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- /* Copyright (C) 2014 Stony Brook University
- This file is part of Graphene Library OS.
- Graphene Library OS is free software: you can redistribute it and/or
- modify it under the terms of the GNU Lesser General Public License
- as published by the Free Software Foundation, either version 3 of the
- License, or (at your option) any later version.
- Graphene Library OS is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU Lesser General Public License for more details.
- You should have received a copy of the GNU Lesser General Public License
- along with this program. If not, see <http://www.gnu.org/licenses/>. */
- /*
- * db_signal.c
- *
- * This file contains APIs to set up handlers of exceptions issued by the
- * host, and the methods to pass the exceptions to the upcalls.
- */
- #include "pal_defs.h"
- #include "pal_linux_defs.h"
- #include "pal.h"
- #include "pal_internal.h"
- #include "pal_linux.h"
- #include "pal_error.h"
- #include "pal_security.h"
- #include "api.h"
- #include "ecall_types.h"
- #include <atomic.h>
- #include <sigset.h>
- #include <linux/signal.h>
- #include <ucontext.h>
- typedef struct exception_event {
- PAL_IDX event_num;
- PAL_CONTEXT * context;
- struct pal_frame * frame;
- } PAL_EVENT;
- static void _DkGenericEventTrigger (PAL_IDX event_num, PAL_EVENT_HANDLER upcall,
- PAL_NUM arg, struct pal_frame * frame,
- PAL_CONTEXT * context)
- {
- struct exception_event event;
- event.event_num = event_num;
- event.context = context;
- event.frame = frame;
- (*upcall) ((PAL_PTR) &event, arg, context);
- }
- static bool
- _DkGenericSignalHandle (int event_num, PAL_NUM arg, struct pal_frame * frame,
- PAL_CONTEXT * context)
- {
- PAL_EVENT_HANDLER upcall = _DkGetExceptionHandler(event_num);
- if (upcall) {
- _DkGenericEventTrigger(event_num, upcall, arg, frame, context);
- return true;
- }
- return false;
- }
- #define ADDR_IN_PAL(addr) \
- ((void*)(addr) > TEXT_START && (void*)(addr) < TEXT_END)
- static struct pal_frame * get_frame (sgx_cpu_context_t * uc)
- {
- unsigned long rbp;
- if (uc) {
- unsigned long rip = uc->rip;
- rbp = uc->rbp;
- if (!ADDR_IN_PAL(rip))
- return NULL;
- } else {
- __asm__ volatile ("movq %%rbp, %0" : "=r"(rbp) :: "memory");
- }
- while (ADDR_IN_PAL(((unsigned long *) rbp)[1]))
- rbp = *(unsigned long *) rbp;
- struct pal_frame * frame = (struct pal_frame *) rbp - 1;
- for (int i = 0 ; i < 8 ; i++) {
- if (frame->identifier == PAL_FRAME_IDENTIFIER)
- return frame;
- frame = (struct pal_frame *) ((void *) frame - 8);
- }
- return NULL;
- }
- __asm__ (".type arch_exception_return_asm, @function;"
- "arch_exception_return_asm:"
- " pop %rax;"
- " pop %rbx;"
- " pop %rcx;"
- " pop %rdx;"
- " pop %rsi;"
- " pop %rdi;"
- " pop %r8;"
- " pop %r9;"
- " pop %r10;"
- " pop %r11;"
- " pop %r12;"
- " pop %r13;"
- " pop %r14;"
- " pop %r15;"
- " retq;");
- extern void arch_exception_return (void) __asm__ ("arch_exception_return_asm");
- void _DkExceptionRealHandler (int event, PAL_NUM arg, struct pal_frame * frame,
- PAL_CONTEXT * context)
- {
- if (frame) {
- frame = __alloca(sizeof(struct pal_frame));
- frame->identifier = PAL_FRAME_IDENTIFIER;
- frame->func = &_DkExceptionRealHandler;
- frame->funcname = "_DkExceptionRealHandler";
- store_register(rsp, frame->arch.rsp);
- store_register(rbp, frame->arch.rbp);
- unsigned long * last_frame = ((unsigned long *) frame->arch.rbp) + 1;
- last_frame[0] = (unsigned long) arch_exception_return;
- last_frame[1] = context->rax;
- last_frame[2] = context->rbx;
- last_frame[3] = context->rcx;
- last_frame[4] = context->rdx;
- last_frame[5] = context->rsi;
- last_frame[6] = context->rdi;
- last_frame[7] = context->r8;
- last_frame[8] = context->r9;
- last_frame[9] = context->r10;
- last_frame[10] = context->r11;
- last_frame[11] = context->r12;
- last_frame[12] = context->r13;
- last_frame[13] = context->r14;
- last_frame[14] = context->r15;
- last_frame[15] = context->rip;
- }
- _DkGenericSignalHandle(event, arg, frame, context);
- }
- /*
- * return value:
- * true: #UD is handled.
