/* -*- 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 OSCAR lab, 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 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see . */
/*
* 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 "linux_list.h"
#include
#include
#include
#include
#include
#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 (__sigismember(&linux_state.set_signals, sigs[i]))
continue;
#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;
__sigaddset(&linux_state.set_signals, sigs[i]);
}
bool maskset = false;
int ret = 0;
__sigset_t mask;
__sigemptyset(&mask);
for (int i = 0 ; i < nsig ; i++)
if (__sigismember(&linux_state.blocked_signals, sigs[i])) {
__sigdelset(&linux_state.blocked_signals, sigs[i]);
__sigaddset(&mask, sigs[i]);
maskset = true;
}
if (maskset) {
#if defined(__i386__)
ret = INLINE_SYSCALL(sigprocmask, 3, SIG_UNBLOCK, &mask, NULL)
#else
ret = INLINE_SYSCALL(rt_sigprocmask, 4, SIG_UNBLOCK, &mask, NULL,
sizeof(sigset_t));
#endif
}
if (IS_ERR(ret))
return -PAL_ERROR_DENIED;
return 0;
}
int block_signals (int * sigs, int nsig)
{
bool maskset = false;
int ret = 0;
__sigset_t mask;
__sigemptyset(&mask);
for (int i = 0 ; i < nsig ; i++)
if (!__sigismember(&linux_state.blocked_signals, sigs[i])) {
__sigaddset(&linux_state.blocked_signals, sigs[i]);
__sigaddset(&mask, sigs[i]);
maskset = true;
}
if (maskset) {
#if defined(__i386__)
ret = INLINE_SYSCALL(sigprocmask, 3, SIG_BLOCK, &mask, NULL)
#else
ret = INLINE_SYSCALL(rt_sigprocmask, 4, SIG_BLOCK, &mask, NULL,
sizeof(sigset_t));
#endif
}
if (IS_ERR(ret))
return -PAL_ERROR_DENIED;
return 0;
}
int unblock_signals (int * sigs, int nsig)
{
bool maskset = false;
int ret = 0;
__sigset_t mask;
__sigemptyset(&mask);
for (int i = 0 ; i < nsig ; i++)
if (__sigismember(&linux_state.blocked_signals, sigs[i])) {
__sigdelset(&linux_state.blocked_signals, sigs[i]);
__sigaddset(&mask, sigs[i]);
maskset = true;
}
if (maskset) {
#if defined(__i386__)
ret = INLINE_SYSCALL(sigprocmask, 3, SIG_UNBLOCK, &mask, NULL)
#else
ret = INLINE_SYSCALL(rt_sigprocmask, 4, SIG_UNBLOCK, &mask, NULL,
sizeof(sigset_t));
#endif
}
if (IS_ERR(ret))
return -PAL_ERROR_DENIED;
return 0;
}
struct exception_handler {
struct mutex_handle lock;
int flags;
PAL_UPCALL upcall;
} __attribute__((aligned(sizeof(int))));
struct exception_event {
int event_num;
int flags;
PAL_CONTEXT context;
ucontext_t * uc;
void * eframe;
};
#define DECLARE_HANDLER_HEAD(event) \
static struct exception_handler handler_##event = \
{ .lock = MUTEX_HANDLE_INIT, \
.upcall = NULL, \
.flags = 0, };
DECLARE_HANDLER_HEAD(DivZero);
DECLARE_HANDLER_HEAD(MemFault);
DECLARE_HANDLER_HEAD(Illegal);
DECLARE_HANDLER_HEAD(Quit);
DECLARE_HANDLER_HEAD(Suspend);
DECLARE_HANDLER_HEAD(Resume);
DECLARE_HANDLER_HEAD(Failure);
struct exception_handler * pal_handlers [PAL_EVENT_NUM_BOUND] = {
NULL, /* reserved */
&handler_DivZero,
&handler_MemFault,
&handler_Illegal,
&handler_Quit,
&handler_Suspend,
&handler_Resume,
&handler_Failure,
};
#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: 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 (int event_num, PAL_UPCALL upcall,
int flags, PAL_NUM arg, struct pal_frame * frame,
ucontext_t * uc, void * eframe)
{
struct exception_event event;
event.event_num = event_num;
event.flags = flags;
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];
}
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)
{
struct exception_handler * handler = pal_handlers[event_num];
_DkMutexLock(&handler->lock);
PAL_UPCALL upcall = handler->upcall;
int flags = handler->flags;
_DkMutexUnlock(&handler->lock);
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, flags, 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 - 1024;
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->self == frame)
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" ::: "memory");
}
static void _DkGenericSighandler (int signum, siginfo_t * info,
struct ucontext * uc)
{
#if 0
/* reseurrect this code if signal handler if giving segmentation fault */
if (signum == SIGSEGV) {
int pid = INLINE_SYSCALL(getpid, 0);
char msg[24] = "--- SIGSEGV --- [ ]\n";
msg[17] = '0' + pid / 10000;
msg[18] = '0' + (pid / 1000) % 10;
msg[19] = '0' + (pid / 100) % 10;
