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authorSam Ravnborg <sam@ravnborg.org>2008-12-03 03:08:37 -0800
committerDavid S. Miller <davem@davemloft.net>2008-12-04 09:17:20 -0800
commitd670bd4f803c8b646acd20f3ba21e65458293faf (patch)
treeeabc30aadce1556023c4aa445c649ba9e1d3f352 /arch/sparc/kernel/signal_32.c
parent478b8fecda511942404ac232897a718cecd13e48 (diff)
sparc: prepare kernel/ for unification
o sparc32 files with identical names to sparc64 renamed to <name>_32.S o introduced a few Kconfig helpers to simplify Makefile logic o refactored Makefile to prepare for unification - use obj-$(CONFIG_SPARC32) for sparc32 specific files - use <name>_$(BITS) for files where sparc64 has a _64 variant - sparc64 directly include a few files where sparc32 builds them, refer to these files directly (no BITS) - sneaked in -Werror as used by sparc64 o modified sparc/Makefile to use the new names for head/init_task Signed-off-by: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/sparc/kernel/signal_32.c')
-rw-r--r--arch/sparc/kernel/signal_32.c631
1 files changed, 631 insertions, 0 deletions
diff --git a/arch/sparc/kernel/signal_32.c b/arch/sparc/kernel/signal_32.c
new file mode 100644
index 00000000000..c94f91c8b6e
--- /dev/null
+++ b/arch/sparc/kernel/signal_32.c
@@ -0,0 +1,631 @@
+/* linux/arch/sparc/kernel/signal.c
+ *
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
+ * Copyright (C) 1996 Miguel de Icaza (miguel@nuclecu.unam.mx)
+ * Copyright (C) 1997 Eddie C. Dost (ecd@skynet.be)
+ */
+
+#include <linux/sched.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/mm.h>
+#include <linux/tty.h>
+#include <linux/smp.h>
+#include <linux/binfmts.h> /* do_coredum */
+#include <linux/bitops.h>
+#include <linux/tracehook.h>
+
+#include <asm/uaccess.h>
+#include <asm/ptrace.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+#include <asm/cacheflush.h> /* flush_sig_insns */
+
+#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
+
+extern void fpsave(unsigned long *fpregs, unsigned long *fsr,
+ void *fpqueue, unsigned long *fpqdepth);
+extern void fpload(unsigned long *fpregs, unsigned long *fsr);
+
+struct signal_frame {
+ struct sparc_stackf ss;
+ __siginfo_t info;
+ __siginfo_fpu_t __user *fpu_save;
+ unsigned long insns[2] __attribute__ ((aligned (8)));
+ unsigned int extramask[_NSIG_WORDS - 1];
+ unsigned int extra_size; /* Should be 0 */
+ __siginfo_fpu_t fpu_state;
+};
+
+struct rt_signal_frame {
+ struct sparc_stackf ss;
+ siginfo_t info;
+ struct pt_regs regs;
+ sigset_t mask;
+ __siginfo_fpu_t __user *fpu_save;
+ unsigned int insns[2];
+ stack_t stack;
+ unsigned int extra_size; /* Should be 0 */
+ __siginfo_fpu_t fpu_state;
+};
+
+/* Align macros */
+#define SF_ALIGNEDSZ (((sizeof(struct signal_frame) + 7) & (~7)))
