Merge tag 'x86-misc-2022-12-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull misc x86 updates from Thomas Gleixner:
 "Updates for miscellaneous x86 areas:

   - Reserve a new boot loader type for barebox which is usally used on
     ARM and MIPS, but can also be utilized as EFI payload on x86 to
     provide watchdog-supervised boot up.

   - Consolidate the native and compat 32bit signal handling code and
     split the 64bit version out into a separate source file

   - Switch the ESPFIX random usage to get_random_long()"

* tag 'x86-misc-2022-12-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/espfix: Use get_random_long() rather than archrandom
  x86/signal/64: Move 64-bit signal code to its own file
  x86/signal/32: Merge native and compat 32-bit signal code
  x86/signal: Add ABI prefixes to frame setup functions
  x86/signal: Merge get_sigframe()
  x86: Remove __USER32_DS
  signal/compat: Remove compat_sigset_t override
  x86/signal: Remove sigset_t parameter from frame setup functions
  x86/signal: Remove sig parameter from frame setup functions
  Documentation/x86/boot: Reserve type_of_loader=13 for barebox

5 files changed, 794 insertions, 638 deletions

diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index f901658d9f7c..cceaafdd2d84 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -44,7 +44,7 @@ obj-y			+= head_$(BITS).o
 obj-y			+= head$(BITS).o
 obj-y			+= ebda.o
 obj-y			+= platform-quirks.o
-obj-y			+= process_$(BITS).o signal.o
+obj-y			+= process_$(BITS).o signal.o signal_$(BITS).o
 obj-$(CONFIG_COMPAT)	+= signal_compat.o
 obj-y			+= traps.o idt.o irq.o irq_$(BITS).o dumpstack_$(BITS).o
 obj-y			+= time.o ioport.o dumpstack.o nmi.o
@@ -54,7 +54,7 @@ obj-$(CONFIG_JUMP_LABEL)	+= jump_label.o
 obj-$(CONFIG_IRQ_WORK)  += irq_work.o
 obj-y			+= probe_roms.o
 obj-$(CONFIG_X86_32)	+= sys_ia32.o
-obj-$(CONFIG_IA32_EMULATION)	+= sys_ia32.o
+obj-$(CONFIG_IA32_EMULATION)	+= sys_ia32.o signal_32.o
 obj-$(CONFIG_X86_64)	+= sys_x86_64.o
 obj-$(CONFIG_X86_ESPFIX64)	+= espfix_64.o
 obj-$(CONFIG_SYSFS)	+= ksysfs.o
diff --git a/arch/x86/kernel/espfix_64.c b/arch/x86/kernel/espfix_64.c
index 9417d5aa7305..16f9814c9be0 100644
--- a/arch/x86/kernel/espfix_64.c
+++ b/arch/x86/kernel/espfix_64.c
@@ -94,17 +94,7 @@ static inline unsigned long espfix_base_addr(unsigned int cpu)
 
 static void init_espfix_random(void)
 {
-	unsigned long rand;
-
-	/*
-	 * This is run before the entropy pools are initialized,
-	 * but this is hopefully better than nothing.
-	 */
-	if (!arch_get_random_longs(&rand, 1)) {
-		/* The constant is an arbitrary large prime */
-		rand = rdtsc();
-		rand *= 0xc345c6b72fd16123UL;
-	}
+	unsigned long rand = get_random_long();
 
 	slot_random = rand % ESPFIX_STACKS_PER_PAGE;
 	page_random = (rand / ESPFIX_STACKS_PER_PAGE)
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 9c7265b524c7..1504eb8d25aa 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -37,180 +37,27 @@
 #include <asm/sighandling.h>
 #include <asm/vm86.h>
 
-#ifdef CONFIG_X86_64
-#include <linux/compat.h>
-#include <asm/proto.h>
-#include <asm/ia32_unistd.h>
-#include <asm/fpu/xstate.h>
-#endif /* CONFIG_X86_64 */
-
 #include <asm/syscall.h>
 #include <asm/sigframe.h>
 #include <asm/signal.h>
 
-#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)
+static inline int is_ia32_compat_frame(struct ksignal *ksig)
 {
-	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;
+	return IS_ENABLED(CONFIG_IA32_EMULATION) &&
+		ksig->ka.sa.sa_flags & SA_IA32_ABI;
 }
-# define CONTEXT_COPY_SIZE	offsetof(struct sigcontext, reserved1)
-#else
-# define CONTEXT_COPY_SIZE	sizeof(struct sigcontext)
-#endif
 
