renegade-project/linux-next
2
0
Fork 0
mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-25 05:34:00 +08:00
Code
40f0933d51
linux-next/arch/x86/kernel/signal_64.c
Roland McGrath 40f0933d51 x86: ia32 syscall restart fix 
The code to restart syscalls after signals depends on checking for a
negative orig_ax, and for particular negative -ERESTART* values in ax.
These fields are 64 bits and for a 32-bit task they get zero-extended.
The syscall restart behavior is lost, a regression from a native 32-bit
kernel and from 64-bit tasks' behavior.

This patch fixes the problem by doing sign-extension where it matters.

For orig_ax, the only time the value should be -1 but winds up as
0x0ffffffff is via a 32-bit ptrace call. So the patch changes ptrace to
sign-extend the 32-bit orig_eax value when it's stored; it doesn't
change the checks on orig_ax, though it uses the new current_syscall()
inline to better document the subtle importance of the used of
signedness there.

The ax value is stored a lot of ways and it seems hard to get them all
sign-extended at their origins. So for that, we use the
current_syscall_ret() to sign-extend it only for 32-bit tasks at the
time of the -ERESTART* comparisons.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-03-11 17:11:54 +01:00

524 lines
14 KiB
C
Raw Blame History

/*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
*
* 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
* 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes
* 2000-2002 x86-64 support by Andi Kleen
*/
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/personality.h>
#include <linux/compiler.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/i387.h>
#include <asm/proto.h>
#include <asm/ia32_unistd.h>
#include <asm/mce.h>
/* #define DEBUG_SIG 1 */
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
sigset_t *set, struct pt_regs * regs);
int ia32_setup_frame(int sig, struct k_sigaction *ka,
sigset_t *set, struct pt_regs * regs);
asmlinkage long
sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
struct pt_regs *regs)
{
return do_sigaltstack(uss, uoss, regs->sp);
}
/*
* Do a signal return; undo the signal stack.
*/
struct rt_sigframe
{
char __user *pretcode;
struct ucontext uc;
struct siginfo info;
};
static int
restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, unsigned long *prax)
{
unsigned int err = 0;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
#define COPY(x) err |= __get_user(regs->x, &sc->x)
COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
COPY(dx); COPY(cx); COPY(ip);
COPY(r8);
COPY(r9);
COPY(r10);
COPY(r11);
COPY(r12);
COPY(r13);
COPY(r14);
COPY(r15);
/* Kernel saves and restores only the CS segment register on signals,
* which is the bare minimum needed to allow mixed 32/64-bit code.
* App's signal handler can save/restore other segments if needed. */
{
unsigned cs;
err |= __get_user(cs, &sc->cs);
regs->cs = cs | 3; /* Force into user mode */
}
{
unsigned int tmpflags;
err |= __get_user(tmpflags, &sc->flags);
regs->flags = (regs->flags & ~0x40DD5) | (tmpflags & 0x40DD5);
regs->orig_ax = -1; /* disable syscall checks */
}
{
struct _fpstate __user * buf;
err |= __get_user(buf, &sc->fpstate);
if (buf) {
if (!access_ok(VERIFY_READ, buf, sizeof(*buf)))
goto badframe;
err |= restore_i387(buf);
} else {
struct task_struct *me = current;
if (used_math()) {
clear_fpu(me);
clear_used_math();
}
}
}
err |= __get_user(*prax, &sc->ax);
return err;
badframe:
return 1;
}
asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
{
struct rt_sigframe __user *frame;
sigset_t set;
unsigned long ax;
frame = (struct rt_sigframe __user *)(regs->sp - 8);
if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) {
goto badframe;
}
if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) {
goto badframe;
}
sigdelsetmask(&set, ~_BLOCKABLE);
spin_lock_irq(&current->sighand->siglock);
current->blocked = set;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
goto badframe;
#ifdef DEBUG_SIG
printk("%d sigreturn ip:%lx sp:%lx frame:%p ax:%lx\n",current->pid,regs->ip,regs->sp,frame,ax);
#endif
if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
goto badframe;
return ax;
badframe:
signal_fault(regs,frame,"sigreturn");
return 0;
}
/*
* Set up a signal frame.
*/
static inline int
setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, unsigned long mask, struct task_struct *me)
{
int err = 0;
err |= __put_user(regs->cs, &sc->cs);
err |= __put_user(0, &sc->gs);
err |= __put_user(0, &sc->fs);
err |= __put_user(regs->di, &sc->di);