+#define RT_ALIGNEDSZ (((sizeof(struct rt_signal_frame) + 7) & (~7)))
+
+static int _sigpause_common(old_sigset_t set)
+{
+ set &= _BLOCKABLE;
+ spin_lock_irq(&current->sighand->siglock);
+ current->saved_sigmask = current->blocked;
+ siginitset(&current->blocked, set);
+ recalc_sigpending();
+ spin_unlock_irq(&current->sighand->siglock);
+
+ current->state = TASK_INTERRUPTIBLE;
+ schedule();
+ set_thread_flag(TIF_RESTORE_SIGMASK);
+
+ return -ERESTARTNOHAND;
+}
+
+asmlinkage int sys_sigsuspend(old_sigset_t set)
+{
+ return _sigpause_common(set);
+}
+
+static inline int
+restore_fpu_state(struct pt_regs *regs, __siginfo_fpu_t __user *fpu)
+{
+ int err;
+#ifdef CONFIG_SMP
+ if (test_tsk_thread_flag(current, TIF_USEDFPU))
+ regs->psr &= ~PSR_EF;
+#else
+ if (current == last_task_used_math) {
+ last_task_used_math = NULL;
+ regs->psr &= ~PSR_EF;
+ }
+#endif
+ set_used_math();
+ clear_tsk_thread_flag(current, TIF_USEDFPU);
+
+ if (!access_ok(VERIFY_READ, fpu, sizeof(*fpu)))
+ return -EFAULT;
+
+ err = __copy_from_user(&current->thread.float_regs[0], &fpu->si_float_regs[0],
+ (sizeof(unsigned long) * 32));
+ err |= __get_user(current->thread.fsr, &fpu->si_fsr);
+ err |= __get_user(current->thread.fpqdepth, &fpu->si_fpqdepth);
+ if (current->thread.fpqdepth != 0)
+ err |= __copy_from_user(&current->thread.fpqueue[0],
+ &fpu->si_fpqueue[0],
+ ((sizeof(unsigned long) +
+ (sizeof(unsigned long *)))*16));
+ return err;
+}
+
+asmlinkage void do_sigreturn(struct pt_regs *regs)
+{
+ struct signal_frame __user *sf;
+ unsigned long up_psr, pc, npc;
+ sigset_t set;
+ __siginfo_fpu_t __user *fpu_save;
+ int err;
+
+ /* Always make any pending restarted system calls return -EINTR */
+ current_thread_info()->restart_block.fn = do_no_restart_syscall;
+
+ synchronize_user_stack();
+
+ sf = (struct signal_frame __user *) regs->u_regs[UREG_FP];
+
+ /* 1. Make sure we are not getting garbage from the user */
+ if (!access_ok(VERIFY_READ, sf, sizeof(*sf)))
+ goto segv_and_exit;
+
+ if (((unsigned long) sf) & 3)
+ goto segv_and_exit;
+
+ err = __get_user(pc, &sf->info.si_regs.pc);
+ err |= __get_user(npc, &sf->info.si_regs.npc);
+
+ if ((pc | npc) & 3)
+ goto segv_and_exit;
+
+ /* 2. Restore the state */
+ up_psr = regs->psr;
+ err |= __copy_from_user(regs, &sf->info.si_regs, sizeof(struct pt_regs));
+
+ /* User can only change condition codes and FPU enabling in %psr. */
+ regs->psr = (up_psr & ~(PSR_ICC | PSR_EF))
+ | (regs->psr & (PSR_ICC | PSR_EF));
+
+ /* Prevent syscall restart. */
+ pt_regs_clear_syscall(regs);
+
+ err |= __get_user(fpu_save, &sf->fpu_save);
+
+ if (fpu_save)
+ err |= restore_fpu_state(regs, fpu_save);
+
+ /* This is pretty much atomic, no amount locking would prevent
+ * the races which exist anyways.
