kernel-ark/arch/arm/kernel/signal.c
Hugh Dickins 69b0475456 [PATCH] mm: arm ready for split ptlock
Prepare arm for the split page_table_lock: three issues.

Signal handling's preserve and restore of iwmmxt context currently involves
reading and writing that context to and from user space, while holding
page_table_lock to secure the user page(s) against kswapd.  If we split the
lock, then the structure might span two pages, secured by to read into and
write from a kernel stack buffer, copying that out and in without locking (the
structure is 160 bytes in size, and here we're near the top of the kernel
stack).  Or would the overhead be noticeable?

arm_syscall's cmpxchg emulation use pte_offset_map_lock, instead of
pte_offset_map and mm-wide page_table_lock; and strictly, it should now also
take mmap_sem before descending to pmd, to guard against another thread
munmapping, and the page table pulled out beneath this thread.

Updated two comments in fault-armv.c.  adjust_pte is interesting, since its
modification of a pte in one part of the mm depends on the lock held when
calling update_mmu_cache for a pte in some other part of that mm.  This can't
be done with a split page_table_lock (and we've already taken the lowest lock
in the hierarchy here): so we'll have to disable split on arm, unless
CONFIG_CPU_CACHE_VIPT to ensures adjust_pte never used.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 21:40:42 -07:00

699 lines
18 KiB
C

/*
* linux/arch/arm/kernel/signal.c
*
* Copyright (C) 1995-2002 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/config.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/ptrace.h>
#include <linux/personality.h>
#include <asm/cacheflush.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
#include "ptrace.h"
#include "signal.h"
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
/*
* For ARM syscalls, we encode the syscall number into the instruction.
*/
#define SWI_SYS_SIGRETURN (0xef000000|(__NR_sigreturn))
#define SWI_SYS_RT_SIGRETURN (0xef000000|(__NR_rt_sigreturn))
/*
* For Thumb syscalls, we pass the syscall number via r7. We therefore
* need two 16-bit instructions.
*/
#define SWI_THUMB_SIGRETURN (0xdf00 << 16 | 0x2700 | (__NR_sigreturn - __NR_SYSCALL_BASE))
#define SWI_THUMB_RT_SIGRETURN (0xdf00 << 16 | 0x2700 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))
const unsigned long sigreturn_codes[4] = {
SWI_SYS_SIGRETURN, SWI_THUMB_SIGRETURN,
SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN
};
static int do_signal(sigset_t *oldset, struct pt_regs * regs, int syscall);
/*
* atomically swap in the new signal mask, and wait for a signal.
*/
asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask, struct pt_regs *regs)
{
sigset_t saveset;
mask &= _BLOCKABLE;
spin_lock_irq(&current->sighand->siglock);
saveset = current->blocked;
siginitset(&current->blocked, mask);
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
regs->ARM_r0 = -EINTR;
while (1) {
current->state = TASK_INTERRUPTIBLE;
schedule();
if (do_signal(&saveset, regs, 0))
return regs->ARM_r0;
}
}
asmlinkage int
sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize, struct pt_regs *regs)
{
sigset_t saveset, newset;
/* XXX: Don't preclude handling different sized sigset_t's. */
if (sigsetsize != sizeof(sigset_t))
return -EINVAL;
if (copy_from_user(&newset, unewset, sizeof(newset)))
return -EFAULT;
sigdelsetmask(&newset, ~_BLOCKABLE);
spin_lock_irq(&current->sighand->siglock);
saveset = current->blocked;
current->blocked = newset;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
regs->ARM_r0 = -EINTR;
while (1) {
current->state = TASK_INTERRUPTIBLE;
schedule();
if (do_signal(&saveset, regs, 0))
return regs->ARM_r0;
}
}
asmlinkage int
sys_sigaction(int sig, const struct old_sigaction __user *act,
struct old_sigaction __user *oact)
{
struct k_sigaction new_ka, old_ka;
int ret;
if (act) {
old_sigset_t mask;
if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
