db_interface.c

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    1 /*
    2  * Mach Operating System
    3  * Copyright (c) 1991,1990 Carnegie Mellon University
    4  * All Rights Reserved.
    5  *
    6  * Permission to use, copy, modify and distribute this software and its
    7  * documentation is hereby granted, provided that both the copyright
    8  * notice and this permission notice appear in all copies of the
    9  * software, derivative works or modified versions, and any portions
   10  * thereof, and that both notices appear in supporting documentation.
   11  *
   12  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS
   13  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
   14  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
   15  *
   16  * Carnegie Mellon requests users of this software to return to
   17  *
   18  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
   19  *  School of Computer Science
   20  *  Carnegie Mellon University
   21  *  Pittsburgh PA 15213-3890
   22  *
   23  * any improvements or extensions that they make and grant Carnegie the
   24  * rights to redistribute these changes.
   25  *
   26  * $FreeBSD$
   27  */
   28 
   29 /*
   30  * Interface to new debugger.
   31  */
   32 #include <sys/param.h>
   33 #include <sys/systm.h>
   34 #include <sys/reboot.h>
   35 
   36 #include <machine/cons.h>
   37 #include <machine/cpu.h>
   38 #ifdef SMP
   39 #include <machine/smp.h>
   40 #include <machine/smptests.h>   /** CPUSTOP_ON_DDBBREAK */
   41 #endif
   42 
   43 #include <vm/vm.h>
   44 #include <vm/pmap.h>
   45 
   46 #include <ddb/ddb.h>
   47 
   48 #include <setjmp.h>
   49 
   50 static jmp_buf *db_nofault = 0;
   51 extern jmp_buf  db_jmpbuf;
   52 
   53 extern void     gdb_handle_exception __P((db_regs_t *, int, int));
   54 
   55 db_regs_t ddb_regs;
   56 
   57 static jmp_buf  db_global_jmpbuf;
   58 static int      db_global_jmpbuf_valid;
   59 
   60 #ifdef __GNUC__
   61 #define rss() ({u_short ss; __asm __volatile("movl %%ss,%0" : "=r" (ss)); ss;})
   62 #endif
   63 
   64 /*
   65  *  kdb_trap - field a TRACE or BPT trap
   66  */
   67 int
   68 kdb_trap(type, code, regs)
   69         int     type, code;
   70         register struct i386_saved_state *regs;
   71 {
   72         volatile int ddb_mode = !(boothowto & RB_GDB);
   73 
   74         /*
   75          * XXX try to do nothing if the console is in graphics mode.
   76          * Handle trace traps (and hardware breakpoints...) by ignoring
   77          * them except for forgetting about them.  Return 0 for other
   78          * traps to say that we haven't done anything.  The trap handler
   79          * will usually panic.  We should handle breakpoint traps for
   80          * our breakpoints by disarming our breakpoints and fixing up
   81          * %eip.
   82          */
   83         if (cons_unavail && ddb_mode) {
   84             if (type == T_TRCTRAP) {
   85                 regs->tf_eflags &= ~PSL_T;
   86                 return (1);
   87             }
   88             return (0);
   89         }
   90 
   91         switch (type) {
   92             case T_BPTFLT:      /* breakpoint */
   93             case T_TRCTRAP:     /* debug exception */
   94                 break;
   95 
   96             default:
   97                 /*
   98                  * XXX this is almost useless now.  In most cases,
   99                  * trap_fatal() has already printed a much more verbose
  100                  * message.  However, it is dangerous to print things in
  101                  * trap_fatal() - printf() might be reentered and trap.
  102                  * The debugger should be given control first.
  103                  */
  104                 if (ddb_mode)
  105                     db_printf("kernel: type %d trap, code=%x\n", type, code);
  106 
  107                 if (db_nofault) {
  108                     jmp_buf *no_fault = db_nofault;
  109                     db_nofault = 0;
  110                     longjmp(*no_fault, 1);
  111                 }
  112         }
  113 
  114         /*
  115          * This handles unexpected traps in ddb commands, including calls to
  116          * non-ddb functions.  db_nofault only applies to memory accesses by
  117          * internal ddb commands.
