Adding upstream version 4.19.249.upstream/4.19.249upstream

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

1 files changed, 878 insertions, 0 deletions

diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
new file mode 100644
index 000000000..16e908000
--- /dev/null
+++ b/arch/x86/kernel/signal.c
@@ -0,0 +1,878 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  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
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/wait.h>
+#include <linux/tracehook.h>
+#include <linux/unistd.h>
+#include <linux/stddef.h>
+#include <linux/personality.h>
+#include <linux/uaccess.h>
+#include <linux/user-return-notifier.h>
+#include <linux/uprobes.h>
+#include <linux/context_tracking.h>
+#include <linux/syscalls.h>
+
+#include <asm/processor.h>
+#include <asm/ucontext.h>
+#include <asm/fpu/internal.h>
+#include <asm/fpu/signal.h>
+#include <asm/vdso.h>
+#include <asm/mce.h>
+#include <asm/sighandling.h>
+#include <asm/vm86.h>
+
+#ifdef CONFIG_X86_64
+#include <asm/proto.h>
+#include <asm/ia32_unistd.h>
+#endif /* CONFIG_X86_64 */
+
+#include <asm/syscall.h>
+#include <asm/syscalls.h>
+
+#include <asm/sigframe.h>
+#include <asm/signal.h>
+
+#define COPY(x)			do {			\
+	get_user_ex(regs->x, &sc->x);			\
+} while (0)
+
+#define GET_SEG(seg)		({			\
+	unsigned short tmp;				\
+	get_user_ex(tmp, &sc->seg);			\
+	tmp;						\
+})
+
+#define COPY_SEG(seg)		do {			\
+	regs->seg = GET_SEG(seg);			\
+} while (0)
+
+#define COPY_SEG_CPL3(seg)	do {			\
+	regs->seg = GET_SEG(seg) | 3;			\
+} while (0)
+
+#ifdef CONFIG_X86_64
+/*
+ * If regs->ss will cause an IRET fault, change it.  Otherwise leave it
+ * alone.  Using this generally makes no sense unless
+ * user_64bit_mode(regs) would return true.
+ */
+static void force_valid_ss(struct pt_regs *regs)
+{
+	u32 ar;
+	asm volatile ("lar %[old_ss], %[ar]\n\t"
+		      "jz 1f\n\t"		/* If invalid: */
+		      "xorl %[ar], %[ar]\n\t"	/* set ar = 0 */
+		      "1:"
+		      : [ar] "=r" (ar)
+		      : [old_ss] "rm" ((u16)regs->ss));
+
+	/*
+	 * For a valid 64-bit user context, we need DPL 3, type
+	 * read-write data or read-write exp-down data, and S and P
+	 * set.  We can't use VERW because VERW doesn't check the
+	 * P bit.
+	 */
+	ar &= AR_DPL_MASK | AR_S | AR_P | AR_TYPE_MASK;
+	if (ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA) &&
+	    ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN))
+		regs->ss = __USER_DS;
+}
+#endif
+
+static int restore_sigcontext(struct pt_regs *regs,
+			      struct sigcontext __user *sc,
+			      unsigned long uc_flags)
+{
+	unsigned long buf_val;
+	void __user *buf;
+	unsigned int tmpflags;
+	unsigned int err = 0;
+
+	/* Always make any pending restarted system calls return -EINTR */
+	current->restart_block.fn = do_no_restart_syscall;
+
+	get_user_try {
+
+#ifdef CONFIG_X86_32
+		set_user_gs(regs, GET_SEG(gs));
+		COPY_SEG(fs);
+		COPY_SEG(es);
+		COPY_SEG(ds);
+#endif /* CONFIG_X86_32 */
+
+		COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
+		COPY(dx); COPY(cx); COPY(ip); COPY(ax);
+
+#ifdef CONFIG_X86_64
+		COPY(r8);
+		COPY(r9);
+		COPY(r10);
+		COPY(r11);
+		COPY(r12);
+		COPY(r13);
+		COPY(r14);
+		COPY(r15);
+#endif /* CONFIG_X86_64 */
+
+		COPY_SEG_CPL3(cs);
+		COPY_SEG_CPL3(ss);
+
+		get_user_ex(tmpflags, &sc->flags);
+		regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
+		regs->orig_ax = -1;		/* disable syscall checks */
+
+		get_user_ex(buf_val, &sc->fpstate);
+		buf = (void __user *)buf_val;
+	} get_user_catch(err);
+
+#ifdef CONFIG_X86_64
+	/*
+	 * Fix up SS if needed for the benefit of old DOSEMU and
+	 * CRIU.