__get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
__get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
return -EFAULT;
__get_user(new_ka.sa.sa_flags, &act->sa_flags);
__get_user(mask, &act->sa_mask);
siginitset(&new_ka.sa.sa_mask, mask);
}
ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
if (!ret && oact) {
if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
__put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
__put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
return -EFAULT;
__put_user(old_ka.sa.sa_flags, &oact->sa_flags);
__put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
}
return ret;
}
#ifdef CONFIG_IWMMXT
/* iwmmxt_area is 0x98 bytes long, preceeded by 8 bytes of signature */
#define IWMMXT_STORAGE_SIZE (0x98 + 8)
#define IWMMXT_MAGIC0 0x12ef842a
#define IWMMXT_MAGIC1 0x1c07ca71
struct iwmmxt_sigframe {
unsigned long magic0;
unsigned long magic1;
unsigned long storage[0x98/4];
};
static int preserve_iwmmxt_context(struct iwmmxt_sigframe *frame)
{
char kbuf[sizeof(*frame) + 8];
struct iwmmxt_sigframe *kframe;
/* the iWMMXt context must be 64 bit aligned */
kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
kframe->magic0 = IWMMXT_MAGIC0;
kframe->magic1 = IWMMXT_MAGIC1;
iwmmxt_task_copy(current_thread_info(), &kframe->storage);
return __copy_to_user(frame, kframe, sizeof(*frame));
}
static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame)
{
char kbuf[sizeof(*frame) + 8];
struct iwmmxt_sigframe *kframe;
/* the iWMMXt context must be 64 bit aligned */
kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
if (__copy_from_user(kframe, frame, sizeof(*frame)))
return -1;
if (kframe->magic0 != IWMMXT_MAGIC0 ||
kframe->magic1 != IWMMXT_MAGIC1)
return -1;
iwmmxt_task_restore(current_thread_info(), &kframe->storage);
return 0;
}
#endif
/*
* Auxiliary signal frame. This saves stuff like FP state.
* The layout of this structure is not part of the user ABI.
*/
struct aux_sigframe {
#ifdef CONFIG_IWMMXT
struct iwmmxt_sigframe iwmmxt;
#endif
#ifdef CONFIG_VFP
union vfp_state vfp;
#endif
};
/*
* Do a signal return; undo the signal stack. These are aligned to 64-bit.
*/
struct sigframe {
struct sigcontext sc;
unsigned long extramask[_NSIG_WORDS-1];
unsigned long retcode;
struct aux_sigframe aux __attribute__((aligned(8)));
};
struct rt_sigframe {
struct siginfo __user *pinfo;
void __user *puc;
struct siginfo info;
struct ucontext uc;
unsigned long retcode;
struct aux_sigframe aux __attribute__((aligned(8)));
};
static int
restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
struct aux_sigframe __user *aux)
{
int err = 0;
__get_user_error(regs->ARM_r0, &sc->arm_r0, err);
__get_user_error(regs->ARM_r1, &sc->arm_r1, err);
__get_user_error(regs->ARM_r2, &sc->arm_r2, err);
__get_user_error(regs->ARM_r3, &sc->arm_r3, err);
__get_user_error(regs->ARM_r4, &sc->arm_r4, err);
__get_user_error(regs->ARM_r5, &sc->arm_r5, err);
__get_user_error(regs->ARM_r6, &sc->arm_r6, err);
__get_user_error(regs->ARM_r7, &sc->arm_r7, err);
__get_user_error(regs->ARM_r8, &sc->arm_r8, err);
__get_user_error(regs->ARM_r9, &sc->arm_r9, err);
__get_user_error(regs->ARM_r10, &sc->arm_r10, err);
__get_user_error(regs->ARM_fp, &sc->arm_fp, err);
__get_user_error(regs->ARM_ip, &sc->arm_ip, err);
__get_user_error(regs->ARM_sp, &sc->arm_sp, err);
__get_user_error(regs->ARM_lr, &sc->arm_lr, err);
__get_user_error(regs->ARM_pc, &sc->arm_pc, err);
__get_user_error(regs->ARM_cpsr, &sc->arm_cpsr, err);
err |= !valid_user_regs(regs);
#ifdef CONFIG_IWMMXT
if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
err |= restore_iwmmxt_context(&aux->iwmmxt);
#endif
#ifdef CONFIG_VFP
// if (err == 0)
// err |= vfp_restore_state(&aux->vfp);
#endif
return err;
}
asmlinkage int sys_sigreturn(struct pt_regs *regs)
{
struct sigframe __user *frame;
sigset_t set;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
/*
* Since we stacked the signal on a 64-bit boundary,
* then 'sp' should be word aligned here. If it's
* not, then the user is trying to mess with us.