  118          */
  119         if (db_global_jmpbuf_valid)
  120             longjmp(db_global_jmpbuf, 1);
  121 
  122         /*
  123          * XXX We really should switch to a local stack here.
  124          */
  125         ddb_regs = *regs;
  126 
  127         /*
  128          * If in kernel mode, esp and ss are not saved, so dummy them up.
  129          */
  130         if (ISPL(regs->tf_cs) == 0) {
  131             ddb_regs.tf_esp = (int)&regs->tf_esp;
  132             ddb_regs.tf_ss = rss();
  133         }
  134 
  135         cnpollc(TRUE);
  136 
  137 #ifdef SMP
  138 #ifdef CPUSTOP_ON_DDBBREAK
  139 
  140 #if defined(VERBOSE_CPUSTOP_ON_DDBBREAK)
  141         db_printf("\nCPU%d stopping CPUs: 0x%08x\n", cpuid, other_cpus);
  142 #endif /* VERBOSE_CPUSTOP_ON_DDBBREAK */
  143 
  144         /* We stop all CPUs except ourselves (obviously) */
  145         stop_cpus(other_cpus);
  146 
  147 #if defined(VERBOSE_CPUSTOP_ON_DDBBREAK)
  148         db_printf(" stopped\n");
  149 #endif /* VERBOSE_CPUSTOP_ON_DDBBREAK */
  150 
  151 #endif /* CPUSTOP_ON_DDBBREAK */
  152 #endif /* SMP */
  153 
  154         (void) setjmp(db_global_jmpbuf);
  155         db_global_jmpbuf_valid = TRUE;
  156         if (ddb_mode)
  157             db_trap(type, code);
  158         else
  159             gdb_handle_exception(&ddb_regs, type, code);
  160         db_global_jmpbuf_valid = FALSE;
  161 
  162 #ifdef SMP
  163 #ifdef CPUSTOP_ON_DDBBREAK
  164 
  165 #if defined(VERBOSE_CPUSTOP_ON_DDBBREAK)
  166         db_printf("\nCPU%d restarting CPUs: 0x%08x\n", cpuid, stopped_cpus);
  167 #endif /* VERBOSE_CPUSTOP_ON_DDBBREAK */
  168 
  169         /* Restart all the CPUs we previously stopped */
  170         if (stopped_cpus != other_cpus) {
  171                 db_printf("whoa, other_cpus: 0x%08x, stopped_cpus: 0x%08x\n",
  172                           other_cpus, stopped_cpus);
  173                 panic("stop_cpus() failed");
  174         }
  175         restart_cpus(stopped_cpus);
  176 
  177 #if defined(VERBOSE_CPUSTOP_ON_DDBBREAK)
  178         db_printf(" restarted\n");
  179 #endif /* VERBOSE_CPUSTOP_ON_DDBBREAK */
  180 
  181 #endif /* CPUSTOP_ON_DDBBREAK */
  182 #endif /* SMP */
  183 
  184         cnpollc(FALSE);
  185 
  186         regs->tf_eip    = ddb_regs.tf_eip;
  187         regs->tf_eflags = ddb_regs.tf_eflags;
  188         regs->tf_eax    = ddb_regs.tf_eax;
  189         regs->tf_ecx    = ddb_regs.tf_ecx;
  190         regs->tf_edx    = ddb_regs.tf_edx;
  191         regs->tf_ebx    = ddb_regs.tf_ebx;
  192 
  193         /*
  194          * If in user mode, the saved ESP and SS were valid, restore them.