- * the execution can be continued without propagating #UD.
- * false: #UD is not handled.
- * the exception needs to be raised up to LibOS or user application.
- */
- static bool handle_ud(sgx_cpu_context_t * uc)
- {
- uint8_t * instr = (uint8_t *) uc->rip;
- if (instr[0] == 0xcc) { /* skip int 3 */
- uc->rip++;
- return true;
- } else if (instr[0] == 0x0f && instr[1] == 0xa2) {
- /* cpuid */
- unsigned int values[4];
- if (!_DkCpuIdRetrieve(uc->rax & 0xffffffff,
- uc->rcx & 0xffffffff, values)) {
- uc->rip += 2;
- uc->rax = values[0];
- uc->rbx = values[1];
- uc->rcx = values[2];
- uc->rdx = values[3];
- return true;
- }
- } else if (instr[0] == 0x0f && instr[1] == 0x31) {
- /* rdtsc */
- uc->rip += 2;
- uc->rdx = 0;
- uc->rax = 0;
- return true;
- } else if (instr[0] == 0x0f && instr[1] == 0x05) {
- /* syscall: LibOS may know how to handle this */
- return false;
- }
- SGX_DBG(DBG_E, "Unknown or illegal instruction at RIP 0x%016lx\n", uc->rip);
- return false;
- }
- void _DkExceptionHandler (unsigned int exit_info, sgx_cpu_context_t * uc)
- {
- union {
- sgx_arch_exit_info_t info;
- unsigned int intval;
- } ei = { .intval = exit_info };
- int event_num;
- if (!ei.info.valid) {
- event_num = exit_info;
- } else {
- switch (ei.info.vector) {
- case SGX_EXCEPTION_VECTOR_BR:
- event_num = PAL_EVENT_NUM_BOUND;
- break;
- case SGX_EXCEPTION_VECTOR_UD:
- if (handle_ud(uc)) {
- restore_sgx_context(uc);
- return;
- }
- event_num = PAL_EVENT_ILLEGAL;
- break;
- case SGX_EXCEPTION_VECTOR_DE:
- case SGX_EXCEPTION_VECTOR_MF:
- case SGX_EXCEPTION_VECTOR_XM:
- event_num = PAL_EVENT_ARITHMETIC_ERROR;
- break;
- case SGX_EXCEPTION_VECTOR_AC:
- event_num = PAL_EVENT_MEMFAULT;
- break;
- case SGX_EXCEPTION_VECTOR_DB:
- case SGX_EXCEPTION_VECTOR_BP:
- default:
- restore_sgx_context(uc);
- return;
- }
- }
- if (ADDR_IN_PAL(uc->rip) &&
- /* event isn't asynchronous */
- (event_num != PAL_EVENT_QUIT &&
- event_num != PAL_EVENT_SUSPEND &&
- event_num != PAL_EVENT_RESUME)) {
- printf("*** An unexpected AEX vector occurred inside PAL. "
- "Exiting the thread. *** \n"
- "(vector = 0x%x, type = 0x%x valid = %d, RIP = +0x%08lx)\n"
- "rax: 0x%08lx rcx: 0x%08lx rdx: 0x%08lx rbx: 0x%08lx\n"
- "rsp: 0x%08lx rbp: 0x%08lx rsi: 0x%08lx rdi: 0x%08lx\n"
- "r8 : 0x%08lx r9 : 0x%08lx r10: 0x%08lx r11: 0x%08lx\n"
- "r12: 0x%08lx r13: 0x%08lx r14: 0x%08lx r15: 0x%08lx\n"
- "rflags: 0x%08lx rip: 0x%08lx\n",
- ei.info.vector, ei.info.exit_type, ei.info.valid,
- uc->rip - (uintptr_t) TEXT_START,
- uc->rax, uc->rcx, uc->rdx, uc->rbx,
- uc->rsp, uc->rbp, uc->rsi, uc->rdi,
- uc->r8, uc->r9, uc->r10, uc->r11,
- uc->r12, uc->r13, uc->r14, uc->r15,
- uc->rflags, uc->rip);
- #ifdef DEBUG
- printf("pausing for debug\n");
- while (true)
- __asm__ volatile("pause");
- #endif
- _DkThreadExit();
- }
- PAL_CONTEXT ctx;
- memset(&ctx, 0, sizeof(ctx));
- ctx.rax = uc->rax;
- ctx.rbx = uc->rbx;
- ctx.rcx = uc->rcx;
- ctx.rdx = uc->rdx;
- ctx.rsp = uc->rsp;
- ctx.rbp = uc->rbp;
- ctx.rsi = uc->rsi;
- ctx.rdi = uc->rdi;
- ctx.r8 = uc->r8;
- ctx.r9 = uc->r9;
- ctx.r10 = uc->r10;
- ctx.r11 = uc->r11;
- ctx.r12 = uc->r12;
- ctx.r13 = uc->r13;
- ctx.r14 = uc->r14;
- ctx.r15 = uc->r15;
- ctx.efl = uc->rflags;
- ctx.rip = uc->rip;
- struct pal_frame * frame = get_frame(uc);
- PAL_NUM arg = 0;
- switch (event_num) {
- case PAL_EVENT_ILLEGAL:
- arg = uc->rip;
- break;
- case PAL_EVENT_MEMFAULT:
- /* TODO
- * SGX1 doesn't provide fault address.
