osfmk/i386/bsd_i386_native.c

   1 /*
   2  * Copyright (c) 2010-2012 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 #include <mach_rt.h>
  29 #include <mach_debug.h>
  30 #include <mach_ldebug.h>
  31
  32 #include <mach/kern_return.h>
  33 #include <mach/mach_traps.h>
  34 #include <mach/thread_status.h>
  35 #include <mach/vm_param.h>
  36
  37 #include <kern/counters.h>
  38 #include <kern/cpu_data.h>
  39 #include <kern/mach_param.h>
  40 #include <kern/task.h>
  41 #include <kern/thread.h>
  42 #include <kern/sched_prim.h>
  43 #include <kern/misc_protos.h>
  44 #include <kern/assert.h>
  45 #include <kern/debug.h>
  46 #include <kern/spl.h>
  47 #include <kern/syscall_sw.h>
  48 #include <ipc/ipc_port.h>
  49 #include <vm/vm_kern.h>
  50 #include <vm/pmap.h>
  51
  52 #include <i386/cpu_number.h>
  53 #include <i386/eflags.h>
  54 #include <i386/proc_reg.h>
  55 #include <i386/tss.h>
  56 #include <i386/user_ldt.h>
  57 #include <i386/fpu.h>
  58 #include <i386/machdep_call.h>
  59 #include <i386/vmparam.h>
  60 #include <i386/mp_desc.h>
  61 #include <i386/misc_protos.h>
  62 #include <i386/thread.h>
  63 #include <i386/trap.h>
  64 #include <i386/seg.h>
  65 #include <mach/i386/syscall_sw.h>
  66 #include <sys/syscall.h>
  67 #include <sys/kdebug.h>
  68 #include <sys/errno.h>
  69 #include <../bsd/sys/sysent.h>
  70
  71
  72 /*
  73  * Duplicate parent state in child
  74  * for U**X fork.
  75  */
  76 kern_return_t
  77 machine_thread_dup(
  78     thread_t            parent,
  79     thread_t            child
  80 )
  81 {
  82
  83         pcb_t           parent_pcb = THREAD_TO_PCB(parent);
  84         pcb_t           child_pcb = THREAD_TO_PCB(child);
  85
  86         /*
  87          * Copy over the x86_saved_state registers
  88          */
  89         if (thread_is_64bit(parent))
  90                 bcopy(USER_REGS64(parent), USER_REGS64(child), sizeof(x86_saved_state64_t));
  91         else
  92                 bcopy(USER_REGS32(parent), USER_REGS32(child), sizeof(x86_saved_state32_t));
  93
  94         /*
  95          * Check to see if parent is using floating point
  96          * and if so, copy the registers to the child
  97          */
  98         fpu_dup_fxstate(parent, child);
  99
 100 #ifdef  MACH_BSD
 101         /*
 102          * Copy the parent's cthread id and USER_CTHREAD descriptor, if 32-bit.
 103          */
 104         child_pcb->cthread_self = parent_pcb->cthread_self;
 105         if (!thread_is_64bit(parent))
 106                 child_pcb->cthread_desc = parent_pcb->cthread_desc;
 107
 108         /*
 109          * FIXME - should a user specified LDT, TSS and V86 info
 110          * be duplicated as well?? - probably not.
 111          */
 112         // duplicate any use LDT entry that was set I think this is appropriate.
 113         if (parent_pcb->uldt_selector!= 0) {
 114                 child_pcb->uldt_selector = parent_pcb->uldt_selector;
 115                 child_pcb->uldt_desc = parent_pcb->uldt_desc;
 116         }
 117 #endif
 118
 119         return (KERN_SUCCESS);
 120 }
 121
 122 void thread_set_parent(thread_t parent, int pid);
 123
 124 void
 125 thread_set_parent(thread_t parent, int pid)
 126 {
 127         pal_register_cache_state(parent, DIRTY);
 128
 129         if (thread_is_64bit(parent)) {
 130                 x86_saved_state64_t     *iss64;
 131
 132                 iss64 = USER_REGS64(parent);
 133
 134                 iss64->rax = pid;
 135                 iss64->rdx = 0;
 136                 iss64->isf.rflags &= ~EFL_CF;
 137         } else {
 138                 x86_saved_state32_t     *iss32;
 139
 140                 iss32 = USER_REGS32(parent);
 141
 142                 iss32->eax = pid;
 143                 iss32->edx = 0;
 144                 iss32->efl &= ~EFL_CF;
 145         }
 146 }
 147
 148 /*
 149  * thread_fast_set_cthread_self: Sets the machine kernel thread ID of the
 150  * current thread to the given thread ID; fast version for 32-bit processes
 151  *
 152  * Parameters:    self                    Thread ID to set
 153  *
 154  * Returns:        0                      Success
 155  *                !0                      Not success
 156  */
 157 kern_return_t
 158 thread_fast_set_cthread_self(uint32_t self)
 159 {
 160         thread_t thread = current_thread();
 161         pcb_t pcb = THREAD_TO_PCB(thread);
 162         struct real_descriptor desc = {
 163                 .limit_low = 1,
 164                 .limit_high = 0,
 165                 .base_low = self & 0xffff,
 166                 .base_med = (self >> 16) & 0xff,
 167                 .base_high = (self >> 24) & 0xff,
