Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 727 insertions, 0 deletions

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
new file mode 100644
index 000000000..a3a38d0a4
--- /dev/null
+++ b/arch/arm/kernel/signal.c
@@ -0,0 +1,727 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  linux/arch/arm/kernel/signal.c
+ *
+ *  Copyright (C) 1995-2009 Russell King
+ */
+#include <linux/errno.h>
+#include <linux/random.h>
+#include <linux/signal.h>
+#include <linux/personality.h>
+#include <linux/uaccess.h>
+#include <linux/tracehook.h>
+#include <linux/uprobes.h>
+#include <linux/syscalls.h>
+
+#include <asm/elf.h>
+#include <asm/cacheflush.h>
+#include <asm/traps.h>
+#include <asm/unistd.h>
+#include <asm/vfp.h>
+
+#include "signal.h"
+
+extern const unsigned long sigreturn_codes[17];
+
+static unsigned long signal_return_offset;
+
+#ifdef CONFIG_CRUNCH
+static int preserve_crunch_context(struct crunch_sigframe __user *frame)
+{
+	char kbuf[sizeof(*frame) + 8];
+	struct crunch_sigframe *kframe;
+
+	/* the crunch context must be 64 bit aligned */
+	kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
+	kframe->magic = CRUNCH_MAGIC;
+	kframe->size = CRUNCH_STORAGE_SIZE;
+	crunch_task_copy(current_thread_info(), &kframe->storage);
+	return __copy_to_user(frame, kframe, sizeof(*frame));
+}
+
+static int restore_crunch_context(char __user **auxp)
+{
+	struct crunch_sigframe __user *frame =
+		(struct crunch_sigframe __user *)*auxp;
+	char kbuf[sizeof(*frame) + 8];
+	struct crunch_sigframe *kframe;
+
+	/* the crunch context must be 64 bit aligned */
+	kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
+	if (__copy_from_user(kframe, frame, sizeof(*frame)))
+		return -1;
+	if (kframe->magic != CRUNCH_MAGIC ||
+	    kframe->size != CRUNCH_STORAGE_SIZE)
+		return -1;
+	*auxp += CRUNCH_STORAGE_SIZE;
+	crunch_task_restore(current_thread_info(), &kframe->storage);
+	return 0;
+}
+#endif
+
+#ifdef CONFIG_IWMMXT
+
+static int preserve_iwmmxt_context(struct iwmmxt_sigframe __user *frame)
+{
+	char kbuf[sizeof(*frame) + 8];
+	struct iwmmxt_sigframe *kframe;
+	int err = 0;
+
+	/* the iWMMXt context must be 64 bit aligned */
+	kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
+
+	if (test_thread_flag(TIF_USING_IWMMXT)) {
+		kframe->magic = IWMMXT_MAGIC;
+		kframe->size = IWMMXT_STORAGE_SIZE;
+		iwmmxt_task_copy(current_thread_info(), &kframe->storage);
+	} else {
+		/*
+		 * For bug-compatibility with older kernels, some space
+		 * has to be reserved for iWMMXt even if it's not used.
