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 000000000000..12cb10f38527
--- /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();
+}