 168                 .access = ACC_P|ACC_PL_U|ACC_DATA_W,
 169                 .granularity = SZ_32|SZ_G,
 170         };
 171
 172         current_thread()->machine.cthread_self = (uint64_t) self;       /* preserve old func too */
 173
 174         /* assign descriptor */
 175         mp_disable_preemption();
 176         pcb->cthread_desc = desc;
 177         *ldt_desc_p(USER_CTHREAD) = desc;
 178         saved_state32(pcb->iss)->gs = USER_CTHREAD;
 179         mp_enable_preemption();
 180
 181         return (USER_CTHREAD);
 182 }
 183
 184 /*
 185  * thread_fast_set_cthread_self64: Sets the machine kernel thread ID of the
 186  * current thread to the given thread ID; fast version for 64-bit processes
 187  *
 188  * Parameters:    self                    Thread ID
 189  *
 190  * Returns:        0                      Success
 191  *                !0                      Not success
 192  */
 193 kern_return_t
 194 thread_fast_set_cthread_self64(uint64_t self)
 195 {
 196         pcb_t pcb = THREAD_TO_PCB(current_thread());
 197         cpu_data_t              *cdp;
 198
 199         /* check for canonical address, set 0 otherwise  */
 200         if (!IS_USERADDR64_CANONICAL(self))
 201                 self = 0ULL;
 202
 203         pcb->cthread_self = self;
 204         mp_disable_preemption();
 205         cdp = current_cpu_datap();
 206         if ((cdp->cpu_uber.cu_user_gs_base != pcb->cthread_self) ||
 207             (pcb->cthread_self != rdmsr64(MSR_IA32_KERNEL_GS_BASE)))
 208                 wrmsr64(MSR_IA32_KERNEL_GS_BASE, self);
 209         cdp->cpu_uber.cu_user_gs_base = self;
 210         mp_enable_preemption();
 211         return (USER_CTHREAD); /* N.B.: not a kern_return_t! */
 212 }
 213
 214 /*
 215  * thread_set_user_ldt routine is the interface for the user level
 216  * settable ldt entry feature.  allowing a user to create arbitrary
 217  * ldt entries seems to be too large of a security hole, so instead
 218  * this mechanism is in place to allow user level processes to have
 219  * an ldt entry that can be used in conjunction with the FS register.
 220  *
 221  * Swapping occurs inside the pcb.c file along with initialization
 222  * when a thread is created. The basic functioning theory is that the
 223  * pcb->uldt_selector variable will contain either 0 meaning the
 224  * process has not set up any entry, or the selector to be used in
 225  * the FS register. pcb->uldt_desc contains the actual descriptor the
 226  * user has set up stored in machine usable ldt format.
 227  *
 228  * Currently one entry is shared by all threads (USER_SETTABLE), but
 229  * this could be changed in the future by changing how this routine
 230  * allocates the selector. There seems to be no real reason at this
 231  * time to have this added feature, but in the future it might be
 232  * needed.
 233  *
 234  * address is the linear address of the start of the data area size
 235  * is the size in bytes of the area flags should always be set to 0
 236  * for now. in the future it could be used to set R/W permisions or
 237  * other functions. Currently the segment is created as a data segment
 238  * up to 1 megabyte in size with full read/write permisions only.
 239  *
 240  * this call returns the segment selector or -1 if any error occurs
 241  */
 242 kern_return_t
 243 thread_set_user_ldt(uint32_t address, uint32_t size, uint32_t flags)
 244 {
 245         pcb_t pcb;
 246         struct fake_descriptor temp;
 247
 248         if (flags != 0)
 249                 return -1;              // flags not supported
 250         if (size > 0xFFFFF)
 251                 return -1;              // size too big, 1 meg is the limit
 252
 253         mp_disable_preemption();
 254
 255         // create a "fake" descriptor so we can use fix_desc()
 256         // to build a real one...
 257         //   32 bit default operation size
 258         //   standard read/write perms for a data segment
 259         pcb = THREAD_TO_PCB(current_thread());
 260         temp.offset = address;
 261         temp.lim_or_seg = size;
 262         temp.size_or_wdct = SZ_32;
 263         temp.access = ACC_P|ACC_PL_U|ACC_DATA_W;
 264
 265         // turn this into a real descriptor
 266         fix_desc(&temp,1);
 267
 268         // set up our data in the pcb
 269         pcb->uldt_desc = *(struct real_descriptor*)&temp;
 270         pcb->uldt_selector = USER_SETTABLE;             // set the selector value
 271
 272         // now set it up in the current table...
 273         *ldt_desc_p(USER_SETTABLE) = *(struct real_descriptor*)&temp;
 274
 275         mp_enable_preemption();
 276
 277         return USER_SETTABLE;
 278 }