usr/src/boot/sys/boot/efi/loader/arch/amd64/trap.c

   1 /*-
   2  * Copyright (c) 2016 The FreeBSD Foundation
   3  * All rights reserved.
   4  *
   5  * This software was developed by Konstantin Belousov under sponsorship
   6  * from the FreeBSD Foundation.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 #include <sys/cdefs.h>
  31
  32 #include <stand.h>
  33 #include <string.h>
  34 #include <sys/param.h>
  35 #include <machine/cpufunc.h>
  36 #include <machine/psl.h>
  37 #include <machine/segments.h>
  38 #include <machine/frame.h>
  39 #include <machine/tss.h>
  40
  41 #include <efi.h>
  42 #include <efilib.h>
  43
  44 #include "bootstrap.h"
  45 #include "loader_efi.h"
  46
  47 #define NUM_IST 8
  48 #define NUM_EXC 32
  49
  50 /*
  51  * This code catches exceptions but forwards hardware interrupts to
  52  * handlers installed by firmware.  It differentiates exceptions
  53  * vs. interrupts by presence of the error code on the stack, which
  54  * causes different stack pointer value on trap handler entry.
  55  *
  56  * Use kernel layout for the trapframe just to not be original.
  57  *
  58  * Use free IST slot in existing TSS, or create our own TSS if
  59  * firmware did not configured any, to have stack switched to
  60  * IST-specified one, e.g. to handle #SS.  If hand-off cannot find
  61  * unused IST slot, or create a new descriptor in GDT, we bail out.
  62  */
  63
  64 static struct region_descriptor fw_idt; /* Descriptor for pristine fw IDT */
  65 static struct region_descriptor loader_idt;/* Descriptor for loader
  66                                            shadow IDT */
  67 static EFI_PHYSICAL_ADDRESS lidt_pa;    /* Address of loader shadow IDT */
  68 static EFI_PHYSICAL_ADDRESS tss_pa;     /* Address of TSS */
  69 static EFI_PHYSICAL_ADDRESS exc_stack_pa;/* Address of IST stack for loader */
  70 EFI_PHYSICAL_ADDRESS exc_rsp;   /* %rsp value on our IST stack when
  71                                    exception happens */
  72 EFI_PHYSICAL_ADDRESS fw_intr_handlers[NUM_EXC]; /* fw handlers for < 32 IDT
  73                                                    vectors */
  74 static int intercepted[NUM_EXC];
  75 static int ist;                         /* IST for exception handlers */
  76 static uint32_t tss_fw_seg;             /* Fw TSS segment */
  77 static uint32_t loader_tss;             /* Loader TSS segment */
  78 static struct region_descriptor fw_gdt; /* Descriptor of pristine GDT */
  79 static EFI_PHYSICAL_ADDRESS loader_gdt_pa; /* Address of loader shadow GDT */
  80
  81 void report_exc(struct trapframe *tf);
  82 void
  83 report_exc(struct trapframe *tf)
  84 {
  85
  86         /*
  87          * printf() depends on loader runtime and UEFI firmware health
  88          * to produce the console output, in case of exception, the
  89          * loader or firmware runtime may fail to support the printf().
  90          */
  91         printf("===================================================="
  92             "============================\n");
  93         printf("Exception %u\n", tf->tf_trapno);
  94         printf("ss 0x%04hx cs 0x%04hx ds 0x%04hx es 0x%04hx fs 0x%04hx "
  95             "gs 0x%04hx\n",
  96             (uint16_t)tf->tf_ss, (uint16_t)tf->tf_cs, (uint16_t)tf->tf_ds,
  97             (uint16_t)tf->tf_es, (uint16_t)tf->tf_fs, (uint16_t)tf->tf_gs);
  98         printf("err 0x%08x rfl 0x%08x addr 0x%016lx\n"
  99             "rsp 0x%016lx rip 0x%016lx\n",
 100             (uint32_t)tf->tf_err, (uint32_t)tf->tf_rflags, tf->tf_addr,
 101             tf->tf_rsp, tf->tf_rip);
 102         printf(
 103             "rdi 0x%016lx rsi 0x%016lx rdx 0x%016lx\n"
 104             "rcx 0x%016lx r8  0x%016lx r9  0x%016lx\n"
 105             "rax 0x%016lx rbx 0x%016lx rbp 0x%016lx\n"
 106             "r10 0x%016lx r11 0x%016lx r12 0x%016lx\n"
 107             "r13 0x%016lx r14 0x%016lx r15 0x%016lx\n",
 108             tf->tf_rdi, tf->tf_rsi, tf->tf_rdx, tf->tf_rcx, tf->tf_r8,
