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/amd64/amd64/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/amd64/amd64/db_interface.c 115403 2003-05-30 01:01:07Z peter $
   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 
   42 #include <vm/vm.h>
   43 #include <vm/pmap.h>
   44 
   45 #include <ddb/ddb.h>
   46 
   47 #include <machine/setjmp.h>
   48 
   49 static jmp_buf *db_nofault = 0;
   50 extern jmp_buf  db_jmpbuf;
   51 
   52 extern void     gdb_handle_exception(db_regs_t *, int, int);
   53 
   54 int     db_active;
   55 db_regs_t ddb_regs;
   56 
   57 static jmp_buf  db_global_jmpbuf;
   58 
   59 static __inline u_short
   60 rss(void)
   61 {
   62         u_short ss;
   63 #ifdef __GNUC__
   64         __asm __volatile("mov %%ss,%0" : "=r" (ss));
   65 #else
   66         ss = 0; /* XXXX Fix for other compilers. */
   67 #endif
   68         return ss;
   69 }
   70 
   71 /*
   72  *  kdb_trap - field a TRACE or BPT trap
   73  */
   74 int
   75 kdb_trap(int type, int code, struct amd64_saved_state *regs)
   76 {
   77         u_long ef;
   78         volatile int ddb_mode = !(boothowto & RB_GDB);
   79 
   80         /*
   81          * XXX try to do nothing if the console is in graphics mode.
   82          * Handle trace traps (and hardware breakpoints...) by ignoring
   83          * them except for forgetting about them.  Return 0 for other
   84          * traps to say that we haven't done anything.  The trap handler
   85          * will usually panic.  We should handle breakpoint traps for
   86          * our breakpoints by disarming our breakpoints and fixing up
   87          * %eip.
   88          */
   89         if (cons_unavail && ddb_mode) {
   90             if (type == T_TRCTRAP) {
   91                 regs->tf_rflags &= ~PSL_T;
   92                 return (1);
   93             }
   94             return (0);
   95         }
   96 
   97         ef = read_rflags();
   98         disable_intr();
   99 
  100         switch (type) {
  101             case T_BPTFLT:      /* breakpoint */
  102             case T_TRCTRAP:     /* debug exception */
  103                 break;
  104 
  105             default:
  106                 /*
  107                  * XXX this is almost useless now.  In most cases,
  108                  * trap_fatal() has already printed a much more verbose
  109                  * message.  However, it is dangerous to print things in
  110                  * trap_fatal() - printf() might be reentered and trap.
  111                  * The debugger should be given control first.
  112                  */
  113                 if (ddb_mode)
  114                     db_printf("kernel: type %d trap, code=%x\n", type, code);
  115 
  116                 if (db_nofault) {
  117                     jmp_buf *no_fault = db_nofault;
  118                     db_nofault = 0;
  119                     longjmp(*no_fault, 1);
  120                 }
  121         }
  122 
  123         /*
  124          * This handles unexpected traps in ddb commands, including calls to
  125          * non-ddb functions.  db_nofault only applies to memory accesses by
  126          * internal ddb commands.
  127          */
  128         if (db_active)
  129             longjmp(db_global_jmpbuf, 1);
  130 
  131         /*
  132          * XXX We really should switch to a local stack here.
  133          */
  134         ddb_regs = *regs;
  135 
  136         /*
  137          * If in kernel mode, esp and ss are not saved, so dummy them up.
  138          */
  139         if (ISPL(regs->tf_cs) == 0) {
  140             ddb_regs.tf_rsp = (long)&regs->tf_rsp;
  141             ddb_regs.tf_ss = rss();
  142         }
  143 
  144         (void) setjmp(db_global_jmpbuf);
  145         if (ddb_mode) {
  146             if (!db_active)
  147                 cndbctl(TRUE);
  148             db_active = 1;
  149             db_trap(type, code);
  150             cndbctl(FALSE);
  151         } else {
  152             db_active = 1;
  153             gdb_handle_exception(&ddb_regs, type, code);
  154         }
  155         db_active = 0;
  156 
  157         regs->tf_rip    = ddb_regs.tf_rip;
  158         regs->tf_rflags = ddb_regs.tf_rflags;
  159         regs->tf_rax    = ddb_regs.tf_rax;
  160         regs->tf_rcx    = ddb_regs.tf_rcx;
  161         regs->tf_rdx    = ddb_regs.tf_rdx;
  162         regs->tf_rbx    = ddb_regs.tf_rbx;
  163 
  164         /*
  165          * If in user mode, the saved ESP and SS were valid, restore them.
