[PATCH] xtensa: Architecture support for Tensilica Xtensa Part 3

The attached patches provides part 3 of an architecture implementation for the
Tensilica Xtensa CPU series.

Signed-off-by: Chris Zankel <chris@zankel.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 498 insertions, 0 deletions

diff --git a/arch/xtensa/kernel/traps.c b/arch/xtensa/kernel/traps.c
new file mode 100644
index 000000000000..804246e743b1
--- /dev/null
+++ b/arch/xtensa/kernel/traps.c
@@ -0,0 +1,498 @@
+/*
+ * arch/xtensa/kernel/traps.c
+ *
+ * Exception handling.
+ *
+ * Derived from code with the following copyrights:
+ * Copyright (C) 1994 - 1999 by Ralf Baechle
+ * Modified for R3000 by Paul M. Antoine, 1995, 1996
+ * Complete output from die() by Ulf Carlsson, 1998
+ * Copyright (C) 1999 Silicon Graphics, Inc.
+ *
+ * Essentially rewritten for the Xtensa architecture port.
+ *
+ * Copyright (C) 2001 - 2005 Tensilica Inc.
+ *
+ * Joe Taylor   <joe@tensilica.com, joetylr@yahoo.com>
+ * Chris Zankel <chris@zankel.net>
+ * Marc Gauthier<marc@tensilica.com, marc@alumni.uwaterloo.ca>
+ * Kevin Chea
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/stringify.h>
+#include <linux/kallsyms.h>
+
+#include <asm/ptrace.h>
+#include <asm/timex.h>
+#include <asm/uaccess.h>
+#include <asm/pgtable.h>
+#include <asm/processor.h>
+
+#ifdef CONFIG_KGDB
+extern int gdb_enter;
+extern int return_from_debug_flag;
+#endif
+
+/*
+ * Machine specific interrupt handlers
+ */
+
+extern void kernel_exception(void);
+extern void user_exception(void);
+
+extern void fast_syscall_kernel(void);
+extern void fast_syscall_user(void);
+extern void fast_alloca(void);
+extern void fast_unaligned(void);
+extern void fast_second_level_miss(void);
+extern void fast_store_prohibited(void);
+extern void fast_coprocessor(void);
+
+extern void do_illegal_instruction (struct pt_regs*);
+extern void do_interrupt (struct pt_regs*);
+extern void do_unaligned_user (struct pt_regs*);
+extern void do_multihit (struct pt_regs*, unsigned long);
+extern void do_page_fault (struct pt_regs*, unsigned long);
+extern void do_debug (struct pt_regs*);
+extern void system_call (struct pt_regs*);
+
+/*
+ * The vector table must be preceded by a save area (which
+ * implies it must be in RAM, unless one places RAM immediately
+ * before a ROM and puts the vector at the start of the ROM (!))
+ */
+
+#define KRNL            0x01
+#define USER            0x02
+
+#define COPROCESSOR(x)                                                  \
+{ XCHAL_EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_coprocessor }
+
+typedef struct {
+        int cause;
+        int fast;
+        void* handler;
+} dispatch_init_table_t;
+
+dispatch_init_table_t __init dispatch_init_table[] = {
+
+{ XCHAL_EXCCAUSE_ILLEGAL_INSTRUCTION,   0,         do_illegal_instruction},
+{ XCHAL_EXCCAUSE_SYSTEM_CALL,           KRNL,      fast_syscall_kernel },
+{ XCHAL_EXCCAUSE_SYSTEM_CALL,           USER,      fast_syscall_user },
+{ XCHAL_EXCCAUSE_SYSTEM_CALL,           0,         system_call },
+/* XCHAL_EXCCAUSE_INSTRUCTION_FETCH unhandled */
+/* XCHAL_EXCCAUSE_LOAD_STORE_ERROR unhandled*/
+{ XCHAL_EXCCAUSE_LEVEL1_INTERRUPT,      0,         do_interrupt },
+{ XCHAL_EXCCAUSE_ALLOCA,                USER|KRNL, fast_alloca },
+/* XCHAL_EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */
+/* XCHAL_EXCCAUSE_PRIVILEGED unhandled */
+#if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