+		 * Set the magic and size appropriately so that properly
+		 * written userspace can skip it reliably:
+		 */
+		*kframe = (struct iwmmxt_sigframe) {
+			.magic = DUMMY_MAGIC,
+			.size  = IWMMXT_STORAGE_SIZE,
+		};
+	}
+
+	err = __copy_to_user(frame, kframe, sizeof(*kframe));
+
+	return err;
+}
+
+static int restore_iwmmxt_context(char __user **auxp)
+{
+	struct iwmmxt_sigframe __user *frame =
+		(struct iwmmxt_sigframe __user *)*auxp;
+	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;
+
+	/*
+	 * For non-iWMMXt threads: a single iwmmxt_sigframe-sized dummy
+	 * block is discarded for compatibility with setup_sigframe() if
+	 * present, but we don't mandate its presence.  If some other
+	 * magic is here, it's not for us:
+	 */
+	if (!test_thread_flag(TIF_USING_IWMMXT) &&
+	    kframe->magic != DUMMY_MAGIC)
+		return 0;
+
+	if (kframe->size != IWMMXT_STORAGE_SIZE)
+		return -1;
+
+	if (test_thread_flag(TIF_USING_IWMMXT)) {
+		if (kframe->magic != IWMMXT_MAGIC)
+			return -1;
+
+		iwmmxt_task_restore(current_thread_info(), &kframe->storage);
+	}
+
+	*auxp += IWMMXT_STORAGE_SIZE;
+	return 0;
+}
+
+#endif
+
+#ifdef CONFIG_VFP
+
+static int preserve_vfp_context(struct vfp_sigframe __user *frame)
+{
+	struct vfp_sigframe kframe;
+	int err = 0;
+
+	memset(&kframe, 0, sizeof(kframe));
+	kframe.magic = VFP_MAGIC;
+	kframe.size = VFP_STORAGE_SIZE;
+
+	err = vfp_preserve_user_clear_hwstate(&kframe.ufp, &kframe.ufp_exc);
+	if (err)
+		return err;
+
+	return __copy_to_user(frame, &kframe, sizeof(kframe));
+}
+
+static int restore_vfp_context(char __user **auxp)
+{
+	struct vfp_sigframe frame;
+	int err;
+
+	err = __copy_from_user(&frame, *auxp, sizeof(frame));
+	if (err)
+		return err;
+
+	if (frame.magic != VFP_MAGIC || frame.size != VFP_STORAGE_SIZE)
+		return -EINVAL;
+
+	*auxp += sizeof(frame);
+	return vfp_restore_user_hwstate(&frame.ufp, &frame.ufp_exc);
+}
+
+#endif
+
+/*
+ * Do a signal return; undo the signal stack.  These are aligned to 64-bit.
+ */
+
+static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
+{
+	struct sigcontext context;
+	char __user *aux;
+	sigset_t set;
+	int err;
+
+	err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
+	if (err == 0)
+		set_current_blocked(&set);
+
+	err |= __copy_from_user(&context, &sf->uc.uc_mcontext, sizeof(context));
+	if (err == 0) {
+		regs->ARM_r0 = context.arm_r0;
+		regs->ARM_r1 = context.arm_r1;
+		regs->ARM_r2 = context.arm_r2;
+		regs->ARM_r3 = context.arm_r3;
+		regs->ARM_r4 = context.arm_r4;
+		regs->ARM_r5 = context.arm_r5;
+		regs->ARM_r6 = context.arm_r6;
+		regs->ARM_r7 = context.arm_r7;
+		regs->ARM_r8 = context.arm_r8;
+		regs->ARM_r9 = context.arm_r9;
+		regs->ARM_r10 = context.arm_r10;
+		regs->ARM_fp = context.arm_fp;
+		regs->ARM_ip = context.arm_ip;
+		regs->ARM_sp = context.arm_sp;
+		regs->ARM_lr = context.arm_lr;
+		regs->ARM_pc = context.arm_pc;
+		regs->ARM_cpsr = context.arm_cpsr;
+	}
+
+	err |= !valid_user_regs(regs);
+
+	aux = (char __user *) sf->uc.uc_regspace;
+#ifdef CONFIG_CRUNCH
+	if (err == 0)
+		err |= restore_crunch_context(&aux);
+#endif
+#ifdef CONFIG_IWMMXT
+	if (err == 0)
+		err |= restore_iwmmxt_context(&aux);
+#endif
+#ifdef CONFIG_VFP
+	if (err == 0)
+		err |= restore_vfp_context(&aux);
+#endif
+
+	return err;
+}
+
+asmlinkage int sys_sigreturn(struct pt_regs *regs)
+{
+	struct sigframe __user *frame;
+
+	/* Always make any pending restarted system calls return -EINTR */
+	current->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(frame, sizeof (*frame)))
+		goto badframe;
+
+	if (restore_sigframe(regs, frame))
+		goto badframe;
+
+	return regs->ARM_r0;
+
+badframe:
+	force_sig(SIGSEGV);
+	return 0;
+}
+
+asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
+{
+	struct rt_sigframe __user *frame;
+
+	/* Always make any pending restarted system calls return -EINTR */
