 #include <sys/mman.h>
  32 #include "reactos/internal/mm.h"  /* for PAGE_SIZE */
  33
  34
  35 static greg_t val_exceptionstack_top;
  36
  37 static gboolean instr_mov_greg_to_fsmem(int greg,const void *fsmem,struct ucontext *ucontext)
  38 {
  39         if (fsmem==0x00000000) {        /* exception stack top pointer */
  40                 /* moving from %esp is required to pass! */
  41                 val_exceptionstack_top=ucontext->uc_mcontext.gregs[greg];
  42                 return TRUE;
  43                 }
  44         g_return_val_if_reached(FALSE);
  45 }
  46
  47 static gboolean instr_mov_fsmem_to_greg(const void *fsmem,int greg,struct ucontext *ucontext)
  48 {
  49         if (fsmem==0x00000000) {        /* exception stack top pointer */
  50                 /* moving to %esp is required to pass! */
  51                 ucontext->uc_mcontext.gregs[greg]=val_exceptionstack_top;
  52                 return TRUE;
  53                 }
  54         g_return_val_if_reached(FALSE);
  55 }
  56
  57 static int op_regcode_to_greg(guint8 regcode)
  58 {
  59         switch (regcode) {
  60                 case 0x00: return REG_EAX;
  61                 case 0x01: return REG_ECX;
  62                 case 0x02: return REG_EDX;
  63                 case 0x03: return REG_EBX;
  64                 case 0x04: return REG_ESP;
  65                 case 0x05: return REG_EBP;
  66                 case 0x06: return REG_ESI;
  67                 case 0x07: return REG_EDI;
  68                 }
  69         g_return_val_if_reached(REG_EAX);
  70 }
  71
  72 static void sigaction_SIGSEGV(int signo,siginfo_t *siginfo,struct ucontext *ucontext)
  73 {
  74 const guint8 *reg_eip;
  75 const void *reg_eip_aligned;
  76
  77         g_return_if_fail(signo==SIGSEGV);
  78         g_return_if_fail(siginfo->si_signo==SIGSEGV);
  79         /* siginfo->si_code is weird, seen to have value 128 */
  80
  81         reg_eip=(void *)ucontext->uc_mcontext.gregs[REG_EIP];
  82
  83         /* 'reg_eip' is not yet PAGE_SIZE-aligned but we need the aligned ptr for captive_mmap_map_get().
  84          * glib NOTE: YOU MAY NOT STORE POINTERS IN INTEGERS.
  85          */
  86         reg_eip_aligned=(const void *)(((char *)reg_eip)-(GPOINTER_TO_UINT(reg_eip)&(PAGE_SIZE-1)));
  87         g_assert(reg_eip_aligned!=NULL);
  88         g_return_if_fail(!(captive_mmap_map_get(reg_eip_aligned)&PROT_EXEC));
  89
  90         /* all instruction notation comments are written in AT&T 'instr src,dest' syntax! */
  91         if (*reg_eip==0x64) {   /* prefix '%fs:' */
  92                 reg_eip++;
  93                 if (*reg_eip==0xA3) {   /* 'mov %eax,%fs:{reg_eip[1..4]}' */
  94                         reg_eip++;
  95                         if (instr_mov_greg_to_fsmem(REG_EAX,*(const void **)reg_eip,ucontext)) {
  96                                 reg_eip+=4;
  97                                 goto ok;
  98                                 }
  99                         g_assert_not_reached();
 100                         }
 101                 if (*reg_eip==0x89) {   /* prefix 0x89 */
 102                         reg_eip++;
 103                         if ((*reg_eip & ~0x38)==0x05)   { /* 'mov %{op_regcode_to_greg(*reg_eip[b3..b5])},%fs:{reg_eip[1..4]} */
 104                                 reg_eip++;
 105                                 if (instr_mov_greg_to_fsmem(op_regcode_to_greg(reg_eip[-1]>>3U),*(const void **)reg_eip,ucontext)) {
 106                                         reg_eip+=4;
 107                                         goto ok;
 108                                         }
 109                                 g_assert_not_reached();