+	 */
+	if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && user_64bit_mode(regs)))
+		force_valid_ss(regs);
+#endif
+
+	err |= fpu__restore_sig(buf, IS_ENABLED(CONFIG_X86_32));
+
+	force_iret();
+
+	return err;
+}
+
+int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
+		     struct pt_regs *regs, unsigned long mask)
+{
+	int err = 0;
+
+	put_user_try {
+
+#ifdef CONFIG_X86_32
+		put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs);
+		put_user_ex(regs->fs, (unsigned int __user *)&sc->fs);
+		put_user_ex(regs->es, (unsigned int __user *)&sc->es);
+		put_user_ex(regs->ds, (unsigned int __user *)&sc->ds);
+#endif /* CONFIG_X86_32 */
+
+		put_user_ex(regs->di, &sc->di);
+		put_user_ex(regs->si, &sc->si);
+		put_user_ex(regs->bp, &sc->bp);
+		put_user_ex(regs->sp, &sc->sp);
+		put_user_ex(regs->bx, &sc->bx);
+		put_user_ex(regs->dx, &sc->dx);
+		put_user_ex(regs->cx, &sc->cx);
+		put_user_ex(regs->ax, &sc->ax);
+#ifdef CONFIG_X86_64
+		put_user_ex(regs->r8, &sc->r8);
+		put_user_ex(regs->r9, &sc->r9);
+		put_user_ex(regs->r10, &sc->r10);
+		put_user_ex(regs->r11, &sc->r11);
+		put_user_ex(regs->r12, &sc->r12);
+		put_user_ex(regs->r13, &sc->r13);
+		put_user_ex(regs->r14, &sc->r14);
+		put_user_ex(regs->r15, &sc->r15);
+#endif /* CONFIG_X86_64 */
+
+		put_user_ex(current->thread.trap_nr, &sc->trapno);
+		put_user_ex(current->thread.error_code, &sc->err);
+		put_user_ex(regs->ip, &sc->ip);
+#ifdef CONFIG_X86_32
+		put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
+		put_user_ex(regs->flags, &sc->flags);
+		put_user_ex(regs->sp, &sc->sp_at_signal);
+		put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
+#else /* !CONFIG_X86_32 */
+		put_user_ex(regs->flags, &sc->flags);
+		put_user_ex(regs->cs, &sc->cs);
+		put_user_ex(0, &sc->gs);
+		put_user_ex(0, &sc->fs);
+		put_user_ex(regs->ss, &sc->ss);
+#endif /* CONFIG_X86_32 */
+
+		put_user_ex(fpstate, &sc->fpstate);
+
+		/* non-iBCS2 extensions.. */
+		put_user_ex(mask, &sc->oldmask);
+		put_user_ex(current->thread.cr2, &sc->cr2);
+	} put_user_catch(err);
+
+	return err;
+}
+
+/*
+ * Set up a signal frame.
+ */
+
+/*
+ * Determine which stack to use..
+ */
+static unsigned long align_sigframe(unsigned long sp)
+{
+#ifdef CONFIG_X86_32
+	/*
+	 * Align the stack pointer according to the i386 ABI,
+	 * i.e. so that on function entry ((sp + 4) & 15) == 0.
