osfmk/arm64/bsd_arm64.c

   1 /*
   2  * Copyright (c) 2019 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
  29 #ifdef  MACH_BSD
  30 #include <mach_debug.h>
  31 #include <mach_ldebug.h>
  32
  33 #include <mach/kern_return.h>
  34 #include <mach/mach_traps.h>
  35 #include <mach/vm_param.h>
  36
  37 #include <kern/cpu_data.h>
  38 #include <arm/cpu_data_internal.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/spl.h>
  46 #include <kern/syscall_sw.h>
  47 #include <ipc/ipc_port.h>
  48 #include <vm/vm_kern.h>
  49 #include <mach/thread_status.h>
  50 #include <vm/pmap.h>
  51
  52 #include <sys/kdebug.h>
  53
  54 #include <sys/syscall.h>
  55
  56 #if CONFIG_MACF
  57 #include <security/mac_mach_internal.h>
  58 #endif
  59
  60 extern void throttle_lowpri_io(int);
  61 extern arm_debug_state64_t *find_or_allocate_debug_state64(thread_t thread);
  62 void mach_syscall(struct arm_saved_state*);
  63 typedef kern_return_t (*mach_call_t)(void *);
  64
  65 struct mach_call_args {
  66         syscall_arg_t arg1;
  67         syscall_arg_t arg2;
  68         syscall_arg_t arg3;
  69         syscall_arg_t arg4;
  70         syscall_arg_t arg5;
  71         syscall_arg_t arg6;
  72         syscall_arg_t arg7;
  73         syscall_arg_t arg8;
  74         syscall_arg_t arg9;
  75 };
  76
  77 static void
  78 arm_set_mach_syscall_ret(struct arm_saved_state *state, int retval)
  79 {
  80         if (is_saved_state32(state)) {
  81                 saved_state32(state)->r[0] = retval;
  82         } else {
  83                 saved_state64(state)->x[0] = retval;
  84         }
  85 }
  86
  87 static kern_return_t
  88 arm_get_mach_syscall_args(struct arm_saved_state *state, struct mach_call_args *dest, const mach_trap_t *trapp)
  89 {
  90         uint32_t reg_count;
  91
  92         if (is_saved_state32(state)) {
  93                 /* The trap table entry defines the number of 32-bit words to be copied in from userspace. */
  94                 reg_count = trapp->mach_trap_u32_words;
  95
  96                 /*
  97                  * We get 7 contiguous words; r0-r6, hop over r7
  98                  * (frame pointer), optionally r8
  99                  */
 100                 if (reg_count <= 7) {
 101                         bcopy((char*)saved_state32(state), (char*)dest, sizeof(uint32_t) * reg_count);
 102                 } else if (reg_count <= 9) {
 103                         bcopy((char*)saved_state32(state), (char*)dest, sizeof(uint32_t) * 7);
 104                         bcopy((char*)&saved_state32(state)->r[8], ((char*)dest) + sizeof(uint32_t) * 7,
 105                             reg_count - 7);
 106                 } else {
 107                         panic("Trap with %d words of args? We only support 9.", reg_count);
 108                 }
 109
 110 #if CONFIG_REQUIRES_U32_MUNGING
 111                 trapp->mach_trap_arg_munge32(dest);
 112 #else
 113 #error U32 mach traps on ARM64 kernel requires munging
 114 #endif
 115         } else {
 116                 assert(is_saved_state64(state));
 117                 bcopy((char*)saved_state64(state), (char*)dest, trapp->mach_trap_arg_count * sizeof(uint64_t));
 118         }
 119
 120         return KERN_SUCCESS;
 121 }
 122
 123 /**
 124  *  Marks or unmarks the given thread to be single stepped such
 125  *  that it executes exactly one instruction and then takes an exception to
 126  *  prevent further execution.
 127  *
 128  *  @param thread 64 bit thread to be single stepped
 129  *  @param on boolean value representing whether the thread should be
 130  *            single stepped (on is true) or not (on is false)
 131  *
 132  *  @returns KERN_SUCCESS if the status is successfully set or KERN_FAILURE if
 133  *           it fails for any reason.