-static bool restore_sigcontext(struct pt_regs *regs,
-			       struct sigcontext __user *usc,
-			       unsigned long uc_flags)
+static inline int is_ia32_frame(struct ksignal *ksig)
 {
-	struct sigcontext sc;
-
-	/* Always make any pending restarted system calls return -EINTR */
-	current->restart_block.fn = do_no_restart_syscall;
-
-	if (copy_from_user(&sc, usc, CONTEXT_COPY_SIZE))
-		return false;
-
-#ifdef CONFIG_X86_32
-	loadsegment(gs, sc.gs);
-	regs->fs = sc.fs;
-	regs->es = sc.es;
-	regs->ds = sc.ds;
-#endif /* CONFIG_X86_32 */
-
-	regs->bx = sc.bx;
-	regs->cx = sc.cx;
-	regs->dx = sc.dx;
-	regs->si = sc.si;
-	regs->di = sc.di;
-	regs->bp = sc.bp;
-	regs->ax = sc.ax;
-	regs->sp = sc.sp;
-	regs->ip = sc.ip;
-
-#ifdef CONFIG_X86_64
-	regs->r8 = sc.r8;
-	regs->r9 = sc.r9;
-	regs->r10 = sc.r10;
-	regs->r11 = sc.r11;
-	regs->r12 = sc.r12;
-	regs->r13 = sc.r13;
-	regs->r14 = sc.r14;
-	regs->r15 = sc.r15;
-#endif /* CONFIG_X86_64 */
-
-	/* Get CS/SS and force CPL3 */
-	regs->cs = sc.cs | 0x03;
-	regs->ss = sc.ss | 0x03;
-
-	regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS);
-	/* disable syscall checks */
-	regs->orig_ax = -1;
-
-#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
-
-	return fpu__restore_sig((void __user *)sc.fpstate,
-			       IS_ENABLED(CONFIG_X86_32));
+	return IS_ENABLED(CONFIG_X86_32) || is_ia32_compat_frame(ksig);
 }
 
-static __always_inline int
-__unsafe_setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
-		     struct pt_regs *regs, unsigned long mask)
+static inline int is_x32_frame(struct ksignal *ksig)
 {
-#ifdef CONFIG_X86_32
-	unsigned int gs;
-	savesegment(gs, gs);
-
-	unsafe_put_user(gs,	  (unsigned int __user *)&sc->gs, Efault);
-	unsafe_put_user(regs->fs, (unsigned int __user *)&sc->fs, Efault);
-	unsafe_put_user(regs->es, (unsigned int __user *)&sc->es, Efault);
-	unsafe_put_user(regs->ds, (unsigned int __user *)&sc->ds, Efault);
-#endif /* CONFIG_X86_32 */
-
-	unsafe_put_user(regs->di, &sc->di, Efault);
-	unsafe_put_user(regs->si, &sc->si, Efault);
-	unsafe_put_user(regs->bp, &sc->bp, Efault);
-	unsafe_put_user(regs->sp, &sc->sp, Efault);
-	unsafe_put_user(regs->bx, &sc->bx, Efault);
-	unsafe_put_user(regs->dx, &sc->dx, Efault);
-	unsafe_put_user(regs->cx, &sc->cx, Efault);
-	unsafe_put_user(regs->ax, &sc->ax, Efault);
-#ifdef CONFIG_X86_64
-	unsafe_put_user(regs->r8, &sc->r8, Efault);
-	unsafe_put_user(regs->r9, &sc->r9, Efault);
-	unsafe_put_user(regs->r10, &sc->r10, Efault);
-	unsafe_put_user(regs->r11, &sc->r11, Efault);
-	unsafe_put_user(regs->r12, &sc->r12, Efault);
-	unsafe_put_user(regs->r13, &sc->r13, Efault);
-	unsafe_put_user(regs->r14, &sc->r14, Efault);
-	unsafe_put_user(regs->r15, &sc->r15, Efault);
-#endif /* CONFIG_X86_64 */
-
-	unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault);
-	unsafe_put_user(current->thread.error_code, &sc->err, Efault);
-	unsafe_put_user(regs->ip, &sc->ip, Efault);
-#ifdef CONFIG_X86_32
-	unsafe_put_user(regs->cs, (unsigned int __user *)&sc->cs, Efault);
-	unsafe_put_user(regs->flags, &sc->flags, Efault);
-	unsafe_put_user(regs->sp, &sc->sp_at_signal, Efault);
-	unsafe_put_user(regs->ss, (unsigned int __user *)&sc->ss, Efault);
-#else /* !CONFIG_X86_32 */
-	unsafe_put_user(regs->flags, &sc->flags, Efault);
-	unsafe_put_user(regs->cs, &sc->cs, Efault);
-	unsafe_put_user(0, &sc->gs, Efault);
-	unsafe_put_user(0, &sc->fs, Efault);
-	unsafe_put_user(regs->ss, &sc->ss, Efault);
-#endif /* CONFIG_X86_32 */
-
-	unsafe_put_user(fpstate, (unsigned long __user *)&sc->fpstate, Efault);
-
-	/* non-iBCS2 extensions.. */
-	unsafe_put_user(mask, &sc->oldmask, Efault);
-	unsafe_put_user(current->thread.cr2, &sc->cr2, Efault);
-	return 0;
-Efault:
-	return -EFAULT;
+	return IS_ENABLED(CONFIG_X86_X32_ABI) &&
+		ksig->ka.sa.sa_flags & SA_X32_ABI;
 }
 