- * SGX2 gives providing page. (lower address bits are masked)
- */
- break;
- default:
- /* nothing */
- break;
- }
- _DkExceptionRealHandler(event_num, arg, frame, &ctx);
- restore_sgx_context(uc);
- }
- void _DkRaiseFailure (int error)
- {
- PAL_EVENT_HANDLER upcall = _DkGetExceptionHandler(PAL_EVENT_FAILURE);
- if (!upcall)
- return;
- PAL_EVENT event;
- event.event_num = PAL_EVENT_FAILURE;
- event.context = NULL;
- event.frame = NULL;
- (*upcall) ((PAL_PTR) &event, error, NULL);
- }
- void _DkExceptionReturn (void * event)
- {
- PAL_EVENT * e = event;
- PAL_CONTEXT * ctx = e->context;
- if (!ctx) {
- struct pal_frame * frame = e->frame;
- if (!frame)
- return;
- __clear_frame(frame);
- arch_restore_frame(&frame->arch);
- __asm__ volatile (
- "xor %%rax, %%rax\r\n"
- "leaveq\r\n"
- "retq\r\n" ::: "memory");
- }
- // Allocate sgx_cpu_context_t just below the "normal" stack (honoring the red
- // zone) and then copy the content of ctx there. This is needed by
- // restore_sgx_context.
- sgx_cpu_context_t * uc = (void *)ctx->rsp - sizeof(sgx_cpu_context_t) - RED_ZONE_SIZE;
- uc->rax = ctx->rax;
- uc->rbx = ctx->rbx;
- uc->rcx = ctx->rcx;
- uc->rdx = ctx->rdx;
- uc->rsp = ctx->rsp;
- uc->rbp = ctx->rbp;
- uc->rsi = ctx->rsi;
- uc->rdi = ctx->rdi;
- uc->r8 = ctx->r8;
- uc->r9 = ctx->r9;
- uc->r10 = ctx->r10;
- uc->r11 = ctx->r11;
- uc->r12 = ctx->r12;
- uc->r13 = ctx->r13;
- uc->r14 = ctx->r14;
- uc->r15 = ctx->r15;
- uc->rflags = ctx->efl;
- uc->rip = ctx->rip;
- restore_sgx_context(uc);
- }
- void _DkHandleExternalEvent (PAL_NUM event, sgx_cpu_context_t * uc)
- {
- struct pal_frame * frame = get_frame(uc);
- if (event == PAL_EVENT_RESUME &&
- frame && frame->func == DkObjectsWaitAny)
- return;
- if (!frame) {
- frame = __alloca(sizeof(struct pal_frame));
- frame->identifier = PAL_FRAME_IDENTIFIER;
- frame->func = &_DkHandleExternalEvent;
- frame->funcname = "_DkHandleExternalEvent";
- arch_store_frame(&frame->arch);
- }
- /* We only end up in _DkHandleExternalEvent() if interrupted during
- * host syscall; Dk* function will be unwound, so we must inform LibOS
- * layer that PAL was interrupted (by setting PAL_ERRNO). */
- _DkRaiseFailure(PAL_ERROR_INTERRUPTED);
- if (!_DkGenericSignalHandle(event, 0, frame, NULL)
- && event != PAL_EVENT_RESUME)
- _DkThreadExit();
- }
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