+	 */
+	sp = ((sp + 4) & -16ul) - 4;
+#else /* !CONFIG_X86_32 */
+	sp = round_down(sp, 16) - 8;
+#endif
+	return sp;
+}
+
+static void __user *
+get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
+	     void __user **fpstate)
+{
+	/* Default to using normal stack */
+	unsigned long math_size = 0;
+	unsigned long sp = regs->sp;
+	unsigned long buf_fx = 0;
+	int onsigstack = on_sig_stack(sp);
+	struct fpu *fpu = &current->thread.fpu;
+
+	/* redzone */
+	if (IS_ENABLED(CONFIG_X86_64))
+		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;
+	} else if (IS_ENABLED(CONFIG_X86_32) &&
+		   !onsigstack &&
+		   regs->ss != __USER_DS &&
+		   !(ka->sa.sa_flags & SA_RESTORER) &&
+		   ka->sa.sa_restorer) {
+		/* This is the legacy signal stack switching. */
+		sp = (unsigned long) ka->sa.sa_restorer;
+	}
+
+	if (fpu->initialized) {
+		sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32),
+					  &buf_fx, &math_size);
+		*fpstate = (void __user *)sp;
+	}
+
+	sp = align_sigframe(sp - frame_size);
+
+	/*
+	 * 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 (onsigstack && !likely(on_sig_stack(sp)))
+		return (void __user *)-1L;
+
+	/* save i387 and extended state */
+	if (fpu->initialized &&
+	    copy_fpstate_to_sigframe(*fpstate, (void __user *)buf_fx, math_size) < 0)
+		return (void __user *)-1L;
+
+	return (void __user *)sp;
+}
+
+#ifdef CONFIG_X86_32
+static const struct {
+	u16 poplmovl;
+	u32 val;
+	u16 int80;
+} __attribute__((packed)) retcode = {
+	0xb858,		/* popl %eax; movl $..., %eax */
+	__NR_sigreturn,
+	0x80cd,		/* int $0x80 */
+};
+
+static const struct {
+	u8  movl;
+	u32 val;
+	u16 int80;
+	u8  pad;
+} __attribute__((packed)) rt_retcode = {
+	0xb8,		/* movl $..., %eax */
+	__NR_rt_sigreturn,
+	0x80cd,		/* int $0x80 */
+	0
+};
+
+static int
+__setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
+	      struct pt_regs *regs)
+{
+	struct sigframe __user *frame;
+	void __user *restorer;
+	int err = 0;
+	void __user *fpstate = NULL;
+
+	frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
+
+	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
+		return -EFAULT;
+
+	if (__put_user(sig, &frame->sig))
+		return -EFAULT;
+
+	if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
+		return -EFAULT;
+
+	if (_NSIG_WORDS > 1) {
+		if (__copy_to_user(&frame->extramask, &set->sig[1],
+				   sizeof(frame->extramask)))
+			return -EFAULT;
+	}
+
+	if (current->mm->context.vdso)
+		restorer = current->mm->context.vdso +
+			vdso_image_32.sym___kernel_sigreturn;
+	else
+		restorer = &frame->retcode;
+	if (ksig->ka.sa.sa_flags & SA_RESTORER)
+		restorer = ksig->ka.sa.sa_restorer;
+
+	/* Set up to return from userspace.  */
+	err |= __put_user(restorer, &frame->pretcode);
+
+	/*
+	 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
+	 *
+	 * WE DO NOT USE IT ANY MORE! It's only left here for historical
+	 * reasons and because gdb uses it as a signature to notice
+	 * signal handler stack frames.
+	 */
+	err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
+
+	if (err)
+		return -EFAULT;
+
+	/* Set up registers for signal handler */
+	regs->sp = (unsigned long)frame;
+	regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
+	regs->ax = (unsigned long)sig;
+	regs->dx = 0;
+	regs->cx = 0;
+
+	regs->ds = __USER_DS;
+	regs->es = __USER_DS;
+	regs->ss = __USER_DS;
+	regs->cs = __USER_CS;
+
+	return 0;
+}
+
+static int __setup_rt_frame(int sig, struct ksignal *ksig,
+			    sigset_t *set, struct pt_regs *regs)
+{
+	struct rt_sigframe __user *frame;
+	void __user *restorer;
+	int err = 0;
+	void __user *fpstate = NULL;
+
+	frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
+
+	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
+		return -EFAULT;
+
+	put_user_try {
+		put_user_ex(sig, &frame->sig);
+		put_user_ex(&frame->info, &frame->pinfo);
+		put_user_ex(&frame->uc, &frame->puc);
+
+		/* Create the ucontext.  */
+		if (boot_cpu_has(X86_FEATURE_XSAVE))
+			put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
+		else
+			put_user_ex(0, &frame->uc.uc_flags);
+		put_user_ex(0, &frame->uc.uc_link);
+		save_altstack_ex(&frame->uc.uc_stack, regs->sp);
+
+		/* Set up to return from userspace.  */
+		restorer = current->mm->context.vdso +
+			vdso_image_32.sym___kernel_rt_sigreturn;
+		if (ksig->ka.sa.sa_flags & SA_RESTORER)
+			restorer = ksig->ka.sa.sa_restorer;
+		put_user_ex(restorer, &frame->pretcode);
+
+		/*
+		 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
+		 *
+		 * WE DO NOT USE IT ANY MORE! It's only left here for historical
+		 * reasons and because gdb uses it as a signature to notice
+		 * signal handler stack frames.
