1 /*- 2 * Copyright (c) 2016 The FreeBSD Foundation 3 * 4 * This software was developed by Konstantin Belousov under sponsorship 5 * from the FreeBSD Foundation. 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 #include <stand.h> 31 #include <string.h> 32 #include <sys/param.h> 33 #include <machine/cpufunc.h> 34 #include <machine/psl.h> 35 #include <machine/segments.h> 36 #include <machine/frame.h> 37 #include <machine/tss.h> 38 39 #include <efi.h> 40 #include <efilib.h> 41 42 #include "bootstrap.h" 43 #include "loader_efi.h" 44 45 #define NUM_IST 8 46 #define NUM_EXC 32 47 48 /* 49 * This code catches exceptions but forwards hardware interrupts to 50 * handlers installed by firmware. It differentiates exceptions 51 * vs. interrupts by presence of the error code on the stack, which 52 * causes different stack pointer value on trap handler entry. 53 * 54 * Use kernel layout for the trapframe just to not be original. 55 * 56 * Use free IST slot in existing TSS, or create our own TSS if 57 * firmware did not configured any, to have stack switched to 58 * IST-specified one, e.g. to handle #SS. If hand-off cannot find 59 * unused IST slot, or create a new descriptor in GDT, we bail out. 60 */ 61 62 static struct region_descriptor fw_idt; /* Descriptor for pristine fw IDT */ 63 static struct region_descriptor loader_idt;/* Descriptor for loader 64 shadow IDT */ 65 static EFI_PHYSICAL_ADDRESS lidt_pa; /* Address of loader shadow IDT */ 66 static EFI_PHYSICAL_ADDRESS tss_pa; /* Address of TSS */ 67 static EFI_PHYSICAL_ADDRESS exc_stack_pa;/* Address of IST stack for loader */ 68 EFI_PHYSICAL_ADDRESS exc_rsp; /* %rsp value on our IST stack when 69 exception happens */ 70 EFI_PHYSICAL_ADDRESS fw_intr_handlers[NUM_EXC]; /* fw handlers for < 32 IDT 71 vectors */ 72 static int intercepted[NUM_EXC]; 73 static int ist; /* IST for exception handlers */ 74 static uint32_t tss_fw_seg; /* Fw TSS segment */ 75 static uint32_t loader_tss; /* Loader TSS segment */ 76 static struct region_descriptor fw_gdt; /* Descriptor of pristine GDT */ 77 static EFI_PHYSICAL_ADDRESS loader_gdt_pa; /* Address of loader shadow GDT */ 78 79 struct frame { 80 struct frame *fr_savfp; 81 uintptr_t fr_savpc; 82 }; 83 84 void report_exc(struct trapframe *tf); 85 void 86 report_exc(struct trapframe *tf) 87 { 88 struct frame *fp; 89 uintptr_t pc, base; 90 char buf[80]; 91 int ret; 92 93 base = (uintptr_t)boot_img->ImageBase; 94 /* 95 * printf() depends on loader runtime and UEFI firmware health 96 * to produce the console output, in case of exception, the 97 * loader or firmware runtime may fail to support the printf(). 98 */ 99 printf("====================================================" 100 "============================\n"); 101 printf("Exception %u\n", tf->tf_trapno); 102 printf("ss 0x%04hx cs 0x%04hx ds 0x%04hx es 0x%04hx fs 0x%04hx " 103 "gs 0x%04hx\n", 104 (uint16_t)tf->tf_ss, (uint16_t)tf->tf_cs, (uint16_t)tf->tf_ds, 105 (uint16_t)tf->tf_es, (uint16_t)tf->tf_fs, (uint16_t)tf->tf_gs); 106 printf("err 0x%08x rfl 0x%08x addr 0x%016lx\n" 107 "rsp 0x%016lx rip 0x%016lx\n", 108 (uint32_t)tf->tf_err, (uint32_t)tf->tf_rflags, tf->tf_addr, 