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
report_exc(struct trapframe * tf)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
prepare_exception(unsigned idx,uint64_t my_handler,int ist_use_table[static NUM_IST])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
free_tables(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
efi_setup_tss(struct region_descriptor * gdt,uint32_t loader_tss_idx,struct amd64tss ** tss)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
efi_redirect_exceptions(void)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
efi_unredirect_exceptions(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
command_grab_faults(int argc,char * argv[])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
command_ungrab_faults(int argc,char * argv[])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
command_fault(int argc,char * argv[])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