arch/tile: core support for Tilera 32-bit chips.

This change is the core kernel support for TILEPro and TILE64 chips.
No driver support (except the console driver) is included yet.

This includes the relevant Linux headers in asm/; the low-level
low-level "Tile architecture" headers in arch/, which are
shared with the hypervisor, etc., and are build-system agnostic;
and the relevant hypervisor headers in hv/.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Reviewed-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 237 insertions, 0 deletions

diff --git a/arch/tile/kernel/traps.c b/arch/tile/kernel/traps.c
new file mode 100644
index 00000000000..12cb10f3852
--- /dev/null
+++ b/arch/tile/kernel/traps.c
@@ -0,0 +1,237 @@
+/*
+ * Copyright 2010 Tilera Corporation. All Rights Reserved.
+ *
+ *   This program is free software; you can redistribute it and/or
+ *   modify it under the terms of the GNU General Public License
+ *   as published by the Free Software Foundation, version 2.
+ *
+ *   This program is distributed in the hope that it will be useful, but
+ *   WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ *   NON INFRINGEMENT.  See the GNU General Public License for
+ *   more details.
+ */
+
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/kprobes.h>
+#include <linux/module.h>
+#include <linux/reboot.h>
+#include <linux/uaccess.h>
+#include <linux/ptrace.h>
+#include <asm/opcode-tile.h>
+
+#include <arch/interrupts.h>
+#include <arch/spr_def.h>
+
+void __init trap_init(void)
+{
+	/* Nothing needed here since we link code at .intrpt1 */
+}
+
+int unaligned_fixup = 1;
+
+static int __init setup_unaligned_fixup(char *str)
+{
+	/*
+	 * Say "=-1" to completely disable it.  If you just do "=0", we
+	 * will still parse the instruction, then fire a SIGBUS with
+	 * the correct address from inside the single_step code.
+	 */
+	long val;
+	if (strict_strtol(str, 0, &val) != 0)
+		return 0;
+	unaligned_fixup = val;
+	printk("Fixups for unaligned data accesses are %s\n",
+	       unaligned_fixup >= 0 ?
+	       (unaligned_fixup ? "enabled" : "disabled") :
+	       "completely disabled");
+	return 1;
+}
+__setup("unaligned_fixup=", setup_unaligned_fixup);
+
+#if CHIP_HAS_TILE_DMA()
+
+static int dma_disabled;
+
+static int __init nodma(char *str)
+{
+	printk("User-space DMA is disabled\n");
+	dma_disabled = 1;
+	return 1;
+}
+__setup("nodma", nodma);
+
+/* How to decode SPR_GPV_REASON */
+#define IRET_ERROR (1U << 31)
+#define MT_ERROR   (1U << 30)
+#define MF_ERROR   (1U << 29)
+#define SPR_INDEX  ((1U << 15) - 1)
+#define SPR_MPL_SHIFT  9  /* starting bit position for MPL encoded in SPR */
+
+/*
+ * See if this GPV is just to notify the kernel of SPR use and we can
+ * retry the user instruction after adjusting some MPLs suitably.
+ */
+static int retry_gpv(unsigned int gpv_reason)
+{
+	int mpl;
+
+	if (gpv_reason & IRET_ERROR)
+		return 0;
+
+	BUG_ON((gpv_reason & (MT_ERROR|MF_ERROR)) == 0);
+	mpl = (gpv_reason & SPR_INDEX) >> SPR_MPL_SHIFT;
+	if (mpl == INT_DMA_NOTIFY && !dma_disabled) {
+		/* User is turning on DMA. Allow it and retry. */
+		printk(KERN_DEBUG "Process %d/%s is now enabled for DMA\n",
+		       current->pid, current->comm);
+		BUG_ON(current->thread.tile_dma_state.enabled);
+		current->thread.tile_dma_state.enabled = 1;
+		grant_dma_mpls();
+		return 1;
+	}
+
+	return 0;
+}
+
+#endif /* CHIP_HAS_TILE_DMA() */
+
