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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 10:05:51 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 10:05:51 +0000
commit5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 (patch)
treea94efe259b9009378be6d90eb30d2b019d95c194 /arch/sparc/kernel/sys_sparc_64.c
parentInitial commit. (diff)
downloadlinux-5d1646d90e1f2cceb9f0828f4b28318cd0ec7744.tar.xz
linux-5d1646d90e1f2cceb9f0828f4b28318cd0ec7744.zip
Adding upstream version 5.10.209.upstream/5.10.209upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/sparc/kernel/sys_sparc_64.c')
-rw-r--r--arch/sparc/kernel/sys_sparc_64.c709
1 files changed, 709 insertions, 0 deletions
diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
new file mode 100644
index 000000000..6b92fadb6
--- /dev/null
+++ b/arch/sparc/kernel/sys_sparc_64.c
@@ -0,0 +1,709 @@
+// SPDX-License-Identifier: GPL-2.0
+/* linux/arch/sparc64/kernel/sys_sparc.c
+ *
+ * This file contains various random system calls that
+ * have a non-standard calling sequence on the Linux/sparc
+ * platform.
+ */
+
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/mm.h>
+#include <linux/sched/debug.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/mm.h>
+#include <linux/sem.h>
+#include <linux/msg.h>
+#include <linux/shm.h>
+#include <linux/stat.h>
+#include <linux/mman.h>
+#include <linux/utsname.h>
+#include <linux/smp.h>
+#include <linux/slab.h>
+#include <linux/syscalls.h>
+#include <linux/ipc.h>
+#include <linux/personality.h>
+#include <linux/random.h>
+#include <linux/export.h>
+#include <linux/context_tracking.h>
+#include <linux/timex.h>
+#include <linux/uaccess.h>
+
+#include <asm/utrap.h>
+#include <asm/unistd.h>
+
+#include "entry.h"
+#include "kernel.h"
+#include "systbls.h"
+
+/* #define DEBUG_UNIMP_SYSCALL */
+
+SYSCALL_DEFINE0(getpagesize)
+{
+ return PAGE_SIZE;
+}
+
+/* Does addr --> addr+len fall within 4GB of the VA-space hole or
+ * overflow past the end of the 64-bit address space?
+ */
+static inline int invalid_64bit_range(unsigned long addr, unsigned long len)
+{
+ unsigned long va_exclude_start, va_exclude_end;
+
+ va_exclude_start = VA_EXCLUDE_START;
+ va_exclude_end = VA_EXCLUDE_END;
+
+ if (unlikely(len >= va_exclude_start))
+ return 1;
+
+ if (unlikely((addr + len) < addr))
+ return 1;
+
+ if (unlikely((addr >= va_exclude_start && addr < va_exclude_end) ||
+ ((addr + len) >= va_exclude_start &&
+ (addr + len) < va_exclude_end)))
+ return 1;
+
+ return 0;
+}
+
+/* These functions differ from the default implementations in
+ * mm/mmap.c in two ways:
+ *
+ * 1) For file backed MAP_SHARED mmap()'s we D-cache color align,
+ * for fixed such mappings we just validate what the user gave us.
+ * 2) For 64-bit tasks we avoid mapping anything within 4GB of
+ * the spitfire/niagara VA-hole.
+ */
+
+static inline unsigned long COLOR_ALIGN(unsigned long addr,
+ unsigned long pgoff)
+{
+ unsigned long base = (addr+SHMLBA-1)&~(SHMLBA-1);
+ unsigned long off = (pgoff<<PAGE_SHIFT) & (SHMLBA-1);
+
+ return base + off;
+}
+
+unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct * vma;
+ unsigned long task_size = TASK_SIZE;
+ int do_color_align;
+ struct vm_unmapped_area_info info;
+
+ if (flags & MAP_FIXED) {
+ /* We do not accept a shared mapping if it would violate
+ * cache aliasing constraints.