 109             tf->tf_r9, tf->tf_rax, tf->tf_rbx, tf->tf_rbp, tf->tf_r10,
 110             tf->tf_r11, tf->tf_r12, tf->tf_r13, tf->tf_r14, tf->tf_r15);
 111         printf("Machine stopped.\n");
 112 }
 113
 114 static void
 115 prepare_exception(unsigned idx, uint64_t my_handler,
 116     int ist_use_table[static NUM_IST])
 117 {
 118         struct gate_descriptor *fw_idt_e, *loader_idt_e;
 119
 120         fw_idt_e = &((struct gate_descriptor *)fw_idt.rd_base)[idx];
 121         loader_idt_e = &((struct gate_descriptor *)loader_idt.rd_base)[idx];
 122         fw_intr_handlers[idx] = fw_idt_e->gd_looffset +
 123             (fw_idt_e->gd_hioffset << 16);
 124         intercepted[idx] = 1;
 125         ist_use_table[fw_idt_e->gd_ist]++;
 126         loader_idt_e->gd_looffset = my_handler;
 127         loader_idt_e->gd_hioffset = my_handler >> 16;
 128         /*
 129          * We reuse uefi selector for the code segment for the exception
 130          * handler code, while the reason for the fault might be the
 131          * corruption of that gdt entry. On the other hand, allocating
 132          * our own descriptor might be not much better, if gdt is corrupted.
 133          */
 134         loader_idt_e->gd_selector = fw_idt_e->gd_selector;
 135         loader_idt_e->gd_ist = 0;
 136         loader_idt_e->gd_type = SDT_SYSIGT;
 137         loader_idt_e->gd_dpl = 0;
 138         loader_idt_e->gd_p = 1;
 139         loader_idt_e->gd_xx = 0;
 140         loader_idt_e->sd_xx1 = 0;
 141 }
 142 #define PREPARE_EXCEPTION(N)                                            \
 143     extern char EXC##N##_handler[];                                     \
 144     prepare_exception(N, (uintptr_t)EXC##N##_handler, ist_use_table);
 145
 146 static void
 147 free_tables(void)
 148 {
 149
 150         if (lidt_pa != 0) {
 151                 BS->FreePages(lidt_pa, EFI_SIZE_TO_PAGES(fw_idt.rd_limit));
 152                 lidt_pa = 0;
 153         }
 154         if (exc_stack_pa != 0) {
 155                 BS->FreePages(exc_stack_pa, 1);
 156                 exc_stack_pa = 0;
 157         }
 158         if (tss_pa != 0 && tss_fw_seg == 0) {
 159                 BS->FreePages(tss_pa, EFI_SIZE_TO_PAGES(sizeof(struct
 160                     amd64tss)));
 161                 tss_pa = 0;
 162         }
 163         if (loader_gdt_pa != 0) {
 164                 BS->FreePages(tss_pa, 2);
 165                 loader_gdt_pa = 0;
 166         }
 167         ist = 0;
 168         loader_tss = 0;
 169 }
 170
 171 static int
 172 efi_setup_tss(struct region_descriptor *gdt, uint32_t loader_tss_idx,
 173     struct amd64tss **tss)
 174 {
 175         EFI_STATUS status;
 176         struct system_segment_descriptor *tss_desc;
 177
 178         tss_desc = (struct system_segment_descriptor *)(gdt->rd_base +
 179             (loader_tss_idx << 3));
 180         status = BS->AllocatePages(AllocateAnyPages, EfiLoaderData,
 181             EFI_SIZE_TO_PAGES(sizeof(struct amd64tss)), &tss_pa);
 182         if (EFI_ERROR(status)) {
 183                 printf("efi_setup_tss: AllocatePages tss error %lu\n",
 184                     EFI_ERROR_CODE(status));
 185                 return (0);
 186         }
 187         *tss = (struct amd64tss *)tss_pa;
 188         bzero(*tss, sizeof(**tss));
 189         tss_desc->sd_lolimit = sizeof(struct amd64tss);
 190         tss_desc->sd_lobase = tss_pa;
 191         tss_desc->sd_type = SDT_SYSTSS;
 192         tss_desc->sd_dpl = 0;
 193         tss_desc->sd_p = 1;
 194         tss_desc->sd_hilimit = sizeof(struct amd64tss) >> 16;
 195         tss_desc->sd_gran = 0;
 196         tss_desc->sd_hibase = tss_pa >> 24;
 197         tss_desc->sd_xx0 = 0;
 198         tss_desc->sd_xx1 = 0;
 199         tss_desc->sd_mbz = 0;
 200         tss_desc->sd_xx2 = 0;
 201         return (1);
 202 }
 203
 204 static int
 205 efi_redirect_exceptions(void)
 206 {
 207         int ist_use_table[NUM_IST];
 208         struct gate_descriptor *loader_idt_e;