+#ifdef CONFIG_UNALIGNED_USER
+{ XCHAL_EXCCAUSE_UNALIGNED,             USER,      fast_unaligned },
+#else
+{ XCHAL_EXCCAUSE_UNALIGNED,             0,         do_unaligned_user },
+#endif
+{ XCHAL_EXCCAUSE_UNALIGNED,             KRNL,      fast_unaligned },
+#endif
+{ XCHAL_EXCCAUSE_ITLB_MISS,             0,         do_page_fault },
+{ XCHAL_EXCCAUSE_ITLB_MISS,             USER|KRNL, fast_second_level_miss},
+{ XCHAL_EXCCAUSE_ITLB_MULTIHIT,         0,         do_multihit },
+{ XCHAL_EXCCAUSE_ITLB_PRIVILEGE,        0,         do_page_fault },
+/* XCHAL_EXCCAUSE_SIZE_RESTRICTION unhandled */
+{ XCHAL_EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0,         do_page_fault },
+{ XCHAL_EXCCAUSE_DTLB_MISS,             USER|KRNL, fast_second_level_miss},
+{ XCHAL_EXCCAUSE_DTLB_MISS,             0,         do_page_fault },
+{ XCHAL_EXCCAUSE_DTLB_MULTIHIT,         0,         do_multihit },
+{ XCHAL_EXCCAUSE_DTLB_PRIVILEGE,        0,         do_page_fault },
+/* XCHAL_EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */
+{ XCHAL_EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited },
+{ XCHAL_EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0,         do_page_fault },
+{ XCHAL_EXCCAUSE_LOAD_CACHE_ATTRIBUTE,  0,         do_page_fault },
+/* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
+#if (XCHAL_CP_MASK & 1)
+COPROCESSOR(0),
+#endif
+#if (XCHAL_CP_MASK & 2)
+COPROCESSOR(1),
+#endif
+#if (XCHAL_CP_MASK & 4)
+COPROCESSOR(2),
+#endif
+#if (XCHAL_CP_MASK & 8)
+COPROCESSOR(3),
+#endif
+#if (XCHAL_CP_MASK & 16)
+COPROCESSOR(4),
+#endif
+#if (XCHAL_CP_MASK & 32)
+COPROCESSOR(5),
+#endif
+#if (XCHAL_CP_MASK & 64)
+COPROCESSOR(6),
+#endif
+#if (XCHAL_CP_MASK & 128)
+COPROCESSOR(7),
+#endif
+{ EXCCAUSE_MAPPED_DEBUG,                0,              do_debug },
+{ -1, -1, 0 }
+
+};
+
+/* The exception table <exc_table> serves two functions:
+ * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
+ * 2. it is a temporary memory buffer for the exception handlers.
+ */
+
+unsigned long exc_table[EXC_TABLE_SIZE/4];
+
+void die(const char*, struct pt_regs*, long);
+
+static inline void
+__die_if_kernel(const char *str, struct pt_regs *regs, long err)
+{
+        if (!user_mode(regs))
+                die(str, regs, err);
+}
+
+/*
+ * Unhandled Exceptions. Kill user task or panic if in kernel space.
+ */
+
+void do_unhandled(struct pt_regs *regs, unsigned long exccause)
+{
+        __die_if_kernel("Caught unhandled exception - should not happen",
+                        regs, SIGKILL);
+
+        /* If in user mode, send SIGILL signal to current process */
+        printk("Caught unhandled exception in '%s' "
+               "(pid = %d, pc = %#010lx) - should not happen\n"
+               "\tEXCCAUSE is %ld\n",
+               current->comm, current->pid, regs->pc, exccause);
+        force_sig(SIGILL, current);
+}
+
+/*
+ * Multi-hit exception. This if fatal!
+ */
+
+void do_multihit(struct pt_regs *regs, unsigned long exccause)
+{
+        die("Caught multihit exception", regs, SIGKILL);
+}
+
+/*
+ * Level-1 interrupt.
+ * We currently have no priority encoding.
+ */
+
+unsigned long ignored_level1_interrupts;
+extern void do_IRQ(int, struct pt_regs *);
+
+void do_interrupt (struct pt_regs *regs)
+{
+        unsigned long intread = get_sr (INTREAD);
+        unsigned long intenable = get_sr (INTENABLE);
+        int i, mask;
+
+        /* Handle all interrupts (no priorities).