+ */
+ if ((flags & MAP_SHARED) &&
+ ((addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)))
+ return -EINVAL;
+ return addr;
+ }
+
+ if (test_thread_flag(TIF_32BIT))
+ task_size = STACK_TOP32;
+ if (unlikely(len > task_size || len >= VA_EXCLUDE_START))
+ return -ENOMEM;
+
+ do_color_align = 0;
+ if (filp || (flags & MAP_SHARED))
+ do_color_align = 1;
+
+ if (addr) {
+ if (do_color_align)
+ addr = COLOR_ALIGN(addr, pgoff);
+ else
+ addr = PAGE_ALIGN(addr);
+
+ vma = find_vma(mm, addr);
+ if (task_size - len >= addr &&
+ (!vma || addr + len <= vm_start_gap(vma)))
+ return addr;
+ }
+
+ info.flags = 0;
+ info.length = len;
+ info.low_limit = TASK_UNMAPPED_BASE;
+ info.high_limit = min(task_size, VA_EXCLUDE_START);
+ info.align_mask = do_color_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
+ info.align_offset = pgoff << PAGE_SHIFT;
+ addr = vm_unmapped_area(&info);
+
+ if ((addr & ~PAGE_MASK) && task_size > VA_EXCLUDE_END) {
+ VM_BUG_ON(addr != -ENOMEM);
+ info.low_limit = VA_EXCLUDE_END;
+ info.high_limit = task_size;
+ addr = vm_unmapped_area(&info);
+ }
+
+ return addr;
+}
+
+unsigned long
+arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
+ const unsigned long len, const unsigned long pgoff,
+ const unsigned long flags)
+{
+ struct vm_area_struct *vma;
+ struct mm_struct *mm = current->mm;
+ unsigned long task_size = STACK_TOP32;
+ unsigned long addr = addr0;
+ int do_color_align;
+ struct vm_unmapped_area_info info;
+
+ /* This should only ever run for 32-bit processes. */
+ BUG_ON(!test_thread_flag(TIF_32BIT));
+
+ if (flags & MAP_FIXED) {
+ /* We do not accept a shared mapping if it would violate
+ * cache aliasing constraints.
+ */
+ if ((flags & MAP_SHARED) &&
+ ((addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)))
+ return -EINVAL;
+ return addr;
+ }
+
+ if (unlikely(len > task_size))
+ return -ENOMEM;
+
+ do_color_align = 0;
+ if (filp || (flags & MAP_SHARED))
+ do_color_align = 1;
+
+ /* requesting a specific address */
+ if (addr) {
+ if (do_color_align)
+ addr = COLOR_ALIGN(addr, pgoff);
+ else
+ addr = PAGE_ALIGN(addr);
+
+ vma = find_vma(mm, addr);
+ if (task_size - len >= addr &&
+ (!vma || addr + len <= vm_start_gap(vma)))
+ return addr;
+ }
+
+ info.flags = VM_UNMAPPED_AREA_TOPDOWN;
+ info.length = len;
+ info.low_limit = PAGE_SIZE;
+ info.high_limit = mm->mmap_base;
+ info.align_mask = do_color_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
+ info.align_offset = pgoff << PAGE_SHIFT;
+ addr = vm_unmapped_area(&info);
+
+ /*
+ * A failed mmap() very likely causes application failure,
+ * so fall back to the bottom-up function here. This scenario
+ * can happen with large stack limits and large mmap()
+ * allocations.