+		 */
+		put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode);
+	} put_user_catch(err);
+	
+	err |= copy_siginfo_to_user(&frame->info, &ksig->info);
+	err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
+				regs, set->sig[0]);
+	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
+
+	if (err)
+		return -EFAULT;
+
+	/* Set up registers for signal handler */
+	regs->sp = (unsigned long)frame;
+	regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
+	regs->ax = (unsigned long)sig;
+	regs->dx = (unsigned long)&frame->info;
+	regs->cx = (unsigned long)&frame->uc;
+
+	regs->ds = __USER_DS;
+	regs->es = __USER_DS;
+	regs->ss = __USER_DS;
+	regs->cs = __USER_CS;
+
+	return 0;
+}
+#else /* !CONFIG_X86_32 */
+static unsigned long frame_uc_flags(struct pt_regs *regs)
+{
+	unsigned long flags;
+
+	if (boot_cpu_has(X86_FEATURE_XSAVE))
+		flags = UC_FP_XSTATE | UC_SIGCONTEXT_SS;
+	else
+		flags = UC_SIGCONTEXT_SS;
+
+	if (likely(user_64bit_mode(regs)))
+		flags |= UC_STRICT_RESTORE_SS;
+
+	return flags;
+}
+
+static int __setup_rt_frame(int sig, struct ksignal *ksig,
+			    sigset_t *set, struct pt_regs *regs)
+{
+	struct rt_sigframe __user *frame;
+	void __user *fp = NULL;
+	unsigned long uc_flags;
+	int err = 0;
+
+	frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
+
+	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
+		return -EFAULT;
+
+	if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
+		if (copy_siginfo_to_user(&frame->info, &ksig->info))
+			return -EFAULT;
+	}
+
+	uc_flags = frame_uc_flags(regs);
+
+	put_user_try {
+		/* Create the ucontext.  */
+		put_user_ex(uc_flags, &frame->uc.uc_flags);
+		put_user_ex(0, &frame->uc.uc_link);
+		save_altstack_ex(&frame->uc.uc_stack, regs->sp);
+
+		/* Set up to return from userspace.  If provided, use a stub
+		   already in userspace.  */
+		/* x86-64 should always use SA_RESTORER. */
+		if (ksig->ka.sa.sa_flags & SA_RESTORER) {
+			put_user_ex(ksig->ka.sa.sa_restorer, &frame->pretcode);
+		} else {
+			/* could use a vstub here */
+			err |= -EFAULT;
+		}
+	} put_user_catch(err);
+
+	err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]);
+	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
+
+	if (err)
+		return -EFAULT;
+
+	/* 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) ksig->ka.sa.sa_handler;
+
+	regs->sp = (unsigned long)frame;
+
+	/*
+	 * Set up the CS and SS registers to run signal handlers in
+	 * 64-bit mode, even if the handler happens to be interrupting
+	 * 32-bit or 16-bit code.
+	 *
+	 * SS is subtle.  In 64-bit mode, we don't need any particular
+	 * SS descriptor, but we do need SS to be valid.  It's possible
+	 * that the old SS is entirely bogus -- this can happen if the
+	 * signal we're trying to deliver is #GP or #SS caused by a bad
+	 * SS value.  We also have a compatbility issue here: DOSEMU
+	 * relies on the contents of the SS register indicating the
+	 * SS value at the time of the signal, even though that code in
+	 * DOSEMU predates sigreturn's ability to restore SS.  (DOSEMU
+	 * avoids relying on sigreturn to restore SS; instead it uses
+	 * a trampoline.)  So we do our best: if the old SS was valid,
+	 * we keep it.  Otherwise we replace it.