+	current->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(frame, sizeof (*frame)))
+		goto badframe;
+
+	if (restore_sigframe(regs, &frame->sig))
+		goto badframe;
+
+	if (restore_altstack(&frame->sig.uc.uc_stack))
+		goto badframe;
+
+	return regs->ARM_r0;
+
+badframe:
+	force_sig(SIGSEGV);
+	return 0;
+}
+
+static int
+setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set)
+{
+	struct aux_sigframe __user *aux;
+	struct sigcontext context;
+	int err = 0;
+
+	context = (struct sigcontext) {
+		.arm_r0        = regs->ARM_r0,
+		.arm_r1        = regs->ARM_r1,
+		.arm_r2        = regs->ARM_r2,
+		.arm_r3        = regs->ARM_r3,
+		.arm_r4        = regs->ARM_r4,
+		.arm_r5        = regs->ARM_r5,
+		.arm_r6        = regs->ARM_r6,
+		.arm_r7        = regs->ARM_r7,
+		.arm_r8        = regs->ARM_r8,
+		.arm_r9        = regs->ARM_r9,
+		.arm_r10       = regs->ARM_r10,
+		.arm_fp        = regs->ARM_fp,
+		.arm_ip        = regs->ARM_ip,
+		.arm_sp        = regs->ARM_sp,
+		.arm_lr        = regs->ARM_lr,
+		.arm_pc        = regs->ARM_pc,
+		.arm_cpsr      = regs->ARM_cpsr,
+
+		.trap_no       = current->thread.trap_no,
+		.error_code    = current->thread.error_code,
+		.fault_address = current->thread.address,
+		.oldmask       = set->sig[0],
+	};
+
+	err |= __copy_to_user(&sf->uc.uc_mcontext, &context, sizeof(context));
+
+	err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
+
+	aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
+#ifdef CONFIG_CRUNCH
+	if (err == 0)
+		err |= preserve_crunch_context(&aux->crunch);
+#endif
+#ifdef CONFIG_IWMMXT
+	if (err == 0)
+		err |= preserve_iwmmxt_context(&aux->iwmmxt);
+#endif
+#ifdef CONFIG_VFP
+	if (err == 0)
+		err |= preserve_vfp_context(&aux->vfp);
+#endif
+	err |= __put_user(0, &aux->end_magic);
+
+	return err;
+}
+
+static inline void __user *
+get_sigframe(struct ksignal *ksig, struct pt_regs *regs, int framesize)
+{
+	unsigned long sp = sigsp(regs->ARM_sp, ksig);
+	void __user *frame;
+
+	/*
+	 * 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(frame, framesize))
+		frame = NULL;
+
+	return frame;
+}
+
+static int
+setup_return(struct pt_regs *regs, struct ksignal *ksig,
+	     unsigned long __user *rc, void __user *frame)
+{
+	unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler;
+	unsigned long handler_fdpic_GOT = 0;
+	unsigned long retcode;
+	unsigned int idx, thumb = 0;
+	unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT);
+	bool fdpic = IS_ENABLED(CONFIG_BINFMT_ELF_FDPIC) &&
+		     (current->personality & FDPIC_FUNCPTRS);
+
+	if (fdpic) {
+		unsigned long __user *fdpic_func_desc =
+					(unsigned long __user *)handler;
+		if (__get_user(handler, &fdpic_func_desc[0]) ||
+		    __get_user(handler_fdpic_GOT, &fdpic_func_desc[1]))
+			return 1;
+	}
+
+	cpsr |= PSR_ENDSTATE;
+
+	/*
+	 * Maybe we need to deliver a 32-bit signal to a 26-bit task.
+	 */
+	if (ksig->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;
+
+		/*
+		 * Clear the If-Then Thumb-2 execution state.  ARM spec
+		 * requires this to be all 000s in ARM mode.  Snapdragon
+		 * S4/Krait misbehaves on a Thumb=>ARM signal transition
+		 * without this.
+		 *
+		 * We must do this whenever we are running on a Thumb-2
+		 * capable CPU, which includes ARMv6T2.  However, we elect
+		 * to always do this to simplify the code; this field is
+		 * marked UNK/SBZP for older architectures.
+		 */
+		cpsr &= ~PSR_IT_MASK;
+
+		if (thumb) {
+			cpsr |= PSR_T_BIT;
+		} else
+			cpsr &= ~PSR_T_BIT;
+	}
+#endif
+
+	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
+		retcode = (unsigned long)ksig->ka.sa.sa_restorer;
+		if (fdpic) {
+			/*
+			 * We need code to load the function descriptor.
+			 * That code follows the standard sigreturn code
+			 * (6 words), and is made of 3 + 2 words for each
+			 * variant. The 4th copied word is the actual FD
+			 * address that the assembly code expects.
