The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/i386/i386/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: releng/5.1/sys/i386/i386/db_interface.c 112836 2003-03-30 01:16:19Z jake $
   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 #include <sys/cons.h>
   36 #include <sys/pcpu.h>
   37 #include <sys/proc.h>
   38 #include <sys/smp.h>
   39 
   40 #include <machine/cpu.h>
   41 #ifdef SMP
   42 #include <machine/smptests.h>   /** CPUSTOP_ON_DDBBREAK */
   43 #endif
   44 
   45 #include <vm/vm.h>
   46 #include <vm/pmap.h>
   47 
   48 #include <ddb/ddb.h>
   49 
   50 #include <machine/setjmp.h>
   51 
   52 static jmp_buf *db_nofault = 0;
   53 extern jmp_buf  db_jmpbuf;
   54 
   55 extern void     gdb_handle_exception(db_regs_t *, int, int);
   56 
   57 int     db_active;
   58 db_regs_t ddb_regs;
   59 
   60 static jmp_buf  db_global_jmpbuf;
   61 
   62 static __inline u_short
   63 rss(void)
   64 {
   65         u_short ss;
   66 #ifdef __GNUC__
   67         __asm __volatile("mov %%ss,%0" : "=r" (ss));
   68 #else
   69         ss = 0; /* XXXX Fix for other compilers. */
   70 #endif
   71         return ss;
   72 }
   73 
   74 /*
   75  *  kdb_trap - field a TRACE or BPT trap
   76  */
   77 int
   78 kdb_trap(int type, int code, struct i386_saved_state *regs)
   79 {
   80         u_int ef;
   81         volatile int ddb_mode = !(boothowto & RB_GDB);
   82 
   83         /*
   84          * XXX try to do nothing if the console is in graphics mode.
   85          * Handle trace traps (and hardware breakpoints...) by ignoring
   86          * them except for forgetting about them.  Return 0 for other
   87          * traps to say that we haven't done anything.  The trap handler
   88          * will usually panic.  We should handle breakpoint traps for
   89          * our breakpoints by disarming our breakpoints and fixing up
   90          * %eip.
   91          */
   92         if (cons_unavail && ddb_mode) {
   93             if (type == T_TRCTRAP) {
   94                 regs->tf_eflags &= ~PSL_T;
   95                 return (1);
   96             }
   97             return (0);
   98         }
   99 
  100         ef = read_eflags();
  101         disable_intr();
  102 
  103         switch (type) {
  104             case T_BPTFLT:      /* breakpoint */
  105             case T_TRCTRAP:     /* debug exception */
  106                 break;
  107 
  108             default:
  109                 /*
  110                  * XXX this is almost useless now.  In most cases,
  111                  * trap_fatal() has already printed a much more verbose
  112                  * message.  However, it is dangerous to print things in
  113                  * trap_fatal() - printf() might be reentered and trap.
  114                  * The debugger should be given control first.
  115                  */
  116                 if (ddb_mode)
  117                     db_printf("kernel: type %d trap, code=%x\n", type, code);
  118 
  119                 if (db_nofault) {
  120                     jmp_buf *no_fault = db_nofault;
  121                     db_nofault = 0;
  122                     longjmp(*no_fault, 1);
  123                 }
  124         }
  125 
  126         /*
  127          * This handles unexpected traps in ddb commands, including calls to
  128          * non-ddb functions.  db_nofault only applies to memory accesses by
  129          * internal ddb commands.
  130          */
  131         if (db_active)
  132             longjmp(db_global_jmpbuf, 1);
  133 
  134         /*
  135          * XXX We really should switch to a local stack here.
  136          */
  137         ddb_regs = *regs;
  138 
  139         /*
  140          * If in kernel mode, esp and ss are not saved, so dummy them up.
  141          */
  142         if (ISPL(regs->tf_cs) == 0) {
  143             ddb_regs.tf_esp = (int)&regs->tf_esp;
  144             ddb_regs.tf_ss = rss();
  145         }
  146 
  147 #ifdef SMP
  148 #ifdef CPUSTOP_ON_DDBBREAK
  149 
  150 #if defined(VERBOSE_CPUSTOP_ON_DDBBREAK)
  151         db_printf("\nCPU%d stopping CPUs: 0x%08x...", PCPU_GET(cpuid),
  152             PCPU_GET(other_cpus));
  153 #endif /* VERBOSE_CPUSTOP_ON_DDBBREAK */
  154 
  155         /* We stop all CPUs except ourselves (obviously) */
  156         stop_cpus(PCPU_GET(other_cpus));
  157 
  158 #if defined(VERBOSE_CPUSTOP_ON_DDBBREAK)
  159         db_printf(" stopped.\n");
  160 #endif /* VERBOSE_CPUSTOP_ON_DDBBREAK */
  161 
  162 #endif /* CPUSTOP_ON_DDBBREAK */
  163 #endif /* SMP */
  164 
  165         (void) setjmp(db_global_jmpbuf);
  166         if (ddb_mode) {
  167             if (!db_active)
  168                 cndbctl(TRUE);
  169             db_active = 1;
  170             db_trap(type, code);
  171             cndbctl(FALSE);
  172         } else {
  173             db_active = 1;
  174             gdb_handle_exception(&ddb_regs, type, code);
  175         }
  176         db_active = 0;
  177 
  178 #ifdef SMP
  179 #ifdef CPUSTOP_ON_DDBBREAK
  180 
  181 #if defined(VERBOSE_CPUSTOP_ON_DDBBREAK)
  182         db_printf("\nCPU%d restarting CPUs: 0x%08x...", PCPU_GET(cpuid),
  183             stopped_cpus);
  184 #endif /* VERBOSE_CPUSTOP_ON_DDBBREAK */
  185 
  186         /* Restart all the CPUs we previously stopped */
  187         if (stopped_cpus != PCPU_GET(other_cpus) && smp_started != 0) {
  188                 db_printf("whoa, other_cpus: 0x%08x, stopped_cpus: 0x%08x\n",
  189                           PCPU_GET(other_cpus), stopped_cpus);
  190                 panic("stop_cpus() failed");
  191         }
  192         restart_cpus(stopped_cpus);
  193 
  194 #if defined(VERBOSE_CPUSTOP_ON_DDBBREAK)
  195         db_printf(" restarted.\n");
  196 #endif /* VERBOSE_CPUSTOP_ON_DDBBREAK */
  197 
  198 #endif /* CPUSTOP_ON_DDBBREAK */
  199 #endif /* SMP */
  200 
  201         regs->tf_eip    = ddb_regs.tf_eip;
  202         regs->tf_eflags = ddb_regs.tf_eflags;
  203         regs->tf_eax    = ddb_regs.tf_eax;
  204         regs->tf_ecx    = ddb_regs.tf_ecx;
  205         regs->tf_edx    = ddb_regs.tf_edx;
  206         regs->tf_ebx    = ddb_regs.tf_ebx;
  207 
  208         /*
  209          * If in user mode, the saved ESP and SS were valid, restore them.