+ */
+ if (addr & ~PAGE_MASK) {
+ VM_BUG_ON(addr != -ENOMEM);
+ info.flags = 0;
+ info.low_limit = TASK_UNMAPPED_BASE;
+ info.high_limit = STACK_TOP32;
+ addr = vm_unmapped_area(&info);
+ }
+
+ return addr;
+}
+
+/* Try to align mapping such that we align it as much as possible. */
+unsigned long get_fb_unmapped_area(struct file *filp, unsigned long orig_addr, unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+ unsigned long align_goal, addr = -ENOMEM;
+ unsigned long (*get_area)(struct file *, unsigned long,
+ unsigned long, unsigned long, unsigned long);
+
+ get_area = current->mm->get_unmapped_area;
+
+ if (flags & MAP_FIXED) {
+ /* Ok, don't mess with it. */
+ return get_area(NULL, orig_addr, len, pgoff, flags);
+ }
+ flags &= ~MAP_SHARED;
+
+ align_goal = PAGE_SIZE;
+ if (len >= (4UL * 1024 * 1024))
+ align_goal = (4UL * 1024 * 1024);
+ else if (len >= (512UL * 1024))
+ align_goal = (512UL * 1024);
+ else if (len >= (64UL * 1024))
+ align_goal = (64UL * 1024);
+
+ do {
+ addr = get_area(NULL, orig_addr, len + (align_goal - PAGE_SIZE), pgoff, flags);
+ if (!(addr & ~PAGE_MASK)) {
+ addr = (addr + (align_goal - 1UL)) & ~(align_goal - 1UL);
+ break;
+ }
+
+ if (align_goal == (4UL * 1024 * 1024))
+ align_goal = (512UL * 1024);
+ else if (align_goal == (512UL * 1024))
+ align_goal = (64UL * 1024);
+ else
+ align_goal = PAGE_SIZE;
+ } while ((addr & ~PAGE_MASK) && align_goal > PAGE_SIZE);
+
+ /* Mapping is smaller than 64K or larger areas could not
+ * be obtained.
+ */
+ if (addr & ~PAGE_MASK)
+ addr = get_area(NULL, orig_addr, len, pgoff, flags);
+
+ return addr;
+}
+EXPORT_SYMBOL(get_fb_unmapped_area);
+
+/* Essentially the same as PowerPC. */
+static unsigned long mmap_rnd(void)
+{
+ unsigned long rnd = 0UL;
+
+ if (current->flags & PF_RANDOMIZE) {
+ unsigned long val = get_random_long();
+ if (test_thread_flag(TIF_32BIT))
+ rnd = (val % (1UL << (23UL-PAGE_SHIFT)));
+ else
+ rnd = (val % (1UL << (30UL-PAGE_SHIFT)));
+ }
+ return rnd << PAGE_SHIFT;
+}
+
+void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
+{
+ unsigned long random_factor = mmap_rnd();
+ unsigned long gap;
+
+ /*
+ * Fall back to the standard layout if the personality
+ * bit is set, or if the expected stack growth is unlimited:
+ */
+ gap = rlim_stack->rlim_cur;
+ if (!test_thread_flag(TIF_32BIT) ||
+ (current->personality & ADDR_COMPAT_LAYOUT) ||
+ gap == RLIM_INFINITY ||
+ sysctl_legacy_va_layout) {
+ mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
+ mm->get_unmapped_area = arch_get_unmapped_area;
+ } else {
+ /* We know it's 32-bit */
+ unsigned long task_size = STACK_TOP32;
+
+ if (gap < 128 * 1024 * 1024)
+ gap = 128 * 1024 * 1024;
+ if (gap > (task_size / 6 * 5))
+ gap = (task_size / 6 * 5);
+
+ mm->mmap_base = PAGE_ALIGN(task_size - gap - random_factor);
+ mm->get_unmapped_area = arch_get_unmapped_area_topdown;
+ }
+}
+
+/*
+ * sys_pipe() is the normal C calling standard for creating
+ * a pipe. It's not the way unix traditionally does this, though.
+ */
+SYSCALL_DEFINE0(sparc_pipe)
+{
+ int fd[2];
+ int error;
+
+ error = do_pipe_flags(fd, 0);
+ if (error)
+ goto out;
+ current_pt_regs()->u_regs[UREG_I1] = fd[1];
+ error = fd[0];
+out:
+ return error;
+}
+
+/*
+ * sys_ipc() is the de-multiplexer for the SysV IPC calls..
+ *
+ * This is really horribly ugly.