+/* Defined inside do_trap(), below. */
+#ifdef __tilegx__
+extern tilegx_bundle_bits bpt_code;
+#else
+extern tile_bundle_bits bpt_code;
+#endif
+
+void __kprobes do_trap(struct pt_regs *regs, int fault_num,
+		       unsigned long reason)
+{
+	siginfo_t info = { 0 };
+	int signo, code;
+	unsigned long address;
+	__typeof__(bpt_code) instr;
+
+	/* Re-enable interrupts. */
+	local_irq_enable();
+
+	/*
+	 * If it hits in kernel mode and we can't fix it up, just exit the
+	 * current process and hope for the best.
+	 */
+	if (!user_mode(regs)) {
+		if (fixup_exception(regs))  /* only UNALIGN_DATA in practice */
+			return;
+		printk(KERN_ALERT "Kernel took bad trap %d at PC %#lx\n",
+		       fault_num, regs->pc);
+		if (fault_num == INT_GPV)
+			printk(KERN_ALERT "GPV_REASON is %#lx\n", reason);
+		show_regs(regs);
+		do_exit(SIGKILL);  /* FIXME: implement i386 die() */
+		return;
+	}
+
+	switch (fault_num) {
+	case INT_ILL:
+		asm(".pushsection .rodata.bpt_code,\"a\";"
+		    ".align 8;"
+		    "bpt_code: bpt;"
+		    ".size bpt_code,.-bpt_code;"
+		    ".popsection");
+
+		if (copy_from_user(&instr, (void *)regs->pc, sizeof(instr))) {
+			printk(KERN_ERR "Unreadable instruction for INT_ILL:"
+			       " %#lx\n", regs->pc);
+			do_exit(SIGKILL);
+			return;
+		}
+		if (instr == bpt_code) {
+			signo = SIGTRAP;
+			code = TRAP_BRKPT;
+		} else {
+			signo = SIGILL;
+			code = ILL_ILLOPC;
+		}
+		address = regs->pc;
+		break;
+	case INT_GPV:
+#if CHIP_HAS_TILE_DMA()
+		if (retry_gpv(reason))
+			return;
+#endif
+		/*FALLTHROUGH*/
+	case INT_UDN_ACCESS:
+	case INT_IDN_ACCESS:
+#if CHIP_HAS_SN()
+	case INT_SN_ACCESS:
+#endif
+		signo = SIGILL;
+		code = ILL_PRVREG;
+		address = regs->pc;
+		break;
+	case INT_SWINT_3:
+	case INT_SWINT_2:
+	case INT_SWINT_0:
+		signo = SIGILL;
+		code = ILL_ILLTRP;
+		address = regs->pc;
+		break;
+	case INT_UNALIGN_DATA:
+#ifndef __tilegx__  /* FIXME: GX: no single-step yet */
+		if (unaligned_fixup >= 0) {
+			struct single_step_state *state =
+				current_thread_info()->step_state;
+			if (!state || (void *)(regs->pc) != state->buffer) {
+				single_step_once(regs);
+				return;
+			}
+		}
+#endif
+		signo = SIGBUS;
+		code = BUS_ADRALN;
+		address = 0;
+		break;
+	case INT_DOUBLE_FAULT:
+		/*
+		 * For double fault, "reason" is actually passed as
+		 * SYSTEM_SAVE_1_2, the hypervisor's double-fault info, so
+		 * we can provide the original fault number rather than
+		 * the uninteresting "INT_DOUBLE_FAULT" so the user can
+		 * learn what actually struck while PL0 ICS was set.
+		 */
+		fault_num = reason;
+		signo = SIGILL;
+		code = ILL_DBLFLT;
+		address = regs->pc;
+		break;
+#ifdef __tilegx__
+	case INT_ILL_TRANS:
+		signo = SIGSEGV;
+		code = SEGV_MAPERR;
+		if (reason & SPR_ILL_TRANS_REASON__I_STREAM_VA_RMASK)
+			address = regs->pc;
+		else
+			address = 0;  /* FIXME: GX: single-step for address */
+		break;
+#endif
+	default:
+		panic("Unexpected do_trap interrupt number %d", fault_num);
+		return;
+	}
+
+	info.si_signo = signo;
+	info.si_code = code;
+	info.si_addr = (void *)address;
+	if (signo == SIGILL)
+		info.si_trapno = fault_num;
+	force_sig_info(signo, &info, current);
+}
+
+extern void _dump_stack(int dummy, ulong pc, ulong lr, ulong sp, ulong r52);
+
+void kernel_double_fault(int dummy, ulong pc, ulong lr, ulong sp, ulong r52)
+{
+	_dump_stack(dummy, pc, lr, sp, r52);
+	printk("Double fault: exiting\n");
+	machine_halt();
+}