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 #ifdef __ASSEMBLY__
  15 #define _ASMLANGUAGE
  16 #endif
  17
  18 #include <xtensa/config/core.h>
  19 #include <xtensa/config/specreg.h>
  20 #include <xtensa/config/tie.h>
  21 #include <xtensa/config/system.h>
  22
  23 #include <asm/ptrace.h>
  24 #include <asm/types.h>
  25 #include <asm/coprocessor.h>
  26
  27 /* Assertions. */
  28
  29 #if (XCHAL_HAVE_WINDOWED != 1)
  30 #error Linux requires the Xtensa Windowed Registers Option.
  31 #endif
  32
  33 /*
  34  * User space process size: 1 GB.
  35  * Windowed call ABI requires caller and callee to be located within the same
  36  * 1 GB region. The C compiler places trampoline code on the stack for sources
  37  * that take the address of a nested C function (a feature used by glibc), so
  38  * the 1 GB requirement applies to the stack as well.
  39  */
  40
  41 #define TASK_SIZE       0x40000000
  42
  43 /*
  44  * General exception cause assigned to debug exceptions. Debug exceptions go
  45  * to their own vector, rather than the general exception vectors (user,
  46  * kernel, double); and their specific causes are reported via DEBUGCAUSE
  47  * rather than EXCCAUSE.  However it is sometimes convenient to redirect debug
  48  * exceptions to the general exception mechanism.  To do this, an otherwise
  49  * unused EXCCAUSE value was assigned to debug exceptions for this purpose.
  50  */
  51
  52 #define EXCCAUSE_MAPPED_DEBUG   63
  53
  54 /*
  55  * We use DEPC also as a flag to distinguish between double and regular
  56  * exceptions. For performance reasons, DEPC might contain the value of
  57  * EXCCAUSE for regular exceptions, so we use this definition to mark a
  58  * valid double exception address.
  59  * (Note: We use it in bgeui, so it should be 64, 128, or 256)
  60  */
  61
  62 #define VALID_DOUBLE_EXCEPTION_ADDRESS  64
  63
  64 /* LOCKLEVEL defines the interrupt level that masks all
  65  * general-purpose interrupts.
  66  */
  67 #define LOCKLEVEL 1
  68
  69 /* WSBITS and WBBITS are the width of the WINDOWSTART and WINDOWBASE
  70  * registers
  71  */
  72 #define WSBITS  (XCHAL_NUM_AREGS / 4)      /* width of WINDOWSTART in bits */
  73 #define WBBITS  (XCHAL_NUM_AREGS_LOG2 - 2) /* width of WINDOWBASE in bits */
  74
  75 #ifndef __ASSEMBLY__
  76
  77 /* Build a valid return address for the specified call winsize.
  78  * winsize must be 1 (call4), 2 (call8), or 3 (call12)
  79  */
  80 #define MAKE_RA_FOR_CALL(ra,ws)   (((ra) & 0x3fffffff) | (ws) << 30)
  81
  82 /* Convert return address to a valid pc
  83  * Note: We assume that the stack pointer is in the same 1GB ranges as the ra
  84  */
  85 #define MAKE_PC_FROM_RA(ra,sp)    (((ra) & 0x3fffffff) | ((sp) & 0xc0000000))
  86
  87 typedef struct {
  88     unsigned long seg;
  89 } mm_segment_t;
  90
  91 struct thread_struct {
  92
  93         /* kernel's return address and stack pointer for context switching */
  94         unsigned long ra; /* kernel's a0: return address and window call size */
  95         unsigned long sp; /* kernel's a1: stack pointer */
  96
  97         mm_segment_t current_ds;    /* see uaccess.h for example uses */
  98
  99         /* struct xtensa_cpuinfo info; */
 100
 101         unsigned long bad_vaddr; /* last user fault */
 102         unsigned long bad_uaddr; /* last kernel fault accessing user space */
 103         unsigned long error_code;
 104
 105         unsigned long ibreak[XCHAL_NUM_IBREAK];
 106         unsigned long dbreaka[XCHAL_NUM_DBREAK];
 107         unsigned long dbreakc[XCHAL_NUM_DBREAK];
 108
 109         /* Allocate storage for extra state and coprocessor state. */
 110         unsigned char cp_save[XTENSA_CP_EXTRA_SIZE]
 111                 __attribute__ ((aligned(XTENSA_CP_EXTRA_ALIGN)));
 112
 113         /* Make structure 16 bytes aligned. */
 114         int align[0] __attribute__ ((aligned(16)));
 115 };
 116
 117
 118 /*
 119  * Default implementation of macro that returns current
 120  * instruction pointer ("program counter").