109 tf->tf_rsp, tf->tf_rip); 110 printf( 111 "rdi 0x%016lx rsi 0x%016lx rdx 0x%016lx\n" 112 "rcx 0x%016lx r8 0x%016lx r9 0x%016lx\n" 113 "rax 0x%016lx rbx 0x%016lx rbp 0x%016lx\n" 114 "r10 0x%016lx r11 0x%016lx r12 0x%016lx\n" 115 "r13 0x%016lx r14 0x%016lx r15 0x%016lx\n", 116 tf->tf_rdi, tf->tf_rsi, tf->tf_rdx, tf->tf_rcx, tf->tf_r8, 117 tf->tf_r9, tf->tf_rax, tf->tf_rbx, tf->tf_rbp, tf->tf_r10, 118 tf->tf_r11, tf->tf_r12, tf->tf_r13, tf->tf_r14, tf->tf_r15); 119 120 fp = (struct frame *)tf->tf_rbp; 121 pc = tf->tf_rip; 122 123 printf("Stack trace:\n"); 124 pager_open(); 125 while (fp != NULL || pc != 0) { 126 char *source = "PC"; 127 128 if (pc >= base && pc < base + boot_img->ImageSize) { 129 pc -= base; 130 source = "loader PC"; 131 } 132 (void) snprintf(buf, sizeof (buf), "FP %016lx: %s 0x%016lx\n", 133 (uintptr_t)fp, source, pc); 134 if (pager_output(buf)) 135 break; 136 137 if (fp != NULL) 138 fp = fp->fr_savfp; 139 140 if (fp != NULL) 141 pc = fp->fr_savpc; 142 else 143 pc = 0; 144 } 145 pager_close(); 146 printf("Machine stopped.\n"); 147 } 148 149 static void 150 prepare_exception(unsigned idx, uint64_t my_handler, 151 int ist_use_table[static NUM_IST]) 152 { 153 struct gate_descriptor *fw_idt_e, *loader_idt_e; 154 155 fw_idt_e = &((struct gate_descriptor *)fw_idt.rd_base)[idx]; 156 loader_idt_e = &((struct gate_descriptor *)loader_idt.rd_base)[idx]; 157 fw_intr_handlers[idx] = fw_idt_e->gd_looffset + 158 (fw_idt_e->gd_hioffset << 16); 159 intercepted[idx] = 1; 160 ist_use_table[fw_idt_e->gd_ist]++; 161 loader_idt_e->gd_looffset = my_handler; 162 loader_idt_e->gd_hioffset = my_handler >> 16; 163 /* 164 * We reuse uefi selector for the code segment for the exception 165 * handler code, while the reason for the fault might be the 166 * corruption of that gdt entry. On the other hand, allocating 167 * our own descriptor might be not much better, if gdt is corrupted. 168 */ 169 loader_idt_e->gd_selector = fw_idt_e->gd_selector; 170 loader_idt_e->gd_ist = 0; 171 loader_idt_e->gd_type = SDT_SYSIGT; 172 loader_idt_e->gd_dpl = 0; 173 loader_idt_e->gd_p = 1; 174 loader_idt_e->gd_xx = 0; 175 loader_idt_e->sd_xx1 = 0; 176 } 177 #define PREPARE_EXCEPTION(N) \ 178 extern char EXC##N##_handler[]; \ 179 prepare_exception(N, (uintptr_t)EXC##N##_handler, ist_use_table); 180 181 static void 182 free_tables(void) 183 { 184 185 if (lidt_pa != 0) { 186 BS->FreePages(lidt_pa, EFI_SIZE_TO_PAGES(fw_idt.rd_limit)); 187 lidt_pa = 0; 188 } 189 if (exc_stack_pa != 0) { 190 BS->FreePages(exc_stack_pa, 1); 191 exc_stack_pa = 0; 192 } 193 if (tss_pa != 0 && tss_fw_seg == 0) { 194 BS->FreePages(tss_pa, EFI_SIZE_TO_PAGES(sizeof(struct 195 amd64tss))); 196 tss_pa = 0; 197 } 198 if (loader_gdt_pa != 0) { 199 BS->FreePages(tss_pa, 2); 200 loader_gdt_pa = 0; 201 } 202 ist = 0; 203 loader_tss = 0; 204 } 205 206 static int 207 efi_setup_tss(struct region_descriptor *gdt, uint32_t loader_tss_idx, 208 struct amd64tss **tss) 209 { 210 EFI_STATUS status; 211 struct system_segment_descriptor *tss_desc; 212 213 tss_desc = (struct system_segment_descriptor *)(gdt->rd_base + 214 (loader_tss_idx << 3)); 215 status = BS->AllocatePages(AllocateAnyPages, EfiLoaderData, 216 EFI_SIZE_TO_PAGES(sizeof(struct amd64tss)), &tss_pa); 217 if (EFI_ERROR(status)) { 218 printf("efi_setup_tss: AllocatePages tss error %lu\n", 219 EFI_ERROR_CODE(status)); 220 return (0); 221 } 222 *tss = (struct amd64tss *)tss_pa; 223 bzero(*tss, sizeof(**tss)); 224 tss_desc->sd_lolimit = sizeof(struct amd64tss); 225 tss_desc->sd_lobase = tss_pa; 226 tss_desc->sd_type = SDT_SYSTSS; 227 tss_desc->sd_dpl = 0; 228 tss_desc->sd_p = 1; 229 tss_desc->sd_hilimit = sizeof(struct amd64tss) >> 16; 230 tss_desc->sd_gran = 0; 231 tss_desc->sd_hibase = tss_pa >> 24; 232 tss_desc->sd_xx0 = 0; 233 tss_desc->sd_xx1 = 0; 234 tss_desc->sd_mbz = 0; 235 tss_desc->sd_xx2 = 0; 236 return (1); 237 } 238 239 static int 240 efi_redirect_exceptions(void) 241 { 242 int ist_use_table[NUM_IST]; 243 struct gate_descriptor *loader_idt_e; 244 struct system_segment_descriptor *tss_desc, *gdt_desc; 245 struct amd64tss *tss; 246 struct region_descriptor *gdt_rd, loader_gdt; 247 uint32_t i; 248 EFI_STATUS status; 249 register_t rfl; 250 251 sidt(&fw_idt); 252 status = BS->AllocatePages(AllocateAnyPages, EfiLoaderData, 253 EFI_SIZE_TO_PAGES(fw_idt.rd_limit), &lidt_pa); 254 if (EFI_ERROR(status)) { 255 printf("efi_redirect_exceptions: AllocatePages IDT error %lu\n", 256 EFI_ERROR_CODE(status)); 257 lidt_pa = 0; 258 return (0); 259 } 260 status = BS->AllocatePages(AllocateAnyPages, EfiLoaderData, 1, 261 &exc_stack_pa); 262 if (EFI_ERROR(status)) { 263 printf("efi_redirect_exceptions: AllocatePages stk error %lu\n", 264 EFI_ERROR_CODE(status)); 265 exc_stack_pa = 0; 266 free_tables(); 267 return (0); 268 } 269 loader_idt.rd_limit = fw_idt.rd_limit; 270 bcopy((void *)fw_idt.rd_base, (void *)loader_idt.rd_base, 271 loader_idt.rd_limit); 272 bzero(ist_use_table, sizeof(ist_use_table)); 273 bzero(fw_intr_handlers, sizeof(fw_intr_handlers)); 274 bzero(intercepted, sizeof(intercepted)); 275 276 sgdt(&fw_gdt); 277 tss_fw_seg = read_tr(); 278 gdt_rd = NULL; 279 if (tss_fw_seg == 0) { 280 for (i = 2; (i << 3) + sizeof(*gdt_desc) <= fw_gdt.rd_limit; 281 i += 2) { 282 gdt_desc = (struct system_segment_descriptor *)( 283 fw_gdt.rd_base + (i << 3)); 284 if (gdt_desc->sd_type == 0 && gdt_desc->sd_mbz == 0) { 285 gdt_rd = &fw_gdt; 286 break; 287 } 288 } 289 if (gdt_rd == NULL) { 290 if (i >= 8190) { 291 printf("efi_redirect_exceptions: all slots " 292 "in gdt are used\n"); 293 free_tables(); 294 return (0); 295 } 296 loader_gdt.rd_limit = roundup2(fw_gdt.rd_limit + 297 sizeof(struct system_segment_descriptor), 298 sizeof(struct system_segment_descriptor)) - 1; 299 i = (loader_gdt.rd_limit + 1 - 300 sizeof(struct system_segment_descriptor)) / 301 sizeof(struct system_segment_descriptor) * 2; 302 status = BS->AllocatePages(AllocateAnyPages, 303 EfiLoaderData, 304 EFI_SIZE_TO_PAGES(loader_gdt.rd_limit), 305 &loader_gdt_pa); 306 if (EFI_ERROR(status)) { 307 printf("efi_setup_tss: AllocatePages gdt error " 308 "%lu\n", EFI_ERROR_CODE(status)); 309 loader_gdt_pa = 0; 310 free_tables(); 311 return (0); 312 } 313 loader_gdt.rd_base = loader_gdt_pa; 314 bzero((void *)loader_gdt.rd_base, loader_gdt.rd_limit); 