-#define unsafe_put_sigcontext(sc, fp, regs, set, label)			\
-do {									\
-	if (__unsafe_setup_sigcontext(sc, fp, regs, set->sig[0]))	\
-		goto label;						\
-} while(0);
-
-#define unsafe_put_sigmask(set, frame, label) \
-	unsafe_put_user(*(__u64 *)(set), \
-			(__u64 __user *)&(frame)->uc.uc_sigmask, \
-			label)
-
 /*
  * Set up a signal frame.
  */
@@ -223,24 +70,12 @@ do {									\
 /*
  * 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) & -FRAME_ALIGNMENT) - 4;
-#else /* !CONFIG_X86_32 */
-	sp = round_down(sp, FRAME_ALIGNMENT) - 8;
-#endif
-	return sp;
-}
-
-static void __user *
-get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
+void __user *
+get_sigframe(struct ksignal *ksig, struct pt_regs *regs, size_t frame_size,
 	     void __user **fpstate)
 {
+	struct k_sigaction *ka = &ksig->ka;
+	int ia32_frame = is_ia32_frame(ksig);
 	/* Default to using normal stack */
 	bool nested_altstack = on_sig_stack(regs->sp);
 	bool entering_altstack = false;
@@ -249,7 +84,7 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
 	unsigned long buf_fx = 0;
 
 	/* redzone */
-	if (IS_ENABLED(CONFIG_X86_64))
+	if (!ia32_frame)
 		sp -= 128;
 
 	/* This is the X/Open sanctioned signal stack switching.  */
@@ -263,7 +98,7 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
 			sp = current->sas_ss_sp + current->sas_ss_size;
 			entering_altstack = true;
 		}
-	} else if (IS_ENABLED(CONFIG_X86_32) &&
+	} else if (ia32_frame &&
 		   !nested_altstack &&
 		   regs->ss != __USER_DS &&
 		   !(ka->sa.sa_flags & SA_RESTORER) &&
@@ -273,11 +108,19 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
 		entering_altstack = true;
 	}
 
-	sp = fpu__alloc_mathframe(sp, IS_ENABLED(CONFIG_X86_32),
-				  &buf_fx, &math_size);
+	sp = fpu__alloc_mathframe(sp, ia32_frame, &buf_fx, &math_size);
 	*fpstate = (void __user *)sp;
 
-	sp = align_sigframe(sp - frame_size);
+	sp -= frame_size;
+
+	if (ia32_frame)
+		/*
+		 * Align the stack pointer according to the i386 ABI,
+		 * i.e. so that on function entry ((sp + 4) & 15) == 0.
+		 */
+		sp = ((sp + 4) & -FRAME_ALIGNMENT) - 4;
+	else
+		sp = round_down(sp, FRAME_ALIGNMENT) - 8;
 
 	/*
 	 * If we are on the alternate signal stack and would overflow it, don't.
@@ -300,391 +143,6 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
 	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;
-	void __user *fp = NULL;
-
-	frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
-
-	if (!user_access_begin(frame, sizeof(*frame)))
-		return -EFAULT;
-
-	unsafe_put_user(sig, &frame->sig, Efault);
-	unsafe_put_sigcontext(&frame->sc, fp, regs, set, Efault);
-	unsafe_put_user(set->sig[1], &frame->extramask[0], 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.  */
-	unsafe_put_user(restorer, &frame->pretcode, Efault);
-
-	/*
-	 * 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.
-	 */
-	unsafe_put_user(*((u64 *)&retcode), (u64 *)frame->retcode, Efault);
-	user_access_end();
-
-	/* 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;
-
-Efault:
-	user_access_end();
-	return -EFAULT;
-}
-
-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;
-	void __user *fp = NULL;
-
-	frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
-
-	if (!user_access_begin(frame, sizeof(*frame)))
-		return -EFAULT;
-
-	unsafe_put_user(sig, &frame->sig, Efault);
-	unsafe_put_user(&frame->info, &frame->pinfo, Efault);
-	unsafe_put_user(&frame->uc, &frame->puc, Efault);
-
-	/* Create the ucontext.  */
-	if (static_cpu_has(X86_FEATURE_XSAVE))
-		unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault);
-	else
-		unsafe_put_user(0, &frame->uc.uc_flags, Efault);
-	unsafe_put_user(0, &frame->uc.uc_link, Efault);
-	unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
-
-	/* 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;
-	unsafe_put_user(restorer, &frame->pretcode, Efault);
-
-	/*
-	 * 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.
-	 */