 134  */
 135 kern_return_t
 136 thread_setsinglestep(thread_t thread, int on)
 137 {
 138         arm_debug_state64_t *thread_state = find_or_allocate_debug_state64(thread);
 139
 140         if (thread_state == NULL) {
 141                 return KERN_FAILURE;
 142         }
 143
 144         if (on) {
 145                 thread_state->mdscr_el1 |= MDSCR_SS;
 146         } else {
 147                 thread_state->mdscr_el1 &= ~MDSCR_SS;
 148         }
 149
 150         if (thread == current_thread()) {
 151                 arm_debug_set64(thread->machine.DebugData);
 152         }
 153         return KERN_SUCCESS;
 154 }
 155
 156 #if CONFIG_DTRACE
 157
 158 vm_offset_t dtrace_get_cpu_int_stack_top(void);
 159
 160 vm_offset_t
 161 dtrace_get_cpu_int_stack_top(void)
 162 {
 163         return getCpuDatap()->intstack_top;
 164 }
 165 #endif /* CONFIG_DTRACE */
 166 extern const char *const mach_syscall_name_table[];
 167
 168 /* ARM64_TODO: remove this. still TODO?*/
 169 extern struct proc* current_proc(void);
 170 extern int proc_pid(struct proc*);
 171
 172 void
 173 mach_syscall(struct arm_saved_state *state)
 174 {
 175         kern_return_t retval;
 176         mach_call_t mach_call;
 177         struct mach_call_args args = {
 178                 .arg1 = 0,
 179                 .arg2 = 0,
 180                 .arg3 = 0,
 181                 .arg4 = 0,
 182                 .arg5 = 0,
 183                 .arg6 = 0,
 184                 .arg7 = 0,
 185                 .arg8 = 0,
 186                 .arg9 = 0
 187         };
 188         int call_number = get_saved_state_svc_number(state);
 189         int64_t exc_code;
 190         int argc;
 191
 192         struct uthread *ut = get_bsdthread_info(current_thread());
 193         uthread_reset_proc_refcount(ut);
 194
 195         assert(call_number < 0); /* Otherwise it would be a Unix syscall */
 196         call_number = -call_number;
 197
 198         if (call_number >= MACH_TRAP_TABLE_COUNT) {
 199                 goto bad;
 200         }
 201
 202         DEBUG_KPRINT_SYSCALL_MACH(
 203                 "mach_syscall: code=%d(%s) (pid %d, tid %lld)\n",
 204                 call_number, mach_syscall_name_table[call_number],
 205                 proc_pid(current_proc()), thread_tid(current_thread()));
 206
 207 #if DEBUG_TRACE
 208         kprintf("mach_syscall(0x%08x) code=%d\n", state, call_number);
 209 #endif
 210
 211         mach_call = (mach_call_t)mach_trap_table[call_number].mach_trap_function;
 212
 213         if (mach_call == (mach_call_t)kern_invalid) {
 214                 DEBUG_KPRINT_SYSCALL_MACH(
 215                         "mach_syscall: kern_invalid 0x%x\n", call_number);
 216                 goto bad;
 217         }
 218
 219         argc = mach_trap_table[call_number].mach_trap_arg_count;
 220         if (argc) {
 221                 retval = arm_get_mach_syscall_args(state, &args, &mach_trap_table[call_number]);
 222                 if (retval != KERN_SUCCESS) {
 223                         arm_set_mach_syscall_ret(state, retval);
 224
 225                         DEBUG_KPRINT_SYSCALL_MACH(
 226                                 "mach_syscall: retval=0x%x\n", retval);
 227                         return;
 228                 }
 229         }
 230
 231         KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
 232             MACHDBG_CODE(DBG_MACH_EXCP_SC, (call_number)) | DBG_FUNC_START,
 233             args.arg1, args.arg2, args.arg3, args.arg4, 0);
 234
 235 #if CONFIG_MACF
 236         /*
 237          * Check syscall filter mask, if exists.
 238          *
 239          * Not all mach traps are filtered. e.g., mach_absolute_time() and
 240          * mach_continuous_time(). See handle_svc().
 241          */
 242         task_t task = current_task();
 243         uint8_t *filter_mask = task->mach_trap_filter_mask;
 244
 245         if (__improbable(filter_mask != NULL &&
 246             !bitstr_test(filter_mask, call_number))) {
 247                 if (mac_task_mach_trap_evaluate != NULL) {
 248                         retval = mac_task_mach_trap_evaluate(get_bsdtask_info(task),
 249                             call_number);
 250                         if (retval) {
 251                                 goto skip_machcall;
 252                         }
 253                 }
 254         }
 255 #endif /* CONFIG_MACF */
 256
 257         retval = mach_call(&args);
 258
 259 #if CONFIG_MACF
 260 skip_machcall:
 261 #endif
 262
 263         DEBUG_KPRINT_SYSCALL_MACH("mach_syscall: retval=0x%x (pid %d, tid %lld)\n", retval,
 264             proc_pid(current_proc()), thread_tid(current_thread()));
 265
 266         KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
 267             MACHDBG_CODE(DBG_MACH_EXCP_SC, (call_number)) | DBG_FUNC_END,
 268             retval, 0, 0, 0, 0);
 269
 270         arm_set_mach_syscall_ret(state, retval);
 271
 272         throttle_lowpri_io(1);
 273
 274 #if DEBUG || DEVELOPMENT
 275         kern_allocation_name_t
 276         prior __assert_only = thread_get_kernel_state(current_thread())->allocation_name;
 277         assertf(prior == NULL, "thread_set_allocation_name(\"%s\") not cleared", kern_allocation_get_name(prior));
 278 #endif /* DEBUG || DEVELOPMENT */
 279
 280 #if PROC_REF_DEBUG
 281         if (__improbable(uthread_get_proc_refcount(ut) != 0)) {
 282                 panic("system call returned with uu_proc_refcount != 0");
 283         }
 284 #endif
 285
 286         return;
 287
 288 bad:
 289         exc_code = call_number;
 290         exception_triage(EXC_SYSCALL, &exc_code, 1);
 291         /* NOTREACHED */
 292         panic("Returned from exception_triage()?\n");
 293 }
 294 #endif /* MACH_BSD */