315 bcopy((void *)fw_gdt.rd_base, 316 (void *)loader_gdt.rd_base, fw_gdt.rd_limit); 317 gdt_rd = &loader_gdt; 318 } 319 loader_tss = i << 3; 320 if (!efi_setup_tss(gdt_rd, i, &tss)) { 321 tss_pa = 0; 322 free_tables(); 323 return (0); 324 } 325 } else { 326 tss_desc = (struct system_segment_descriptor *)((char *) 327 fw_gdt.rd_base + tss_fw_seg); 328 if (tss_desc->sd_type != SDT_SYSTSS && 329 tss_desc->sd_type != SDT_SYSBSY) { 330 printf("LTR points to non-TSS descriptor\n"); 331 free_tables(); 332 return (0); 333 } 334 tss_pa = tss_desc->sd_lobase + (tss_desc->sd_hibase << 16); 335 tss = (struct amd64tss *)tss_pa; 336 tss_desc->sd_type = SDT_SYSTSS; /* unbusy */ 337 } 338 339 PREPARE_EXCEPTION(0); 340 PREPARE_EXCEPTION(1); 341 PREPARE_EXCEPTION(2); 342 PREPARE_EXCEPTION(3); 343 PREPARE_EXCEPTION(4); 344 PREPARE_EXCEPTION(5); 345 PREPARE_EXCEPTION(6); 346 PREPARE_EXCEPTION(7); 347 PREPARE_EXCEPTION(8); 348 PREPARE_EXCEPTION(9); 349 PREPARE_EXCEPTION(10); 350 PREPARE_EXCEPTION(11); 351 PREPARE_EXCEPTION(12); 352 PREPARE_EXCEPTION(13); 353 PREPARE_EXCEPTION(14); 354 PREPARE_EXCEPTION(16); 355 PREPARE_EXCEPTION(17); 356 PREPARE_EXCEPTION(18); 357 PREPARE_EXCEPTION(19); 358 PREPARE_EXCEPTION(20); 359 360 exc_rsp = exc_stack_pa + PAGE_SIZE - 361 (6 /* hw exception frame */ + 3 /* scratch regs */) * 8; 362 363 /* Find free IST and use it */ 364 for (ist = 1; ist < NUM_IST; ist++) { 365 if (ist_use_table[ist] == 0) 366 break; 367 } 368 if (ist == NUM_IST) { 369 printf("efi_redirect_exceptions: all ISTs used\n"); 370 free_tables(); 371 lidt_pa = 0; 372 return (0); 373 } 374 for (i = 0; i < NUM_EXC; i++) { 375 loader_idt_e = &((struct gate_descriptor *)loader_idt. 376 rd_base)[i]; 377 if (intercepted[i]) 378 loader_idt_e->gd_ist = ist; 379 } 380 (&(tss->tss_ist1))[ist - 1] = exc_stack_pa + PAGE_SIZE; 381 382 /* Switch to new IDT */ 383 rfl = intr_disable(); 384 if (loader_gdt_pa != 0) 385 bare_lgdt(&loader_gdt); 386 if (loader_tss != 0) 387 ltr(loader_tss); 388 lidt(&loader_idt); 389 intr_restore(rfl); 390 return (1); 391 } 392 393 static void 394 efi_unredirect_exceptions(void) 395 { 396 register_t rfl; 397 398 if (lidt_pa == 0) 399 return; 400 401 rfl = intr_disable(); 402 if (ist != 0) 403 (&(((struct amd64tss *)tss_pa)->tss_ist1))[ist - 1] = 0; 404 if (loader_gdt_pa != 0) 405 bare_lgdt(&fw_gdt); 406 if (loader_tss != 0) 407 ltr(tss_fw_seg); 408 lidt(&fw_idt); 409 intr_restore(rfl); 410 free_tables(); 411 } 412 413 static int 414 command_grab_faults(int argc, char *argv[]) 415 { 416 int res; 417 418 res = efi_redirect_exceptions(); 419 if (!res) 420 printf("failed\n"); 421 return (CMD_OK); 422 } 423 COMMAND_SET(grap_faults, "grab_faults", "grab faults", command_grab_faults); 424 425 static int 426 command_ungrab_faults(int argc, char *argv[]) 427 { 428 429 efi_unredirect_exceptions(); 430 return (CMD_OK); 431 } 432 COMMAND_SET(ungrab_faults, "ungrab_faults", "ungrab faults", 433 command_ungrab_faults); 434 435 static int 436 command_fault(int argc, char *argv[]) 437 { 438 439 __asm("ud2"); 440 return (CMD_OK); 441 } 442 COMMAND_SET(fault, "fault", "generate fault", command_fault); 443