 110                                 }
 111                         g_assert_not_reached();
 112                         }
 113                 if (*reg_eip==0xA1) {   /* 'mov %fs:{reg_eip[1..4]},%eax' */
 114                         reg_eip++;
 115                         if (instr_mov_fsmem_to_greg(*(const void **)reg_eip,REG_EAX,ucontext)) {
 116                                 reg_eip+=4;
 117                                 goto ok;
 118                                 }
 119                         g_assert_not_reached();
 120                         }
 121                 if (*reg_eip==0x8B) {   /* prefix 0x8B */
 122                         reg_eip++;
 123                         if ((*reg_eip & ~0x38)==0x05) { /* 'mov %fs:{reg_eip[1..4]},%{op_regcode_to_greg(*reg_eip[b3..b5])} */
 124                                 reg_eip++;
 125                                 if (instr_mov_fsmem_to_greg(*(const void **)reg_eip,op_regcode_to_greg(reg_eip[-1]>>3U),ucontext)) {
 126                                         reg_eip+=4;
 127                                         goto ok;
 128                                         }
 129                                 g_assert_not_reached();
 130                                 }
 131                         g_assert_not_reached();
 132                         }
 133                 g_assert_not_reached();
 134                 }
 135         g_assert_not_reached();
 136
 137 ok:
 138         ucontext->uc_mcontext.gregs[REG_EIP]=(greg_t)reg_eip;
 139         /* success */
 140 }
 141
 142 /**
 143  * captive_signal_init:
 144  *
 145  * Initialize UNIX signal handling to be able to emulate foreign W32
 146  * instructions. These instructions must be located inside address
 147  * space of foreign W32 binary code which is identified by successful
 148  * call to captive_mmap_map_get() returning #PROT_EXEC bit set.
 149  * This bit should be set from MmAllocateSection() called from
 150  * ntoskrnl/ldr/loader.c/LdrPEProcessModule().
 151  *
 152  * Currently emulated set is the access to %fs register offset %0
 153  * where the exception stack top pointer is located.
 154  *
 155  * Returns: %TRUE if successful.
 156  */
 157 gboolean captive_signal_init(void)
 158 {
 159 gint errint;
 160 struct sigaction sigaction_struct;
 161 sigset_t sigset;
 162
 163         CAPTIVE_MEMZERO(&sigaction_struct);     /* this structure may have unpredictable fields */
 164
 165         /* Init 'sigaction_struct.sa_mask'. */
 166         errint=sigemptyset(&sigaction_struct.sa_mask);
 167         g_return_val_if_fail(errint==0,FALSE);
 168         errint=sigaddset(&sigaction_struct.sa_mask,SIGSEGV);
 169         g_return_val_if_fail(errint==0,FALSE);
 170
 171         /* Set the signal sigaction handler. */
 172         sigaction_struct.sa_sigaction=(void (*)(int,siginfo_t *,void *))sigaction_SIGSEGV;
 173         sigaction_struct.sa_flags=0
 174                         |SA_SIGINFO;    /* Use 'sa_sigaction' (not 'sa_handler') */
 175         errint=sigaction(SIGSEGV,
 176                         &sigaction_struct,      /* act */
 177                         NULL);  /* oldact */
 178         g_return_val_if_fail(errint==0,FALSE);
 179
 180         /* Enable SIGSEGV signal (should be default). */
 181         errint=sigemptyset(&sigset);
 182         g_return_val_if_fail(errint==0,FALSE);
 183         errint=sigaddset(&sigset,SIGSEGV);
 184         g_return_val_if_fail(errint==0,FALSE);
 185         errint=sigprocmask(SIG_UNBLOCK,
 186                         &sigset,        /* set */
 187                         NULL);  /* oldset */
 188         g_return_val_if_fail(errint==0,FALSE);
 189
 190         return TRUE;
 191 }