Adding upstream version 6.6.15.upstream/6.6.15

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

1 files changed, 992 insertions, 0 deletions

diff --git a/arch/alpha/kernel/traps.c b/arch/alpha/kernel/traps.c
new file mode 100644
index 0000000000..d9a67b370e
--- /dev/null
+++ b/arch/alpha/kernel/traps.c
@@ -0,0 +1,992 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * arch/alpha/kernel/traps.c
+ *
+ * (C) Copyright 1994 Linus Torvalds
+ */
+
+/*
+ * This file initializes the trap entry points
+ */
+
+#include <linux/jiffies.h>
+#include <linux/mm.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/debug.h>
+#include <linux/tty.h>
+#include <linux/delay.h>
+#include <linux/extable.h>
+#include <linux/kallsyms.h>
+#include <linux/ratelimit.h>
+
+#include <asm/gentrap.h>
+#include <linux/uaccess.h>
+#include <asm/unaligned.h>
+#include <asm/sysinfo.h>
+#include <asm/hwrpb.h>
+#include <asm/mmu_context.h>
+#include <asm/special_insns.h>
+
+#include "proto.h"
+
+/* Work-around for some SRMs which mishandle opDEC faults.  */
+
+static int opDEC_fix;
+
+static void
+opDEC_check(void)
+{
+	__asm__ __volatile__ (
+	/* Load the address of... */
+	"	br	$16, 1f\n"
+	/* A stub instruction fault handler.  Just add 4 to the
+	   pc and continue.  */
+	"	ldq	$16, 8($sp)\n"
+	"	addq	$16, 4, $16\n"
+	"	stq	$16, 8($sp)\n"
+	"	call_pal %[rti]\n"
+	/* Install the instruction fault handler.  */
+	"1:	lda	$17, 3\n"
+	"	call_pal %[wrent]\n"
+	/* With that in place, the fault from the round-to-minf fp
+	   insn will arrive either at the "lda 4" insn (bad) or one
+	   past that (good).  This places the correct fixup in %0.  */
+	"	lda %[fix], 0\n"
+	"	cvttq/svm $f31,$f31\n"
+	"	lda %[fix], 4"
+	: [fix] "=r" (opDEC_fix)
+	: [rti] "n" (PAL_rti), [wrent] "n" (PAL_wrent)
+	: "$0", "$1", "$16", "$17", "$22", "$23", "$24", "$25");
+
+	if (opDEC_fix)
+		printk("opDEC fixup enabled.\n");
+}
+
+void
+dik_show_regs(struct pt_regs *regs, unsigned long *r9_15)
+{
+	printk("pc = [<%016lx>]  ra = [<%016lx>]  ps = %04lx    %s\n",
+	       regs->pc, regs->r26, regs->ps, print_tainted());
+	printk("pc is at %pSR\n", (void *)regs->pc);
+	printk("ra is at %pSR\n", (void *)regs->r26);
+	printk("v0 = %016lx  t0 = %016lx  t1 = %016lx\n",
+	       regs->r0, regs->r1, regs->r2);
+	printk("t2 = %016lx  t3 = %016lx  t4 = %016lx\n",
+ 	       regs->r3, regs->r4, regs->r5);
+	printk("t5 = %016lx  t6 = %016lx  t7 = %016lx\n",
+	       regs->r6, regs->r7, regs->r8);
+
+	if (r9_15) {
+		printk("s0 = %016lx  s1 = %016lx  s2 = %016lx\n",
+		       r9_15[9], r9_15[10], r9_15[11]);
+		printk("s3 = %016lx  s4 = %016lx  s5 = %016lx\n",
+		       r9_15[12], r9_15[13], r9_15[14]);
+		printk("s6 = %016lx\n", r9_15[15]);
+	}
+
+	printk("a0 = %016lx  a1 = %016lx  a2 = %016lx\n",
+	       regs->r16, regs->r17, regs->r18);
+	printk("a3 = %016lx  a4 = %016lx  a5 = %016lx\n",
+ 	       regs->r19, regs->r20, regs->r21);
+ 	printk("t8 = %016lx  t9 = %016lx  t10= %016lx\n",
+	       regs->r22, regs->r23, regs->r24);
+	printk("t11= %016lx  pv = %016lx  at = %016lx\n",
+	       regs->r25, regs->r27, regs->r28);
+	printk("gp = %016lx  sp = %p\n", regs->gp, regs+1);
+#if 0
+__halt();
+#endif
+}
+
+#if 0
+static char * ireg_name[] = {"v0", "t0", "t1", "t2", "t3", "t4", "t5", "t6",
+			   "t7", "s0", "s1", "s2", "s3", "s4", "s5", "s6",
+			   "a0", "a1", "a2", "a3", "a4", "a5", "t8", "t9",
+			   "t10", "t11", "ra", "pv", "at", "gp", "sp", "zero"};
+#endif
+
+static void
+dik_show_code(unsigned int *pc)
+{
+	long i;
+
+	printk("Code:");
+	for (i = -6; i < 2; i++) {
+		unsigned int insn;
+		if (__get_user(insn, (unsigned int __user *)pc + i))
+			break;
+		printk("%c%08x%c", i ? ' ' : '<', insn, i ? ' ' : '>');
+	}
+	printk("\n");
+}
+
+static void
+dik_show_trace(unsigned long *sp, const char *loglvl)
+{
+	long i = 0;
+	printk("%sTrace:\n", loglvl);
+	while (0x1ff8 & (unsigned long) sp) {
+		extern char _stext[], _etext[];
+		unsigned long tmp = *sp;
+		sp++;
+		if (!is_kernel_text(tmp))
+			continue;
+		printk("%s[<%lx>] %pSR\n", loglvl, tmp, (void *)tmp);
+		if (i > 40) {
+			printk("%s ...", loglvl);
+			break;
+		}
+	}
+	printk("%s\n", loglvl);
+}
+
+static int kstack_depth_to_print = 24;
+
+void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
+{
+	unsigned long *stack;
+	int i;
+
+	/*
+	 * debugging aid: "show_stack(NULL, NULL, KERN_EMERG);" prints the
+	 * back trace for this cpu.
