1 files changed, 317 insertions, 0 deletions
diff --git a/arch/tile/kernel/traps.c b/arch/tile/kernel/traps.c
new file mode 100644
index 00000000000..3870abbeeaa
--- /dev/null
+++ b/arch/tile/kernel/traps.c
@@ -0,0 +1,317 @@
+/*
+ * 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 <asm/opcode_constants.h>
+#include <asm/stack.h>
+#include <asm/traps.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;
+	pr_info("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)
+{
+	pr_info("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() */
+
+#ifdef __tilegx__
+#define bundle_bits tilegx_bundle_bits
+#else
+#define bundle_bits tile_bundle_bits
+#endif
+
+extern bundle_bits bpt_code;
+
+asm(".pushsection .rodata.bpt_code,\"a\";"
+    ".align 8;"
+    "bpt_code: bpt;"
+    ".size bpt_code,.-bpt_code;"
+    ".popsection");
+
+static int special_ill(bundle_bits bundle, int *sigp, int *codep)
+{
+	int sig, code, maxcode;
+
+	if (bundle == bpt_code) {
+		*sigp = SIGTRAP;
+		*codep = TRAP_BRKPT;
+		return 1;
+	}
+
+	/* If it's a "raise" bundle, then "ill" must be in pipe X1. */
+#ifdef __tilegx__
+	if ((bundle & TILEGX_BUNDLE_MODE_MASK) != 0)
+		return 0;
+	if (get_Opcode_X1(bundle) != UNARY_OPCODE_X1)
+		return 0;
+	if (get_UnaryOpcodeExtension_X1(bundle) != ILL_UNARY_OPCODE_X1)
+		return 0;
+#else
+	if (bundle & TILE_BUNDLE_Y_ENCODING_MASK)
+		return 0;
+	if (get_Opcode_X1(bundle) != SHUN_0_OPCODE_X1)
+		return 0;
+	if (get_UnShOpcodeExtension_X1(bundle) != UN_0_SHUN_0_OPCODE_X1)
+		return 0;
+	if (get_UnOpcodeExtension_X1(bundle) != ILL_UN_0_SHUN_0_OPCODE_X1)
+		return 0;
+#endif
+
+	/* Check that the magic distinguishers are set to mean "raise". */
+	if (get_Dest_X1(bundle) != 29 || get_SrcA_X1(bundle) != 37)
+		return 0;
+
+	/* There must be an "addli zero, zero, VAL" in X0. */
+	if (get_Opcode_X0(bundle) != ADDLI_OPCODE_X0)
+		return 0;
+	if (get_Dest_X0(bundle) != TREG_ZERO)
+		return 0;
+	if (get_SrcA_X0(bundle) != TREG_ZERO)
+		return 0;
+
+	/*
+	 * Validate the proposed signal number and si_code value.
+	 * Note that we embed these in the static instruction itself
+	 * so that we perturb the register state as little as possible
+	 * at the time of the actual fault; it's unlikely you'd ever
+	 * need to dynamically choose which kind of fault to raise
+	 * from user space.
+	 */
+	sig = get_Imm16_X0(bundle) & 0x3f;
+	switch (sig) {
+	case SIGILL:
+		maxcode = NSIGILL;
+		break;
+	case SIGFPE:
+		maxcode = NSIGFPE;
+		break;
+	case SIGSEGV:
+		maxcode = NSIGSEGV;
+		break;
+	case SIGBUS:
+		maxcode = NSIGBUS;
+		break;
+	case SIGTRAP:
+		maxcode = NSIGTRAP;
+		break;
+	default:
+		return 0;
+	}
+	code = (get_Imm16_X0(bundle) >> 6) & 0xf;
+	if (code <= 0 || code > maxcode)
+		return 0;
+
+	/* Make it the requested signal. */
+	*sigp = sig;
+	*codep = code | __SI_FAULT;
+	return 1;
+}
+
+void __kprobes do_trap(struct pt_regs *regs, int fault_num,
+		       unsigned long reason)
+{
+	siginfo_t info = { 0 };
+	int signo, code;
+	unsigned long address;
+	bundle_bits 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;
+		pr_alert("Kernel took bad trap %d at PC %#lx\n",
+		       fault_num, regs->pc);
+		if (fault_num == INT_GPV)
+			pr_alert("GPV_REASON is %#lx\n", reason);
+		show_regs(regs);
+		do_exit(SIGKILL);  /* FIXME: implement i386 die() */
+		return;
+	}
+
+	switch (fault_num) {
+	case INT_ILL:
+		if (copy_from_user(&instr, (void __user *)regs->pc,
+				   sizeof(instr))) {
+			pr_err("Unreadable instruction for INT_ILL:"
+			       " %#lx\n", regs->pc);
+			do_exit(SIGKILL);
+			return;
+		}
+		if (!special_ill(instr, &signo, &code)) {
+			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 __user *)(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 __user *)address;
+	if (signo == SIGILL)
+		info.si_trapno = fault_num;
+	force_sig_info(signo, &info, current);
+}
+
+void kernel_double_fault(int dummy, ulong pc, ulong lr, ulong sp, ulong r52)
+{
+	_dump_stack(dummy, pc, lr, sp, r52);
+	pr_emerg("Double fault: exiting\n");
+	machine_halt();
+}