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- /* -*- mode:c; c-file-style:"k&r"; c-basic-offset: 4; tab-width:4; indent-tabs-mode:nil; mode:auto-fill; fill-column:78; -*- */
- /* vim: set ts=4 sw=4 et tw=78 fo=cqt wm=0: */
- /* 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 <atomic.h>
- #include <sigset.h>
- #include <linux/signal.h>
- #include <ucontext.h>
- #include <asm/errno.h>
- #if !defined(__i386__)
- /* In x86_64 kernels, sigaction is required to have a user-defined
- * restorer. Also, they not yet support SA_INFO. The reference:
- * http://lxr.linux.no/linux+v2.6.35/arch/x86/kernel/signal.c#L448
- *
- * / * x86-64 should always use SA_RESTORER. * /
- * if (ka->sa.sa_flags & SA_RESTORER) {
- * put_user_ex(ka->sa.sa_restorer, &frame->pretcode);
- * } else {
- * / * could use a vstub here * /
- * err |= -EFAULT;
- * }
- */
- void restore_rt (void) asm ("__restore_rt");
- #ifndef SA_RESTORER
- #define SA_RESTORER 0x04000000
- #endif
- #define DEFINE_RESTORE_RT(syscall) DEFINE_RESTORE_RT2(syscall)
- # define DEFINE_RESTORE_RT2(syscall) \
- asm ( \
- " nop\n" \
- ".align 16\n" \
- ".LSTART_restore_rt:\n" \
- " .type __restore_rt,@function\n" \
- "__restore_rt:\n" \
- " movq $" #syscall ", %rax\n" \
- " syscall\n");
- DEFINE_RESTORE_RT(__NR_rt_sigreturn)
- #endif
- int set_sighandler (int * sigs, int nsig, void * handler)
- {
- struct sigaction action;
- if (handler) {
- action.sa_handler = (void (*)(int)) handler;
- action.sa_flags = SA_SIGINFO;
- #if !defined(__i386__)
- action.sa_flags |= SA_RESTORER;
- action.sa_restorer = restore_rt;
- #endif
- } else {
- action.sa_handler = SIG_IGN;
- }
- #ifdef DEBUG
- if (!linux_state.in_gdb)
- #endif
- action.sa_flags |= SA_NOCLDWAIT;
- __sigemptyset((__sigset_t *) &action.sa_mask);
- __sigaddset((__sigset_t *) &action.sa_mask, SIGCONT);
- for (int i = 0 ; i < nsig ; i++) {
- #if defined(__i386__)
- int ret = INLINE_SYSCALL(sigaction, 3, sigs[i], &action, NULL)
- #else
- int ret = INLINE_SYSCALL(rt_sigaction, 4, sigs[i], &action, NULL,
- sizeof(sigset_t));
- #endif
- if (IS_ERR(ret))
- return -PAL_ERROR_DENIED;
- }
- return 0;
- }
- typedef struct {
- PAL_IDX event_num;
- PAL_CONTEXT context;
- ucontext_t * uc;
- PAL_PTR eframe;
- } PAL_EVENT;
- #define SIGNAL_MASK_TIME 1000
- #define save_return_point(ptr) \
- asm volatile ("leaq 0(%%rip), %%rax\r\n" \
- "movq %%rax, %0\r\n" \
- : "=b"(ptr) :: "memory", "rax")
- static int get_event_num (int signum)
- {
- switch(signum) {
- case SIGFPE: return PAL_EVENT_DIVZERO;
- case SIGSEGV: case SIGBUS: return PAL_EVENT_MEMFAULT;
- case SIGILL: case SIGSYS: return PAL_EVENT_ILLEGAL;
- case SIGTERM: return PAL_EVENT_QUIT;
- case SIGINT: return PAL_EVENT_SUSPEND;
- case SIGCONT: return PAL_EVENT_RESUME;
- default: return -1;
- }
- }
- void _DkGenericEventTrigger (PAL_IDX event_num, PAL_EVENT_HANDLER upcall,
- PAL_NUM arg, struct pal_frame * frame,
- ucontext_t * uc, void * eframe)
- {
- PAL_EVENT event;
- event.event_num = event_num;
- if (uc)
- memcpy(&event.context, uc->uc_mcontext.gregs, sizeof(PAL_CONTEXT));
- if (frame) {