+ */
+ err |= __get_user(set.sig[0], &sf->info.si_mask);
+ err |= __copy_from_user(&set.sig[1], &sf->extramask,
+ (_NSIG_WORDS-1) * sizeof(unsigned int));
+
+ if (err)
+ goto segv_and_exit;
+
+ sigdelsetmask(&set, ~_BLOCKABLE);
+ spin_lock_irq(&current->sighand->siglock);
+ current->blocked = set;
+ recalc_sigpending();
+ spin_unlock_irq(&current->sighand->siglock);
+ return;
+
+segv_and_exit:
+ force_sig(SIGSEGV, current);
+}
+
+asmlinkage void do_rt_sigreturn(struct pt_regs *regs)
+{
+ struct rt_signal_frame __user *sf;
+ unsigned int psr, pc, npc;
+ __siginfo_fpu_t __user *fpu_save;
+ mm_segment_t old_fs;
+ sigset_t set;
+ stack_t st;
+ int err;
+
+ synchronize_user_stack();
+ sf = (struct rt_signal_frame __user *) regs->u_regs[UREG_FP];
+ if (!access_ok(VERIFY_READ, sf, sizeof(*sf)) ||
+ (((unsigned long) sf) & 0x03))
+ goto segv;
+
+ err = __get_user(pc, &sf->regs.pc);
+ err |= __get_user(npc, &sf->regs.npc);
+ err |= ((pc | npc) & 0x03);
+
+ err |= __get_user(regs->y, &sf->regs.y);
+ err |= __get_user(psr, &sf->regs.psr);
+
+ err |= __copy_from_user(&regs->u_regs[UREG_G1],
+ &sf->regs.u_regs[UREG_G1], 15 * sizeof(u32));
+
+ regs->psr = (regs->psr & ~PSR_ICC) | (psr & PSR_ICC);
+
+ /* Prevent syscall restart. */
+ pt_regs_clear_syscall(regs);
+
+ err |= __get_user(fpu_save, &sf->fpu_save);
+
+ if (fpu_save)
+ err |= restore_fpu_state(regs, fpu_save);
+ err |= __copy_from_user(&set, &sf->mask, sizeof(sigset_t));
+
+ err |= __copy_from_user(&st, &sf->stack, sizeof(stack_t));
+
+ if (err)
+ goto segv;
+
+ regs->pc = pc;
+ regs->npc = npc;
+
+ /* It is more difficult to avoid calling this function than to
+ * call it and ignore errors.
+ */
+ old_fs = get_fs();
+ set_fs(KERNEL_DS);
+ do_sigaltstack((const stack_t __user *) &st, NULL, (unsigned long)sf);
+ set_fs(old_fs);
+
+ sigdelsetmask(&set, ~_BLOCKABLE);
+ spin_lock_irq(&current->sighand->siglock);
+ current->blocked = set;
+ recalc_sigpending();
+ spin_unlock_irq(&current->sighand->siglock);
+ return;
+segv:
+ force_sig(SIGSEGV, current);
+}
+
+/* Checks if the fp is valid */
+static inline int invalid_frame_pointer(void __user *fp, int fplen)
+{
+ if ((((unsigned long) fp) & 7) ||
+ !__access_ok((unsigned long)fp, fplen) ||
+ ((sparc_cpu_model == sun4 || sparc_cpu_model == sun4c) &&
+ ((unsigned long) fp < 0xe0000000 && (unsigned long) fp >= 0x20000000)))
+ return 1;
+
+ return 0;
+}
+
+static inline void __user *get_sigframe(struct sigaction *sa, struct pt_regs *regs, unsigned long framesize)
+{
+ unsigned long sp = regs->u_regs[UREG_FP];
+
+ /*
+ * If we are on the alternate signal stack and would overflow it, don't.
+ * Return an always-bogus address instead so we will die with SIGSEGV.
+ */
+ if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
+ return (void __user *) -1L;
+
+ /* This is the X/Open sanctioned signal stack switching. */
+ if (sa->sa_flags & SA_ONSTACK) {
+ if (sas_ss_flags(sp) == 0)
+ sp = current->sas_ss_sp + current->sas_ss_size;
+ }
+
+ /* Always align the stack frame. This handles two cases. First,
+ * sigaltstack need not be mindful of platform specific stack
+ * alignment. Second, if we took this signal because the stack
+ * is not aligned properly, we'd like to take the signal cleanly
+ * and report that.