+			 */
+			idx = 6 + thumb * 3;
+			if (ksig->ka.sa.sa_flags & SA_SIGINFO)
+				idx += 5;
+			if (__put_user(sigreturn_codes[idx],   rc  ) ||
+			    __put_user(sigreturn_codes[idx+1], rc+1) ||
+			    __put_user(sigreturn_codes[idx+2], rc+2) ||
+			    __put_user(retcode,                rc+3))
+				return 1;
+			goto rc_finish;
+		}
+	} else {
+		idx = thumb << 1;
+		if (ksig->ka.sa.sa_flags & SA_SIGINFO)
+			idx += 3;
+
+		/*
+		 * Put the sigreturn code on the stack no matter which return
+		 * mechanism we use in order to remain ABI compliant
+		 */
+		if (__put_user(sigreturn_codes[idx],   rc) ||
+		    __put_user(sigreturn_codes[idx+1], rc+1))
+			return 1;
+
+rc_finish:
+#ifdef CONFIG_MMU
+		if (cpsr & MODE32_BIT) {
+			struct mm_struct *mm = current->mm;
+
+			/*
+			 * 32-bit code can use the signal return page
+			 * except when the MPU has protected the vectors
+			 * page from PL0
+			 */
+			retcode = mm->context.sigpage + signal_return_offset +
+				  (idx << 2) + thumb;
+		} else
+#endif
+		{
+			/*
+			 * Ensure that the instruction cache sees
+			 * the return code written onto the stack.
+			 */
+			flush_icache_range((unsigned long)rc,
+					   (unsigned long)(rc + 3));
+
+			retcode = ((unsigned long)rc) + thumb;
+		}
+	}
+
+	regs->ARM_r0 = ksig->sig;
+	regs->ARM_sp = (unsigned long)frame;
+	regs->ARM_lr = retcode;
+	regs->ARM_pc = handler;
+	if (fdpic)
+		regs->ARM_r9 = handler_fdpic_GOT;
+	regs->ARM_cpsr = cpsr;
+
+	return 0;
+}
+
+static int
+setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
+{
+	struct sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame));
+	int err = 0;
+
+	if (!frame)
+		return 1;
+
+	/*
+	 * Set uc.uc_flags to a value which sc.trap_no would never have.
+	 */
+	err = __put_user(0x5ac3c35a, &frame->uc.uc_flags);
+
+	err |= setup_sigframe(frame, regs, set);
+	if (err == 0)
+		err = setup_return(regs, ksig, frame->retcode, frame);
+
+	return err;
+}
+
+static int
+setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
+{
+	struct rt_sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame));
+	int err = 0;
+
+	if (!frame)
+		return 1;
+
+	err |= copy_siginfo_to_user(&frame->info, &ksig->info);
+
+	err |= __put_user(0, &frame->sig.uc.uc_flags);
+	err |= __put_user(NULL, &frame->sig.uc.uc_link);
+
+	err |= __save_altstack(&frame->sig.uc.uc_stack, regs->ARM_sp);
+	err |= setup_sigframe(&frame->sig, regs, set);
+	if (err == 0)
+		err = setup_return(regs, ksig, frame->sig.retcode, frame);
+
+	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->sig.uc;
+	}
+
+	return err;
+}
+
+/*
+ * OK, we're invoking a handler
+ */	
+static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
+{
+	sigset_t *oldset = sigmask_to_save();
+	int ret;
+
+	/*
+	 * Perform fixup for the pre-signal frame.
+	 */
+	rseq_signal_deliver(ksig, regs);
+
+	/*
+	 * Set up the stack frame
+	 */
+	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
+		ret = setup_rt_frame(ksig, oldset, regs);
+	else
+		ret = setup_frame(ksig, oldset, regs);
+
+	/*
+	 * Check that the resulting registers are actually sane.
+	 */
+	ret |= !valid_user_regs(regs);
+
+	signal_setup_done(ret, ksig, 0);
+}
+
+/*
+ * 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(struct pt_regs *regs, int syscall)
+{
+	unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
+	struct ksignal ksig;
+	int restart = 0;
+
+	/*
+	 * If we were from a system call, check for system call restarting...
