LXR linux/include/asm-xtensa/processor.h

   1/*
   2 * include/asm-xtensa/processor.h
   3 *
   4 * This file is subject to the terms and conditions of the GNU General Public
   5 * License.  See the file "COPYING" in the main directory of this archive
   6 * for more details.
   7 *
   8 * Copyright (C) 2001 - 2005 Tensilica Inc.
   9 */
  10
  11#ifndef _XTENSA_PROCESSOR_H
  12#define _XTENSA_PROCESSOR_H
  13
  14#include <asm/variant/core.h>
  15#include <asm/coprocessor.h>
  16
  17#include <linux/compiler.h>
  18#include <asm/ptrace.h>
  19#include <asm/types.h>
  20#include <asm/regs.h>
  21
  22/* Assertions. */
  23
  24#if (XCHAL_HAVE_WINDOWED != 1)
  25# error Linux requires the Xtensa Windowed Registers Option.
  26#endif
  27
  28/*
  29 * User space process size: 1 GB.
  30 * Windowed call ABI requires caller and callee to be located within the same
  31 * 1 GB region. The C compiler places trampoline code on the stack for sources
  32 * that take the address of a nested C function (a feature used by glibc), so
  33 * the 1 GB requirement applies to the stack as well.
  34 */
  35
  36#define TASK_SIZE       __XTENSA_UL_CONST(0x40000000)
  37#define STACK_TOP       TASK_SIZE
  38#define STACK_TOP_MAX   STACK_TOP
  39
  40/*
  41 * General exception cause assigned to debug exceptions. Debug exceptions go
  42 * to their own vector, rather than the general exception vectors (user,
  43 * kernel, double); and their specific causes are reported via DEBUGCAUSE
  44 * rather than EXCCAUSE.  However it is sometimes convenient to redirect debug
  45 * exceptions to the general exception mechanism.  To do this, an otherwise
  46 * unused EXCCAUSE value was assigned to debug exceptions for this purpose.
  47 */
  48
  49#define EXCCAUSE_MAPPED_DEBUG   63
  50
  51/*
  52 * We use DEPC also as a flag to distinguish between double and regular
  53 * exceptions. For performance reasons, DEPC might contain the value of
  54 * EXCCAUSE for regular exceptions, so we use this definition to mark a
  55 * valid double exception address.
  56 * (Note: We use it in bgeui, so it should be 64, 128, or 256)
  57 */
  58
  59#define VALID_DOUBLE_EXCEPTION_ADDRESS  64
  60
  61/* LOCKLEVEL defines the interrupt level that masks all
  62 * general-purpose interrupts.
  63 */
  64#define LOCKLEVEL 1
  65
  66/* WSBITS and WBBITS are the width of the WINDOWSTART and WINDOWBASE
  67 * registers
  68 */
  69#define WSBITS  (XCHAL_NUM_AREGS / 4)      /* width of WINDOWSTART in bits */
  70#define WBBITS  (XCHAL_NUM_AREGS_LOG2 - 2) /* width of WINDOWBASE in bits */
  71
  72#ifndef __ASSEMBLY__
  73
  74/* Build a valid return address for the specified call winsize.
  75 * winsize must be 1 (call4), 2 (call8), or 3 (call12)
  76 */
  77#define MAKE_RA_FOR_CALL(ra,ws)   (((ra) & 0x3fffffff) | (ws) << 30)
  78
  79/* Convert return address to a valid pc
  80 * Note: We assume that the stack pointer is in the same 1GB ranges as the ra
  81 */
  82#define MAKE_PC_FROM_RA(ra,sp)    (((ra) & 0x3fffffff) | ((sp) & 0xc0000000))
  83
  84typedef struct {
  85    unsigned long seg;
  86} mm_segment_t;
  87
  88struct thread_struct {
  89
  90        /* kernel's return address and stack pointer for context switching */
  91        unsigned long ra; /* kernel's a0: return address and window call size */
  92        unsigned long sp; /* kernel's a1: stack pointer */
  93
  94        mm_segment_t current_ds;    /* see uaccess.h for example uses */
  95
  96        /* struct xtensa_cpuinfo info; */
  97
  98        unsigned long bad_vaddr; /* last user fault */
  99        unsigned long bad_uaddr; /* last kernel fault accessing user space */
 100        unsigned long error_code;
 101
 102        unsigned long ibreak[XCHAL_NUM_IBREAK];
 103        unsigned long dbreaka[XCHAL_NUM_DBREAK];
 104        unsigned long dbreakc[XCHAL_NUM_DBREAK];
 105
 106        /* Make structure 16 bytes aligned. */
 107        int align[0] __attribute__ ((aligned(16)));
 108};
 109
 110
 111/*
 112 * Default implementation of macro that returns current
 113 * instruction pointer ("program counter").