+ */
+
+SYSCALL_DEFINE6(sparc_ipc, unsigned int, call, int, first, unsigned long, second,
+ unsigned long, third, void __user *, ptr, long, fifth)
+{
+ long err;
+
+ if (!IS_ENABLED(CONFIG_SYSVIPC))
+ return -ENOSYS;
+
+ /* No need for backward compatibility. We can start fresh... */
+ if (call <= SEMTIMEDOP) {
+ switch (call) {
+ case SEMOP:
+ err = ksys_semtimedop(first, ptr,
+ (unsigned int)second, NULL);
+ goto out;
+ case SEMTIMEDOP:
+ err = ksys_semtimedop(first, ptr, (unsigned int)second,
+ (const struct __kernel_timespec __user *)
+ (unsigned long) fifth);
+ goto out;
+ case SEMGET:
+ err = ksys_semget(first, (int)second, (int)third);
+ goto out;
+ case SEMCTL: {
+ err = ksys_old_semctl(first, second,
+ (int)third | IPC_64,
+ (unsigned long) ptr);
+ goto out;
+ }
+ default:
+ err = -ENOSYS;
+ goto out;
+ }
+ }
+ if (call <= MSGCTL) {
+ switch (call) {
+ case MSGSND:
+ err = ksys_msgsnd(first, ptr, (size_t)second,
+ (int)third);
+ goto out;
+ case MSGRCV:
+ err = ksys_msgrcv(first, ptr, (size_t)second, fifth,
+ (int)third);
+ goto out;
+ case MSGGET:
+ err = ksys_msgget((key_t)first, (int)second);
+ goto out;
+ case MSGCTL:
+ err = ksys_old_msgctl(first, (int)second | IPC_64, ptr);
+ goto out;
+ default:
+ err = -ENOSYS;
+ goto out;
+ }
+ }
+ if (call <= SHMCTL) {
+ switch (call) {
+ case SHMAT: {
+ ulong raddr;
+ err = do_shmat(first, ptr, (int)second, &raddr, SHMLBA);
+ if (!err) {
+ if (put_user(raddr,
+ (ulong __user *) third))
+ err = -EFAULT;
+ }
+ goto out;
+ }
+ case SHMDT:
+ err = ksys_shmdt(ptr);
+ goto out;
+ case SHMGET:
+ err = ksys_shmget(first, (size_t)second, (int)third);
+ goto out;
+ case SHMCTL:
+ err = ksys_old_shmctl(first, (int)second | IPC_64, ptr);
+ goto out;
+ default:
+ err = -ENOSYS;
+ goto out;
+ }
+ } else {
+ err = -ENOSYS;
+ }
+out:
+ return err;
+}
+
+SYSCALL_DEFINE1(sparc64_personality, unsigned long, personality)
+{
+ long ret;
+
+ if (personality(current->personality) == PER_LINUX32 &&
+ personality(personality) == PER_LINUX)
+ personality |= PER_LINUX32;
+ ret = sys_personality(personality);
+ if (personality(ret) == PER_LINUX32)
+ ret &= ~PER_LINUX32;
+
+ return ret;
+}
+
+int sparc_mmap_check(unsigned long addr, unsigned long len)
+{
+ if (test_thread_flag(TIF_32BIT)) {
+ if (len >= STACK_TOP32)
+ return -EINVAL;
+
+ if (addr > STACK_TOP32 - len)
+ return -EINVAL;
+ } else {
+ if (len >= VA_EXCLUDE_START)
+ return -EINVAL;
+
+ if (invalid_64bit_range(addr, len))
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+/* Linux version of mmap */
+SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
+ unsigned long, prot, unsigned long, flags, unsigned long, fd,
+ unsigned long, off)
+{
+ unsigned long retval = -EINVAL;
+
+ if ((off + PAGE_ALIGN(len)) < off)
+ goto out;
+ if (off & ~PAGE_MASK)
+ goto out;
+ retval = ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
+out:
+ return retval;
+}
+
+SYSCALL_DEFINE2(64_munmap, unsigned long, addr, size_t, len)
