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/linux/linux_ptrace.c

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    1 /*-
    2  * Copyright (c) 2001 Alexander Kabaev
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer
   10  *    in this position and unchanged.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  * 3. The name of the author may not be used to endorse or promote products
   15  *    derived from this software without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   27  */
   28 
   29 #include <sys/cdefs.h>
   30 __FBSDID("$FreeBSD: src/sys/i386/linux/linux_ptrace.c,v 1.13.2.2 2005/01/31 23:26:06 imp Exp $");
   31 
   32 #include "opt_cpu.h"
   33 
   34 #include <sys/param.h>
   35 #include <sys/lock.h>
   36 #include <sys/mutex.h>
   37 #include <sys/proc.h>
   38 #include <sys/ptrace.h>
   39 #include <sys/syscallsubr.h>
   40 #include <sys/systm.h>
   41 
   42 #include <machine/md_var.h>
   43 #include <machine/pcb.h>
   44 #include <machine/reg.h>
   45 
   46 #include <i386/linux/linux.h>
   47 #include <i386/linux/linux_proto.h>
   48 
   49 #if !defined(CPU_ENABLE_SSE) && defined(I686_CPU)
   50 #define CPU_ENABLE_SSE
   51 #endif
   52 #if defined(CPU_DISABLE_SSE)
   53 #undef CPU_ENABLE_SSE
   54 #endif
   55 
   56 /*
   57  *   Linux ptrace requests numbers. Mostly identical to FreeBSD,
   58  *   except for MD ones and PT_ATTACH/PT_DETACH.
   59  */
   60 #define PTRACE_TRACEME          0
   61 #define PTRACE_PEEKTEXT         1
   62 #define PTRACE_PEEKDATA         2
   63 #define PTRACE_PEEKUSR          3
   64 #define PTRACE_POKETEXT         4
   65 #define PTRACE_POKEDATA         5
   66 #define PTRACE_POKEUSR          6
   67 #define PTRACE_CONT             7
   68 #define PTRACE_KILL             8
   69 #define PTRACE_SINGLESTEP       9
   70 
   71 #define PTRACE_ATTACH           16
   72 #define PTRACE_DETACH           17
   73 
   74 #define PTRACE_SYSCALL          24
   75 
   76 #define PTRACE_GETREGS          12
   77 #define PTRACE_SETREGS          13
   78 #define PTRACE_GETFPREGS        14
   79 #define PTRACE_SETFPREGS        15
   80 #define PTRACE_GETFPXREGS       18
   81 #define PTRACE_SETFPXREGS       19
   82 
   83 #define PTRACE_SETOPTIONS       21
   84 
   85 /*
   86  * Linux keeps debug registers at the following
   87  * offset in the user struct
   88  */
   89 #define LINUX_DBREG_OFFSET      252
   90 #define LINUX_DBREG_SIZE        (8*sizeof(l_int))
   91 
   92 static __inline int
   93 map_signum(int signum)
   94 {
   95 
   96         if (signum > 0 && signum <= LINUX_SIGTBLSZ)
   97                 signum = linux_to_bsd_signal[_SIG_IDX(signum)];
   98         return ((signum == SIGSTOP)? 0 : signum);
   99 }
  100 
  101 struct linux_pt_reg {
  102         l_long  ebx;
  103         l_long  ecx;
  104         l_long  edx;
  105         l_long  esi;
  106         l_long  edi;
  107         l_long  ebp;
  108         l_long  eax;
  109         l_int   xds;
  110         l_int   xes;
  111         l_int   xfs;
  112         l_int   xgs;
  113         l_long  orig_eax;
  114         l_long  eip;
  115         l_int   xcs;
  116         l_long  eflags;
  117         l_long  esp;
  118         l_int   xss;
  119 };
  120 
  121 /*
  122  *   Translate i386 ptrace registers between Linux and FreeBSD formats.