  210          */
  211         if (ISPL(regs->tf_cs)) {
  212             regs->tf_esp = ddb_regs.tf_esp;
  213             regs->tf_ss  = ddb_regs.tf_ss & 0xffff;
  214         }
  215 
  216         regs->tf_ebp    = ddb_regs.tf_ebp;
  217         regs->tf_esi    = ddb_regs.tf_esi;
  218         regs->tf_edi    = ddb_regs.tf_edi;
  219         regs->tf_es     = ddb_regs.tf_es & 0xffff;
  220         regs->tf_fs     = ddb_regs.tf_fs & 0xffff;
  221         regs->tf_cs     = ddb_regs.tf_cs & 0xffff;
  222         regs->tf_ds     = ddb_regs.tf_ds & 0xffff;
  223 
  224         write_eflags(ef);
  225 
  226         return (1);
  227 }
  228 
  229 /*
  230  * Read bytes from kernel address space for debugger.
  231  */
  232 void
  233 db_read_bytes(vm_offset_t addr, size_t size, char *data)
  234 {
  235         char    *src;
  236 
  237         db_nofault = &db_jmpbuf;
  238 
  239         src = (char *)addr;
  240         while (size-- > 0)
  241             *data++ = *src++;
  242 
  243         db_nofault = 0;
  244 }
  245 
  246 /*
  247  * Write bytes to kernel address space for debugger.
  248  */
  249 void
  250 db_write_bytes(vm_offset_t addr, size_t size, char *data)
  251 {
  252         char    *dst;
  253 
  254         pt_entry_t      *ptep0 = NULL;
  255         pt_entry_t      oldmap0 = 0;
  256         vm_offset_t     addr1;
  257         pt_entry_t      *ptep1 = NULL;
  258         pt_entry_t      oldmap1 = 0;
  259 
  260         db_nofault = &db_jmpbuf;
  261 
  262         if (addr > trunc_page((vm_offset_t)btext) - size &&
  263             addr < round_page((vm_offset_t)etext)) {
  264 
  265             ptep0 = pmap_pte_quick(kernel_pmap, addr);
  266             oldmap0 = *ptep0;
  267             *ptep0 |= PG_RW;
  268 
  269             /* Map another page if the data crosses a page boundary. */
  270             if ((*ptep0 & PG_PS) == 0) {
  271                 addr1 = trunc_page(addr + size - 1);
  272                 if (trunc_page(addr) != addr1) {
  273                     ptep1 = pmap_pte_quick(kernel_pmap, addr1);
  274                     oldmap1 = *ptep1;
  275                     *ptep1 |= PG_RW;
  276                 }
  277             } else {
  278                 addr1 = trunc_4mpage(addr + size - 1);
  279                 if (trunc_4mpage(addr) != addr1) {
  280                     ptep1 = pmap_pte_quick(kernel_pmap, addr1);
  281                     oldmap1 = *ptep1;
  282                     *ptep1 |= PG_RW;
  283                 }
  284             }
  285 
  286             invltlb();
  287         }
  288 
  289         dst = (char *)addr;
  290 
  291         while (size-- > 0)
  292             *dst++ = *data++;
  293 
  294         db_nofault = 0;
  295 
  296         if (ptep0) {
  297             *ptep0 = oldmap0;
  298 
  299             if (ptep1)
  300                 *ptep1 = oldmap1;
  301 
  302             invltlb();
  303         }
  304 }
  305 
  306 /*
  307  * XXX
  308  * Move this to machdep.c and allow it to be called if any debugger is
  309  * installed.
  310  */
  311 void
  312 Debugger(const char *msg)
  313 {
  314         static volatile u_int in_Debugger;
  315 
  316         /*
  317          * XXX
  318          * Do nothing if the console is in graphics mode.  This is
  319          * OK if the call is for the debugger hotkey but not if the call
  320          * is a weak form of panicing.
  321          */
  322         if (cons_unavail && !(boothowto & RB_GDB))
  323             return;
  324 
  325         if (atomic_cmpset_acq_int(&in_Debugger, 0, 1)) {
  326             db_printf("Debugger(\"%s\")\n", msg);
  327             breakpoint();
  328             atomic_store_rel_int(&in_Debugger, 0);
  329         }
  330 }
  331 
  332 void
  333 db_show_mdpcpu(struct pcpu *pc)
  334 {
  335 
  336         db_printf("currentldt   = 0x%x\n", pc->pc_currentldt);
  337 }

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