 121  */
 122 #define current_text_addr()  ({ __label__ _l; _l: &&_l;})
 123
 124
 125 /* This decides where the kernel will search for a free chunk of vm
 126  * space during mmap's.
 127  */
 128 #define TASK_UNMAPPED_BASE      (TASK_SIZE / 2)
 129
 130 #define INIT_THREAD  \
 131 {                                                                       \
 132         ra:             0,                                              \
 133         sp:             sizeof(init_stack) + (long) &init_stack,        \
 134         current_ds:     {0},                                            \
 135         /*info:         {0}, */                                         \
 136         bad_vaddr:      0,                                              \
 137         bad_uaddr:      0,                                              \
 138         error_code:     0,                                              \
 139 }
 140
 141
 142 /*
 143  * Do necessary setup to start up a newly executed thread.
 144  * Note: We set-up ps as if we did a call4 to the new pc.
 145  *       set_thread_state in signal.c depends on it.
 146  */
 147 #define USER_PS_VALUE ( (1 << XCHAL_PS_WOE_SHIFT) + \
 148                         (1 << XCHAL_PS_CALLINC_SHIFT) + \
 149                         (USER_RING << XCHAL_PS_RING_SHIFT) + \
 150                         (1 << XCHAL_PS_PROGSTACK_SHIFT) + \
 151                         (1 << XCHAL_PS_EXCM_SHIFT) )
 152
 153 /* Clearing a0 terminates the backtrace. */
 154 #define start_thread(regs, new_pc, new_sp) \
 155         regs->pc = new_pc; \
 156         regs->ps = USER_PS_VALUE; \
 157         regs->areg[1] = new_sp; \
 158         regs->areg[0] = 0; \
 159         regs->wmask = 1; \
 160         regs->depc = 0; \
 161         regs->windowbase = 0; \
 162         regs->windowstart = 1;
 163
 164 /* Forward declaration */
 165 struct task_struct;
 166 struct mm_struct;
 167
 168 // FIXME: do we need release_thread for CP??
 169 /* Free all resources held by a thread. */
 170 #define release_thread(thread) do { } while(0)
 171
 172 // FIXME: do we need prepare_to_copy (lazy status) for CP??
 173 /* Prepare to copy thread state - unlazy all lazy status */
 174 #define prepare_to_copy(tsk)    do { } while (0)
 175
 176 /*
 177  * create a kernel thread without removing it from tasklists
 178  */
 179 extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 180
 181 /* Copy and release all segment info associated with a VM */
 182
 183 #define copy_segments(p, mm)    do { } while(0)
 184 #define release_segments(mm)    do { } while(0)
 185 #define forget_segments()       do { } while (0)
 186
 187 #define thread_saved_pc(tsk)    (task_pt_regs(tsk)->pc)
 188
 189 extern unsigned long get_wchan(struct task_struct *p);
 190
 191 #define KSTK_EIP(tsk)           (task_pt_regs(tsk)->pc)
 192 #define KSTK_ESP(tsk)           (task_pt_regs(tsk)->areg[1])
 193
 194 #define cpu_relax()  do { } while (0)
 195
 196 /* Special register access. */
 197
 198 #define WSR(v,sr) __asm__ __volatile__ ("wsr %0,"__stringify(sr) :: "a"(v));
 199 #define RSR(v,sr) __asm__ __volatile__ ("rsr %0,"__stringify(sr) : "=a"(v));
 200
 201 #define set_sr(x,sr) ({unsigned int v=(unsigned int)x; WSR(v,sr);})
 202 #define get_sr(sr) ({unsigned int v; RSR(v,sr); v; })
 203
 204 #endif  /* __ASSEMBLY__ */
 205 #endif  /* _XTENSA_PROCESSOR_H */