  195          */
  196         if (ISPL(regs->tf_cs)) {
  197             regs->tf_esp = ddb_regs.tf_esp;
  198             regs->tf_ss  = ddb_regs.tf_ss & 0xffff;
  199         }
  200 
  201         regs->tf_ebp    = ddb_regs.tf_ebp;
  202         regs->tf_esi    = ddb_regs.tf_esi;
  203         regs->tf_edi    = ddb_regs.tf_edi;
  204         regs->tf_es     = ddb_regs.tf_es & 0xffff;
  205         regs->tf_cs     = ddb_regs.tf_cs & 0xffff;
  206         regs->tf_ds     = ddb_regs.tf_ds & 0xffff;
  207         return (1);
  208 }
  209 
  210 /*
  211  * Read bytes from kernel address space for debugger.
  212  */
  213 void
  214 db_read_bytes(addr, size, data)
  215         vm_offset_t     addr;
  216         register size_t size;
  217         register char   *data;
  218 {
  219         register char   *src;
  220 
  221         db_nofault = &db_jmpbuf;
  222 
  223         src = (char *)addr;
  224         while (size-- > 0)
  225             *data++ = *src++;
  226 
  227         db_nofault = 0;
  228 }
  229 
  230 /*
  231  * Write bytes to kernel address space for debugger.
  232  */
  233 void
  234 db_write_bytes(addr, size, data)
  235         vm_offset_t     addr;
  236         register size_t size;
  237         register char   *data;
  238 {
  239         register char   *dst;
  240 
  241         unsigned        *ptep0 = NULL;
  242         unsigned        oldmap0 = 0;
  243         vm_offset_t     addr1;
  244         unsigned        *ptep1 = NULL;
  245         unsigned        oldmap1 = 0;
  246 
  247         db_nofault = &db_jmpbuf;
  248 
  249         if (addr > trunc_page((vm_offset_t)btext) - size &&
  250             addr < round_page((vm_offset_t)etext)) {
  251 
  252             ptep0 = pmap_pte(kernel_pmap, addr);
  253             oldmap0 = *ptep0;
  254             *ptep0 |= PG_RW;
  255 
  256             /* Map another page if the data crosses a page boundary. */
  257             if ((*ptep0 & PG_PS) == 0) {
  258                 addr1 = trunc_page(addr + size - 1);
  259                 if (trunc_page(addr) != addr1) {
  260                     ptep1 = pmap_pte(kernel_pmap, addr1);
  261                     oldmap1 = *ptep1;
  262                     *ptep1 |= PG_RW;
  263                 }
  264             } else {
  265                 addr1 = trunc_4mpage(addr + size - 1);
  266                 if (trunc_4mpage(addr) != addr1) {
  267                     ptep1 = pmap_pte(kernel_pmap, addr1);
  268                     oldmap1 = *ptep1;
  269                     *ptep1 |= PG_RW;
  270                 }
  271             }
  272 
  273             invltlb();
  274         }
  275 
  276         dst = (char *)addr;
  277 
  278         while (size-- > 0)
  279             *dst++ = *data++;
  280 
  281         db_nofault = 0;
  282 
  283         if (ptep0) {
  284             *ptep0 = oldmap0;
  285 
  286             if (ptep1)
  287                 *ptep1 = oldmap1;
  288 
  289             invltlb();
  290         }
  291 }
  292 
  293 /*
  294  * XXX
  295  * Move this to machdep.c and allow it to be called if any debugger is
  296  * installed.
  297  */
  298 volatile int in_Debugger = 0;
  299 
  300 void
  301 Debugger(msg)
  302         const char *msg;
  303 {
  304 
  305         /*
  306          * XXX
  307          * Do nothing if the console is in graphics mode.  This is
  308          * OK if the call is for the debugger hotkey but not if the call
  309          * is a weak form of panicing.
  310          */
  311         if (cons_unavail && !(boothowto & RB_GDB))
  312             return;
  313 
  314         if (!in_Debugger) {
  315             in_Debugger = 1;
  316             db_printf("Debugger(\"%s\")\n", msg);
  317             breakpoint();
  318             in_Debugger = 0;
  319         }
  320 }

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FreeBSD/Linux Kernel Cross Reference sys/i386/i386/db_interface.c

FreeBSD/Linux Kernel Cross Reference
sys/i386/i386/db_interface.c