+	 */
+	regs->cs = __USER_CS;
+
+	if (unlikely(regs->ss != __USER_DS))
+		force_valid_ss(regs);
+
+	return 0;
+}
+#endif /* CONFIG_X86_32 */
+
+static int x32_setup_rt_frame(struct ksignal *ksig,
+			      compat_sigset_t *set,
+			      struct pt_regs *regs)
+{
+#ifdef CONFIG_X86_X32_ABI
+	struct rt_sigframe_x32 __user *frame;
+	unsigned long uc_flags;
+	void __user *restorer;
+	int err = 0;
+	void __user *fpstate = NULL;
+
+	frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate);
+
+	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
+		return -EFAULT;
+
+	if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
+		if (__copy_siginfo_to_user32(&frame->info, &ksig->info, true))
+			return -EFAULT;
+	}
+
+	uc_flags = frame_uc_flags(regs);
+
+	put_user_try {
+		/* Create the ucontext.  */
+		put_user_ex(uc_flags, &frame->uc.uc_flags);
+		put_user_ex(0, &frame->uc.uc_link);
+		compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
+		put_user_ex(0, &frame->uc.uc__pad0);
+
+		if (ksig->ka.sa.sa_flags & SA_RESTORER) {
+			restorer = ksig->ka.sa.sa_restorer;
+		} else {
+			/* could use a vstub here */
+			restorer = NULL;
+			err |= -EFAULT;
+		}
+		put_user_ex(restorer, &frame->pretcode);
+	} put_user_catch(err);
+
+	err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
+				regs, set->sig[0]);
+	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
+
+	if (err)
+		return -EFAULT;
+
+	/* Set up registers for signal handler */
+	regs->sp = (unsigned long) frame;
+	regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
+
+	/* We use the x32 calling convention here... */
+	regs->di = ksig->sig;
+	regs->si = (unsigned long) &frame->info;
+	regs->dx = (unsigned long) &frame->uc;
+
+	loadsegment(ds, __USER_DS);
+	loadsegment(es, __USER_DS);
+
+	regs->cs = __USER_CS;
+	regs->ss = __USER_DS;
+#endif	/* CONFIG_X86_X32_ABI */
+
+	return 0;
+}
+
+/*
+ * Do a signal return; undo the signal stack.
+ */
+#ifdef CONFIG_X86_32
+SYSCALL_DEFINE0(sigreturn)
+{
+	struct pt_regs *regs = current_pt_regs();
+	struct sigframe __user *frame;
+	sigset_t set;
+
+	frame = (struct sigframe __user *)(regs->sp - 8);
+
+	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;
+
+	set_current_blocked(&set);
+
+	/*
+	 * x86_32 has no uc_flags bits relevant to restore_sigcontext.
+	 * Save a few cycles by skipping the __get_user.
+	 */
+	if (restore_sigcontext(regs, &frame->sc, 0))
+		goto badframe;
+	return regs->ax;
+
+badframe:
+	signal_fault(regs, frame, "sigreturn");
+
+	return 0;
+}
+#endif /* CONFIG_X86_32 */
+
+SYSCALL_DEFINE0(rt_sigreturn)
+{
+	struct pt_regs *regs = current_pt_regs();
+	struct rt_sigframe __user *frame;
+	sigset_t set;
+	unsigned long uc_flags;
+
+	frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
+	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
+		goto badframe;
+	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
+		goto badframe;
+	if (__get_user(uc_flags, &frame->uc.uc_flags))
+		goto badframe;
+
+	set_current_blocked(&set);
+
+	if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
+		goto badframe;
+
+	if (restore_altstack(&frame->uc.uc_stack))
+		goto badframe;
+
+	return regs->ax;
+
+badframe:
+	signal_fault(regs, frame, "rt_sigreturn");
+	return 0;
+}
+
+static inline int is_ia32_compat_frame(struct ksignal *ksig)
+{
+	return IS_ENABLED(CONFIG_IA32_EMULATION) &&
+		ksig->ka.sa.sa_flags & SA_IA32_ABI;
+}
+
+static inline int is_ia32_frame(struct ksignal *ksig)
+{
+	return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig);
+}
+
+static inline int is_x32_frame(struct ksignal *ksig)
+{
+	return IS_ENABLED(CONFIG_X86_X32_ABI) &&
+		ksig->ka.sa.sa_flags & SA_X32_ABI;
+}
+
+static int
+setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
+{
+	int usig = ksig->sig;
+	sigset_t *set = sigmask_to_save();
+	compat_sigset_t *cset = (compat_sigset_t *) set;
+
+	/*
+	 * Increment event counter and perform fixup for the pre-signal
+	 * frame.