+	 */
+	if(sp==NULL)
+		sp=(unsigned long*)&sp;
+
+	stack = sp;
+	for(i=0; i < kstack_depth_to_print; i++) {
+		if (((long) stack & (THREAD_SIZE-1)) == 0)
+			break;
+		if ((i % 4) == 0) {
+			if (i)
+				pr_cont("\n");
+			printk("%s       ", loglvl);
+		} else {
+			pr_cont(" ");
+		}
+		pr_cont("%016lx", *stack++);
+	}
+	pr_cont("\n");
+	dik_show_trace(sp, loglvl);
+}
+
+void
+die_if_kernel(char * str, struct pt_regs *regs, long err, unsigned long *r9_15)
+{
+	if (regs->ps & 8)
+		return;
+#ifdef CONFIG_SMP
+	printk("CPU %d ", hard_smp_processor_id());
+#endif
+	printk("%s(%d): %s %ld\n", current->comm, task_pid_nr(current), str, err);
+	dik_show_regs(regs, r9_15);
+	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
+	dik_show_trace((unsigned long *)(regs+1), KERN_DEFAULT);
+	dik_show_code((unsigned int *)regs->pc);
+
+	if (test_and_set_thread_flag (TIF_DIE_IF_KERNEL)) {
+		printk("die_if_kernel recursion detected.\n");
+		local_irq_enable();
+		while (1);
+	}
+	make_task_dead(SIGSEGV);
+}
+
+#ifndef CONFIG_MATHEMU
+static long dummy_emul(void) { return 0; }
+long (*alpha_fp_emul_imprecise)(struct pt_regs *regs, unsigned long writemask)
+  = (void *)dummy_emul;
+EXPORT_SYMBOL_GPL(alpha_fp_emul_imprecise);
+long (*alpha_fp_emul) (unsigned long pc)
+  = (void *)dummy_emul;
+EXPORT_SYMBOL_GPL(alpha_fp_emul);
+#else
+long alpha_fp_emul_imprecise(struct pt_regs *regs, unsigned long writemask);
+long alpha_fp_emul (unsigned long pc);
+#endif
+
+asmlinkage void
+do_entArith(unsigned long summary, unsigned long write_mask,
+	    struct pt_regs *regs)
+{
+	long si_code = FPE_FLTINV;
+
+	if (summary & 1) {
+		/* Software-completion summary bit is set, so try to
+		   emulate the instruction.  If the processor supports
+		   precise exceptions, we don't have to search.  */
+		if (!amask(AMASK_PRECISE_TRAP))
+			si_code = alpha_fp_emul(regs->pc - 4);
+		else
+			si_code = alpha_fp_emul_imprecise(regs, write_mask);
+		if (si_code == 0)
+			return;
+	}
+	die_if_kernel("Arithmetic fault", regs, 0, NULL);
+
+	send_sig_fault_trapno(SIGFPE, si_code, (void __user *) regs->pc, 0, current);
+}
+
+asmlinkage void
+do_entIF(unsigned long type, struct pt_regs *regs)
+{
+	int signo, code;
+
+	if (type == 3) { /* FEN fault */
+		/* Irritating users can call PAL_clrfen to disable the
+		   FPU for the process.  The kernel will then trap in
+		   do_switch_stack and undo_switch_stack when we try
+		   to save and restore the FP registers.
