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 <stand.h> 30 #include <string.h> 31 #include <sys/param.h> 32 #include <machine/cpufunc.h> 33 #include <machine/psl.h> 34 #include <machine/segments.h> 35 #include <machine/frame.h> 36 #include <machine/tss.h> 37 38 #include <efi.h> 39 #include <efilib.h> 40 41 #include "bootstrap.h" 42 #include "loader_efi.h" 43 44 #define NUM_IST 8 45 #define NUM_EXC 32 46 47 /* 48 * This code catches exceptions but forwards hardware interrupts to 49 * handlers installed by firmware. It differentiates exceptions 50 * vs. interrupts by presence of the error code on the stack, which 51 * causes different stack pointer value on trap handler entry. 52 * 53 * Use kernel layout for the trapframe just to not be original. 54 * 55 * Use free IST slot in existing TSS, or create our own TSS if 56 * firmware did not configured any, to have stack switched to 57 * IST-specified one, e.g. to handle #SS. If hand-off cannot find 58 * unused IST slot, or create a new descriptor in GDT, we bail out. 59 */ 60 61 static struct region_descriptor fw_idt; /* Descriptor for pristine fw IDT */ 62 static struct region_descriptor loader_idt;/* Descriptor for loader 63 shadow IDT */ 64 static EFI_PHYSICAL_ADDRESS lidt_pa; /* Address of loader shadow IDT */ 65 static EFI_PHYSICAL_ADDRESS tss_pa; /* Address of TSS */ 66 static EFI_PHYSICAL_ADDRESS exc_stack_pa;/* Address of IST stack for loader */ 67 EFI_PHYSICAL_ADDRESS exc_rsp; /* %rsp value on our IST stack when 68 exception happens */ 69 EFI_PHYSICAL_ADDRESS fw_intr_handlers[NUM_EXC]; /* fw handlers for < 32 IDT 70 vectors */ 71 static int intercepted[NUM_EXC]; 72 static int ist; /* IST for exception handlers */ 73 static uint32_t tss_fw_seg; /* Fw TSS segment */ 74 static uint32_t loader_tss; /* Loader TSS segment */ 75 static struct region_descriptor fw_gdt; /* Descriptor of pristine GDT */ 76 static EFI_PHYSICAL_ADDRESS loader_gdt_pa; /* Address of loader shadow GDT */ 77 78 struct frame { 79 struct frame *fr_savfp; 80 uintptr_t fr_savpc; 81 }; 82 83 void report_exc(struct trapframe *tf); 84 void 85 report_exc(struct trapframe *tf) 86 { 87 struct frame *fp; 88 uintptr_t pc, base; 89 char buf[80]; 90 91 base = (uintptr_t)boot_img->ImageBase; 92 /* 93 * printf() depends on loader runtime and UEFI firmware health 94 * to produce the console output, in case of exception, the 95 * loader or firmware runtime may fail to support the printf(). 96 */ 97 printf("====================================================" 98 "============================\n"); 99 printf("Exception %u\n", tf->tf_trapno); 100 printf("ss 0x%04hx cs 0x%04hx ds 0x%04hx es 0x%04hx fs 0x%04hx " 101 "gs 0x%04hx\n", 102 (uint16_t)tf->tf_ss, (uint16_t)tf->tf_cs, (uint16_t)tf->tf_ds, 103 (uint16_t)tf->tf_es, (uint16_t)tf->tf_fs, (uint16_t)tf->tf_gs); 104 printf("err 0x%08x rfl 0x%08x addr 0x%016lx\n" 105 "rsp 0x%016lx rip 0x%016lx\n", 106 (uint32_t)tf->tf_err, (uint32_t)tf->tf_rflags, tf->tf_addr, 107 tf->tf_rsp, tf->tf_rip); 108 printf( 109 "rdi 0x%016lx rsi 0x%016lx rdx 0x%016lx\n" 110 "rcx 0x%016lx r8 0x%016lx r9 0x%016lx\n" 