 209         struct system_segment_descriptor *tss_desc, *gdt_desc;
 210         struct amd64tss *tss;
 211         struct region_descriptor *gdt_rd, loader_gdt;
 212         uint32_t i;
 213         EFI_STATUS status;
 214         register_t rfl;
 215
 216         sidt(&fw_idt);
 217         status = BS->AllocatePages(AllocateAnyPages, EfiLoaderData,
 218             EFI_SIZE_TO_PAGES(fw_idt.rd_limit), &lidt_pa);
 219         if (EFI_ERROR(status)) {
 220                 printf("efi_redirect_exceptions: AllocatePages IDT error %lu\n",
 221                     EFI_ERROR_CODE(status));
 222                 lidt_pa = 0;
 223                 return (0);
 224         }
 225         status = BS->AllocatePages(AllocateAnyPages, EfiLoaderData, 1,
 226             &exc_stack_pa);
 227         if (EFI_ERROR(status)) {
 228                 printf("efi_redirect_exceptions: AllocatePages stk error %lu\n",
 229                     EFI_ERROR_CODE(status));
 230                 exc_stack_pa = 0;
 231                 free_tables();
 232                 return (0);
 233         }
 234         loader_idt.rd_limit = fw_idt.rd_limit;
 235         bcopy((void *)fw_idt.rd_base, (void *)loader_idt.rd_base,
 236             loader_idt.rd_limit);
 237         bzero(ist_use_table, sizeof(ist_use_table));
 238         bzero(fw_intr_handlers, sizeof(fw_intr_handlers));
 239         bzero(intercepted, sizeof(intercepted));
 240
 241         sgdt(&fw_gdt);
 242         tss_fw_seg = read_tr();
 243         gdt_rd = NULL;
 244         if (tss_fw_seg == 0) {
 245                 for (i = 2; (i << 3) + sizeof(*gdt_desc) <= fw_gdt.rd_limit;
 246                     i += 2) {
 247                         gdt_desc = (struct system_segment_descriptor *)(
 248                             fw_gdt.rd_base + (i << 3));
 249                         if (gdt_desc->sd_type == 0 && gdt_desc->sd_mbz == 0) {
 250                                 gdt_rd = &fw_gdt;
 251                                 break;
 252                         }
 253                 }
 254                 if (gdt_rd == NULL) {
 255                         if (i >= 8190) {
 256                                 printf("efi_redirect_exceptions: all slots "
 257                                     "in gdt are used\n");
 258                                 free_tables();
 259                                 return (0);
 260                         }
 261                         loader_gdt.rd_limit = roundup2(fw_gdt.rd_limit +
 262                             sizeof(struct system_segment_descriptor),
 263                             sizeof(struct system_segment_descriptor)) - 1;
 264                         i = (loader_gdt.rd_limit + 1 -
 265                             sizeof(struct system_segment_descriptor)) /
 266                             sizeof(struct system_segment_descriptor) * 2;
 267                         status = BS->AllocatePages(AllocateAnyPages,
 268                             EfiLoaderData,
 269                             EFI_SIZE_TO_PAGES(loader_gdt.rd_limit),
 270                             &loader_gdt_pa);
 271                         if (EFI_ERROR(status)) {
 272                                 printf("efi_setup_tss: AllocatePages gdt error "
 273                                     "%lu\n",  EFI_ERROR_CODE(status));
 274                                 loader_gdt_pa = 0;
 275                                 free_tables();
 276                                 return (0);
 277                         }
 278                         loader_gdt.rd_base = loader_gdt_pa;
 279                         bzero((void *)loader_gdt.rd_base, loader_gdt.rd_limit);
 280                         bcopy((void *)fw_gdt.rd_base,
 281                             (void *)loader_gdt.rd_base, fw_gdt.rd_limit);
 282                         gdt_rd = &loader_gdt;
 283                 }
 284                 loader_tss = i << 3;
 285                 if (!efi_setup_tss(gdt_rd, i, &tss)) {
 286                         tss_pa = 0;
 287                         free_tables();