+	 */
+	rseq_signal_deliver(ksig, regs);
+
+	/* Set up the stack frame */
+	if (is_ia32_frame(ksig)) {
+		if (ksig->ka.sa.sa_flags & SA_SIGINFO)
+			return ia32_setup_rt_frame(usig, ksig, cset, regs);
+		else
+			return ia32_setup_frame(usig, ksig, cset, regs);
+	} else if (is_x32_frame(ksig)) {
+		return x32_setup_rt_frame(ksig, cset, regs);
+	} else {
+		return __setup_rt_frame(ksig->sig, ksig, set, regs);
+	}
+}
+
+static void
+handle_signal(struct ksignal *ksig, struct pt_regs *regs)
+{
+	bool stepping, failed;
+	struct fpu *fpu = &current->thread.fpu;
+
+	if (v8086_mode(regs))
+		save_v86_state((struct kernel_vm86_regs *) regs, VM86_SIGNAL);
+
+	/* Are we from a system call? */
+	if (syscall_get_nr(current, regs) >= 0) {
+		/* If so, check system call restarting.. */
+		switch (syscall_get_error(current, regs)) {
+		case -ERESTART_RESTARTBLOCK:
+		case -ERESTARTNOHAND:
+			regs->ax = -EINTR;
+			break;
+
+		case -ERESTARTSYS:
+			if (!(ksig->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 TF now
+	 * so that register information in the sigcontext is correct and
+	 * then notify the tracer before entering the signal handler.
+	 */
+	stepping = test_thread_flag(TIF_SINGLESTEP);
+	if (stepping)
+		user_disable_single_step(current);
+
+	failed = (setup_rt_frame(ksig, regs) < 0);
+	if (!failed) {
+		/*
+		 * Clear the direction flag as per the ABI for function entry.
+		 *
+		 * Clear RF when entering the signal handler, because
+		 * it might disable possible debug exception from the
+		 * signal handler.
+		 *
+		 * Clear TF for the case when it wasn't set by debugger to
+		 * avoid the recursive send_sigtrap() in SIGTRAP handler.
+		 */
+		regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
+		/*
+		 * Ensure the signal handler starts with the new fpu state.
+		 */
+		if (fpu->initialized)
+			fpu__clear(fpu);
+	}
+	signal_setup_done(failed, ksig, stepping);
+}
+
+static inline unsigned long get_nr_restart_syscall(const struct pt_regs *regs)
+{
+#ifdef CONFIG_IA32_EMULATION
+	if (current_thread_info()->status & TS_COMPAT_RESTART)
+		return __NR_ia32_restart_syscall;
+#endif
+#ifdef CONFIG_X86_X32_ABI
+	return __NR_restart_syscall | (regs->orig_ax & __X32_SYSCALL_BIT);
+#else
+	return __NR_restart_syscall;
+#endif
+}
+
+/*
+ * 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.
+ */
+void do_signal(struct pt_regs *regs)
+{
+	struct ksignal ksig;
+
+	if (get_signal(&ksig)) {
+		/* Whee! Actually deliver the signal.  */
+		handle_signal(&ksig, regs);
+		return;
+	}
+
+	/* Did we come from a system call? */
+	if (syscall_get_nr(current, regs) >= 0) {
+		/* Restart the system call - no handlers present */
+		switch (syscall_get_error(current, regs)) {
+		case -ERESTARTNOHAND:
+		case -ERESTARTSYS:
+		case -ERESTARTNOINTR:
+			regs->ax = regs->orig_ax;
+			regs->ip -= 2;
+			break;
+
+		case -ERESTART_RESTARTBLOCK:
+			regs->ax = get_nr_restart_syscall(regs);
+			regs->ip -= 2;
+			break;
+		}
+	}
+
+	/*
+	 * If there's no signal to deliver, we just put the saved sigmask
+	 * back.
+	 */
+	restore_saved_sigmask();
+}
+
+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"
+		       "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx",
+		       task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
+		       me->comm, me->pid, where, frame,
+		       regs->ip, regs->sp, regs->orig_ax);
+		print_vma_addr(KERN_CONT " in ", regs->ip);
+		pr_cont("\n");
+	}
+
+	force_sig(SIGSEGV, me);
+}
+
+#ifdef CONFIG_X86_X32_ABI
+asmlinkage long sys32_x32_rt_sigreturn(void)
+{
+	struct pt_regs *regs = current_pt_regs();
+	struct rt_sigframe_x32 __user *frame;
+	sigset_t set;
+	unsigned long uc_flags;
+
+	frame = (struct rt_sigframe_x32 __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;
+	if (__get_user(uc_flags, &frame->uc.uc_flags))
+		goto badframe;
+
+	set_current_blocked(&set);
+
+	if (restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
+		goto badframe;
+
+	if (compat_restore_altstack(&frame->uc.uc_stack))
+		goto badframe;
+
+	return regs->ax;
+
+badframe:
+	signal_fault(regs, frame, "x32 rt_sigreturn");
+	return 0;
+}
+#endif