111 "rax 0x%016lx rbx 0x%016lx rbp 0x%016lx\n" 112 "r10 0x%016lx r11 0x%016lx r12 0x%016lx\n" 113 "r13 0x%016lx r14 0x%016lx r15 0x%016lx\n", 114 tf->tf_rdi, tf->tf_rsi, tf->tf_rdx, tf->tf_rcx, tf->tf_r8, 115 tf->tf_r9, tf->tf_rax, tf->tf_rbx, tf->tf_rbp, tf->tf_r10, 116 tf->tf_r11, tf->tf_r12, tf->tf_r13, tf->tf_r14, tf->tf_r15); 117 118 fp = (struct frame *)tf->tf_rbp; 119 pc = tf->tf_rip; 120 121 printf("Stack trace:\n"); 122 pager_open(); 123 while (fp != NULL || pc != 0) { 124 char *source = "PC"; 125 126 if (pc >= base && pc < base + boot_img->ImageSize) { 127 pc -= base; 128 source = "loader PC"; 129 } 130 (void) snprintf(buf, sizeof (buf), "FP %016lx: %s 0x%016lx\n", 131 (uintptr_t)fp, source, pc); 132 if (pager_output(buf)) 133 break; 134 135 if (fp != NULL) 136 fp = fp->fr_savfp; 137 138 if (fp != NULL) 139 pc = fp->fr_savpc; 140 else 141 pc = 0; 142 } 143 pager_close(); 144 printf("Machine stopped.\n"); 145 } 146 147 static void 148 prepare_exception(unsigned idx, uint64_t my_handler, 149 int ist_use_table[static NUM_IST]) 150 { 151 struct gate_descriptor *fw_idt_e, *loader_idt_e; 152 153 fw_idt_e = &((struct gate_descriptor *)fw_idt.rd_base)[idx]; 154 loader_idt_e = &((struct gate_descriptor *)loader_idt.rd_base)[idx]; 155 fw_intr_handlers[idx] = fw_idt_e->gd_looffset + 156 (fw_idt_e->gd_hioffset << 16); 157 intercepted[idx] = 1; 158 ist_use_table[fw_idt_e->gd_ist]++; 159 loader_idt_e->gd_looffset = my_handler; 160 loader_idt_e->gd_hioffset = my_handler >> 16; 161 /* 162 * We reuse uefi selector for the code segment for the exception 163 * handler code, while the reason for the fault might be the 164 * corruption of that gdt entry. On the other hand, allocating 165 * our own descriptor might be not much better, if gdt is corrupted. 166 */ 167 loader_idt_e->gd_selector = fw_idt_e->gd_selector; 168 loader_idt_e->gd_ist = 0; 169 loader_idt_e->gd_type = SDT_SYSIGT; 170 loader_idt_e->gd_dpl = 0; 171 loader_idt_e->gd_p = 1; 172 loader_idt_e->gd_xx = 0; 173 loader_idt_e->sd_xx1 = 0; 174 } 175 #define PREPARE_EXCEPTION(N) \ 176 extern char EXC##N##_handler[]; \ 177 prepare_exception(N, (uintptr_t)EXC##N##_handler, ist_use_table); 178 179 static void 180 free_tables(void) 181 { 182 183 if (lidt_pa != 0) { 184 BS->FreePages(lidt_pa, EFI_SIZE_TO_PAGES(fw_idt.rd_limit)); 185 lidt_pa = 0; 186 } 187 if (exc_stack_pa != 0) { 188 BS->FreePages(exc_stack_pa, 1); 189 exc_stack_pa = 0; 190 } 191 if (tss_pa != 0 && tss_fw_seg == 0) { 192 BS->FreePages(tss_pa, EFI_SIZE_TO_PAGES(sizeof(struct 193 amd64tss))); 194 tss_pa = 0; 195 } 196 if (loader_gdt_pa != 0) { 197 BS->FreePages(tss_pa, 2); 198 loader_gdt_pa = 0; 199 } 200 ist = 0; 201 loader_tss = 0; 202 } 203 204 static int 205 efi_setup_tss(struct region_descriptor *gdt, uint32_t loader_tss_idx, 206 struct amd64tss **tss) 207 { 208 EFI_STATUS status; 209 struct system_segment_descriptor *tss_desc; 210 211 tss_desc = (struct system_segment_descriptor *)(gdt->rd_base + 212 (loader_tss_idx << 3)); 213 status = BS->AllocatePages(AllocateAnyPages, EfiLoaderData, 214 EFI_SIZE_TO_PAGES(sizeof(struct