+	 */
+	if (syscall) {
+		continue_addr = regs->ARM_pc;
+		restart_addr = continue_addr - (thumb_mode(regs) ? 2 : 4);
+		retval = regs->ARM_r0;
+
+		/*
+		 * Prepare for system call restart.  We do this here so that a
+		 * debugger will see the already changed PSW.
+		 */
+		switch (retval) {
+		case -ERESTART_RESTARTBLOCK:
+			restart -= 2;
+			fallthrough;
+		case -ERESTARTNOHAND:
+		case -ERESTARTSYS:
+		case -ERESTARTNOINTR:
+			restart++;
+			regs->ARM_r0 = regs->ARM_ORIG_r0;
+			regs->ARM_pc = restart_addr;
+			break;
+		}
+	}
+
+	/*
+	 * Get the signal to deliver.  When running under ptrace, at this
+	 * point the debugger may change all our registers ...
+	 */
+	/*
+	 * Depending on the signal settings we may need to revert the
+	 * decision to restart the system call.  But skip this if a
+	 * debugger has chosen to restart at a different PC.
+	 */
+	if (get_signal(&ksig)) {
+		/* handler */
+		if (unlikely(restart) && regs->ARM_pc == restart_addr) {
+			if (retval == -ERESTARTNOHAND ||
+			    retval == -ERESTART_RESTARTBLOCK
+			    || (retval == -ERESTARTSYS
+				&& !(ksig.ka.sa.sa_flags & SA_RESTART))) {
+				regs->ARM_r0 = -EINTR;
+				regs->ARM_pc = continue_addr;
+			}
+		}
+		handle_signal(&ksig, regs);
+	} else {
+		/* no handler */
+		restore_saved_sigmask();
+		if (unlikely(restart) && regs->ARM_pc == restart_addr) {
+			regs->ARM_pc = continue_addr;
+			return restart;
+		}
+	}
+	return 0;
+}
+
+asmlinkage int
+do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
+{
+	/*
+	 * The assembly code enters us with IRQs off, but it hasn't
+	 * informed the tracing code of that for efficiency reasons.
+	 * Update the trace code with the current status.
+	 */
+	trace_hardirqs_off();
+	do {
+		if (likely(thread_flags & _TIF_NEED_RESCHED)) {
+			schedule();
+		} else {
+			if (unlikely(!user_mode(regs)))
+				return 0;
+			local_irq_enable();
+			if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) {
+				int restart = do_signal(regs, syscall);
+				if (unlikely(restart)) {
+					/*
+					 * Restart without handlers.
+					 * Deal with it without leaving
+					 * the kernel space.
+					 */
+					return restart;
+				}
+				syscall = 0;
+			} else if (thread_flags & _TIF_UPROBE) {
+				uprobe_notify_resume(regs);
+			} else {
+				tracehook_notify_resume(regs);
+				rseq_handle_notify_resume(NULL, regs);
+			}
+		}
+		local_irq_disable();
+		thread_flags = current_thread_info()->flags;
+	} while (thread_flags & _TIF_WORK_MASK);
+	return 0;
+}
+
+struct page *get_signal_page(void)
+{
+	unsigned long ptr;
+	unsigned offset;
+	struct page *page;
+	void *addr;
+
+	page = alloc_pages(GFP_KERNEL, 0);
+
+	if (!page)
+		return NULL;
+
+	addr = page_address(page);
+
+	/* Poison the entire page */
+	memset32(addr, __opcode_to_mem_arm(0xe7fddef1),
+		 PAGE_SIZE / sizeof(u32));
+
+	/* Give the signal return code some randomness */
+	offset = 0x200 + (get_random_int() & 0x7fc);
+	signal_return_offset = offset;
+
+	/* Copy signal return handlers into the page */
+	memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes));
+
+	/* Flush out all instructions in this page */
+	ptr = (unsigned long)addr;
+	flush_icache_range(ptr, ptr + PAGE_SIZE);
+
+	return page;
+}
+
+/* Defer to generic check */
+asmlinkage void addr_limit_check_failed(void)
+{
+#ifdef CONFIG_MMU
+	addr_limit_user_check();
+#endif
+}
+
+#ifdef CONFIG_DEBUG_RSEQ
+asmlinkage void do_rseq_syscall(struct pt_regs *regs)
+{
+	rseq_syscall(regs);
+}
+#endif