+ */
+ sp &= ~7UL;
+
+ return (void __user *)(sp - framesize);
+}
+
+static inline int
+save_fpu_state(struct pt_regs *regs, __siginfo_fpu_t __user *fpu)
+{
+ int err = 0;
+#ifdef CONFIG_SMP
+ if (test_tsk_thread_flag(current, TIF_USEDFPU)) {
+ put_psr(get_psr() | PSR_EF);
+ fpsave(&current->thread.float_regs[0], &current->thread.fsr,
+ &current->thread.fpqueue[0], &current->thread.fpqdepth);
+ regs->psr &= ~(PSR_EF);
+ clear_tsk_thread_flag(current, TIF_USEDFPU);
+ }
+#else
+ if (current == last_task_used_math) {
+ put_psr(get_psr() | PSR_EF);
+ fpsave(&current->thread.float_regs[0], &current->thread.fsr,
+ &current->thread.fpqueue[0], &current->thread.fpqdepth);
+ last_task_used_math = NULL;
+ regs->psr &= ~(PSR_EF);
+ }
+#endif
+ err |= __copy_to_user(&fpu->si_float_regs[0],
+ &current->thread.float_regs[0],
+ (sizeof(unsigned long) * 32));
+ err |= __put_user(current->thread.fsr, &fpu->si_fsr);
+ err |= __put_user(current->thread.fpqdepth, &fpu->si_fpqdepth);
+ if (current->thread.fpqdepth != 0)
+ err |= __copy_to_user(&fpu->si_fpqueue[0],
+ &current->thread.fpqueue[0],
+ ((sizeof(unsigned long) +
+ (sizeof(unsigned long *)))*16));
+ clear_used_math();
+ return err;
+}
+
+static void setup_frame(struct k_sigaction *ka, struct pt_regs *regs,
+ int signo, sigset_t *oldset)
+{
+ struct signal_frame __user *sf;
+ int sigframe_size, err;
+
+ /* 1. Make sure everything is clean */
+ synchronize_user_stack();
+
+ sigframe_size = SF_ALIGNEDSZ;
+ if (!used_math())
+ sigframe_size -= sizeof(__siginfo_fpu_t);
+
+ sf = (struct signal_frame __user *)
+ get_sigframe(&ka->sa, regs, sigframe_size);
+
+ if (invalid_frame_pointer(sf, sigframe_size))
+ goto sigill_and_return;
+
+ if (current_thread_info()->w_saved != 0)
+ goto sigill_and_return;
+
+ /* 2. Save the current process state */
+ err = __copy_to_user(&sf->info.si_regs, regs, sizeof(struct pt_regs));
+
+ err |= __put_user(0, &sf->extra_size);
+
+ if (used_math()) {
+ err |= save_fpu_state(regs, &sf->fpu_state);
+ err |= __put_user(&sf->fpu_state, &sf->fpu_save);
+ } else {
+ err |= __put_user(0, &sf->fpu_save);
+ }
+
+ err |= __put_user(oldset->sig[0], &sf->info.si_mask);
+ err |= __copy_to_user(sf->extramask, &oldset->sig[1],
+ (_NSIG_WORDS - 1) * sizeof(unsigned int));
+ err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
+ sizeof(struct reg_window));
+ if (err)
+ goto sigsegv;
+
+ /* 3. signal handler back-trampoline and parameters */
+ regs->u_regs[UREG_FP] = (unsigned long) sf;
+ regs->u_regs[UREG_I0] = signo;
+ regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
+ regs->u_regs[UREG_I2] = (unsigned long) &sf->info;
+
+ /* 4. signal handler */
+ regs->pc = (unsigned long) ka->sa.sa_handler;
+ regs->npc = (regs->pc + 4);
+
+ /* 5. return to kernel instructions */
+ if (ka->ka_restorer)
+ regs->u_regs[UREG_I7] = (unsigned long)ka->ka_restorer;
+ else {
+ regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);
+
+ /* mov __NR_sigreturn, %g1 */
+ err |= __put_user(0x821020d8, &sf->insns[0]);
+
+ /* t 0x10 */
+ err |= __put_user(0x91d02010, &sf->insns[1]);
+ if (err)
+ goto sigsegv;
+
+ /* Flush instruction space. */
+ flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
+ }
+ return;
+
+sigill_and_return:
+ do_exit(SIGILL);
+sigsegv:
+ force_sigsegv(signo, current);
+}
+
+static void setup_rt_frame(struct k_sigaction *ka, struct pt_regs *regs,
+ int signo, sigset_t *oldset, siginfo_t *info)
+{
+ struct rt_signal_frame __user *sf;
+ int sigframe_size;
+ unsigned int psr;
+ int err;
+
+ synchronize_user_stack();
+ sigframe_size = RT_ALIGNEDSZ;