amd64tss)), &tss_pa); 215 if (EFI_ERROR(status)) { 216 printf("efi_setup_tss: AllocatePages tss error %lu\n", 217 EFI_ERROR_CODE(status)); 218 return (0); 219 } 220 *tss = (struct amd64tss *)tss_pa; 221 bzero(*tss, sizeof(**tss)); 222 tss_desc->sd_lolimit = sizeof(struct amd64tss); 223 tss_desc->sd_lobase = tss_pa; 224 tss_desc->sd_type = SDT_SYSTSS; 225 tss_desc->sd_dpl = 0; 226 tss_desc->sd_p = 1; 227 tss_desc->sd_hilimit = sizeof(struct amd64tss) >> 16; 228 tss_desc->sd_gran = 0; 229 tss_desc->sd_hibase = tss_pa >> 24; 230 tss_desc->sd_xx0 = 0; 231 tss_desc->sd_xx1 = 0; 232 tss_desc->sd_mbz = 0; 233 tss_desc->sd_xx2 = 0; 234 return (1); 235 } 236 237 static int 238 efi_redirect_exceptions(void) 239 { 240 int ist_use_table[NUM_IST]; 241 struct gate_descriptor *loader_idt_e; 242 struct system_segment_descriptor *tss_desc, *gdt_desc; 243 struct amd64tss *tss; 244 struct region_descriptor *gdt_rd, loader_gdt; 245 uint32_t i; 246 EFI_STATUS status; 247 register_t rfl; 248 249 sidt(&fw_idt); 250 status = BS->AllocatePages(AllocateAnyPages, EfiLoaderData, 251 EFI_SIZE_TO_PAGES(fw_idt.rd_limit), &lidt_pa); 252 if (EFI_ERROR(status)) { 253 printf("efi_redirect_exceptions: AllocatePages IDT error %lu\n", 254 EFI_ERROR_CODE(status)); 255 lidt_pa = 0; 256 return (0); 257 } 258 status = BS->AllocatePages(AllocateAnyPages, EfiLoaderData, 1, 259 &exc_stack_pa); 260 if (EFI_ERROR(status)) { 261 printf("efi_redirect_exceptions: AllocatePages stk error %lu\n", 262 EFI_ERROR_CODE(status)); 263 exc_stack_pa = 0; 264 free_tables(); 265 return (0); 266 } 267 loader_idt.rd_limit = fw_idt.rd_limit; 268 bcopy((void *)fw_idt.rd_base, (void *)loader_idt.rd_base, 269 loader_idt.rd_limit); 270 bzero(ist_use_table, sizeof(ist_use_table)); 271 bzero(fw_intr_handlers, sizeof(fw_intr_handlers)); 272 bzero(intercepted, sizeof(intercepted)); 273 274 sgdt(&fw_gdt); 275 tss_fw_seg = read_tr(); 276 gdt_rd = NULL; 277 if (tss_fw_seg == 0) { 278 for (i = 2; (i << 3) + sizeof(*gdt_desc) <= fw_gdt.rd_limit; 279 i += 2) { 280 gdt_desc = (struct system_segment_descriptor *)( 281 fw_gdt.rd_base + (i << 3)); 282 if (gdt_desc->sd_type == 0 && gdt_desc->sd_mbz == 0) { 283 gdt_rd = &fw_gdt; 284 break; 285 } 286 } 287 if (gdt_rd == NULL) { 288 if (i >= 8190) { 289 printf("efi_redirect_exceptions: all slots " 290 "in gdt are used\n"); 291 free_tables(); 292 return (0); 293 } 294 loader_gdt.rd_limit = roundup2(fw_gdt.rd_limit + 295 sizeof(struct system_segment_descriptor), 296 sizeof(struct system_segment_descriptor)) - 1; 297 i = (loader_gdt.rd_limit + 1 - 298 sizeof(struct system_segment_descriptor)) / 299 sizeof(struct system_segment_descriptor) * 2; 300 status = BS->AllocatePages(AllocateAnyPages, 301 EfiLoaderData, 302 EFI_SIZE_TO_PAGES(loader_gdt.rd_limit), 303 &loader_gdt_pa); 304 if (EFI_ERROR(status)) { 305 printf("efi_setup_tss: AllocatePages gdt error " 306 "%lu\n", EFI_ERROR_CODE(status)); 307 loader_gdt_pa = 0; 308 free_tables(); 309 return (0); 310 } 311 loader_gdt.rd_base = loader_gdt_pa; 312 bzero((void *)loader_gdt.rd_base, loader_gdt.rd_limit); 313 bcopy((void *)fw_gdt.rd_base, 314 (void *)loader_gdt.rd_base, fw_gdt.rd_limit); 315 gdt_rd = &loader_gdt; 316 } 317 loader_tss = i << 3; 318 if (!efi_setup_tss(gdt_rd, i, &tss)) { 319 tss_pa = 0; 320 free_tables(); 321 return (0); 322 } 323 } else { 324 tss_desc = (struct system_segment_descriptor *)((char *) 325 fw_gdt.rd_base + tss_fw_seg); 326 if (tss_desc->sd_type != SDT_SYSTSS && 327 tss_desc->sd_type != SDT_SYSBSY) { 328 printf("LTR points to non-TSS descriptor\n"); 329 free_tables(); 330 return (0); 331 } 332 tss_pa = tss_desc->sd_lobase + (tss_desc->sd_hibase << 16); 333 tss = (struct amd64tss *)tss_pa; 334 tss_desc->sd_type = SDT_SYSTSS; /* unbusy */ 335 } 336 337 PREPARE_EXCEPTION(0); 338 PREPARE_EXCEPTION(1); 339 PREPARE_EXCEPTION(2); 340 PREPARE_EXCEPTION(3); 341 PREPARE_EXCEPTION(4); 342 PREPARE_EXCEPTION(5); 343 PREPARE_EXCEPTION(6); 344 PREPARE_EXCEPTION(7); 345 PREPARE_EXCEPTION(8); 346 PREPARE_EXCEPTION(9); 347 PREPARE_EXCEPTION(10); 348 PREPARE_EXCEPTION(11); 349 PREPARE_EXCEPTION(12); 350 PREPARE_EXCEPTION(13); 351 PREPARE_EXCEPTION(14); 352 PREPARE_EXCEPTION(16); 353 PREPARE_EXCEPTION(17); 354 PREPARE_EXCEPTION(18); 355 PREPARE_EXCEPTION(19); 356 PREPARE_EXCEPTION(20); 357 358 exc_rsp = exc_stack_pa + EFI_PAGE_SIZE - 359 (6 /* hw exception frame */ + 3 /* scratch regs */) * 8; 360 361 /* Find free IST and use it */ 362 for (ist = 1; ist < NUM_IST; ist++) { 363 if (ist_use_table[ist] == 0) 364 break; 365 } 366 if (ist == NUM_IST) { 367 printf("efi_redirect_exceptions: all ISTs used\n"); 368 free_tables(); 369 lidt_pa = 0; 370 return (0); 371 } 372 for (i = 0; i < NUM_EXC; i++) { 373 loader_idt_e = &((struct gate_descriptor *)loader_idt. 374 rd_base)[i]; 375 if (intercepted[i]) 376 loader_idt_e->gd_ist = ist; 377 } 378 (&(tss->tss_ist1))[ist - 1] = exc_stack_pa + EFI_PAGE_SIZE; 379 380 /* Switch to new IDT */ 381 rfl = intr_disable(); 382 if (loader_gdt_pa != 0) 383 bare_lgdt(&loader_gdt); 384 if (loader_tss != 0) 385 ltr(loader_tss); 386 lidt(&loader_idt); 387 intr_restore(rfl); 388 return (1); 389 } 390 391 static void 392 efi_unredirect_exceptions(void) 393 { 394 register_t rfl; 395 396 if (lidt_pa == 0) 397 return; 398 399 rfl = intr_disable(); 400 if (ist != 0) 401 (&(((struct amd64tss *)tss_pa)->tss_ist1))[ist - 1] = 0; 402 if (loader_gdt_pa != 0) 403 bare_lgdt(&fw_gdt); 404 if (loader_tss != 0) 405 ltr(tss_fw_seg); 406 lidt(&fw_idt); 407 intr_restore(rfl); 408 free_tables(); 409 } 410 411 static int 412 command_grab_faults(int argc, char *argv[]) 413 { 414 int res; 415 416 res = efi_redirect_exceptions(); 417 if (!res) 418 printf("failed\n"); 419 return (CMD_OK); 420 } 421 COMMAND_SET(grap_faults, "grab_faults", "grab faults", command_grab_faults); 422 423 static int 424 command_ungrab_faults(int argc, char *argv[]) 425 { 426 427 efi_unredirect_exceptions(); 428 return (CMD_OK); 429 } 430 COMMAND_SET(ungrab_faults, "ungrab_faults", "ungrab faults", 431 command_ungrab_faults); 432 433 static int 434 command_fault(int argc, char *argv[]) 435 { 436 437 __asm("ud2"); 438 return (CMD_OK); 439 } 440 COMMAND_SET(fault, "fault", "generate fault", command_fault); 441