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/5.0/sys/i386/i386/db_interface.c 103753 2002-09-21 18:53:58Z markm $
   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         volatile int ddb_mode = !(boothowto & RB_GDB);
   81 
   82         /*
   83          * XXX try to do nothing if the console is in graphics mode.
   84          * Handle trace traps (and hardware breakpoints...) by ignoring
   85          * them except for forgetting about them.  Return 0 for other
   86          * traps to say that we haven't done anything.  The trap handler
   87          * will usually panic.  We should handle breakpoint traps for
   88          * our breakpoints by disarming our breakpoints and fixing up
   89          * %eip.
   90          */
   91         if (cons_unavail && ddb_mode) {
   92             if (type == T_TRCTRAP) {
   93                 regs->tf_eflags &= ~PSL_T;
   94                 return (1);
   95             }
   96             return (0);
   97         }
   98 
   99         switch (type) {
  100             case T_BPTFLT:      /* breakpoint */
  101             case T_TRCTRAP:     /* debug exception */
  102                 break;
  103 
  104             default:
  105                 /*
  106                  * XXX this is almost useless now.  In most cases,
  107                  * trap_fatal() has already printed a much more verbose
  108                  * message.  However, it is dangerous to print things in
  109                  * trap_fatal() - printf() might be reentered and trap.
  110                  * The debugger should be given control first.
  111                  */
  112                 if (ddb_mode)
  113                     db_printf("kernel: type %d trap, code=%x\n", type, code);
  114 
  115                 if (db_nofault) {
  116                     jmp_buf *no_fault = db_nofault;
  117                     db_nofault = 0;
  118                     longjmp(*no_fault, 1);
  119                 }
  120         }
  121 
  122         /*
  123          * This handles unexpected traps in ddb commands, including calls to
  124          * non-ddb functions.  db_nofault only applies to memory accesses by
  125          * internal ddb commands.
  126          */
  127         if (db_active)
  128             longjmp(db_global_jmpbuf, 1);
  129 
  130         /*
  131          * XXX We really should switch to a local stack here.
  132          */
  133         ddb_regs = *regs;
  134 
  135         /*
  136          * If in kernel mode, esp and ss are not saved, so dummy them up.
  137          */
  138         if (ISPL(regs->tf_cs) == 0) {
  139             ddb_regs.tf_esp = (int)&regs->tf_esp;
  140             ddb_regs.tf_ss = rss();
  141         }
  142 
  143 #ifdef SMP
  144 #ifdef CPUSTOP_ON_DDBBREAK
  145 
  146 #if defined(VERBOSE_CPUSTOP_ON_DDBBREAK)
  147         db_printf("\nCPU%d stopping CPUs: 0x%08x...", PCPU_GET(cpuid),
  148             PCPU_GET(other_cpus));
  149 #endif /* VERBOSE_CPUSTOP_ON_DDBBREAK */
  150 
  151         /* We stop all CPUs except ourselves (obviously) */
  152         stop_cpus(PCPU_GET(other_cpus));
  153 
  154 #if defined(VERBOSE_CPUSTOP_ON_DDBBREAK)
  155         db_printf(" stopped.\n");
  156 #endif /* VERBOSE_CPUSTOP_ON_DDBBREAK */
  157 
  158 #endif /* CPUSTOP_ON_DDBBREAK */
  159 #endif /* SMP */
  160 
  161         (void) setjmp(db_global_jmpbuf);
  162         if (ddb_mode) {
  163             if (!db_active)
  164                 cndbctl(TRUE);
  165             db_active = 1;
  166             db_trap(type, code);
  167             cndbctl(FALSE);
  168         } else {
  169             db_active = 1;
  170             gdb_handle_exception(&ddb_regs, type, code);
  171         }
  172         db_active = 0;
  173 
  174 #ifdef SMP
  175 #ifdef CPUSTOP_ON_DDBBREAK
  176 
  177 #if defined(VERBOSE_CPUSTOP_ON_DDBBREAK)
  178         db_printf("\nCPU%d restarting CPUs: 0x%08x...", PCPU_GET(cpuid),
  179             stopped_cpus);
  180 #endif /* VERBOSE_CPUSTOP_ON_DDBBREAK */
  181 
  182         /* Restart all the CPUs we previously stopped */
  183         if (stopped_cpus != PCPU_GET(other_cpus) && smp_started != 0) {
  184                 db_printf("whoa, other_cpus: 0x%08x, stopped_cpus: 0x%08x\n",
  185                           PCPU_GET(other_cpus), stopped_cpus);
  186                 panic("stop_cpus() failed");
  187         }
  188         restart_cpus(stopped_cpus);
  189 
  190 #if defined(VERBOSE_CPUSTOP_ON_DDBBREAK)
  191         db_printf(" restarted.\n");
  192 #endif /* VERBOSE_CPUSTOP_ON_DDBBREAK */
  193 
  194 #endif /* CPUSTOP_ON_DDBBREAK */
  195 #endif /* SMP */
  196 
  197         regs->tf_eip    = ddb_regs.tf_eip;
  198         regs->tf_eflags = ddb_regs.tf_eflags;
  199         regs->tf_eax    = ddb_regs.tf_eax;
  200         regs->tf_ecx    = ddb_regs.tf_ecx;
  201         regs->tf_edx    = ddb_regs.tf_edx;
  202         regs->tf_ebx    = ddb_regs.tf_ebx;
  203 
  204         /*
  205          * If in user mode, the saved ESP and SS were valid, restore them.