err |= __put_user(regs->si, &sc->si);
err |= __put_user(regs->bp, &sc->bp);
err |= __put_user(regs->sp, &sc->sp);
err |= __put_user(regs->bx, &sc->bx);
err |= __put_user(regs->dx, &sc->dx);
err |= __put_user(regs->cx, &sc->cx);
err |= __put_user(regs->ax, &sc->ax);
err |= __put_user(regs->r8, &sc->r8);
err |= __put_user(regs->r9, &sc->r9);
err |= __put_user(regs->r10, &sc->r10);
err |= __put_user(regs->r11, &sc->r11);
err |= __put_user(regs->r12, &sc->r12);
err |= __put_user(regs->r13, &sc->r13);
err |= __put_user(regs->r14, &sc->r14);
err |= __put_user(regs->r15, &sc->r15);
err |= __put_user(me->thread.trap_no, &sc->trapno);
err |= __put_user(me->thread.error_code, &sc->err);
err |= __put_user(regs->ip, &sc->ip);
err |= __put_user(regs->flags, &sc->flags);
err |= __put_user(mask, &sc->oldmask);
err |= __put_user(me->thread.cr2, &sc->cr2);
return err;
}
/*
* Determine which stack to use..
*/
static void __user *
get_stack(struct k_sigaction *ka, struct pt_regs *regs, unsigned long size)
{
unsigned long sp;
/* Default to using normal stack - redzone*/
sp = regs->sp - 128;
/* This is the X/Open sanctioned signal stack switching. */
if (ka->sa.sa_flags & SA_ONSTACK) {
if (sas_ss_flags(sp) == 0)
sp = current->sas_ss_sp + current->sas_ss_size;
}
return (void __user *)round_down(sp - size, 16);
}
static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
sigset_t *set, struct pt_regs * regs)
{
struct rt_sigframe __user *frame;
struct _fpstate __user *fp = NULL;
int err = 0;
struct task_struct *me = current;
if (used_math()) {
fp = get_stack(ka, regs, sizeof(struct _fpstate));
frame = (void __user *)round_down(
(unsigned long)fp - sizeof(struct rt_sigframe), 16) - 8;
if (!access_ok(VERIFY_WRITE, fp, sizeof(struct _fpstate)))
goto give_sigsegv;
if (save_i387(fp) < 0)
err |= -1;
} else
frame = get_stack(ka, regs, sizeof(struct rt_sigframe)) - 8;
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
goto give_sigsegv;
if (ka->sa.sa_flags & SA_SIGINFO) {
err |= copy_siginfo_to_user(&frame->info, info);
if (err)
goto give_sigsegv;
}
/* Create the ucontext. */
err |= __put_user(0, &frame->uc.uc_flags);
err |= __put_user(0, &frame->uc.uc_link);
err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
err |= __put_user(sas_ss_flags(regs->sp),
&frame->uc.uc_stack.ss_flags);
err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0], me);
err |= __put_user(fp, &frame->uc.uc_mcontext.fpstate);
if (sizeof(*set) == 16) {
__put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]);
__put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]);
} else
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
/* x86-64 should always use SA_RESTORER. */
if (ka->sa.sa_flags & SA_RESTORER) {
err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);
} else {
/* could use a vstub here */
goto give_sigsegv;
}
if (err)
goto give_sigsegv;
#ifdef DEBUG_SIG
printk("%d old ip %lx old sp %lx old ax %lx\n", current->pid,regs->ip,regs->sp,regs->ax);
#endif
/* Set up registers for signal handler */
regs->di = sig;
/* In case the signal handler was declared without prototypes */
regs->ax = 0;
/* This also works for non SA_SIGINFO handlers because they expect the
next argument after the signal number on the stack. */
regs->si = (unsigned long)&frame->info;
regs->dx = (unsigned long)&frame->uc;
regs->ip = (unsigned long) ka->sa.sa_handler;
regs->sp = (unsigned long)frame;
/* Set up the CS register to run signal handlers in 64-bit mode,
even if the handler happens to be interrupting 32-bit code. */
regs->cs = __USER_CS;
/* This, by contrast, has nothing to do with segment registers -
see include/asm-x86_64/uaccess.h for details. */
set_fs(USER_DS);
regs->flags &= ~(X86_EFLAGS_TF | X86_EFLAGS_DF);
if (test_thread_flag(TIF_SINGLESTEP))
ptrace_notify(SIGTRAP);
#ifdef DEBUG_SIG
printk("SIG deliver (%s:%d): sp=%p pc=%lx ra=%p\n",
current->comm, current->pid, frame, regs->ip, frame->pretcode);
#endif
return 0;
give_sigsegv:
force_sigsegv(sig, current);
return -EFAULT;
}
/*
* Return -1L or the syscall number that @regs is executing.
*/
static long current_syscall(struct pt_regs *regs)
{
/*
* We always sign-extend a -1 value being set here,
* so this is always either -1L or a syscall number.
*/
return regs->orig_ax;
}
/*
* Return a value that is -EFOO if the system call in @regs->orig_ax
* returned an error. This only works for @regs from @current.
*/
static long current_syscall_ret(struct pt_regs *regs)
{
#ifdef CONFIG_IA32_EMULATION
if (test_thread_flag(TIF_IA32))
/*
* Sign-extend the value so (int)-EFOO becomes (long)-EFOO
