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_machdep.c

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

Cache object: 53626ee30ae4bd6eab2a46d331173c47


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