*/
if (regs->ARM_sp & 7)
goto badframe;
frame = (struct sigframe __user *)regs->ARM_sp;
if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
goto badframe;
if (__get_user(set.sig[0], &frame->sc.oldmask)
|| (_NSIG_WORDS > 1
&& __copy_from_user(&set.sig[1], &frame->extramask,
sizeof(frame->extramask))))
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->sc, &frame->aux))
goto badframe;
/* Send SIGTRAP if we're single-stepping */
if (current->ptrace & PT_SINGLESTEP) {
ptrace_cancel_bpt(current);
send_sig(SIGTRAP, current, 1);
}
return regs->ARM_r0;
badframe:
force_sig(SIGSEGV, current);
return 0;
}
asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
{
struct rt_sigframe __user *frame;
sigset_t set;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
/*
* Since we stacked the signal on a 64-bit boundary,
* then 'sp' should be word aligned here. If it's
* not, then the user is trying to mess with us.
*/
if (regs->ARM_sp & 7)
goto badframe;
frame = (struct rt_sigframe __user *)regs->ARM_sp;
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, &frame->aux))
goto badframe;
if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->ARM_sp) == -EFAULT)
goto badframe;
/* Send SIGTRAP if we're single-stepping */
if (current->ptrace & PT_SINGLESTEP) {
ptrace_cancel_bpt(current);
send_sig(SIGTRAP, current, 1);
}
return regs->ARM_r0;
badframe:
force_sig(SIGSEGV, current);
return 0;
}
static int
setup_sigcontext(struct sigcontext __user *sc, struct aux_sigframe __user *aux,
struct pt_regs *regs, unsigned long mask)
{
int err = 0;
__put_user_error(regs->ARM_r0, &sc->arm_r0, err);
__put_user_error(regs->ARM_r1, &sc->arm_r1, err);
__put_user_error(regs->ARM_r2, &sc->arm_r2, err);
__put_user_error(regs->ARM_r3, &sc->arm_r3, err);
__put_user_error(regs->ARM_r4, &sc->arm_r4, err);
__put_user_error(regs->ARM_r5, &sc->arm_r5, err);
__put_user_error(regs->ARM_r6, &sc->arm_r6, err);
__put_user_error(regs->ARM_r7, &sc->arm_r7, err);
__put_user_error(regs->ARM_r8, &sc->arm_r8, err);
__put_user_error(regs->ARM_r9, &sc->arm_r9, err);
__put_user_error(regs->ARM_r10, &sc->arm_r10, err);
__put_user_error(regs->ARM_fp, &sc->arm_fp, err);
__put_user_error(regs->ARM_ip, &sc->arm_ip, err);
__put_user_error(regs->ARM_sp, &sc->arm_sp, err);
__put_user_error(regs->ARM_lr, &sc->arm_lr, err);
__put_user_error(regs->ARM_pc, &sc->arm_pc, err);
__put_user_error(regs->ARM_cpsr, &sc->arm_cpsr, err);
__put_user_error(current->thread.trap_no, &sc->trap_no, err);
__put_user_error(current->thread.error_code, &sc->error_code, err);
__put_user_error(current->thread.address, &sc->fault_address, err);
__put_user_error(mask, &sc->oldmask, err);
#ifdef CONFIG_IWMMXT
if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
err |= preserve_iwmmxt_context(&aux->iwmmxt);
#endif
#ifdef CONFIG_VFP
// if (err == 0)
// err |= vfp_save_state(&aux->vfp);
#endif
return err;
}
static inline void __user *
get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
{
unsigned long sp = regs->ARM_sp;
void __user *frame;
/*
* This is the X/Open sanctioned signal stack switching.