* and will match correctly in comparisons.
*/
return (int) regs->ax;
#endif
return regs->ax;
}
/*
* OK, we're invoking a handler
*/
static int
handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
sigset_t *oldset, struct pt_regs *regs)
{
int ret;
#ifdef DEBUG_SIG
printk("handle_signal pid:%d sig:%lu ip:%lx sp:%lx regs=%p\n",
current->pid, sig,
regs->ip, regs->sp, regs);
#endif
/* Are we from a system call? */
if (current_syscall(regs) >= 0) {
/* If so, check system call restarting.. */
switch (current_syscall_ret(regs)) {
case -ERESTART_RESTARTBLOCK:
case -ERESTARTNOHAND:
regs->ax = -EINTR;
break;
case -ERESTARTSYS:
if (!(ka->sa.sa_flags & SA_RESTART)) {
regs->ax = -EINTR;
break;
}
/* fallthrough */
case -ERESTARTNOINTR:
regs->ax = regs->orig_ax;
regs->ip -= 2;
break;
}
}
/*
* If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
* flag so that register information in the sigcontext is correct.
*/
if (unlikely(regs->flags & X86_EFLAGS_TF) &&
likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
regs->flags &= ~X86_EFLAGS_TF;
#ifdef CONFIG_IA32_EMULATION
if (test_thread_flag(TIF_IA32)) {
if (ka->sa.sa_flags & SA_SIGINFO)
ret = ia32_setup_rt_frame(sig, ka, info, oldset, regs);
else
ret = ia32_setup_frame(sig, ka, oldset, regs);
} else
#endif
ret = setup_rt_frame(sig, ka, info, oldset, regs);
if (ret == 0) {
spin_lock_irq(&current->sighand->siglock);
sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
if (!(ka->sa.sa_flags & SA_NODEFER))
sigaddset(&current->blocked,sig);
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
}
return ret;
}
/*
* Note that 'init' is a special process: it doesn't get signals it doesn't
* want to handle. Thus you cannot kill init even with a SIGKILL even by
* mistake.
*/
static void do_signal(struct pt_regs *regs)
{
struct k_sigaction ka;
siginfo_t info;
int signr;
sigset_t *oldset;
/*
* We want the common case to go fast, which
* is why we may in certain cases get here from
* kernel mode. Just return without doing anything
* if so.
*/
if (!user_mode(regs))
return;
if (test_thread_flag(TIF_RESTORE_SIGMASK))
oldset = &current->saved_sigmask;
else
oldset = &current->blocked;
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
if (signr > 0) {
/* Re-enable any watchpoints before delivering the
* signal to user space. The processor register will
* have been cleared if the watchpoint triggered
* inside the kernel.
*/
if (current->thread.debugreg7)
set_debugreg(current->thread.debugreg7, 7);
/* Whee! Actually deliver the signal. */
if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
/* a signal was successfully delivered; the saved
* sigmask will have been stored in the signal frame,
* and will be restored by sigreturn, so we can simply
* clear the TIF_RESTORE_SIGMASK flag */
clear_thread_flag(TIF_RESTORE_SIGMASK);
}
return;
}
/* Did we come from a system call? */
if (current_syscall(regs) >= 0) {
/* Restart the system call - no handlers present */
switch (current_syscall_ret(regs)) {
case -ERESTARTNOHAND:
case -ERESTARTSYS:
case -ERESTARTNOINTR:
regs->ax = regs->orig_ax;
regs->ip -= 2;
break;
case -ERESTART_RESTARTBLOCK:
regs->ax = test_thread_flag(TIF_IA32) ?
__NR_ia32_restart_syscall :
__NR_restart_syscall;
regs->ip -= 2;
break;
}
}
/* if there's no signal to deliver, we just put the saved sigmask
back. */
if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
clear_thread_flag(TIF_RESTORE_SIGMASK);
sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
}
}
void
do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
{
#ifdef DEBUG_SIG
printk("do_notify_resume flags:%x ip:%lx sp:%lx caller:%p pending:%x\n",
thread_info_flags, regs->ip, regs->sp, __builtin_return_address(0),signal_pending(current));
#endif
/* Pending single-step? */
if (thread_info_flags & _TIF_SINGLESTEP) {
regs->flags |= X86_EFLAGS_TF;
clear_thread_flag(TIF_SINGLESTEP);
}
#ifdef CONFIG_X86_MCE
/* notify userspace of pending MCEs */
if (thread_info_flags & _TIF_MCE_NOTIFY)
mce_notify_user();
#endif /* CONFIG_X86_MCE */
/* deal with pending signal delivery */
if (thread_info_flags & (_TIF_SIGPENDING|_TIF_RESTORE_SIGMASK))
do_signal(regs);
if (thread_info_flags & _TIF_HRTICK_RESCHED)
hrtick_resched();
}
void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
{
struct task_struct *me = current;
if (show_unhandled_signals && printk_ratelimit()) {
printk("%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
me->comm,me->pid,where,frame,regs->ip,regs->sp,regs->orig_ax);
print_vma_addr(" in ", regs->ip);
printk("\n");
}
force_sig(SIGSEGV, me);
}
View Git Blame Copy Permalink