+ if (!used_math())
+ sigframe_size -= sizeof(__siginfo_fpu_t);
+ sf = (struct rt_signal_frame __user *)
+ get_sigframe(&ka->sa, regs, sigframe_size);
+ if (invalid_frame_pointer(sf, sigframe_size))
+ goto sigill;
+ if (current_thread_info()->w_saved != 0)
+ goto sigill;
+
+ err = __put_user(regs->pc, &sf->regs.pc);
+ err |= __put_user(regs->npc, &sf->regs.npc);
+ err |= __put_user(regs->y, &sf->regs.y);
+ psr = regs->psr;
+ if (used_math())
+ psr |= PSR_EF;
+ err |= __put_user(psr, &sf->regs.psr);
+ err |= __copy_to_user(&sf->regs.u_regs, regs->u_regs, sizeof(regs->u_regs));
+ err |= __put_user(0, &sf->extra_size);
+
+ if (psr & PSR_EF) {
+ err |= save_fpu_state(regs, &sf->fpu_state);
+ err |= __put_user(&sf->fpu_state, &sf->fpu_save);
+ } else {
+ err |= __put_user(0, &sf->fpu_save);
+ }
+ err |= __copy_to_user(&sf->mask, &oldset->sig[0], sizeof(sigset_t));
+
+ /* Setup sigaltstack */
+ err |= __put_user(current->sas_ss_sp, &sf->stack.ss_sp);
+ err |= __put_user(sas_ss_flags(regs->u_regs[UREG_FP]), &sf->stack.ss_flags);
+ err |= __put_user(current->sas_ss_size, &sf->stack.ss_size);
+
+ err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
+ sizeof(struct reg_window));
+
+ err |= copy_siginfo_to_user(&sf->info, info);
+
+ if (err)
+ goto sigsegv;
+
+ regs->u_regs[UREG_FP] = (unsigned long) sf;
+ regs->u_regs[UREG_I0] = signo;
+ regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
+ regs->u_regs[UREG_I2] = (unsigned long) &sf->regs;
+
+ regs->pc = (unsigned long) ka->sa.sa_handler;
+ regs->npc = (regs->pc + 4);
+
+ if (ka->ka_restorer)
+ regs->u_regs[UREG_I7] = (unsigned long)ka->ka_restorer;
+ else {
+ regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);
+
+ /* mov __NR_sigreturn, %g1 */
+ err |= __put_user(0x821020d8, &sf->insns[0]);
+
+ /* t 0x10 */
+ err |= __put_user(0x91d02010, &sf->insns[1]);
+ if (err)
+ goto sigsegv;
+
+ /* Flush instruction space. */
+ flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
+ }
+ return;
+
+sigill:
+ do_exit(SIGILL);
+sigsegv:
+ force_sigsegv(signo, current);
+}
+
+static inline void
+handle_signal(unsigned long signr, struct k_sigaction *ka,
+ siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
+{
+ if (ka->sa.sa_flags & SA_SIGINFO)
+ setup_rt_frame(ka, regs, signr, oldset, info);
+ else
+ setup_frame(ka, regs, signr, oldset);
+
+ spin_lock_irq(&current->sighand->siglock);
+ sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+ if (!(ka->sa.sa_flags & SA_NOMASK))
+ sigaddset(&current->blocked, signr);
+ recalc_sigpending();
+ spin_unlock_irq(&current->sighand->siglock);
+}
+
+static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs,
+ struct sigaction *sa)
+{
+ switch(regs->u_regs[UREG_I0]) {
+ case ERESTART_RESTARTBLOCK:
+ case ERESTARTNOHAND:
+ no_system_call_restart:
+ regs->u_regs[UREG_I0] = EINTR;
+ regs->psr |= PSR_C;
+ break;
+ case ERESTARTSYS:
+ if (!(sa->sa_flags & SA_RESTART))
+ goto no_system_call_restart;
+ /* fallthrough */
+ case ERESTARTNOINTR:
+ regs->u_regs[UREG_I0] = orig_i0;
+ regs->pc -= 4;
+ regs->npc -= 4;
+ }
+}
+
+/* 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, unsigned long orig_i0)
+{
+ struct k_sigaction ka;
+ int restart_syscall;
+ sigset_t *oldset;
+ siginfo_t info;
+ int signr;
+
+ if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C))
+ restart_syscall = 1;
+ else
+ restart_syscall = 0;
+
+ 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 the debugger messes with the program counter, it clears
+ * the software "in syscall" bit, directing us to not perform
+ * a syscall restart.