+
+		   Given that GCC by default generates code that uses the
+		   FP registers, PAL_clrfen is not useful except for DoS
+		   attacks.  So turn the bleeding FPU back on and be done
+		   with it.  */
+		current_thread_info()->pcb.flags |= 1;
+		__reload_thread(&current_thread_info()->pcb);
+		return;
+	}
+	if (!user_mode(regs)) {
+		if (type == 1) {
+			const unsigned int *data
+			  = (const unsigned int *) regs->pc;
+			printk("Kernel bug at %s:%d\n",
+			       (const char *)(data[1] | (long)data[2] << 32), 
+			       data[0]);
+		}
+#ifdef CONFIG_ALPHA_WTINT
+		if (type == 4) {
+			/* If CALL_PAL WTINT is totally unsupported by the
+			   PALcode, e.g. MILO, "emulate" it by overwriting
+			   the insn.  */
+			unsigned int *pinsn
+			  = (unsigned int *) regs->pc - 1;
+			if (*pinsn == PAL_wtint) {
+				*pinsn = 0x47e01400; /* mov 0,$0 */
+				imb();
+				regs->r0 = 0;
+				return;
+			}
+		}
+#endif /* ALPHA_WTINT */
+		die_if_kernel((type == 1 ? "Kernel Bug" : "Instruction fault"),
+			      regs, type, NULL);
+	}
+
+	switch (type) {
+	      case 0: /* breakpoint */
+		if (ptrace_cancel_bpt(current)) {
+			regs->pc -= 4;	/* make pc point to former bpt */
+		}
+
+		send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc,
+			       current);
+		return;
+
+	      case 1: /* bugcheck */
+		send_sig_fault_trapno(SIGTRAP, TRAP_UNK,
+				      (void __user *) regs->pc, 0, current);
+		return;
+		
+	      case 2: /* gentrap */
+		switch ((long) regs->r16) {
+		case GEN_INTOVF:
+			signo = SIGFPE;
+			code = FPE_INTOVF;
+			break;
+		case GEN_INTDIV:
+			signo = SIGFPE;
+			code = FPE_INTDIV;
+			break;
+		case GEN_FLTOVF:
+			signo = SIGFPE;
+			code = FPE_FLTOVF;
+			break;
+		case GEN_FLTDIV:
+			signo = SIGFPE;
+			code = FPE_FLTDIV;
+			break;
+		case GEN_FLTUND:
+			signo = SIGFPE;
+			code = FPE_FLTUND;
+			break;
+		case GEN_FLTINV:
+			signo = SIGFPE;
+			code = FPE_FLTINV;
+			break;
+		case GEN_FLTINE:
+			signo = SIGFPE;
+			code = FPE_FLTRES;
+			break;
+		case GEN_ROPRAND:
+			signo = SIGFPE;
+			code = FPE_FLTUNK;
+			break;
+
+		case GEN_DECOVF:
+		case GEN_DECDIV:
+		case GEN_DECINV:
+		case GEN_ASSERTERR:
+		case GEN_NULPTRERR:
+		case GEN_STKOVF:
+		case GEN_STRLENERR:
+		case GEN_SUBSTRERR:
+		case GEN_RANGERR:
+		case GEN_SUBRNG:
+		case GEN_SUBRNG1:
+		case GEN_SUBRNG2:
+		case GEN_SUBRNG3:
+		case GEN_SUBRNG4:
+		case GEN_SUBRNG5:
+		case GEN_SUBRNG6:
+		case GEN_SUBRNG7:
+		default:
+			signo = SIGTRAP;
+			code = TRAP_UNK;
+			break;
+		}
+
+		send_sig_fault_trapno(signo, code, (void __user *) regs->pc,
+				      regs->r16, current);
+		return;
+
+	      case 4: /* opDEC */
+		if (implver() == IMPLVER_EV4) {
+			long si_code;
+
+			/* The some versions of SRM do not handle
+			   the opDEC properly - they return the PC of the
+			   opDEC fault, not the instruction after as the
+			   Alpha architecture requires.  Here we fix it up.
+			   We do this by intentionally causing an opDEC
+			   fault during the boot sequence and testing if
+			   we get the correct PC.  If not, we set a flag
+			   to correct it every time through.  */
+			regs->pc += opDEC_fix; 
+			
+			/* EV4 does not implement anything except normal
+			   rounding.  Everything else will come here as
+			   an illegal instruction.  Emulate them.  */
+			si_code = alpha_fp_emul(regs->pc - 4);
+			if (si_code == 0)
+				return;
+			if (si_code > 0) {
+				send_sig_fault_trapno(SIGFPE, si_code,
+						      (void __user *) regs->pc,
+						      0, current);
+				return;
+			}
+		}
+		break;
+
+	      case 5: /* illoc */
+	      default: /* unexpected instruction-fault type */
+		      ;
+	}
+
+	send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc, current);
+}
+
+/* There is an ifdef in the PALcode in MILO that enables a 
+   "kernel debugging entry point" as an unprivileged call_pal.