  206          */
  207         if (ISPL(regs->tf_cs)) {
  208             regs->tf_esp = ddb_regs.tf_esp;
  209             regs->tf_ss  = ddb_regs.tf_ss & 0xffff;
  210         }
  211 
  212         regs->tf_ebp    = ddb_regs.tf_ebp;
  213         regs->tf_esi    = ddb_regs.tf_esi;
  214         regs->tf_edi    = ddb_regs.tf_edi;
  215         regs->tf_es     = ddb_regs.tf_es & 0xffff;
  216         regs->tf_fs     = ddb_regs.tf_fs & 0xffff;
  217         regs->tf_cs     = ddb_regs.tf_cs & 0xffff;
  218         regs->tf_ds     = ddb_regs.tf_ds & 0xffff;
  219         return (1);
  220 }
  221 
  222 /*
  223  * Read bytes from kernel address space for debugger.
  224  */
  225 void
  226 db_read_bytes(vm_offset_t addr, size_t size, char *data)
  227 {
  228         char    *src;
  229 
  230         db_nofault = &db_jmpbuf;
  231 
  232         src = (char *)addr;
  233         while (size-- > 0)
  234             *data++ = *src++;
  235 
  236         db_nofault = 0;
  237 }
  238 
  239 /*
  240  * Write bytes to kernel address space for debugger.
  241  */
  242 void
  243 db_write_bytes(vm_offset_t addr, size_t size, char *data)
  244 {
  245         char    *dst;
  246 
  247         unsigned        *ptep0 = NULL;
  248         unsigned        oldmap0 = 0;
  249         vm_offset_t     addr1;
  250         unsigned        *ptep1 = NULL;
  251         unsigned        oldmap1 = 0;
  252 
  253         db_nofault = &db_jmpbuf;
  254 
  255         if (addr > trunc_page((vm_offset_t)btext) - size &&
  256             addr < round_page((vm_offset_t)etext)) {
  257 
  258             ptep0 = pmap_pte(kernel_pmap, addr);
  259             oldmap0 = *ptep0;
  260             *ptep0 |= PG_RW;
  261 
  262             /* Map another page if the data crosses a page boundary. */
  263             if ((*ptep0 & PG_PS) == 0) {
  264                 addr1 = trunc_page(addr + size - 1);
  265                 if (trunc_page(addr) != addr1) {
  266                     ptep1 = pmap_pte(kernel_pmap, addr1);
  267                     oldmap1 = *ptep1;
  268                     *ptep1 |= PG_RW;
  269                 }
  270             } else {
  271                 addr1 = trunc_4mpage(addr + size - 1);
  272                 if (trunc_4mpage(addr) != addr1) {
  273                     ptep1 = pmap_pte(kernel_pmap, addr1);
  274                     oldmap1 = *ptep1;
  275                     *ptep1 |= PG_RW;
  276                 }
  277             }
  278 
  279             invltlb();
  280         }
  281 
  282         dst = (char *)addr;
  283 
  284         while (size-- > 0)
  285             *dst++ = *data++;
  286 
  287         db_nofault = 0;
  288 
  289         if (ptep0) {
  290             *ptep0 = oldmap0;
  291 
  292             if (ptep1)
  293                 *ptep1 = oldmap1;
  294 
  295             invltlb();
  296         }
  297 }
  298 
  299 /*
  300  * XXX
  301  * Move this to machdep.c and allow it to be called if any debugger is
  302  * installed.
  303  */
  304 void
  305 Debugger(const char *msg)
  306 {
  307         static volatile u_int in_Debugger;
  308 
  309         /*
  310          * XXX
  311          * Do nothing if the console is in graphics mode.  This is
  312          * OK if the call is for the debugger hotkey but not if the call
  313          * is a weak form of panicing.
  314          */
  315         if (cons_unavail && !(boothowto & RB_GDB))
  316             return;
  317 
  318         if (atomic_cmpset_acq_int(&in_Debugger, 0, 1)) {
  319             db_printf("Debugger(\"%s\")\n", msg);
  320             breakpoint();
  321             atomic_store_rel_int(&in_Debugger, 0);
  322         }
  323 }
  324 
  325 void
  326 db_show_mdpcpu(struct pcpu *pc)
  327 {
  328 
  329         db_printf("currentldt   = 0x%x\n", pc->pc_currentldt);
  330 }

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