-	unsafe_put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode, Efault);
-	unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
-	unsafe_put_sigmask(set, frame, Efault);
-	user_access_end();
-	
-	if (copy_siginfo_to_user(&frame->info, &ksig->info))
-		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;
-Efault:
-	user_access_end();
-	return -EFAULT;
-}
-#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;
-
-	/* x86-64 should always use SA_RESTORER. */
-	if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
-		return -EFAULT;
-
-	frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp);
-	uc_flags = frame_uc_flags(regs);
-
-	if (!user_access_begin(frame, sizeof(*frame)))
-		return -EFAULT;
-
-	/* Create the ucontext.  */
-	unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
-	unsafe_put_user(0, &frame->uc.uc_link, Efault);
-	unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
-
-	/* Set up to return from userspace.  If provided, use a stub
-	   already in userspace.  */
-	unsafe_put_user(ksig->ka.sa.sa_restorer, &frame->pretcode, Efault);
-	unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
-	unsafe_put_sigmask(set, frame, Efault);
-	user_access_end();
-
-	if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
-		if (copy_siginfo_to_user(&frame->info, &ksig->info))
-			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 compatibility 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;
-
-Efault:
-	user_access_end();
-	return -EFAULT;
-}
-#endif /* CONFIG_X86_32 */
-
-#ifdef CONFIG_X86_X32_ABI
-static int x32_copy_siginfo_to_user(struct compat_siginfo __user *to,
-		const struct kernel_siginfo *from)
-{
-	struct compat_siginfo new;
-
-	copy_siginfo_to_external32(&new, from);
-	if (from->si_signo == SIGCHLD) {
-		new._sifields._sigchld_x32._utime = from->si_utime;
-		new._sifields._sigchld_x32._stime = from->si_stime;
-	}
-	if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
-		return -EFAULT;
-	return 0;
-}
-
-int copy_siginfo_to_user32(struct compat_siginfo __user *to,
-			   const struct kernel_siginfo *from)
-{
-	if (in_x32_syscall())
-		return x32_copy_siginfo_to_user(to, from);
-	return __copy_siginfo_to_user32(to, from);
-}
-#endif /* CONFIG_X86_X32_ABI */
-
-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;
-	void __user *fp = NULL;
-
-	if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
-		return -EFAULT;
-
-	frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);
-
-	uc_flags = frame_uc_flags(regs);
-
-	if (!user_access_begin(frame, sizeof(*frame)))
-		return -EFAULT;
-
-	/* Create the ucontext.  */
-	unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
-	unsafe_put_user(0, &frame->uc.uc_link, Efault);
-	unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
-	unsafe_put_user(0, &frame->uc.uc__pad0, Efault);
-	restorer = ksig->ka.sa.sa_restorer;
-	unsafe_put_user(restorer, (unsigned long __user *)&frame->pretcode, Efault);
-	unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
-	unsafe_put_sigmask(set, frame, Efault);
-	user_access_end();
-
-	if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
-		if (x32_copy_siginfo_to_user(&frame->info, &ksig->info))
-			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;
-#ifdef CONFIG_X86_X32_ABI
-Efault:
-	user_access_end();
-	return -EFAULT;
-#endif
-}
-
-/*
- * 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(frame, sizeof(*frame)))
-		goto badframe;
-	if (__get_user(set.sig[0], &frame->sc.oldmask) ||
-	    __get_user(set.sig[1], &frame->extramask[0]))
-		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(frame, sizeof(*frame)))
-		goto badframe;
-	if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask))
-		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;
-}
-
 /*
  * There are four different struct types for signal frame: sigframe_ia32,
  * rt_sigframe_ia32, rt_sigframe_x32, and rt_sigframe. Use the worst case
@@ -743,43 +201,22 @@ unsigned long get_sigframe_size(void)
 	return max_frame_size;
 }
 