+
+   We don't want to have anything to do with it, but unfortunately
+   several versions of MILO included in distributions have it enabled,
+   and if we don't put something on the entry point we'll oops.  */
+
+asmlinkage void
+do_entDbg(struct pt_regs *regs)
+{
+	die_if_kernel("Instruction fault", regs, 0, NULL);
+
+	force_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)regs->pc);
+}
+
+
+/*
+ * entUna has a different register layout to be reasonably simple. It
+ * needs access to all the integer registers (the kernel doesn't use
+ * fp-regs), and it needs to have them in order for simpler access.
+ *
+ * Due to the non-standard register layout (and because we don't want
+ * to handle floating-point regs), user-mode unaligned accesses are
+ * handled separately by do_entUnaUser below.
+ *
+ * Oh, btw, we don't handle the "gp" register correctly, but if we fault
+ * on a gp-register unaligned load/store, something is _very_ wrong
+ * in the kernel anyway..
+ */
+struct allregs {
+	unsigned long regs[32];
+	unsigned long ps, pc, gp, a0, a1, a2;
+};
+
+struct unaligned_stat {
+	unsigned long count, va, pc;
+} unaligned[2];
+
+
+/* Macro for exception fixup code to access integer registers.  */
+#define una_reg(r)  (_regs[(r) >= 16 && (r) <= 18 ? (r)+19 : (r)])
+
+
+asmlinkage void
+do_entUna(void * va, unsigned long opcode, unsigned long reg,
+	  struct allregs *regs)
+{
+	long error, tmp1, tmp2, tmp3, tmp4;
+	unsigned long pc = regs->pc - 4;
+	unsigned long *_regs = regs->regs;
+	const struct exception_table_entry *fixup;
+
+	unaligned[0].count++;
+	unaligned[0].va = (unsigned long) va;
+	unaligned[0].pc = pc;
+
+	/* We don't want to use the generic get/put unaligned macros as
+	   we want to trap exceptions.  Only if we actually get an
+	   exception will we decide whether we should have caught it.  */
+
+	switch (opcode) {
+	case 0x0c: /* ldwu */
+		__asm__ __volatile__(
+		"1:	ldq_u %1,0(%3)\n"
+		"2:	ldq_u %2,1(%3)\n"
+		"	extwl %1,%3,%1\n"
+		"	extwh %2,%3,%2\n"
+		"3:\n"
+		EXC(1b,3b,%1,%0)
+		EXC(2b,3b,%2,%0)
+			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2)
+			: "r"(va), "0"(0));
+		if (error)
+			goto got_exception;
+		una_reg(reg) = tmp1|tmp2;
+		return;
+
+	case 0x28: /* ldl */
+		__asm__ __volatile__(
+		"1:	ldq_u %1,0(%3)\n"
+		"2:	ldq_u %2,3(%3)\n"
+		"	extll %1,%3,%1\n"
+		"	extlh %2,%3,%2\n"
+		"3:\n"
+		EXC(1b,3b,%1,%0)
+		EXC(2b,3b,%2,%0)
+			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2)
+			: "r"(va), "0"(0));
+		if (error)
+			goto got_exception;
+		una_reg(reg) = (int)(tmp1|tmp2);
+		return;
+
+	case 0x29: /* ldq */
+		__asm__ __volatile__(
+		"1:	ldq_u %1,0(%3)\n"
+		"2:	ldq_u %2,7(%3)\n"
+		"	extql %1,%3,%1\n"
+		"	extqh %2,%3,%2\n"
+		"3:\n"
+		EXC(1b,3b,%1,%0)
+		EXC(2b,3b,%2,%0)
+			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2)
+			: "r"(va), "0"(0));
+		if (error)
+			goto got_exception;
+		una_reg(reg) = tmp1|tmp2;
+		return;
+
+	/* Note that the store sequences do not indicate that they change
+	   memory because it _should_ be affecting nothing in this context.