+{
+ if (invalid_64bit_range(addr, len))
+ return -EINVAL;
+
+ return vm_munmap(addr, len);
+}
+
+SYSCALL_DEFINE5(64_mremap, unsigned long, addr, unsigned long, old_len,
+ unsigned long, new_len, unsigned long, flags,
+ unsigned long, new_addr)
+{
+ if (test_thread_flag(TIF_32BIT))
+ return -EINVAL;
+ return sys_mremap(addr, old_len, new_len, flags, new_addr);
+}
+
+SYSCALL_DEFINE0(nis_syscall)
+{
+ static int count;
+ struct pt_regs *regs = current_pt_regs();
+
+ /* Don't make the system unusable, if someone goes stuck */
+ if (count++ > 5)
+ return -ENOSYS;
+
+ printk ("Unimplemented SPARC system call %ld\n",regs->u_regs[1]);
+#ifdef DEBUG_UNIMP_SYSCALL
+ show_regs (regs);
+#endif
+
+ return -ENOSYS;
+}
+
+/* #define DEBUG_SPARC_BREAKPOINT */
+
+asmlinkage void sparc_breakpoint(struct pt_regs *regs)
+{
+ enum ctx_state prev_state = exception_enter();
+
+ if (test_thread_flag(TIF_32BIT)) {
+ regs->tpc &= 0xffffffff;
+ regs->tnpc &= 0xffffffff;
+ }
+#ifdef DEBUG_SPARC_BREAKPOINT
+ printk ("TRAP: Entering kernel PC=%lx, nPC=%lx\n", regs->tpc, regs->tnpc);
+#endif
+ force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->tpc, 0);
+#ifdef DEBUG_SPARC_BREAKPOINT
+ printk ("TRAP: Returning to space: PC=%lx nPC=%lx\n", regs->tpc, regs->tnpc);
+#endif
+ exception_exit(prev_state);
+}
+
+SYSCALL_DEFINE2(getdomainname, char __user *, name, int, len)
+{
+ int nlen, err;
+ char tmp[__NEW_UTS_LEN + 1];
+
+ if (len < 0)
+ return -EINVAL;
+
+ down_read(&uts_sem);
+
+ nlen = strlen(utsname()->domainname) + 1;
+ err = -EINVAL;
+ if (nlen > len)
+ goto out_unlock;
+ memcpy(tmp, utsname()->domainname, nlen);
+
+ up_read(&uts_sem);
+
+ if (copy_to_user(name, tmp, nlen))
+ return -EFAULT;
+ return 0;
+
+out_unlock:
+ up_read(&uts_sem);
+ return err;
+}
+
+SYSCALL_DEFINE1(sparc_adjtimex, struct __kernel_timex __user *, txc_p)
+{
+ struct __kernel_timex txc;
+ struct __kernel_old_timeval *tv = (void *)&txc.time;
+ int ret;
+
+ /* Copy the user data space into the kernel copy
+ * structure. But bear in mind that the structures
+ * may change
+ */
+ if (copy_from_user(&txc, txc_p, sizeof(txc)))
+ return -EFAULT;
+
+ /*
+ * override for sparc64 specific timeval type: tv_usec
+ * is 32 bit wide instead of 64-bit in __kernel_timex
+ */
+ txc.time.tv_usec = tv->tv_usec;
+ ret = do_adjtimex(&txc);
+ tv->tv_usec = txc.time.tv_usec;
+
+ return copy_to_user(txc_p, &txc, sizeof(txc)) ? -EFAULT : ret;
+}
+
+SYSCALL_DEFINE2(sparc_clock_adjtime, const clockid_t, which_clock,
+ struct __kernel_timex __user *, txc_p)
+{
+ struct __kernel_timex txc;
+ struct __kernel_old_timeval *tv = (void *)&txc.time;
+ int ret;
+
+ if (!IS_ENABLED(CONFIG_POSIX_TIMERS)) {
+ pr_err_once("process %d (%s) attempted a POSIX timer syscall "
+ "while CONFIG_POSIX_TIMERS is not set\n",
+ current->pid, current->comm);
+
+ return -ENOSYS;
+ }
+
+ /* Copy the user data space into the kernel copy
+ * structure. But bear in mind that the structures
+ * may change