-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;
-
 	/* 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);
+			return ia32_setup_rt_frame(ksig, regs);
 		else
-			return ia32_setup_frame(usig, ksig, cset, regs);
+			return ia32_setup_frame(ksig, regs);
 	} else if (is_x32_frame(ksig)) {
-		return x32_setup_rt_frame(ksig, cset, regs);
+		return x32_setup_rt_frame(ksig, regs);
 	} else {
-		return __setup_rt_frame(ksig->sig, ksig, set, regs);
+		return x64_setup_rt_frame(ksig, regs);
 	}
 }
 
@@ -969,36 +406,3 @@ bool sigaltstack_size_valid(size_t ss_size)
 	return true;
 }
 #endif /* CONFIG_DYNAMIC_SIGFRAME */
-
-#ifdef CONFIG_X86_X32_ABI
-COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn)
-{
-	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(frame, sizeof(*frame)))
-		goto badframe;
-	if (__get_user(set.sig[0], (__u64 __user *)&frame->uc.uc_sigmask))
-		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
diff --git a/arch/x86/kernel/signal_32.c b/arch/x86/kernel/signal_32.c
new file mode 100644
index 000000000000..2553136cf39b
--- /dev/null
+++ b/arch/x86/kernel/signal_32.c
@@ -0,0 +1,379 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
+ *  2000-06-20  Pentium III FXSR, SSE support by Gareth Hughes
+ *  2000-12-*   x86-64 compatibility mode signal handling by Andi Kleen
+ */
+
+#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/unistd.h>
+#include <linux/stddef.h>
+#include <linux/personality.h>
+#include <linux/compat.h>
+#include <linux/binfmts.h>
+#include <linux/syscalls.h>
+#include <asm/ucontext.h>
+#include <linux/uaccess.h>
+#include <asm/fpu/signal.h>
+#include <asm/ptrace.h>
+#include <asm/user32.h>
+#include <uapi/asm/sigcontext.h>
+#include <asm/proto.h>
+#include <asm/vdso.h>
+#include <asm/sigframe.h>
+#include <asm/sighandling.h>
+#include <asm/smap.h>
+
+#ifdef CONFIG_IA32_EMULATION
+#include <asm/ia32_unistd.h>
+
+static inline void reload_segments(struct sigcontext_32 *sc)
+{
+	unsigned int cur;
+
+	savesegment(gs, cur);
+	if ((sc->gs | 0x03) != cur)
+		load_gs_index(sc->gs | 0x03);
+	savesegment(fs, cur);
+	if ((sc->fs | 0x03) != cur)
+		loadsegment(fs, sc->fs | 0x03);
+	savesegment(ds, cur);
+	if ((sc->ds | 0x03) != cur)
+		loadsegment(ds, sc->ds | 0x03);
+	savesegment(es, cur);
+	if ((sc->es | 0x03) != cur)
+		loadsegment(es, sc->es | 0x03);
+}
+
+#define sigset32_t			compat_sigset_t
+#define restore_altstack32		compat_restore_altstack
+#define unsafe_save_altstack32		unsafe_compat_save_altstack
+
+#else
+
+#define sigset32_t			sigset_t
+#define __NR_ia32_sigreturn		__NR_sigreturn
+#define __NR_ia32_rt_sigreturn		__NR_rt_sigreturn
+#define restore_altstack32		restore_altstack
+#define unsafe_save_altstack32		unsafe_save_altstack
+#define __copy_siginfo_to_user32	copy_siginfo_to_user
+
+#endif
+
+/*
+ * Do a signal return; undo the signal stack.
+ */
+static bool ia32_restore_sigcontext(struct pt_regs *regs,
+				    struct sigcontext_32 __user *usc)
+{
+	struct sigcontext_32 sc;
+
+	/* Always make any pending restarted system calls return -EINTR */
+	current->restart_block.fn = do_no_restart_syscall;
+
+	if (unlikely(copy_from_user(&sc, usc, sizeof(sc))))
+		return false;
+
+	/* Get only the ia32 registers. */
+	regs->bx = sc.bx;
+	regs->cx = sc.cx;
+	regs->dx = sc.dx;
+	regs->si = sc.si;
+	regs->di = sc.di;
+	regs->bp = sc.bp;
+	regs->ax = sc.ax;
+	regs->sp = sc.sp;
+	regs->ip = sc.ip;
+
+	/* Get CS/SS and force CPL3 */
+	regs->cs = sc.cs | 0x03;
+	regs->ss = sc.ss | 0x03;
+
+	regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS);
+	/* disable syscall checks */
+	regs->orig_ax = -1;
+
+#ifdef CONFIG_IA32_EMULATION
+	/*
+	 * Reload fs and gs if they have changed in the signal
+	 * handler.  This does not handle long fs/gs base changes in
+	 * the handler, but does not clobber them at least in the
+	 * normal case.
+	 */
+	reload_segments(&sc);
+#else
+	loadsegment(gs, sc.gs);
+	regs->fs = sc.fs;
+	regs->es = sc.es;
+	regs->ds = sc.ds;
+#endif
+
+	return fpu__restore_sig(compat_ptr(sc.fpstate), 1);
+}
+
+SYSCALL32_DEFINE0(sigreturn)
+{
+	struct pt_regs *regs = current_pt_regs();
+	struct sigframe_ia32 __user *frame = (struct sigframe_ia32 __user *)(regs->sp-8);
+	sigset_t set;
+
+	if (!access_ok(frame, sizeof(*frame)))
+		goto badframe;
+	if (__get_user(set.sig[0], &frame->sc.oldmask)
+	    || __get_user(((__u32 *)&set)[1], &frame->extramask[0]))
+		goto badframe;
+
+	set_current_blocked(&set);
+
+	if (!ia32_restore_sigcontext(regs, &frame->sc))
+		goto badframe;
+	return regs->ax;
+
+badframe:
+	signal_fault(regs, frame, "32bit sigreturn");
+	return 0;
+}
+
+SYSCALL32_DEFINE0(rt_sigreturn)
+{
+	struct pt_regs *regs = current_pt_regs();
+	struct rt_sigframe_ia32 __user *frame;
+	sigset_t set;
