linux/arch/x86/kernel/signal_64.c
Andi Kleen 03252919b7 x86: print which shared library/executable faulted in segfault etc. messages v3
They now look like:

hal-resmgr[13791]: segfault at 3c rip 2b9c8caec182 rsp 7fff1e825d30 error 4 in libacl.so.1.1.0[2b9c8caea000+6000]

This makes it easier to pinpoint bugs to specific libraries.

And printing the offset into a mapping also always allows to find the
correct fault point in a library even with randomized mappings. Previously
there was no way to actually find the correct code address inside
the randomized mapping.

Relies on earlier patch to shorten the printk formats.

They are often now longer than 80 characters, but I think that's worth it.

[includes fix from Eric Dumazet to check d_path error value]

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:33:18 +01:00

495 lines
13 KiB
C

/*
* 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;
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;
}
/*
* 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 ((long)regs->orig_ax >= 0) {
/* If so, check system call restarting.. */
switch (regs->ax) {
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 ((long)regs->orig_ax >= 0) {
/* Restart the system call - no handlers present */
long res = regs->ax;
switch (res) {
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);
}