+         * (Clear the interrupt before processing, in case it's
+         *  edge-triggered or software-generated)
+         */
+
+        for (i=0, mask = 1; i < XCHAL_NUM_INTERRUPTS; i++, mask <<= 1) {
+                if (mask & (intread & intenable)) {
+                        set_sr (mask, INTCLEAR);
+                        do_IRQ (i,regs);
+                }
+        }
+}
+
+/*
+ * Illegal instruction. Fatal if in kernel space.
+ */
+
+void
+do_illegal_instruction(struct pt_regs *regs)
+{
+        __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
+
+        /* If in user mode, send SIGILL signal to current process. */
+
+        printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
+            current->comm, current->pid, regs->pc);
+        force_sig(SIGILL, current);
+}
+
+
+/*
+ * Handle unaligned memory accesses from user space. Kill task.
+ *
+ * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
+ * accesses causes from user space.
+ */
+
+#if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
+#ifndef CONFIG_UNALIGNED_USER
+void
+do_unaligned_user (struct pt_regs *regs)
+{
+        siginfo_t info;
+
+        __die_if_kernel("Unhandled unaligned exception in kernel",
+                        regs, SIGKILL);
+
+        current->thread.bad_vaddr = regs->excvaddr;
+        current->thread.error_code = -3;
+        printk("Unaligned memory access to %08lx in '%s' "
+               "(pid = %d, pc = %#010lx)\n",
+               regs->excvaddr, current->comm, current->pid, regs->pc);
+        info.si_signo = SIGBUS;
+        info.si_errno = 0;
+        info.si_code = BUS_ADRALN;
+        info.si_addr = (void *) regs->excvaddr;
+        force_sig_info(SIGSEGV, &info, current);
+
+}
+#endif
+#endif
+
+void
+do_debug(struct pt_regs *regs)
+{
+#ifdef CONFIG_KGDB
+        /* If remote debugging is configured AND enabled, we give control to
+         * kgdb.  Otherwise, we fall through, perhaps giving control to the
+         * native debugger.
+         */
+
+        if (gdb_enter) {
+                extern void gdb_handle_exception(struct pt_regs *);
+                gdb_handle_exception(regs);
+                return_from_debug_flag = 1;
+                return;
+        }
+#endif
+
+        __die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
+
+        /* If in user mode, send SIGTRAP signal to current process */
+
+        force_sig(SIGTRAP, current);
+}
+
+
+/*
+ * Initialize dispatch tables.
+ *
+ * The exception vectors are stored compressed the __init section in the
+ * dispatch_init_table. This function initializes the following three tables
+ * from that compressed table:
+ * - fast user          first dispatch table for user exceptions
+ * - fast kernel        first dispatch table for kernel exceptions
+ * - default C-handler  C-handler called by the default fast handler.
+ *
+ * See vectors.S for more details.
+ */
+
+#define set_handler(idx,handler) (exc_table[idx] = (unsigned long) (handler))
+
+void trap_init(void)
+{
+        int i;
+
+        /* Setup default vectors. */
+
+        for(i = 0; i < 64; i++) {
+                set_handler(EXC_TABLE_FAST_USER/4   + i, user_exception);
+                set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception);
+                set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled);
+        }
+
+        /* Setup specific handlers. */
+
+        for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
+
+                int fast = dispatch_init_table[i].fast;
+                int cause = dispatch_init_table[i].cause;
+                void *handler = dispatch_init_table[i].handler;
+
+                if (fast == 0)
+                        set_handler (EXC_TABLE_DEFAULT/4 + cause, handler);
+                if (fast && fast & USER)
+                        set_handler (EXC_TABLE_FAST_USER/4 + cause, handler);
+                if (fast && fast & KRNL)
+                        set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler);
+        }
+
+        /* Initialize EXCSAVE_1 to hold the address of the exception table. */
+
+        i = (unsigned long)exc_table;
+        __asm__ __volatile__("wsr  %0, "__stringify(EXCSAVE_1)"\n" : : "a" (i));
+}
+
+/*
+ * This function dumps the current valid window frame and other base registers.