+	   (Otherwise we have other, much larger, problems.)  */
+	case 0x0d: /* stw */
+		__asm__ __volatile__(
+		"1:	ldq_u %2,1(%5)\n"
+		"2:	ldq_u %1,0(%5)\n"
+		"	inswh %6,%5,%4\n"
+		"	inswl %6,%5,%3\n"
+		"	mskwh %2,%5,%2\n"
+		"	mskwl %1,%5,%1\n"
+		"	or %2,%4,%2\n"
+		"	or %1,%3,%1\n"
+		"3:	stq_u %2,1(%5)\n"
+		"4:	stq_u %1,0(%5)\n"
+		"5:\n"
+		EXC(1b,5b,%2,%0)
+		EXC(2b,5b,%1,%0)
+		EXC(3b,5b,$31,%0)
+		EXC(4b,5b,$31,%0)
+			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2),
+			  "=&r"(tmp3), "=&r"(tmp4)
+			: "r"(va), "r"(una_reg(reg)), "0"(0));
+		if (error)
+			goto got_exception;
+		return;
+
+	case 0x2c: /* stl */
+		__asm__ __volatile__(
+		"1:	ldq_u %2,3(%5)\n"
+		"2:	ldq_u %1,0(%5)\n"
+		"	inslh %6,%5,%4\n"
+		"	insll %6,%5,%3\n"
+		"	msklh %2,%5,%2\n"
+		"	mskll %1,%5,%1\n"
+		"	or %2,%4,%2\n"
+		"	or %1,%3,%1\n"
+		"3:	stq_u %2,3(%5)\n"
+		"4:	stq_u %1,0(%5)\n"
+		"5:\n"
+		EXC(1b,5b,%2,%0)
+		EXC(2b,5b,%1,%0)
+		EXC(3b,5b,$31,%0)
+		EXC(4b,5b,$31,%0)
+			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2),
+			  "=&r"(tmp3), "=&r"(tmp4)
+			: "r"(va), "r"(una_reg(reg)), "0"(0));
+		if (error)
+			goto got_exception;
+		return;
+
+	case 0x2d: /* stq */
+		__asm__ __volatile__(
+		"1:	ldq_u %2,7(%5)\n"
+		"2:	ldq_u %1,0(%5)\n"
+		"	insqh %6,%5,%4\n"
+		"	insql %6,%5,%3\n"
+		"	mskqh %2,%5,%2\n"
+		"	mskql %1,%5,%1\n"
+		"	or %2,%4,%2\n"
+		"	or %1,%3,%1\n"
+		"3:	stq_u %2,7(%5)\n"
+		"4:	stq_u %1,0(%5)\n"
+		"5:\n"
+		EXC(1b,5b,%2,%0)
+		EXC(2b,5b,%1,%0)
+		EXC(3b,5b,$31,%0)
+		EXC(4b,5b,$31,%0)
+			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2),
+			  "=&r"(tmp3), "=&r"(tmp4)
+			: "r"(va), "r"(una_reg(reg)), "0"(0));
+		if (error)
+			goto got_exception;
+		return;
+	}
+
+	printk("Bad unaligned kernel access at %016lx: %p %lx %lu\n",
+		pc, va, opcode, reg);
+	make_task_dead(SIGSEGV);
+
+got_exception:
+	/* Ok, we caught the exception, but we don't want it.  Is there
+	   someone to pass it along to?  */
+	if ((fixup = search_exception_tables(pc)) != 0) {
+		unsigned long newpc;
+		newpc = fixup_exception(una_reg, fixup, pc);
+
+		printk("Forwarding unaligned exception at %lx (%lx)\n",
+		       pc, newpc);
+
+		regs->pc = newpc;
+		return;
+	}
+
+	/*
+	 * Yikes!  No one to forward the exception to.
+	 * Since the registers are in a weird format, dump them ourselves.
+ 	 */
+
+	printk("%s(%d): unhandled unaligned exception\n",
+	       current->comm, task_pid_nr(current));
+
+	printk("pc = [<%016lx>]  ra = [<%016lx>]  ps = %04lx\n",
+	       pc, una_reg(26), regs->ps);
+	printk("r0 = %016lx  r1 = %016lx  r2 = %016lx\n",
+	       una_reg(0), una_reg(1), una_reg(2));
+	printk("r3 = %016lx  r4 = %016lx  r5 = %016lx\n",
+ 	       una_reg(3), una_reg(4), una_reg(5));
+	printk("r6 = %016lx  r7 = %016lx  r8 = %016lx\n",
+	       una_reg(6), una_reg(7), una_reg(8));
+	printk("r9 = %016lx  r10= %016lx  r11= %016lx\n",
+	       una_reg(9), una_reg(10), una_reg(11));
+	printk("r12= %016lx  r13= %016lx  r14= %016lx\n",
+	       una_reg(12), una_reg(13), una_reg(14));
+	printk("r15= %016lx\n", una_reg(15));
+	printk("r16= %016lx  r17= %016lx  r18= %016lx\n",
+	       una_reg(16), una_reg(17), una_reg(18));
+	printk("r19= %016lx  r20= %016lx  r21= %016lx\n",
+ 	       una_reg(19), una_reg(20), una_reg(21));
+ 	printk("r22= %016lx  r23= %016lx  r24= %016lx\n",
+	       una_reg(22), una_reg(23), una_reg(24));
+	printk("r25= %016lx  r27= %016lx  r28= %016lx\n",
+	       una_reg(25), una_reg(27), una_reg(28));
+	printk("gp = %016lx  sp = %p\n", regs->gp, regs+1);
+
+	dik_show_code((unsigned int *)pc);
+	dik_show_trace((unsigned long *)(regs+1), KERN_DEFAULT);
+
+	if (test_and_set_thread_flag (TIF_DIE_IF_KERNEL)) {
+		printk("die_if_kernel recursion detected.\n");
+		local_irq_enable();
+		while (1);
+	}
+	make_task_dead(SIGSEGV);
+}
+
+/*
+ * Convert an s-floating point value in memory format to the
+ * corresponding value in register format.  The exponent
+ * needs to be remapped to preserve non-finite values
+ * (infinities, not-a-numbers, denormals).
