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
  84 typedef struct {
  85     unsigned long seg;
  86 } mm_segment_t;
  87
  88 struct 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 */
 158 struct task_struct;
 159 struct 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 */
 165 extern void prepare_to_copy(struct task_struct*);
 166
 167 /* Create a kernel thread without removing it from tasklists */
 168 extern 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
 177 extern 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 */