  123  *   The translation is pretty straighforward, for all registers, but
  124  *   orig_eax on Linux side and r_trapno and r_err in FreeBSD
  125  */
  126 static void
  127 map_regs_to_linux(struct reg *bsd_r, struct linux_pt_reg *linux_r)
  128 {
  129         linux_r->ebx = bsd_r->r_ebx;
  130         linux_r->ecx = bsd_r->r_ecx;
  131         linux_r->edx = bsd_r->r_edx;
  132         linux_r->esi = bsd_r->r_esi;
  133         linux_r->edi = bsd_r->r_edi;
  134         linux_r->ebp = bsd_r->r_ebp;
  135         linux_r->eax = bsd_r->r_eax;
  136         linux_r->xds = bsd_r->r_ds;
  137         linux_r->xes = bsd_r->r_es;
  138         linux_r->xfs = bsd_r->r_fs;
  139         linux_r->xgs = bsd_r->r_gs;
  140         linux_r->orig_eax = bsd_r->r_eax;
  141         linux_r->eip = bsd_r->r_eip;
  142         linux_r->xcs = bsd_r->r_cs;
  143         linux_r->eflags = bsd_r->r_eflags;
  144         linux_r->esp = bsd_r->r_esp;
  145         linux_r->xss = bsd_r->r_ss;
  146 }
  147 
  148 static void
  149 map_regs_from_linux(struct reg *bsd_r, struct linux_pt_reg *linux_r)
  150 {
  151         bsd_r->r_ebx = linux_r->ebx;
  152         bsd_r->r_ecx = linux_r->ecx;
  153         bsd_r->r_edx = linux_r->edx;
  154         bsd_r->r_esi = linux_r->esi;
  155         bsd_r->r_edi = linux_r->edi;
  156         bsd_r->r_ebp = linux_r->ebp;
  157         bsd_r->r_eax = linux_r->eax;
  158         bsd_r->r_ds  = linux_r->xds;
  159         bsd_r->r_es  = linux_r->xes;
  160         bsd_r->r_fs  = linux_r->xfs;
  161         bsd_r->r_gs  = linux_r->xgs;
  162         bsd_r->r_eip = linux_r->eip;
  163         bsd_r->r_cs  = linux_r->xcs;
  164         bsd_r->r_eflags = linux_r->eflags;
  165         bsd_r->r_esp = linux_r->esp;
  166         bsd_r->r_ss = linux_r->xss;
  167 }
  168 
  169 struct linux_pt_fpreg {
  170         l_long cwd;
  171         l_long swd;
  172         l_long twd;
  173         l_long fip;
  174         l_long fcs;
  175         l_long foo;
  176         l_long fos;
  177         l_long st_space[2*10];
  178 };
  179 
  180 static void
  181 map_fpregs_to_linux(struct fpreg *bsd_r, struct linux_pt_fpreg *linux_r)
  182 {
  183         linux_r->cwd = bsd_r->fpr_env[0];
  184         linux_r->swd = bsd_r->fpr_env[1];
  185         linux_r->twd = bsd_r->fpr_env[2];
  186         linux_r->fip = bsd_r->fpr_env[3];
  187         linux_r->fcs = bsd_r->fpr_env[4];
  188         linux_r->foo = bsd_r->fpr_env[5];
  189         linux_r->fos = bsd_r->fpr_env[6];
  190         bcopy(bsd_r->fpr_acc, linux_r->st_space, sizeof(linux_r->st_space));
  191 }
  192 
  193 static void
  194 map_fpregs_from_linux(struct fpreg *bsd_r, struct linux_pt_fpreg *linux_r)
  195 {
  196         bsd_r->fpr_env[0] = linux_r->cwd;
  197         bsd_r->fpr_env[1] = linux_r->swd;
  198         bsd_r->fpr_env[2] = linux_r->twd;
  199         bsd_r->fpr_env[3] = linux_r->fip;
  200         bsd_r->fpr_env[4] = linux_r->fcs;
  201         bsd_r->fpr_env[5] = linux_r->foo;
  202         bsd_r->fpr_env[6] = linux_r->fos;
  203         bcopy(bsd_r->fpr_acc, linux_r->st_space, sizeof(bsd_r->fpr_acc));
  204 }
  205 
  206 struct linux_pt_fpxreg {
  207         l_ushort        cwd;
  208         l_ushort        swd;
  209         l_ushort        twd;
  210         l_ushort        fop;
  211         l_long          fip;
  212         l_long          fcs;
  213         l_long          foo;
  214         l_long          fos;
  215         l_long          mxcsr;
  216         l_long          reserved;
  217         l_long          st_space[32];
  218         l_long          xmm_space[32];
  219         l_long          padding[56];
  220 };
  221 
  222 #ifdef CPU_ENABLE_SSE
  223 static int
  224 linux_proc_read_fpxregs(struct thread *td, struct linux_pt_fpxreg *fpxregs)
  225 {
  226 
  227         PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);
  228         if (cpu_fxsr == 0 || (td->td_proc->p_sflag & PS_INMEM) == 0)
  229                 return (EIO);
  230         bcopy(&td->td_pcb->pcb_save.sv_xmm, fpxregs, sizeof(*fpxregs));
  231         return (0);
  232 }
  233 
  234 static int
  235 linux_proc_write_fpxregs(struct thread *td, struct linux_pt_fpxreg *fpxregs)
  236 {
  237 
  238         PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);
  239         if (cpu_fxsr == 0 || (td->td_proc->p_sflag & PS_INMEM) == 0)
  240                 return (EIO);
  241         bcopy(fpxregs, &td->td_pcb->pcb_save.sv_xmm, sizeof(*fpxregs));
  242         return (0);
  243 }
  244 #endif
  245 
  246 int
  247 linux_ptrace(struct thread *td, struct linux_ptrace_args *uap)
  248 {
  249         union {
  250                 struct linux_pt_reg     reg;
  251                 struct linux_pt_fpreg   fpreg;
  252                 struct linux_pt_fpxreg  fpxreg;
  253         } r;
  254         union {
  255                 struct reg              bsd_reg;
  256                 struct fpreg            bsd_fpreg;