+ */
+static inline unsigned long
+s_mem_to_reg (unsigned long s_mem)
+{
+	unsigned long frac    = (s_mem >>  0) & 0x7fffff;
+	unsigned long sign    = (s_mem >> 31) & 0x1;
+	unsigned long exp_msb = (s_mem >> 30) & 0x1;
+	unsigned long exp_low = (s_mem >> 23) & 0x7f;
+	unsigned long exp;
+
+	exp = (exp_msb << 10) | exp_low;	/* common case */
+	if (exp_msb) {
+		if (exp_low == 0x7f) {
+			exp = 0x7ff;
+		}
+	} else {
+		if (exp_low == 0x00) {
+			exp = 0x000;
+		} else {
+			exp |= (0x7 << 7);
+		}
+	}
+	return (sign << 63) | (exp << 52) | (frac << 29);
+}
+
+/*
+ * Convert an s-floating point value in register format to the
+ * corresponding value in memory format.
+ */
+static inline unsigned long
+s_reg_to_mem (unsigned long s_reg)
+{
+	return ((s_reg >> 62) << 30) | ((s_reg << 5) >> 34);
+}
+
+/*
+ * Handle user-level unaligned fault.  Handling user-level unaligned
+ * faults is *extremely* slow and produces nasty messages.  A user
+ * program *should* fix unaligned faults ASAP.
+ *
+ * Notice that we have (almost) the regular kernel stack layout here,
+ * so finding the appropriate registers is a little more difficult
+ * than in the kernel case.
+ *
+ * Finally, we handle regular integer load/stores only.  In
+ * particular, load-linked/store-conditionally and floating point
+ * load/stores are not supported.  The former make no sense with
+ * unaligned faults (they are guaranteed to fail) and I don't think
+ * the latter will occur in any decent program.
+ *
+ * Sigh. We *do* have to handle some FP operations, because GCC will
+ * uses them as temporary storage for integer memory to memory copies.
+ * However, we need to deal with stt/ldt and sts/lds only.
+ */
+
+#define OP_INT_MASK	( 1L << 0x28 | 1L << 0x2c   /* ldl stl */	\
+			| 1L << 0x29 | 1L << 0x2d   /* ldq stq */	\
+			| 1L << 0x0c | 1L << 0x0d   /* ldwu stw */	\
+			| 1L << 0x0a | 1L << 0x0e ) /* ldbu stb */
+
+#define OP_WRITE_MASK	( 1L << 0x26 | 1L << 0x27   /* sts stt */	\
+			| 1L << 0x2c | 1L << 0x2d   /* stl stq */	\
+			| 1L << 0x0d | 1L << 0x0e ) /* stw stb */
+
+#define R(x)	((size_t) &((struct pt_regs *)0)->x)
+
+static int unauser_reg_offsets[32] = {
+	R(r0), R(r1), R(r2), R(r3), R(r4), R(r5), R(r6), R(r7), R(r8),
+	/* r9 ... r15 are stored in front of regs.  */
+	-56, -48, -40, -32, -24, -16, -8,
+	R(r16), R(r17), R(r18),
+	R(r19), R(r20), R(r21), R(r22), R(r23), R(r24), R(r25), R(r26),
+	R(r27), R(r28), R(gp),
+	0, 0
+};
+
+#undef R
+
+asmlinkage void
+do_entUnaUser(void __user * va, unsigned long opcode,
+	      unsigned long reg, struct pt_regs *regs)
+{
+	static DEFINE_RATELIMIT_STATE(ratelimit, 5 * HZ, 5);
+
+	unsigned long tmp1, tmp2, tmp3, tmp4;
+	unsigned long fake_reg, *reg_addr = &fake_reg;
+	int si_code;
+	long error;
+
+	/* Check the UAC bits to decide what the user wants us to do
+	   with the unaligned access.  */
+
+	if (!(current_thread_info()->status & TS_UAC_NOPRINT)) {
+		if (__ratelimit(&ratelimit)) {
+			printk("%s(%d): unaligned trap at %016lx: %p %lx %ld\n",
+			       current->comm, task_pid_nr(current),
+			       regs->pc - 4, va, opcode, reg);