 288                         return (0);
 289                 }
 290         } else {
 291                 tss_desc = (struct system_segment_descriptor *)((char *)
 292                     fw_gdt.rd_base + tss_fw_seg);
 293                 if (tss_desc->sd_type != SDT_SYSTSS &&
 294                     tss_desc->sd_type != SDT_SYSBSY) {
 295                         printf("LTR points to non-TSS descriptor\n");
 296                         free_tables();
 297                         return (0);
 298                 }
 299                 tss_pa = tss_desc->sd_lobase + (tss_desc->sd_hibase << 16);
 300                 tss = (struct amd64tss *)tss_pa;
 301                 tss_desc->sd_type = SDT_SYSTSS; /* unbusy */
 302         }
 303
 304         PREPARE_EXCEPTION(0);
 305         PREPARE_EXCEPTION(1);
 306         PREPARE_EXCEPTION(2);
 307         PREPARE_EXCEPTION(3);
 308         PREPARE_EXCEPTION(4);
 309         PREPARE_EXCEPTION(5);
 310         PREPARE_EXCEPTION(6);
 311         PREPARE_EXCEPTION(7);
 312         PREPARE_EXCEPTION(8);
 313         PREPARE_EXCEPTION(9);
 314         PREPARE_EXCEPTION(10);
 315         PREPARE_EXCEPTION(11);
 316         PREPARE_EXCEPTION(12);
 317         PREPARE_EXCEPTION(13);
 318         PREPARE_EXCEPTION(14);
 319         PREPARE_EXCEPTION(16);
 320         PREPARE_EXCEPTION(17);
 321         PREPARE_EXCEPTION(18);
 322         PREPARE_EXCEPTION(19);
 323         PREPARE_EXCEPTION(20);
 324
 325         exc_rsp = exc_stack_pa + PAGE_SIZE -
 326             (6 /* hw exception frame */ + 3 /* scratch regs */) * 8;
 327
 328         /* Find free IST and use it */
 329         for (ist = 1; ist < NUM_IST; ist++) {
 330                 if (ist_use_table[ist] == 0)
 331                         break;
 332         }
 333         if (ist == NUM_IST) {
 334                 printf("efi_redirect_exceptions: all ISTs used\n");
 335                 free_tables();
 336                 lidt_pa = 0;
 337                 return (0);
 338         }
 339         for (i = 0; i < NUM_EXC; i++) {
 340                 loader_idt_e = &((struct gate_descriptor *)loader_idt.
 341                     rd_base)[i];
 342                 if (intercepted[i])
 343                         loader_idt_e->gd_ist = ist;
 344         }
 345         (&(tss->tss_ist1))[ist - 1] = exc_stack_pa + PAGE_SIZE;
 346
 347         /* Switch to new IDT */
 348         rfl = intr_disable();
 349         if (loader_gdt_pa != 0)
 350                 bare_lgdt(&loader_gdt);
 351         if (loader_tss != 0)
 352                 ltr(loader_tss);
 353         lidt(&loader_idt);
 354         intr_restore(rfl);
 355         return (1);
 356 }
 357
 358 static void
 359 efi_unredirect_exceptions(void)
 360 {
 361         register_t rfl;
 362
 363         if (lidt_pa == 0)
 364                 return;
 365
 366         rfl = intr_disable();
 367         if (ist != 0)
 368                 (&(((struct amd64tss *)tss_pa)->tss_ist1))[ist - 1] = 0;
 369         if (loader_gdt_pa != 0)
 370                 bare_lgdt(&fw_gdt);
 371         if (loader_tss != 0)
 372                 ltr(tss_fw_seg);
 373         lidt(&fw_idt);
 374         intr_restore(rfl);
 375         free_tables();
 376 }
 377
 378 static int
 379 command_grab_faults(int argc, char *argv[])
 380 {
 381         int res;
 382
 383         res = efi_redirect_exceptions();
 384         if (!res)
 385                 printf("failed\n");
 386         return (CMD_OK);
 387 }
 388 COMMAND_SET(grap_faults, "grab_faults", "grab faults", command_grab_faults);
 389
 390 static int
 391 command_ungrab_faults(int argc, char *argv[])
 392 {
 393
 394         efi_unredirect_exceptions();
 395         return (CMD_OK);
 396 }
 397 COMMAND_SET(ungrab_faults, "ungrab_faults", "ungrab faults",
 398     command_ungrab_faults);
 399
 400 static int
 401 command_fault(int argc, char *argv[])
 402 {
 403
 404         __asm("ud2");
 405         return (CMD_OK);
 406 }
 407 COMMAND_SET(fault, "fault", "generate fault", command_fault);