+ */
+ if (restart_syscall && !pt_regs_is_syscall(regs))
+ restart_syscall = 0;
+
+ if (signr > 0) {
+ if (restart_syscall)
+ syscall_restart(orig_i0, regs, &ka.sa);
+ handle_signal(signr, &ka, &info, oldset, regs);
+
+ /* 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.
+ */
+ if (test_thread_flag(TIF_RESTORE_SIGMASK))
+ clear_thread_flag(TIF_RESTORE_SIGMASK);
+
+ tracehook_signal_handler(signr, &info, &ka, regs, 0);
+ return;
+ }
+ if (restart_syscall &&
+ (regs->u_regs[UREG_I0] == ERESTARTNOHAND ||
+ regs->u_regs[UREG_I0] == ERESTARTSYS ||
+ regs->u_regs[UREG_I0] == ERESTARTNOINTR)) {
+ /* replay the system call when we are done */
+ regs->u_regs[UREG_I0] = orig_i0;
+ regs->pc -= 4;
+ regs->npc -= 4;
+ }
+ if (restart_syscall &&
+ regs->u_regs[UREG_I0] == ERESTART_RESTARTBLOCK) {
+ regs->u_regs[UREG_G1] = __NR_restart_syscall;
+ regs->pc -= 4;
+ regs->npc -= 4;
+ }
+
+ /* 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, unsigned long orig_i0,
+ unsigned long thread_info_flags)
+{
+ if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
+ do_signal(regs, orig_i0);
+ if (thread_info_flags & _TIF_NOTIFY_RESUME) {
+ clear_thread_flag(TIF_NOTIFY_RESUME);
+ tracehook_notify_resume(regs);
+ }
+}
+
+asmlinkage int
+do_sys_sigstack(struct sigstack __user *ssptr, struct sigstack __user *ossptr,
+ unsigned long sp)
+{
+ int ret = -EFAULT;
+
+ /* First see if old state is wanted. */
+ if (ossptr) {
+ if (put_user(current->sas_ss_sp + current->sas_ss_size,
+ &ossptr->the_stack) ||
+ __put_user(on_sig_stack(sp), &ossptr->cur_status))
+ goto out;
+ }
+
+ /* Now see if we want to update the new state. */
+ if (ssptr) {
+ char *ss_sp;
+
+ if (get_user(ss_sp, &ssptr->the_stack))
+ goto out;
+ /* If the current stack was set with sigaltstack, don't
+ swap stacks while we are on it. */
+ ret = -EPERM;
+ if (current->sas_ss_sp && on_sig_stack(sp))
+ goto out;
+
+ /* Since we don't know the extent of the stack, and we don't
+ track onstack-ness, but rather calculate it, we must
+ presume a size. Ho hum this interface is lossy. */
+ current->sas_ss_sp = (unsigned long)ss_sp - SIGSTKSZ;
+ current->sas_ss_size = SIGSTKSZ;
+ }
+ ret = 0;
+out:
+ return ret;
+}