*/
if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
sp = current->sas_ss_sp + current->sas_ss_size;
/*
* ATPCS B01 mandates 8-byte alignment
*/
frame = (void __user *)((sp - framesize) & ~7);
/*
* Check that we can actually write to the signal frame.
*/
if (!access_ok(VERIFY_WRITE, frame, framesize))
frame = NULL;
return frame;
}
static int
setup_return(struct pt_regs *regs, struct k_sigaction *ka,
unsigned long __user *rc, void __user *frame, int usig)
{
unsigned long handler = (unsigned long)ka->sa.sa_handler;
unsigned long retcode;
int thumb = 0;
unsigned long cpsr = regs->ARM_cpsr & ~PSR_f;
/*
* Maybe we need to deliver a 32-bit signal to a 26-bit task.
*/
if (ka->sa.sa_flags & SA_THIRTYTWO)
cpsr = (cpsr & ~MODE_MASK) | USR_MODE;
#ifdef CONFIG_ARM_THUMB
if (elf_hwcap & HWCAP_THUMB) {
/*
* The LSB of the handler determines if we're going to
* be using THUMB or ARM mode for this signal handler.
*/
thumb = handler & 1;
if (thumb)
cpsr |= PSR_T_BIT;
else
cpsr &= ~PSR_T_BIT;
}
#endif
if (ka->sa.sa_flags & SA_RESTORER) {
retcode = (unsigned long)ka->sa.sa_restorer;
} else {
unsigned int idx = thumb;
if (ka->sa.sa_flags & SA_SIGINFO)
idx += 2;
if (__put_user(sigreturn_codes[idx], rc))
return 1;
if (cpsr & MODE32_BIT) {
/*
* 32-bit code can use the new high-page
* signal return code support.
*/
retcode = KERN_SIGRETURN_CODE + (idx << 2) + thumb;
} else {
/*
* Ensure that the instruction cache sees
* the return code written onto the stack.
*/
flush_icache_range((unsigned long)rc,
(unsigned long)(rc + 1));
retcode = ((unsigned long)rc) + thumb;
}
}
regs->ARM_r0 = usig;
regs->ARM_sp = (unsigned long)frame;
regs->ARM_lr = retcode;
regs->ARM_pc = handler;
regs->ARM_cpsr = cpsr;
return 0;
}
static int
setup_frame(int usig, struct k_sigaction *ka, sigset_t *set, struct pt_regs *regs)
{
struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
int err = 0;
if (!frame)
return 1;
err |= setup_sigcontext(&frame->sc, &frame->aux, regs, set->sig[0]);
if (_NSIG_WORDS > 1) {
err |= __copy_to_user(frame->extramask, &set->sig[1],
sizeof(frame->extramask));
}
if (err == 0)
err = setup_return(regs, ka, &frame->retcode, frame, usig);
return err;
}
static int
setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
sigset_t *set, struct pt_regs *regs)
{
struct rt_sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
stack_t stack;
int err = 0;
if (!frame)
return 1;
__put_user_error(&frame->info, &frame->pinfo, err);
__put_user_error(&frame->uc, &frame->puc, err);
err |= copy_siginfo_to_user(&frame->info, info);
__put_user_error(0, &frame->uc.uc_flags, err);
__put_user_error(NULL, &frame->uc.uc_link, err);
memset(&stack, 0, sizeof(stack));
stack.ss_sp = (void __user *)current->sas_ss_sp;
stack.ss_flags = sas_ss_flags(regs->ARM_sp);
stack.ss_size = current->sas_ss_size;
err |= __copy_to_user(&frame->uc.uc_stack, &stack, sizeof(stack));
err |= setup_sigcontext(&frame->uc.uc_mcontext, &frame->aux,
regs, set->sig[0]);
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
if (err == 0)
err = setup_return(regs, ka, &frame->retcode, frame, usig);
if (err == 0) {
/*
* For realtime signals we must also set the second and third
* arguments for the signal handler.