+ */
+ if (copy_from_user(&txc, txc_p, sizeof(txc)))
+ return -EFAULT;
+
+ /*
+ * override for sparc64 specific timeval type: tv_usec
+ * is 32 bit wide instead of 64-bit in __kernel_timex
+ */
+ txc.time.tv_usec = tv->tv_usec;
+ ret = do_clock_adjtime(which_clock, &txc);
+ tv->tv_usec = txc.time.tv_usec;
+
+ return copy_to_user(txc_p, &txc, sizeof(txc)) ? -EFAULT : ret;
+}
+
+SYSCALL_DEFINE5(utrap_install, utrap_entry_t, type,
+ utrap_handler_t, new_p, utrap_handler_t, new_d,
+ utrap_handler_t __user *, old_p,
+ utrap_handler_t __user *, old_d)
+{
+ if (type < UT_INSTRUCTION_EXCEPTION || type > UT_TRAP_INSTRUCTION_31)
+ return -EINVAL;
+ if (new_p == (utrap_handler_t)(long)UTH_NOCHANGE) {
+ if (old_p) {
+ if (!current_thread_info()->utraps) {
+ if (put_user(NULL, old_p))
+ return -EFAULT;
+ } else {
+ if (put_user((utrap_handler_t)(current_thread_info()->utraps[type]), old_p))
+ return -EFAULT;
+ }
+ }
+ if (old_d) {
+ if (put_user(NULL, old_d))
+ return -EFAULT;
+ }
+ return 0;
+ }
+ if (!current_thread_info()->utraps) {
+ current_thread_info()->utraps =
+ kcalloc(UT_TRAP_INSTRUCTION_31 + 1, sizeof(long),
+ GFP_KERNEL);
+ if (!current_thread_info()->utraps)
+ return -ENOMEM;
+ current_thread_info()->utraps[0] = 1;
+ } else {
+ if ((utrap_handler_t)current_thread_info()->utraps[type] != new_p &&
+ current_thread_info()->utraps[0] > 1) {
+ unsigned long *p = current_thread_info()->utraps;
+
+ current_thread_info()->utraps =
+ kmalloc_array(UT_TRAP_INSTRUCTION_31 + 1,
+ sizeof(long),
+ GFP_KERNEL);
+ if (!current_thread_info()->utraps) {
+ current_thread_info()->utraps = p;
+ return -ENOMEM;
+ }
+ p[0]--;
+ current_thread_info()->utraps[0] = 1;
+ memcpy(current_thread_info()->utraps+1, p+1,
+ UT_TRAP_INSTRUCTION_31*sizeof(long));
+ }
+ }
+ if (old_p) {
+ if (put_user((utrap_handler_t)(current_thread_info()->utraps[type]), old_p))
+ return -EFAULT;
+ }
+ if (old_d) {
+ if (put_user(NULL, old_d))
+ return -EFAULT;
+ }
+ current_thread_info()->utraps[type] = (long)new_p;
+
+ return 0;
+}
+
+SYSCALL_DEFINE1(memory_ordering, unsigned long, model)
+{
+ struct pt_regs *regs = current_pt_regs();
+ if (model >= 3)
+ return -EINVAL;
+ regs->tstate = (regs->tstate & ~TSTATE_MM) | (model << 14);
+ return 0;
+}
+
+SYSCALL_DEFINE5(rt_sigaction, int, sig, const struct sigaction __user *, act,
+ struct sigaction __user *, oact, void __user *, restorer,
+ size_t, sigsetsize)
+{
+ struct k_sigaction new_ka, old_ka;
+ int ret;
+
+ /* XXX: Don't preclude handling different sized sigset_t's. */
+ if (sigsetsize != sizeof(sigset_t))
+ return -EINVAL;
+
+ if (act) {
+ new_ka.ka_restorer = restorer;
+ if (copy_from_user(&new_ka.sa, act, sizeof(*act)))
+ return -EFAULT;
+ }
+
+ ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
+
+ if (!ret && oact) {
+ if (copy_to_user(oact, &old_ka.sa, sizeof(*oact)))
+ return -EFAULT;
+ }
+
+ return ret;
+}
+
+SYSCALL_DEFINE0(kern_features)
+{
+ return KERN_FEATURE_MIXED_MODE_STACK;
+}