msg[20] = '0' + (pid / 10) % 10;
msg[21] = '0' + pid % 10;
INLINE_SYSCALL(write, 3, 1, msg, 24);
}
#endif
struct pal_frame * frame = get_frame(uc);
void * eframe;
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)
{
_DkMutexLock(&handler_Failure.lock);
PAL_UPCALL upcall = handler_Failure.upcall;
int flags = handler_Failure.flags;
_DkMutexUnlock(&handler_Failure.lock);
if (upcall)
_DkGenericEventTrigger(PAL_EVENT_FAILURE, upcall, flags, error,
NULL, NULL, NULL);
}
struct signal_ops {
int signum[3];
void (*handler) (int signum, siginfo_t * info, ucontext_t * uc);
};
struct signal_ops on_signals[PAL_EVENT_NUM_BOUND] = {
/* reserved */ { .signum = { 0 }, .handler = NULL },
/* DivZero */ { .signum = { SIGFPE, 0 },
.handler = _DkGenericSighandler },
/* MemFault */ { .signum = { SIGSEGV, SIGBUS, 0 },
.handler = _DkGenericSighandler },
/* Illegal */ { .signum = { SIGILL, 0 },
.handler = _DkGenericSighandler },
/* Quit */ { .signum = { SIGTERM, 0, 0 },
.handler = _DkTerminateSighandler },
/* Suspend */ { .signum = { SIGINT, 0 },
.handler = _DkTerminateSighandler },
/* Resume */ { .signum = { SIGCONT, 0 },
.handler = _DkGenericSighandler },
/* Failure */ { .signum = { 0 }, .handler = NULL },
};
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;
}
static int _DkPersistentEventUpcall (int event_num, PAL_UPCALL upcall,
int flags)
{
struct exception_handler * handler = pal_handlers[event_num];
_DkMutexLock(&handler->lock);
handler->upcall = upcall;
handler->flags = flags;
_DkMutexUnlock(&handler->lock);
return _DkPersistentSighandlerSetup(event_num);
}
static int _DkGenericEventUpcall (int event_num, PAL_UPCALL upcall,
int flags)
{
int nsigs, * sigs = on_signals[event_num].signum;
for (nsigs = 0 ; sigs[nsigs] ; nsigs++);
struct exception_handler * handler = pal_handlers[event_num];
int ret = 0;
_DkMutexLock(&handler->lock);
handler->upcall = upcall;
handler->flags = flags;
_DkMutexUnlock(&handler->lock);
if (upcall)
ret = set_sighandler(sigs, nsigs, on_signals[event_num].handler);
else
ret = block_signals(sigs, nsigs);
return ret;
}
static int _DkDummyEventUpcall (int event_num, PAL_UPCALL upcall,
int flags)
{
struct exception_handler * handler = pal_handlers[event_num];
_DkMutexLock(&handler->lock);
handler->upcall = upcall;
handler->flags = flags;
_DkMutexUnlock(&handler->lock);
return 0;
}
typedef void (*PAL_UPCALL) (PAL_PTR, PAL_NUM, PAL_CONTEXT *);
int (*_DkExceptionHandlers[PAL_EVENT_NUM_BOUND])
(int, PAL_UPCALL, int) = {
/* reserved */ NULL,
/* DivZero */ &_DkPersistentEventUpcall,
/* MemFault */ &_DkPersistentEventUpcall,
/* Illegal */ &_DkPersistentEventUpcall,
/* Quit */ &_DkGenericEventUpcall,
/* Suspend */ &_DkGenericEventUpcall,
/* Resume */ &_DkGenericEventUpcall,
/* Failure */ &_DkDummyEventUpcall,
};
static void _DkCompatibilitySighandler (int signum, siginfo_t * info,
ucontext_t * uc)
{
unsigned long args[6] = { uc->uc_mcontext.gregs[REG_RDI],
uc->uc_mcontext.gregs[REG_RSI],
uc->uc_mcontext.gregs[REG_RDX],
uc->uc_mcontext.gregs[REG_R10],
uc->uc_mcontext.gregs[REG_R8],
uc->uc_mcontext.gregs[REG_R9] };
uc->uc_mcontext.gregs[REG_RAX] =
_DkHandleCompatibilityException(uc->uc_mcontext.gregs[REG_RAX], args);
}
void signal_setup (void)
{
int ret, sig = SIGCHLD;
#ifdef DEBUG
if (!linux_state.in_gdb)
#endif
set_sighandler(&sig, 1, NULL);
if ((ret = _DkPersistentEventUpcall(PAL_EVENT_DIVZERO, NULL, 0)) < 0)
goto err;
if ((ret = _DkPersistentEventUpcall(PAL_EVENT_MEMFAULT, NULL, 0)) < 0)
goto err;
if ((ret = _DkPersistentEventUpcall(PAL_EVENT_ILLEGAL, NULL, 0)) < 0)
goto err;
sig = SIGPIPE;
if ((ret = set_sighandler(&sig, 1, &_DkPipeSighandler)) < 0)
goto err;
sig = SIGSYS;
if ((ret = set_sighandler(&sig, 1, &_DkCompatibilitySighandler)) < 0)
goto err;
return;
err:
init_fail(-ret, "cannot setup signal handlers");
}
void _DkExceptionReturn (void * event)
{
struct exception_event * e = (struct exception_event *) 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);
e->context.rax = 0;
}
if (e->uc) {
/* copy the context back to ucontext */
memcpy(e->uc->uc_mcontext.gregs, &e->context, sizeof(PAL_CONTEXT));
/* return to the frame of exception handler */
asm volatile ("movq %0, %%rbp\r\n"
"leaveq\r\n"
"retq\r\n" :: "r"(e->eframe) : "memory");
}
}