  257                 struct dbreg            bsd_dbreg;
  258         } u;
  259         void *addr;
  260         pid_t pid;
  261         int error, req;
  262 
  263         error = 0;
  264 
  265         /* by default, just copy data intact */
  266         req  = uap->req;
  267         pid  = (pid_t)uap->pid;
  268         addr = (void *)uap->addr;
  269 
  270         switch (req) {
  271         case PTRACE_TRACEME:
  272         case PTRACE_POKETEXT:
  273         case PTRACE_POKEDATA:
  274         case PTRACE_KILL:
  275                 error = kern_ptrace(td, req, pid, addr, uap->data);
  276                 break;
  277         case PTRACE_PEEKTEXT:
  278         case PTRACE_PEEKDATA: {
  279                 /* need to preserve return value */
  280                 int rval = td->td_retval[0];
  281                 error = kern_ptrace(td, req, pid, addr, 0);
  282                 if (error == 0)
  283                         error = copyout(td->td_retval, (void *)uap->data,
  284                             sizeof(l_int));
  285                 td->td_retval[0] = rval;
  286                 break;
  287         }
  288         case PTRACE_DETACH:
  289                 error = kern_ptrace(td, PT_DETACH, pid, (void *)1,
  290                      map_signum(uap->data));
  291                 break;
  292         case PTRACE_SINGLESTEP:
  293         case PTRACE_CONT:
  294                 error = kern_ptrace(td, req, pid, (void *)1,
  295                      map_signum(uap->data));
  296                 break;
  297         case PTRACE_ATTACH:
  298                 error = kern_ptrace(td, PT_ATTACH, pid, addr, uap->data);
  299                 break;
  300         case PTRACE_GETREGS:
  301                 /* Linux is using data where FreeBSD is using addr */
  302                 error = kern_ptrace(td, PT_GETREGS, pid, &u.bsd_reg, 0);
  303                 if (error == 0) {
  304                         map_regs_to_linux(&u.bsd_reg, &r.reg);
  305                         error = copyout(&r.reg, (void *)uap->data,
  306                             sizeof(r.reg));
  307                 }
  308                 break;
  309         case PTRACE_SETREGS:
  310                 /* Linux is using data where FreeBSD is using addr */
  311                 error = copyin((void *)uap->data, &r.reg, sizeof(r.reg));
  312                 if (error == 0) {
  313                         map_regs_from_linux(&u.bsd_reg, &r.reg);
  314                         error = kern_ptrace(td, PT_SETREGS, pid, &u.bsd_reg, 0);
  315                 }
  316                 break;
  317         case PTRACE_GETFPREGS:
  318                 /* Linux is using data where FreeBSD is using addr */
  319                 error = kern_ptrace(td, PT_GETFPREGS, pid, &u.bsd_fpreg, 0);
  320                 if (error == 0) {
  321                         map_fpregs_to_linux(&u.bsd_fpreg, &r.fpreg);
  322                         error = copyout(&r.fpreg, (void *)uap->data,
  323                             sizeof(r.fpreg));
  324                 }
  325                 break;
  326         case PTRACE_SETFPREGS:
  327                 /* Linux is using data where FreeBSD is using addr */
  328                 error = copyin((void *)uap->data, &r.fpreg, sizeof(r.fpreg));
  329                 if (error == 0) {
  330                         map_fpregs_from_linux(&u.bsd_fpreg, &r.fpreg);
  331                         error = kern_ptrace(td, PT_SETFPREGS, pid,
  332                             &u.bsd_fpreg, 0);
  333                 }
  334                 break;
  335         case PTRACE_SETFPXREGS:
  336 #ifdef CPU_ENABLE_SSE
  337                 error = copyin((void *)uap->data, &r.fpxreg, sizeof(r.fpxreg));
  338                 if (error)
  339                         break;
  340 #endif
  341                 /* FALL THROUGH */
  342         case PTRACE_GETFPXREGS: {
  343 #ifdef CPU_ENABLE_SSE
  344                 struct proc *p;
  345                 struct thread *td2;
  346 
  347                 if (sizeof(struct linux_pt_fpxreg) != sizeof(struct savexmm)) {
  348                         static int once = 0;
  349                         if (!once) {
  350                                 printf("linux: savexmm != linux_pt_fpxreg\n");
  351                                 once = 1;
  352                         }
  353                         error = EIO;
  354                         break;
  355                 }
  356 
  357                 if ((p = pfind(uap->pid)) == NULL) {
  358                         error = ESRCH;
  359                         break;
  360                 }
  361 
  362                 if ((error = p_candebug(td, p)) != 0)
  363                         goto fail;
  364 
  365                 /* System processes can't be debugged. */
  366                 if ((p->p_flag & P_SYSTEM) != 0) {
  367                         error = EINVAL;
  368                         goto fail;
  369                 }