* -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
*/
regs->ARM_r1 = (unsigned long)&frame->info;
regs->ARM_r2 = (unsigned long)&frame->uc;
}
return err;
}
static inline void restart_syscall(struct pt_regs *regs)
{
regs->ARM_r0 = regs->ARM_ORIG_r0;
regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
}
/*
* OK, we're invoking a handler
*/
static void
handle_signal(unsigned long sig, struct k_sigaction *ka,
siginfo_t *info, sigset_t *oldset,
struct pt_regs * regs, int syscall)
{
struct thread_info *thread = current_thread_info();
struct task_struct *tsk = current;
int usig = sig;
int ret;
/*
* If we were from a system call, check for system call restarting...
*/
if (syscall) {
switch (regs->ARM_r0) {
case -ERESTART_RESTARTBLOCK:
case -ERESTARTNOHAND:
regs->ARM_r0 = -EINTR;
break;
case -ERESTARTSYS:
if (!(ka->sa.sa_flags & SA_RESTART)) {
regs->ARM_r0 = -EINTR;
break;
}
/* fallthrough */
case -ERESTARTNOINTR:
restart_syscall(regs);
}
}
/*
* translate the signal
*/
if (usig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap)
usig = thread->exec_domain->signal_invmap[usig];
/*
* Set up the stack frame
*/
if (ka->sa.sa_flags & SA_SIGINFO)
ret = setup_rt_frame(usig, ka, info, oldset, regs);
else
ret = setup_frame(usig, ka, oldset, regs);
/*
* Check that the resulting registers are actually sane.
*/
ret |= !valid_user_regs(regs);
/*
* Block the signal if we were unsuccessful.
*/
if (ret != 0) {
spin_lock_irq(&tsk->sighand->siglock);
sigorsets(&tsk->blocked, &tsk->blocked,
&ka->sa.sa_mask);
if (!(ka->sa.sa_flags & SA_NODEFER))
sigaddset(&tsk->blocked, sig);
recalc_sigpending();
spin_unlock_irq(&tsk->sighand->siglock);
}
if (ret == 0)
return;
force_sigsegv(sig, tsk);
}
/*
* 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.
*
* Note that we go through the signals twice: once to check the signals that
* the kernel can handle, and then we build all the user-level signal handling
* stack-frames in one go after that.
*/
static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall)
{
struct k_sigaction ka;
siginfo_t info;
int signr;
/*
* 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 0;
if (try_to_freeze())
goto no_signal;
if (current->ptrace & PT_SINGLESTEP)
ptrace_cancel_bpt(current);
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
if (signr > 0) {
handle_signal(signr, &ka, &info, oldset, regs, syscall);
if (current->ptrace & PT_SINGLESTEP)
ptrace_set_bpt(current);
return 1;
}
no_signal:
/*
* No signal to deliver to the process - restart the syscall.
*/
if (syscall) {
if (regs->ARM_r0 == -ERESTART_RESTARTBLOCK) {
if (thumb_mode(regs)) {
regs->ARM_r7 = __NR_restart_syscall;
regs->ARM_pc -= 2;
} else {
u32 __user *usp;
regs->ARM_sp -= 12;
usp = (u32 __user *)regs->ARM_sp;
put_user(regs->ARM_pc, &usp[0]);
/* swi __NR_restart_syscall */
put_user(0xef000000 | __NR_restart_syscall, &usp[1]);
/* ldr pc, [sp], #12 */
put_user(0xe49df00c, &usp[2]);
flush_icache_range((unsigned long)usp,
(unsigned long)(usp + 3));
regs->ARM_pc = regs->ARM_sp + 4;
}
}
if (regs->ARM_r0 == -ERESTARTNOHAND ||
regs->ARM_r0 == -ERESTARTSYS ||
regs->ARM_r0 == -ERESTARTNOINTR) {
restart_syscall(regs);
}
}
if (current->ptrace & PT_SINGLESTEP)
ptrace_set_bpt(current);
return 0;
}
asmlinkage void
do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall)
{
if (thread_flags & _TIF_SIGPENDING)
do_signal(&current->blocked, regs, syscall);
}