- event.context.r15 = frame->arch.r15;
- event.context.r14 = frame->arch.r14;
- event.context.r13 = frame->arch.r13;
- event.context.r12 = frame->arch.r12;
- event.context.rdi = frame->arch.rdi;
- event.context.rsi = frame->arch.rsi;
- event.context.rbx = frame->arch.rbx;
- /* find last frame */
- event.context.rsp = frame->arch.rbp + sizeof(unsigned long) * 2;
- event.context.rbp = ((unsigned long *) frame->arch.rbp)[0];
- event.context.rip = ((unsigned long *) frame->arch.rbp)[1];
- /* making rax = 0 to tell the caller that this PAL call failed */
- event.context.rax = 0;
- }
- event.uc = uc;
- event.eframe = eframe;
- (*upcall) ((PAL_PTR) &event, arg, &event.context);
- }
- static bool _DkGenericSignalHandle (int event_num, siginfo_t * info,
- struct pal_frame * frame,
- ucontext_t * uc, void * eframe)
- {
- PAL_EVENT_HANDLER upcall = _DkGetExceptionHandler(event_num);
- if (upcall) {
- PAL_NUM arg = 0;
- if (event_num == PAL_EVENT_DIVZERO ||
- event_num == PAL_EVENT_MEMFAULT ||
- event_num == PAL_EVENT_ILLEGAL)
- arg = (PAL_NUM) (info ? info->si_addr : 0);
- _DkGenericEventTrigger(event_num, upcall, arg, frame, uc, eframe);
- return true;
- }
- return false;
- }
- #define ADDR_IN_PAL(addr) \
- ((void *) (addr) > TEXT_START && (void *) (addr) < TEXT_END)
- static struct pal_frame * get_frame (ucontext_t * uc)
- {
- unsigned long rip = uc->uc_mcontext.gregs[REG_RIP];
- unsigned long rbp = uc->uc_mcontext.gregs[REG_RBP];
- unsigned long last_rbp = rbp - 64;
- if (!ADDR_IN_PAL(rip))
- return NULL;
- while (ADDR_IN_PAL(((unsigned long *) rbp)[1])) {
- last_rbp = rbp;
- rbp = *(unsigned long *) rbp;
- }
- /* search frame record in the top frame of PAL */
- for (unsigned long ptr = rbp - sizeof(unsigned long) ;
- ptr > last_rbp ; ptr -= 8) {
- struct pal_frame * frame = (struct pal_frame *) ptr;
- if (frame->identifier == PAL_FRAME_IDENTIFIER)
- return frame;
- }
- return NULL;
- }
- static void return_frame (struct pal_frame * frame, int err)
- {
- if (err)
- _DkRaiseFailure(err);
- __clear_frame(frame);
- arch_restore_frame(&frame->arch);
- asm volatile ("xor %rax, %rax\r\n"
- "leaveq\r\n"
- "retq\r\n");
- }
- #if BLOCK_SIGFAULT == 1
- static char exception_msg[24] = "--- SIGSEGV --- [ ]\n";
- static volatile bool cont_exec = false;
- #endif
- static void _DkGenericSighandler (int signum, siginfo_t * info,
- struct ucontext * uc)
- {
- #if BLOCK_SIGFUALT == 1
- /* reseurrect this code if signal handler if giving segmentation fault */
- if (signum == SIGSEGV) {
- int pid = INLINE_SYSCALL(getpid, 0);
- exception_msg[17] = '0' + pid / 10000;
- exception_msg[18] = '0' + (pid / 1000) % 10;
- exception_msg[19] = '0' + (pid / 100) % 10;
- exception_msg[20] = '0' + (pid / 10) % 10;
- exception_msg[21] = '0' + pid % 10;
- INLINE_SYSCALL(write, 3, 1, exception_msg, 24);
- while(!cont_exec);
- }
- #endif
- struct pal_frame * frame = get_frame(uc);
- void * eframe;
- if (signum == SIGCONT && frame && frame->func == DkObjectsWaitAny)
- return;
- asm volatile ("movq %%rbp, %0" : "=r"(eframe));
- if (frame && frame->func != &_DkGenericSighandler &&