  166          */
  167         if (ISPL(regs->tf_cs)) {
  168             regs->tf_rsp = ddb_regs.tf_rsp;
  169             regs->tf_ss  = ddb_regs.tf_ss & 0xffff;
  170         }
  171 
  172         regs->tf_rbp    = ddb_regs.tf_rbp;
  173         regs->tf_rsi    = ddb_regs.tf_rsi;
  174         regs->tf_rdi    = ddb_regs.tf_rdi;
  175 
  176         regs->tf_r8     = ddb_regs.tf_r8;
  177         regs->tf_r9     = ddb_regs.tf_r9;
  178         regs->tf_r10    = ddb_regs.tf_r10;
  179         regs->tf_r11    = ddb_regs.tf_r11;
  180         regs->tf_r12    = ddb_regs.tf_r12;
  181         regs->tf_r13    = ddb_regs.tf_r13;
  182         regs->tf_r14    = ddb_regs.tf_r14;
  183         regs->tf_r15    = ddb_regs.tf_r15;
  184 
  185 #if 0
  186         regs->tf_es     = ddb_regs.tf_es & 0xffff;
  187         regs->tf_fs     = ddb_regs.tf_fs & 0xffff;
  188 #endif
  189         regs->tf_cs     = ddb_regs.tf_cs & 0xffff;
  190 #if 0
  191         regs->tf_ds     = ddb_regs.tf_ds & 0xffff;
  192 #endif
  193 
  194         write_rflags(ef);
  195 
  196         return (1);
  197 }
  198 
  199 /*
  200  * Read bytes from kernel address space for debugger.
  201  */
  202 void
  203 db_read_bytes(vm_offset_t addr, size_t size, char *data)
  204 {
  205         char    *src;
  206 
  207         db_nofault = &db_jmpbuf;
  208 
  209         src = (char *)addr;
  210         while (size-- > 0)
  211             *data++ = *src++;
  212 
  213         db_nofault = 0;
  214 }
  215 
  216 /*
  217  * Write bytes to kernel address space for debugger.
  218  */
  219 void
  220 db_write_bytes(vm_offset_t addr, size_t size, char *data)
  221 {
  222         char    *dst;
  223 
  224         pt_entry_t      *ptep0 = NULL;
  225         pt_entry_t      oldmap0 = 0;
  226         vm_offset_t     addr1;
  227         pt_entry_t      *ptep1 = NULL;
  228         pt_entry_t      oldmap1 = 0;
  229 
  230         db_nofault = &db_jmpbuf;
  231 
  232         if (addr > trunc_page((vm_offset_t)btext) - size &&
  233             addr < round_page((vm_offset_t)etext)) {
  234 
  235             ptep0 = vtopte(addr);
  236             oldmap0 = *ptep0;
  237             *ptep0 |= PG_RW;
  238 
  239             /* Map another page if the data crosses a page boundary. */
  240             if ((*ptep0 & PG_PS) == 0) {
  241                 addr1 = trunc_page(addr + size - 1);
  242                 if (trunc_page(addr) != addr1) {
  243                     ptep1 = vtopte(addr1);
  244                     oldmap1 = *ptep1;
  245                     *ptep1 |= PG_RW;
  246                 }
  247             } else {
  248                 addr1 = trunc_2mpage(addr + size - 1);
  249                 if (trunc_2mpage(addr) != addr1) {
  250                     ptep1 = vtopte(addr1);
  251                     oldmap1 = *ptep1;
  252                     *ptep1 |= PG_RW;
  253                 }
  254             }
  255 
  256             invltlb();
  257         }
  258 
  259         dst = (char *)addr;
  260 
  261         while (size-- > 0)
  262             *dst++ = *data++;
  263 
  264         db_nofault = 0;
  265 
  266         if (ptep0) {
  267             *ptep0 = oldmap0;
  268 
  269             if (ptep1)
  270                 *ptep1 = oldmap1;
  271 
  272             invltlb();
  273         }
  274 }
  275 
  276 /*
  277  * XXX
  278  * Move this to machdep.c and allow it to be called if any debugger is
  279  * installed.
  280  */
  281 void
  282 Debugger(const char *msg)
  283 {
  284         static volatile u_int in_Debugger;
  285 
  286         /*
  287          * XXX
  288          * Do nothing if the console is in graphics mode.  This is
  289          * OK if the call is for the debugger hotkey but not if the call
  290          * is a weak form of panicing.
  291          */
  292         if (cons_unavail && !(boothowto & RB_GDB))
  293             return;
  294 
  295         if (atomic_cmpset_acq_int(&in_Debugger, 0, 1)) {
  296             db_printf("Debugger(\"%s\")\n", msg);
  297             breakpoint();
  298             atomic_store_rel_int(&in_Debugger, 0);
  299         }
  300 }
  301 
  302 void
  303 db_show_mdpcpu(struct pcpu *pc)
  304 {
  305 
  306 #if 0
  307         db_printf("currentldt   = 0x%x\n", pc->pc_currentldt);
  308 #endif
  309 }

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