osfmk/i386/bsd_i386_native.c

   1 /*
   2  * Copyright (c) 2010 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 (cpu_mode_is64bit()) {
  90                 if (thread_is_64bit(parent))
  91                         bcopy(USER_REGS64(parent), USER_REGS64(child), sizeof(x86_saved_state64_t));
  92                 else
  93                         bcopy(USER_REGS32(parent), USER_REGS32(child), sizeof(x86_saved_state_compat32_t));
  94         } else
  95                 bcopy(USER_REGS32(parent), USER_REGS32(child), sizeof(x86_saved_state32_t));
  96
  97         /*
  98          * Check to see if parent is using floating point
  99          * and if so, copy the registers to the child
 100          */
 101         fpu_dup_fxstate(parent, child);
 102
 103 #ifdef  MACH_BSD
 104         /*
 105          * Copy the parent's cthread id and USER_CTHREAD descriptor, if 32-bit.
 106          */
 107         child_pcb->cthread_self = parent_pcb->cthread_self;
 108         if (!thread_is_64bit(parent))
 109                 child_pcb->cthread_desc = parent_pcb->cthread_desc;
 110
 111         /*
 112          * FIXME - should a user specified LDT, TSS and V86 info
 113          * be duplicated as well?? - probably not.
 114          */
 115         // duplicate any use LDT entry that was set I think this is appropriate.
 116         if (parent_pcb->uldt_selector!= 0) {
 117                 child_pcb->uldt_selector = parent_pcb->uldt_selector;
 118                 child_pcb->uldt_desc = parent_pcb->uldt_desc;
 119         }
 120 #endif
 121
 122         return (KERN_SUCCESS);
 123 }
 124
 125 void thread_set_parent(thread_t parent, int pid);
 126
 127 void
 128 thread_set_parent(thread_t parent, int pid)
 129 {
 130         pal_register_cache_state(parent, DIRTY);
 131
 132         if (thread_is_64bit(parent)) {
 133                 x86_saved_state64_t     *iss64;
 134
 135                 iss64 = USER_REGS64(parent);
 136
 137                 iss64->rax = pid;
 138                 iss64->rdx = 0;
 139                 iss64->isf.rflags &= ~EFL_CF;
 140         } else {
 141                 x86_saved_state32_t     *iss32;
 142
 143                 iss32 = USER_REGS32(parent);
 144
 145                 iss32->eax = pid;
 146                 iss32->edx = 0;
 147                 iss32->efl &= ~EFL_CF;
 148         }
 149 }
 150
 151 /*
 152  * thread_fast_set_cthread_self: Sets the machine kernel thread ID of the
 153  * current thread to the given thread ID; fast version for 32-bit processes
 154  *
 155  * Parameters:    self                    Thread ID to set
 156  *
 157  * Returns:        0                      Success
 158  *                !0                      Not success
 159  */
 160 kern_return_t
 161 thread_fast_set_cthread_self(uint32_t self)
 162 {
 163         thread_t thread = current_thread();
 164         pcb_t pcb = THREAD_TO_PCB(thread);
 165         struct real_descriptor desc = {
 166                 .limit_low = 1,
 167                 .limit_high = 0,
 168                 .base_low = self & 0xffff,
 169                 .base_med = (self >> 16) & 0xff,
 170                 .base_high = (self >> 24) & 0xff,
 171                 .access = ACC_P|ACC_PL_U|ACC_DATA_W,
 172                 .granularity = SZ_32|SZ_G,
 173         };
 174
 175         current_thread()->machine.cthread_self = (uint64_t) self;       /* preserve old func too */
 176
 177         /* assign descriptor */
 178         mp_disable_preemption();
 179         pcb->cthread_desc = desc;
 180         *ldt_desc_p(USER_CTHREAD) = desc;
 181         saved_state32(pcb->iss)->gs = USER_CTHREAD;
 182         mp_enable_preemption();
 183
 184         return (USER_CTHREAD);
 185 }
 186
 187 /*
 188  * thread_fast_set_cthread_self64: Sets the machine kernel thread ID of the
 189  * current thread to the given thread ID; fast version for 64-bit processes
 190  *
 191  * Parameters:    self                    Thread ID