+ */
+
+void show_regs(struct pt_regs * regs)
+{
+        int i, wmask;
+
+        wmask = regs->wmask & ~1;
+
+        for (i = 0; i < 32; i++) {
+                if (wmask & (1 << (i / 4)))
+                        break;
+                if ((i % 8) == 0)
+                        printk ("\n" KERN_INFO "a%02d: ", i);
+                printk("%08lx ", regs->areg[i]);
+        }
+        printk("\n");
+
+        printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
+               regs->pc, regs->ps, regs->depc, regs->excvaddr);
+        printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
+               regs->lbeg, regs->lend, regs->lcount, regs->sar);
+        if (user_mode(regs))
+                printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
+                       regs->windowbase, regs->windowstart, regs->wmask,
+                       regs->syscall);
+}
+
+void show_trace(struct task_struct *task, unsigned long *sp)
+{
+        unsigned long a0, a1, pc;
+        unsigned long sp_start, sp_end;
+
+        a1 = (unsigned long)sp;
+
+        if (a1 == 0)
+                __asm__ __volatile__ ("mov %0, a1\n" : "=a"(a1));
+
+
+        sp_start = a1 & ~(THREAD_SIZE-1);
+        sp_end = sp_start + THREAD_SIZE;
+
+        printk("Call Trace:");
+#ifdef CONFIG_KALLSYMS
+        printk("\n");
+#endif
+        spill_registers();
+
+        while (a1 > sp_start && a1 < sp_end) {
+                sp = (unsigned long*)a1;
+
+                a0 = *(sp - 4);
+                a1 = *(sp - 3);
+
+                if (a1 <= (unsigned long) sp)
+                        break;
+
+                pc = MAKE_PC_FROM_RA(a0, a1);
+
+                if (kernel_text_address(pc)) {
+                        printk(" [<%08lx>] ", pc);
+                        print_symbol("%s\n", pc);
+                }
+        }
+        printk("\n");
+}
+
+/*
+ * This routine abuses get_user()/put_user() to reference pointers
+ * with at least a bit of error checking ...
+ */
+
+static int kstack_depth_to_print = 24;
+
+void show_stack(struct task_struct *task, unsigned long *sp)
+{
+        int i = 0;
+        unsigned long *stack;
+
+        if (sp == 0)
+                __asm__ __volatile__ ("mov %0, a1\n" : "=a"(sp));
+
+        stack = sp;
+
+        printk("\nStack: ");
+
+        for (i = 0; i < kstack_depth_to_print; i++) {
+                if (kstack_end(sp))
+                        break;
+                if (i && ((i % 8) == 0))
+                        printk("\n       ");
+                printk("%08lx ", *sp++);
+        }
+        printk("\n");
+        show_trace(task, stack);
+}
+
+void dump_stack(void)
+{
+        show_stack(current, NULL);
+}
+
+EXPORT_SYMBOL(dump_stack);
+
+
+void show_code(unsigned int *pc)
+{
+        long i;
+
+        printk("\nCode:");
+
+        for(i = -3 ; i < 6 ; i++) {
+                unsigned long insn;
+                if (__get_user(insn, pc + i)) {
+                        printk(" (Bad address in pc)\n");
+                        break;
+                }
+                printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>'));
+        }
+}
+
+spinlock_t die_lock = SPIN_LOCK_UNLOCKED;
+
+void die(const char * str, struct pt_regs * regs, long err)
+{
+        static int die_counter;
+        int nl = 0;
+
+        console_verbose();
+        spin_lock_irq(&die_lock);
+
+        printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter);
+#ifdef CONFIG_PREEMPT
+        printk("PREEMPT ");
+        nl = 1;
+#endif
+        if (nl)
+                printk("\n");
+        show_regs(regs);
+        if (!user_mode(regs))
+                show_stack(NULL, (unsigned long*)regs->areg[1]);
+
+        spin_unlock_irq(&die_lock);
+
+        if (in_interrupt())
+                panic("Fatal exception in interrupt");
+
+        if (panic_on_oops) {
+                printk(KERN_EMERG "Fatal exception: panic in 5 seconds\n");
+                set_current_state(TASK_UNINTERRUPTIBLE);
+                schedule_timeout(5 * HZ);
+                panic("Fatal exception");
+        }
+        do_exit(err);
+}
+
+