 114 */
 115#define current_text_addr()  ({ __label__ _l; _l: &&_l;})
 116
 117
 118/* This decides where the kernel will search for a free chunk of vm
 119 * space during mmap's.
 120 */
 121#define TASK_UNMAPPED_BASE      (TASK_SIZE / 2)
 122
 123#define INIT_THREAD  \
 124{                                                                       \
 125        ra:             0,                                              \
 126        sp:             sizeof(init_stack) + (long) &init_stack,        \
 127        current_ds:     {0},                                            \
 128        /*info:         {0}, */                                         \
 129        bad_vaddr:      0,                                              \
 130        bad_uaddr:      0,                                              \
 131        error_code:     0,                                              \
 132}
 133
 134
 135/*
 136 * Do necessary setup to start up a newly executed thread.
 137 * Note: We set-up ps as if we did a call4 to the new pc.
 138 *       set_thread_state in signal.c depends on it.
 139 */
 140#define USER_PS_VALUE ((1 << PS_WOE_BIT) |                              \
 141                       (1 << PS_CALLINC_SHIFT) |                        \
 142                       (USER_RING << PS_RING_SHIFT) |                   \
 143                       (1 << PS_UM_BIT) |                               \
 144                       (1 << PS_EXCM_BIT))
 145
 146/* Clearing a0 terminates the backtrace. */
 147#define start_thread(regs, new_pc, new_sp) \
 148        regs->pc = new_pc; \
 149        regs->ps = USER_PS_VALUE; \
 150        regs->areg[1] = new_sp; \
 151        regs->areg[0] = 0; \
 152        regs->wmask = 1; \
 153        regs->depc = 0; \
 154        regs->windowbase = 0; \
 155        regs->windowstart = 1;
 156
 157/* Forward declaration */
 158struct task_struct;
 159struct mm_struct;
 160
 161/* Free all resources held by a thread. */
 162#define release_thread(thread) do { } while(0)
 163
 164/* Prepare to copy thread state - unlazy all lazy status */
 165extern void prepare_to_copy(struct task_struct*);
 166
 167/* Create a kernel thread without removing it from tasklists */
 168extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 169
 170/* Copy and release all segment info associated with a VM */
 171#define copy_segments(p, mm)    do { } while(0)
 172#define release_segments(mm)    do { } while(0)
 173#define forget_segments()       do { } while (0)
 174
 175#define thread_saved_pc(tsk)    (task_pt_regs(tsk)->pc)
 176
 177extern unsigned long get_wchan(struct task_struct *p);
 178
 179#define KSTK_EIP(tsk)           (task_pt_regs(tsk)->pc)
 180#define KSTK_ESP(tsk)           (task_pt_regs(tsk)->areg[1])
 181
 182#define cpu_relax()  barrier()
 183
 184/* Special register access. */
 185
 186#define WSR(v,sr) __asm__ __volatile__ ("wsr %0,"__stringify(sr) :: "a"(v));
 187#define RSR(v,sr) __asm__ __volatile__ ("rsr %0,"__stringify(sr) : "=a"(v));
 188
 189#define set_sr(x,sr) ({unsigned int v=(unsigned int)x; WSR(v,sr);})
 190#define get_sr(sr) ({unsigned int v; RSR(v,sr); v; })
 191
 192#endif  /* __ASSEMBLY__ */
 193#endif  /* _XTENSA_PROCESSOR_H */
 194