  370 
  371                 /* not being traced... */
  372                 if ((p->p_flag & P_TRACED) == 0) {
  373                         error = EPERM;
  374                         goto fail;
  375                 }
  376 
  377                 /* not being traced by YOU */
  378                 if (p->p_pptr != td->td_proc) {
  379                         error = EBUSY;
  380                         goto fail;
  381                 }
  382 
  383                 /* not currently stopped */
  384                 if (!P_SHOULDSTOP(p) || (p->p_flag & P_WAITED) == 0) {
  385                         error = EBUSY;
  386                         goto fail;
  387                 }
  388 
  389                 if (req == PTRACE_GETFPXREGS) {
  390                         _PHOLD(p);      /* may block */
  391                         td2 = FIRST_THREAD_IN_PROC(p);
  392                         error = linux_proc_read_fpxregs(td2, &r.fpxreg);
  393                         _PRELE(p);
  394                         PROC_UNLOCK(p);
  395                         if (error == 0)
  396                                 error = copyout(&r.fpxreg, (void *)uap->data,
  397                                     sizeof(r.fpxreg));
  398                 } else {
  399                         /* clear dangerous bits exactly as Linux does*/
  400                         r.fpxreg.mxcsr &= 0xffbf;
  401                         _PHOLD(p);      /* may block */
  402                         td2 = FIRST_THREAD_IN_PROC(p);
  403                         error = linux_proc_write_fpxregs(td2, &r.fpxreg);
  404                         _PRELE(p);
  405                         PROC_UNLOCK(p);
  406                 }
  407                 break;
  408 
  409         fail:
  410                 PROC_UNLOCK(p);
  411 #else
  412                 error = EIO;
  413 #endif
  414                 break;
  415         }
  416         case PTRACE_PEEKUSR:
  417         case PTRACE_POKEUSR: {
  418                 error = EIO;
  419 
  420                 /* check addr for alignment */
  421                 if (uap->addr < 0 || uap->addr & (sizeof(l_int) - 1))
  422                         break;
  423                 /*
  424                  * Allow linux programs to access register values in
  425                  * user struct. We simulate this through PT_GET/SETREGS
  426                  * as necessary.
  427                  */
  428                 if (uap->addr < sizeof(struct linux_pt_reg)) {
  429                         error = kern_ptrace(td, PT_GETREGS, pid, &u.bsd_reg, 0);
  430                         if (error != 0)
  431                                 break;
  432 
  433                         map_regs_to_linux(&u.bsd_reg, &r.reg);
  434                         if (req == PTRACE_PEEKUSR) {
  435                                 error = copyout((char *)&r.reg + uap->addr,
  436                                     (void *)uap->data, sizeof(l_int));
  437                                 break;
  438                         }
  439 
  440                         *(l_int *)((char *)&r.reg + uap->addr) =
  441                             (l_int)uap->data;
  442 
  443                         map_regs_from_linux(&u.bsd_reg, &r.reg);
  444                         error = kern_ptrace(td, PT_SETREGS, pid, &u.bsd_reg, 0);
  445                 }
  446 
  447                 /*
  448                  * Simulate debug registers access
  449                  */
  450                 if (uap->addr >= LINUX_DBREG_OFFSET &&
  451                     uap->addr <= LINUX_DBREG_OFFSET + LINUX_DBREG_SIZE) {
  452                         error = kern_ptrace(td, PT_GETDBREGS, pid, &u.bsd_dbreg,
  453                             0);
  454                         if (error != 0)
  455                                 break;
  456 
  457                         uap->addr -= LINUX_DBREG_OFFSET;
  458                         if (req == PTRACE_PEEKUSR) {
  459                                 error = copyout((char *)&u.bsd_dbreg +
  460                                     uap->addr, (void *)uap->data,
  461                                     sizeof(l_int));
  462                                 break;
  463                         }
  464 
  465                         *(l_int *)((char *)&u.bsd_dbreg + uap->addr) =
  466                              uap->data;
  467                         error = kern_ptrace(td, PT_SETDBREGS, pid,
  468                             &u.bsd_dbreg, 0);
  469                 }
  470 
  471                 break;
  472         }
  473         case PTRACE_SYSCALL:
  474                 /* fall through */
  475         default:
  476                 printf("linux: ptrace(%u, ...) not implemented\n",
  477                     (unsigned int)uap->req);
  478                 error = EINVAL;
  479                 break;
  480         }
  481 
  482         return (error);
  483 }

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