- signum != SIGCONT &&
- signum != SIGINT &&
- signum != SIGTERM) {
- return_frame(frame, PAL_ERROR_BADADDR);
- return;
- }
- int event_num = get_event_num(signum);
- if (event_num == -1)
- return;
- _DkGenericSignalHandle(event_num, info, frame, uc, eframe);
- }
- static void _DkTerminateSighandler (int signum, siginfo_t * info,
- struct ucontext * uc)
- {
- struct pal_frame * frame = get_frame(uc);
- void * eframe;
- asm volatile ("movq %%rbp, %0" : "=r"(eframe));
- int event_num = get_event_num(signum);
- if (event_num == -1)
- return;
- if (!_DkGenericSignalHandle(event_num, NULL, frame, uc, eframe))
- _DkThreadExit();
- }
- static void _DkPipeSighandler (int signum, siginfo_t * info,
- struct ucontext * uc)
- {
- return;
- }
- 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.uc = NULL;
- event.eframe = NULL;
- (*upcall) ((PAL_PTR) &event, error, NULL);
- }
- struct signal_ops {
- int signum[3];
- void (*handler) (int signum, siginfo_t * info, ucontext_t * uc);
- };
- struct signal_ops on_signals[] = {
- [PAL_EVENT_DIVZERO] = { .signum = { SIGFPE, 0 },
- .handler = _DkGenericSighandler },
- [PAL_EVENT_MEMFAULT] = { .signum = { SIGSEGV, SIGBUS, 0 },
- .handler = _DkGenericSighandler },
- [PAL_EVENT_ILLEGAL] = { .signum = { SIGILL, SIGSYS, 0 },
- .handler = _DkGenericSighandler },
- [PAL_EVENT_QUIT] = { .signum = { SIGTERM, 0, 0 },
- .handler = _DkTerminateSighandler },
- [PAL_EVENT_SUSPEND] = { .signum = { SIGINT, 0 },
- .handler = _DkTerminateSighandler },
- [PAL_EVENT_RESUME] = { .signum = { SIGCONT, 0 },
- .handler = _DkGenericSighandler },
- };
- static int _DkPersistentSighandlerSetup (int event_num)
- {
- int nsigs, * sigs = on_signals[event_num].signum;
- for (nsigs = 0 ; sigs[nsigs] ; nsigs++);
- int ret = set_sighandler(sigs, nsigs, on_signals[event_num].handler);
- if (ret < 0)
- return ret;
- return 0;
- }
- void signal_setup (void)
- {
- int ret, sig = SIGCHLD;
- #ifdef DEBUG
- if (!linux_state.in_gdb)
- #endif
- set_sighandler(&sig, 1, NULL);
- sig = SIGPIPE;
- if ((ret = set_sighandler(&sig, 1, &_DkPipeSighandler)) < 0)
- goto err;
- int events[] = {
- PAL_EVENT_DIVZERO,
- PAL_EVENT_MEMFAULT,
- PAL_EVENT_ILLEGAL,
- PAL_EVENT_QUIT,
- PAL_EVENT_SUSPEND,
- PAL_EVENT_RESUME,
- };
- for (int e = 0 ; e < sizeof(events) / sizeof(events[0]) ; e++)
- if ((ret = _DkPersistentSighandlerSetup(events[e])) < 0)
- goto err;
- return;
- err:
- init_fail(-ret, "cannot setup signal handlers");
- }
- void _DkExceptionReturn (void * event)
- {
- PAL_EVENT * e = event;
- if (e->eframe) {
- struct pal_frame * frame = (struct pal_frame *) e->eframe;
- int err = 0;
- switch (e->event_num) {
- case PAL_EVENT_MEMFAULT:
- err = PAL_ERROR_BADADDR;
- break;
- case PAL_EVENT_QUIT:
- case PAL_EVENT_SUSPEND:
- case PAL_EVENT_RESUME:
- err = PAL_ERROR_INTERRUPTED;
- break;
- }
- if (err)
- _DkRaiseFailure(err);
- __clear_frame(frame);
- }
- if (e->uc) {
- /* copy the context back to ucontext */
- memcpy(e->uc->uc_mcontext.gregs, &e->context, sizeof(PAL_CONTEXT));
- }
- }
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