+
+	frame = (struct rt_sigframe_ia32 __user *)(regs->sp - 4);
+
+	if (!access_ok(frame, sizeof(*frame)))
+		goto badframe;
+	if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask))
+		goto badframe;
+
+	set_current_blocked(&set);
+
+	if (!ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext))
+		goto badframe;
+
+	if (restore_altstack32(&frame->uc.uc_stack))
+		goto badframe;
+
+	return regs->ax;
+
+badframe:
+	signal_fault(regs, frame, "32bit rt sigreturn");
+	return 0;
+}
+
+/*
+ * Set up a signal frame.
+ */
+
+#define get_user_seg(seg)	({ unsigned int v; savesegment(seg, v); v; })
+
+static __always_inline int
+__unsafe_setup_sigcontext32(struct sigcontext_32 __user *sc,
+			    void __user *fpstate,
+			    struct pt_regs *regs, unsigned int mask)
+{
+	unsafe_put_user(get_user_seg(gs), (unsigned int __user *)&sc->gs, Efault);
+#ifdef CONFIG_IA32_EMULATION
+	unsafe_put_user(get_user_seg(fs), (unsigned int __user *)&sc->fs, Efault);
+	unsafe_put_user(get_user_seg(ds), (unsigned int __user *)&sc->ds, Efault);
+	unsafe_put_user(get_user_seg(es), (unsigned int __user *)&sc->es, Efault);
+#else
+	unsafe_put_user(regs->fs, (unsigned int __user *)&sc->fs, Efault);
+	unsafe_put_user(regs->es, (unsigned int __user *)&sc->es, Efault);
+	unsafe_put_user(regs->ds, (unsigned int __user *)&sc->ds, Efault);
+#endif
+
+	unsafe_put_user(regs->di, &sc->di, Efault);
+	unsafe_put_user(regs->si, &sc->si, Efault);
+	unsafe_put_user(regs->bp, &sc->bp, Efault);
+	unsafe_put_user(regs->sp, &sc->sp, Efault);
+	unsafe_put_user(regs->bx, &sc->bx, Efault);
+	unsafe_put_user(regs->dx, &sc->dx, Efault);
+	unsafe_put_user(regs->cx, &sc->cx, Efault);
+	unsafe_put_user(regs->ax, &sc->ax, Efault);
+	unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault);
+	unsafe_put_user(current->thread.error_code, &sc->err, Efault);
+	unsafe_put_user(regs->ip, &sc->ip, Efault);
+	unsafe_put_user(regs->cs, (unsigned int __user *)&sc->cs, Efault);
+	unsafe_put_user(regs->flags, &sc->flags, Efault);
+	unsafe_put_user(regs->sp, &sc->sp_at_signal, Efault);
+	unsafe_put_user(regs->ss, (unsigned int __user *)&sc->ss, Efault);
+
+	unsafe_put_user(ptr_to_compat(fpstate), &sc->fpstate, Efault);
+
+	/* non-iBCS2 extensions.. */
+	unsafe_put_user(mask, &sc->oldmask, Efault);
+	unsafe_put_user(current->thread.cr2, &sc->cr2, Efault);
+	return 0;
+
+Efault:
+	return -EFAULT;
+}
+
+#define unsafe_put_sigcontext32(sc, fp, regs, set, label)		\
+do {									\
+	if (__unsafe_setup_sigcontext32(sc, fp, regs, set->sig[0]))	\
+		goto label;						\
+} while(0)
+
+int ia32_setup_frame(struct ksignal *ksig, struct pt_regs *regs)
+{
+	sigset32_t *set = (sigset32_t *) sigmask_to_save();
+	struct sigframe_ia32 __user *frame;
+	void __user *restorer;
+	void __user *fp = NULL;
+
+	/* copy_to_user optimizes that into a single 8 byte store */
+	static const struct {
+		u16 poplmovl;
+		u32 val;
+		u16 int80;
+	} __attribute__((packed)) code = {
+		0xb858,		 /* popl %eax ; movl $...,%eax */
+		__NR_ia32_sigreturn,
+		0x80cd,		/* int $0x80 */
+	};
+
+	frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
+
+	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
+		restorer = ksig->ka.sa.sa_restorer;
+	} else {
+		/* Return stub is in 32bit vsyscall page */
+		if (current->mm->context.vdso)
+			restorer = current->mm->context.vdso +
+				vdso_image_32.sym___kernel_sigreturn;
+		else
+			restorer = &frame->retcode;
+	}
+
+	if (!user_access_begin(frame, sizeof(*frame)))
+		return -EFAULT;
+
+	unsafe_put_user(ksig->sig, &frame->sig, Efault);
+	unsafe_put_sigcontext32(&frame->sc, fp, regs, set, Efault);
+	unsafe_put_user(set->sig[1], &frame->extramask[0], Efault);
+	unsafe_put_user(ptr_to_compat(restorer), &frame->pretcode, Efault);
+	/*
+	 * These are actually not used anymore, but left because some
+	 * gdb versions depend on them as a marker.
+	 */
+	unsafe_put_user(*((u64 *)&code), (u64 __user *)frame->retcode, Efault);
+	user_access_end();
+
+	/* Set up registers for signal handler */
+	regs->sp = (unsigned long) frame;
+	regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
+
+	/* Make -mregparm=3 work */
+	regs->ax = ksig->sig;
+	regs->dx = 0;
+	regs->cx = 0;
+
+#ifdef CONFIG_IA32_EMULATION
+	loadsegment(ds, __USER_DS);
+	loadsegment(es, __USER_DS);
+#else
+	regs->ds = __USER_DS;
+	regs->es = __USER_DS;
+#endif
+
+	regs->cs = __USER32_CS;
+	regs->ss = __USER_DS;
+
+	return 0;
+Efault:
+	user_access_end();
+	return -EFAULT;
+}
+
+int ia32_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
+{
+	sigset32_t *set = (sigset32_t *) sigmask_to_save();
+	struct rt_sigframe_ia32 __user *frame;
+	void __user *restorer;
+	void __user *fp = NULL;
+
+	/* unsafe_put_user optimizes that into a single 8 byte store */