+		}
+	}
+	if ((current_thread_info()->status & TS_UAC_SIGBUS))
+		goto give_sigbus;
+	/* Not sure why you'd want to use this, but... */
+	if ((current_thread_info()->status & TS_UAC_NOFIX))
+		return;
+
+	/* Don't bother reading ds in the access check since we already
+	   know that this came from the user.  Also rely on the fact that
+	   the page at TASK_SIZE is unmapped and so can't be touched anyway. */
+	if ((unsigned long)va >= TASK_SIZE)
+		goto give_sigsegv;
+
+	++unaligned[1].count;
+	unaligned[1].va = (unsigned long)va;
+	unaligned[1].pc = regs->pc - 4;
+
+	if ((1L << opcode) & OP_INT_MASK) {
+		/* it's an integer load/store */
+		if (reg < 30) {
+			reg_addr = (unsigned long *)
+			  ((char *)regs + unauser_reg_offsets[reg]);
+		} else if (reg == 30) {
+			/* usp in PAL regs */
+			fake_reg = rdusp();
+		} else {
+			/* zero "register" */
+			fake_reg = 0;
+		}
+	}
+
+	/* We don't want to use the generic get/put unaligned macros as
+	   we want to trap exceptions.  Only if we actually get an
+	   exception will we decide whether we should have caught it.  */
+
+	switch (opcode) {
+	case 0x0c: /* ldwu */
+		__asm__ __volatile__(
+		"1:	ldq_u %1,0(%3)\n"
+		"2:	ldq_u %2,1(%3)\n"
+		"	extwl %1,%3,%1\n"
+		"	extwh %2,%3,%2\n"
+		"3:\n"
+		EXC(1b,3b,%1,%0)
+		EXC(2b,3b,%2,%0)
+			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2)
+			: "r"(va), "0"(0));
+		if (error)
+			goto give_sigsegv;
+		*reg_addr = tmp1|tmp2;
+		break;
+
+	case 0x22: /* lds */
+		__asm__ __volatile__(
+		"1:	ldq_u %1,0(%3)\n"
+		"2:	ldq_u %2,3(%3)\n"
+		"	extll %1,%3,%1\n"
+		"	extlh %2,%3,%2\n"
+		"3:\n"
+		EXC(1b,3b,%1,%0)
+		EXC(2b,3b,%2,%0)
+			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2)
+			: "r"(va), "0"(0));
+		if (error)
+			goto give_sigsegv;
+		alpha_write_fp_reg(reg, s_mem_to_reg((int)(tmp1|tmp2)));
+		return;
+
+	case 0x23: /* ldt */
+		__asm__ __volatile__(
+		"1:	ldq_u %1,0(%3)\n"
+		"2:	ldq_u %2,7(%3)\n"
+		"	extql %1,%3,%1\n"
+		"	extqh %2,%3,%2\n"
+		"3:\n"
+		EXC(1b,3b,%1,%0)
+		EXC(2b,3b,%2,%0)
+			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2)
+			: "r"(va), "0"(0));
+		if (error)
+			goto give_sigsegv;
+		alpha_write_fp_reg(reg, tmp1|tmp2);
+		return;
+
+	case 0x28: /* ldl */
+		__asm__ __volatile__(
+		"1:	ldq_u %1,0(%3)\n"
+		"2:	ldq_u %2,3(%3)\n"
+		"	extll %1,%3,%1\n"
+		"	extlh %2,%3,%2\n"
+		"3:\n"
+		EXC(1b,3b,%1,%0)
+		EXC(2b,3b,%2,%0)
+			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2)
+			: "r"(va), "0"(0));
+		if (error)
+			goto give_sigsegv;
+		*reg_addr = (int)(tmp1|tmp2);
+		break;
+
+	case 0x29: /* ldq */
+		__asm__ __volatile__(
+		"1:	ldq_u %1,0(%3)\n"
+		"2:	ldq_u %2,7(%3)\n"
+		"	extql %1,%3,%1\n"
+		"	extqh %2,%3,%2\n"
+		"3:\n"
+		EXC(1b,3b,%1,%0)
+		EXC(2b,3b,%2,%0)
+			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2)
+			: "r"(va), "0"(0));
+		if (error)
+			goto give_sigsegv;
+		*reg_addr = tmp1|tmp2;
+		break;
+
+	/* Note that the store sequences do not indicate that they change
+	   memory because it _should_ be affecting nothing in this context.