 192  *
 193  * Returns:        0                      Success
 194  *                !0                      Not success
 195  */
 196 kern_return_t
 197 thread_fast_set_cthread_self64(uint64_t self)
 198 {
 199         pcb_t pcb = THREAD_TO_PCB(current_thread());
 200         cpu_data_t              *cdp;
 201
 202         /* check for canonical address, set 0 otherwise  */
 203         if (!IS_USERADDR64_CANONICAL(self))
 204                 self = 0ULL;
 205
 206         pcb->cthread_self = self;
 207         mp_disable_preemption();
 208         cdp = current_cpu_datap();
 209 #if defined(__x86_64__)
 210         if ((cdp->cpu_uber.cu_user_gs_base != pcb->cthread_self) ||
 211             (pcb->cthread_self != rdmsr64(MSR_IA32_KERNEL_GS_BASE)))
 212                 wrmsr64(MSR_IA32_KERNEL_GS_BASE, self);
 213 #endif
 214         cdp->cpu_uber.cu_user_gs_base = self;
 215         mp_enable_preemption();
 216         return (USER_CTHREAD); /* N.B.: not a kern_return_t! */
 217 }
 218
 219 /*
 220  * thread_set_user_ldt routine is the interface for the user level
 221  * settable ldt entry feature.  allowing a user to create arbitrary
 222  * ldt entries seems to be too large of a security hole, so instead
 223  * this mechanism is in place to allow user level processes to have
 224  * an ldt entry that can be used in conjunction with the FS register.
 225  *
 226  * Swapping occurs inside the pcb.c file along with initialization
 227  * when a thread is created. The basic functioning theory is that the
 228  * pcb->uldt_selector variable will contain either 0 meaning the
 229  * process has not set up any entry, or the selector to be used in
 230  * the FS register. pcb->uldt_desc contains the actual descriptor the
 231  * user has set up stored in machine usable ldt format.
 232  *
 233  * Currently one entry is shared by all threads (USER_SETTABLE), but
 234  * this could be changed in the future by changing how this routine
 235  * allocates the selector. There seems to be no real reason at this
 236  * time to have this added feature, but in the future it might be
 237  * needed.
 238  *
 239  * address is the linear address of the start of the data area size
 240  * is the size in bytes of the area flags should always be set to 0
 241  * for now. in the future it could be used to set R/W permisions or
 242  * other functions. Currently the segment is created as a data segment
 243  * up to 1 megabyte in size with full read/write permisions only.
 244  *
 245  * this call returns the segment selector or -1 if any error occurs
 246  */
 247 kern_return_t
 248 thread_set_user_ldt(uint32_t address, uint32_t size, uint32_t flags)
 249 {
 250         pcb_t pcb;
 251         struct fake_descriptor temp;
 252
 253         if (flags != 0)
 254                 return -1;              // flags not supported
 255         if (size > 0xFFFFF)
 256                 return -1;              // size too big, 1 meg is the limit
 257
 258         mp_disable_preemption();
 259
 260         // create a "fake" descriptor so we can use fix_desc()
 261         // to build a real one...
 262         //   32 bit default operation size
 263         //   standard read/write perms for a data segment
 264         pcb = THREAD_TO_PCB(current_thread());
 265         temp.offset = address;
 266         temp.lim_or_seg = size;
 267         temp.size_or_wdct = SZ_32;
 268         temp.access = ACC_P|ACC_PL_U|ACC_DATA_W;
 269
 270         // turn this into a real descriptor
 271         fix_desc(&temp,1);
 272
 273         // set up our data in the pcb
 274         pcb->uldt_desc = *(struct real_descriptor*)&temp;
 275         pcb->uldt_selector = USER_SETTABLE;             // set the selector value
 276
 277         // now set it up in the current table...
 278         *ldt_desc_p(USER_SETTABLE) = *(struct real_descriptor*)&temp;
 279
 280         mp_enable_preemption();
 281
 282         return USER_SETTABLE;
 283 }