+	static const struct {
+		u8 movl;
+		u32 val;
+		u16 int80;
+		u8  pad;
+	} __attribute__((packed)) code = {
+		0xb8,
+		__NR_ia32_rt_sigreturn,
+		0x80cd,
+		0,
+	};
+
+	frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
+
+	if (!user_access_begin(frame, sizeof(*frame)))
+		return -EFAULT;
+
+	unsafe_put_user(ksig->sig, &frame->sig, Efault);
+	unsafe_put_user(ptr_to_compat(&frame->info), &frame->pinfo, Efault);
+	unsafe_put_user(ptr_to_compat(&frame->uc), &frame->puc, Efault);
+
+	/* Create the ucontext.  */
+	if (static_cpu_has(X86_FEATURE_XSAVE))
+		unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault);
+	else
+		unsafe_put_user(0, &frame->uc.uc_flags, Efault);
+	unsafe_put_user(0, &frame->uc.uc_link, Efault);
+	unsafe_save_altstack32(&frame->uc.uc_stack, regs->sp, Efault);
+
+	if (ksig->ka.sa.sa_flags & SA_RESTORER)
+		restorer = ksig->ka.sa.sa_restorer;
+	else
+		restorer = current->mm->context.vdso +
+			vdso_image_32.sym___kernel_rt_sigreturn;
+	unsafe_put_user(ptr_to_compat(restorer), &frame->pretcode, Efault);
+
+	/*
+	 * Not actually used anymore, but left because some gdb
+	 * versions need it.
+	 */
+	unsafe_put_user(*((u64 *)&code), (u64 __user *)frame->retcode, Efault);
+	unsafe_put_sigcontext32(&frame->uc.uc_mcontext, fp, regs, set, Efault);
+	unsafe_put_user(*(__u64 *)set, (__u64 __user *)&frame->uc.uc_sigmask, Efault);
+	user_access_end();
+
+	if (__copy_siginfo_to_user32(&frame->info, &ksig->info))
+		return -EFAULT;
+
+	/* Set up registers for signal handler */
+	regs->sp = (unsigned long) frame;
+	regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
+
+	/* Make -mregparm=3 work */
+	regs->ax = ksig->sig;
+	regs->dx = (unsigned long) &frame->info;
+	regs->cx = (unsigned long) &frame->uc;
+
+#ifdef CONFIG_IA32_EMULATION
+	loadsegment(ds, __USER_DS);
+	loadsegment(es, __USER_DS);
+#else
+	regs->ds = __USER_DS;
+	regs->es = __USER_DS;
+#endif
+
+	regs->cs = __USER32_CS;
+	regs->ss = __USER_DS;
+
+	return 0;
+Efault:
+	user_access_end();
+	return -EFAULT;
+}
diff --git a/arch/x86/kernel/signal_64.c b/arch/x86/kernel/signal_64.c
new file mode 100644
index 000000000000..ff9c55064223
--- /dev/null
+++ b/arch/x86/kernel/signal_64.c
@@ -0,0 +1,383 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *  Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/unistd.h>
+#include <linux/uaccess.h>
+#include <linux/syscalls.h>
+
+#include <asm/ucontext.h>
+#include <asm/fpu/signal.h>
+#include <asm/sighandling.h>
+
+#include <asm/syscall.h>
+#include <asm/sigframe.h>
+#include <asm/signal.h>
+
+/*
+ * 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;
+}
+
+static bool restore_sigcontext(struct pt_regs *regs,
+			       struct sigcontext __user *usc,
+			       unsigned long uc_flags)
+{
+	struct sigcontext sc;
+
+	/* Always make any pending restarted system calls return -EINTR */
+	current->restart_block.fn = do_no_restart_syscall;
+
+	if (copy_from_user(&sc, usc, offsetof(struct sigcontext, reserved1)))
+		return false;
+
+	regs->bx = sc.bx;
+	regs->cx = sc.cx;
+	regs->dx = sc.dx;
+	regs->si = sc.si;
+	regs->di = sc.di;
+	regs->bp = sc.bp;
+	regs->ax = sc.ax;
+	regs->sp = sc.sp;
+	regs->ip = sc.ip;
+	regs->r8 = sc.r8;
+	regs->r9 = sc.r9;
+	regs->r10 = sc.r10;
+	regs->r11 = sc.r11;
+	regs->r12 = sc.r12;
+	regs->r13 = sc.r13;
+	regs->r14 = sc.r14;
+	regs->r15 = sc.r15;
+
+	/* Get CS/SS and force CPL3 */
+	regs->cs = sc.cs | 0x03;
+	regs->ss = sc.ss | 0x03;
+
+	regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS);
+	/* disable syscall checks */
+	regs->orig_ax = -1;
+
+	/*
+	 * 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);
+
+	return fpu__restore_sig((void __user *)sc.fpstate, 0);
+}
+
+static __always_inline int
+__unsafe_setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
+		     struct pt_regs *regs, unsigned long mask)
+{
+	unsafe_put_user(regs->di, &sc->di, Efault);
+	unsafe_put_user(regs->si, &sc->si, Efault);
+	unsafe_put_user(regs->bp, &sc->bp, Efault);
+	unsafe_put_user(regs->sp, &sc->sp, Efault);
+	unsafe_put_user(regs->bx, &sc->bx, Efault);
+	unsafe_put_user(regs->dx, &sc->dx, Efault);
+	unsafe_put_user(regs->cx, &sc->cx, Efault);
+	unsafe_put_user(regs->ax, &sc->ax, Efault);
+	unsafe_put_user(regs->r8, &sc->r8, Efault);
+	unsafe_put_user(regs->r9, &sc->r9, Efault);
+	unsafe_put_user(regs->r10, &sc->r10, Efault);
+	unsafe_put_user(regs->r11, &sc->r11, Efault);
+	unsafe_put_user(regs->r12, &sc->r12, Efault);
+	unsafe_put_user(regs->r13, &sc->r13, Efault);
+	unsafe_put_user(regs->r14, &sc->r14, Efault);
+	unsafe_put_user(regs->r15, &sc->r15, Efault);
+
+	unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault);
+	unsafe_put_user(current->thread.error_code, &sc->err, Efault);