+	   (Otherwise we have other, much larger, problems.)  */
+	case 0x0d: /* stw */
+		__asm__ __volatile__(
+		"1:	ldq_u %2,1(%5)\n"
+		"2:	ldq_u %1,0(%5)\n"
+		"	inswh %6,%5,%4\n"
+		"	inswl %6,%5,%3\n"
+		"	mskwh %2,%5,%2\n"
+		"	mskwl %1,%5,%1\n"
+		"	or %2,%4,%2\n"
+		"	or %1,%3,%1\n"
+		"3:	stq_u %2,1(%5)\n"
+		"4:	stq_u %1,0(%5)\n"
+		"5:\n"
+		EXC(1b,5b,%2,%0)
+		EXC(2b,5b,%1,%0)
+		EXC(3b,5b,$31,%0)
+		EXC(4b,5b,$31,%0)
+			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2),
+			  "=&r"(tmp3), "=&r"(tmp4)
+			: "r"(va), "r"(*reg_addr), "0"(0));
+		if (error)
+			goto give_sigsegv;
+		return;
+
+	case 0x26: /* sts */
+		fake_reg = s_reg_to_mem(alpha_read_fp_reg(reg));
+		fallthrough;
+
+	case 0x2c: /* stl */
+		__asm__ __volatile__(
+		"1:	ldq_u %2,3(%5)\n"
+		"2:	ldq_u %1,0(%5)\n"
+		"	inslh %6,%5,%4\n"
+		"	insll %6,%5,%3\n"
+		"	msklh %2,%5,%2\n"
+		"	mskll %1,%5,%1\n"
+		"	or %2,%4,%2\n"
+		"	or %1,%3,%1\n"
+		"3:	stq_u %2,3(%5)\n"
+		"4:	stq_u %1,0(%5)\n"
+		"5:\n"
+		EXC(1b,5b,%2,%0)
+		EXC(2b,5b,%1,%0)
+		EXC(3b,5b,$31,%0)
+		EXC(4b,5b,$31,%0)
+			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2),
+			  "=&r"(tmp3), "=&r"(tmp4)
+			: "r"(va), "r"(*reg_addr), "0"(0));
+		if (error)
+			goto give_sigsegv;
+		return;
+
+	case 0x27: /* stt */
+		fake_reg = alpha_read_fp_reg(reg);
+		fallthrough;
+
+	case 0x2d: /* stq */
+		__asm__ __volatile__(
+		"1:	ldq_u %2,7(%5)\n"
+		"2:	ldq_u %1,0(%5)\n"
+		"	insqh %6,%5,%4\n"
+		"	insql %6,%5,%3\n"
+		"	mskqh %2,%5,%2\n"
+		"	mskql %1,%5,%1\n"
+		"	or %2,%4,%2\n"
+		"	or %1,%3,%1\n"
+		"3:	stq_u %2,7(%5)\n"
+		"4:	stq_u %1,0(%5)\n"
+		"5:\n"
+		EXC(1b,5b,%2,%0)
+		EXC(2b,5b,%1,%0)
+		EXC(3b,5b,$31,%0)
+		EXC(4b,5b,$31,%0)
+			: "=r"(error), "=&r"(tmp1), "=&r"(tmp2),
+			  "=&r"(tmp3), "=&r"(tmp4)
+			: "r"(va), "r"(*reg_addr), "0"(0));
+		if (error)
+			goto give_sigsegv;
+		return;
+
+	default:
+		/* What instruction were you trying to use, exactly?  */
+		goto give_sigbus;
+	}
+
+	/* Only integer loads should get here; everyone else returns early. */
+	if (reg == 30)
+		wrusp(fake_reg);
+	return;
+
+give_sigsegv:
+	regs->pc -= 4;  /* make pc point to faulting insn */
+
+	/* We need to replicate some of the logic in mm/fault.c,
+	   since we don't have access to the fault code in the
+	   exception handling return path.  */
+	if ((unsigned long)va >= TASK_SIZE)
+		si_code = SEGV_ACCERR;
+	else {
+		struct mm_struct *mm = current->mm;
+		mmap_read_lock(mm);
+		if (find_vma(mm, (unsigned long)va))
+			si_code = SEGV_ACCERR;
+		else
+			si_code = SEGV_MAPERR;
+		mmap_read_unlock(mm);
+	}
+	send_sig_fault(SIGSEGV, si_code, va, current);
+	return;
+
+give_sigbus:
+	regs->pc -= 4;
+	send_sig_fault(SIGBUS, BUS_ADRALN, va, current);
+	return;
+}
+
+void
+trap_init(void)
+{
+	/* Tell PAL-code what global pointer we want in the kernel.  */
+	register unsigned long gptr __asm__("$29");
+	wrkgp(gptr);
+
+	/* Hack for Multia (UDB) and JENSEN: some of their SRMs have
+	   a bug in the handling of the opDEC fault.  Fix it up if so.  */
+	if (implver() == IMPLVER_EV4)
+		opDEC_check();
+
+	wrent(entArith, 1);
+	wrent(entMM, 2);
+	wrent(entIF, 3);
+	wrent(entUna, 4);
+	wrent(entSys, 5);
+	wrent(entDbg, 6);
+}