+	unsafe_put_user(regs->ip, &sc->ip, Efault);
+	unsafe_put_user(regs->flags, &sc->flags, Efault);
+	unsafe_put_user(regs->cs, &sc->cs, Efault);
+	unsafe_put_user(0, &sc->gs, Efault);
+	unsafe_put_user(0, &sc->fs, Efault);
+	unsafe_put_user(regs->ss, &sc->ss, Efault);
+
+	unsafe_put_user(fpstate, (unsigned long __user *)&sc->fpstate, Efault);
+
+	/* non-iBCS2 extensions.. */
+	unsafe_put_user(mask, &sc->oldmask, Efault);
+	unsafe_put_user(current->thread.cr2, &sc->cr2, Efault);
+	return 0;
+Efault:
+	return -EFAULT;
+}
+
+#define unsafe_put_sigcontext(sc, fp, regs, set, label)			\
+do {									\
+	if (__unsafe_setup_sigcontext(sc, fp, regs, set->sig[0]))	\
+		goto label;						\
+} while(0);
+
+#define unsafe_put_sigmask(set, frame, label) \
+	unsafe_put_user(*(__u64 *)(set), \
+			(__u64 __user *)&(frame)->uc.uc_sigmask, \
+			label)
+
+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;
+}
+
+int x64_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
+{
+	sigset_t *set = sigmask_to_save();
+	struct rt_sigframe __user *frame;
+	void __user *fp = NULL;
+	unsigned long uc_flags;
+
+	/* x86-64 should always use SA_RESTORER. */
+	if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
+		return -EFAULT;
+
+	frame = get_sigframe(ksig, regs, sizeof(struct rt_sigframe), &fp);
+	uc_flags = frame_uc_flags(regs);
+
+	if (!user_access_begin(frame, sizeof(*frame)))
+		return -EFAULT;
+
+	/* Create the ucontext.  */
+	unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
+	unsafe_put_user(0, &frame->uc.uc_link, Efault);
+	unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
+
+	/* Set up to return from userspace.  If provided, use a stub
+	   already in userspace.  */
+	unsafe_put_user(ksig->ka.sa.sa_restorer, &frame->pretcode, Efault);
+	unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
+	unsafe_put_sigmask(set, frame, Efault);
+	user_access_end();
+
+	if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
+		if (copy_siginfo_to_user(&frame->info, &ksig->info))
+			return -EFAULT;
+	}
+
+	/* Set up registers for signal handler */
+	regs->di = ksig->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 compatibility 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;
+
+Efault:
+	user_access_end();
+	return -EFAULT;
+}
+
+/*
+ * Do a signal return; undo the signal stack.
+ */
+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(frame, sizeof(*frame)))
+		goto badframe;
+	if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask))
+		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;
+}
+
+#ifdef CONFIG_X86_X32_ABI
+static int x32_copy_siginfo_to_user(struct compat_siginfo __user *to,
+		const struct kernel_siginfo *from)
+{
+	struct compat_siginfo new;
+
+	copy_siginfo_to_external32(&new, from);
+	if (from->si_signo == SIGCHLD) {
+		new._sifields._sigchld_x32._utime = from->si_utime;
+		new._sifields._sigchld_x32._stime = from->si_stime;
+	}
+	if (copy_to_user(to, &new, sizeof(struct compat_siginfo)))
+		return -EFAULT;
+	return 0;
+}
+
+int copy_siginfo_to_user32(struct compat_siginfo __user *to,
+			   const struct kernel_siginfo *from)
+{
+	if (in_x32_syscall())
+		return x32_copy_siginfo_to_user(to, from);
+	return __copy_siginfo_to_user32(to, from);
+}
+
+int x32_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
+{
+	compat_sigset_t *set = (compat_sigset_t *) sigmask_to_save();
+	struct rt_sigframe_x32 __user *frame;
+	unsigned long uc_flags;
+	void __user *restorer;
+	void __user *fp = NULL;
+
+	if (!(ksig->ka.sa.sa_flags & SA_RESTORER))
+		return -EFAULT;
+
+	frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
+
+	uc_flags = frame_uc_flags(regs);
+
+	if (!user_access_begin(frame, sizeof(*frame)))
+		return -EFAULT;
+
+	/* Create the ucontext.  */
+	unsafe_put_user(uc_flags, &frame->uc.uc_flags, Efault);
+	unsafe_put_user(0, &frame->uc.uc_link, Efault);
+	unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
+	unsafe_put_user(0, &frame->uc.uc__pad0, Efault);
+	restorer = ksig->ka.sa.sa_restorer;
+	unsafe_put_user(restorer, (unsigned long __user *)&frame->pretcode, Efault);
+	unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
+	unsafe_put_sigmask(set, frame, Efault);
+	user_access_end();
+
+	if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
+		if (x32_copy_siginfo_to_user(&frame->info, &ksig->info))
+			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;
+
+	return 0;
+
+Efault:
+	user_access_end();
+	return -EFAULT;
+}
+
+COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn)
+{
+	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(frame, sizeof(*frame)))
+		goto badframe;
+	if (__get_user(set.sig[0], (__u64 __user *)&frame->uc.uc_sigmask))
+		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 /* CONFIG_X86_X32_ABI */