arch/arc/lib/start.S

   1 /*
   2  * Copyright (C) 2013-2014 Synopsys, Inc. All rights reserved.
   3  *
   4  * SPDX-License-Identifier:     GPL-2.0+
   5  */
   6
   7 #include <asm-offsets.h>
   8 #include <config.h>
   9 #include <linux/linkage.h>
  10 #include <asm/arcregs.h>
  11
  12 /*
  13  * Note on the LD/ST addressing modes with address register write-back
  14  *
  15  * LD.a same as LD.aw
  16  *
  17  * LD.a    reg1, [reg2, x]  => Pre Incr
  18  *      Eff Addr for load = [reg2 + x]
  19  *
  20  * LD.ab   reg1, [reg2, x]  => Post Incr
  21  *      Eff Addr for load = [reg2]
  22  */
  23
  24 .macro PUSH reg
  25         st.a    \reg, [%sp, -4]
  26 .endm
  27
  28 .macro PUSHAX aux
  29         lr      %r9, [\aux]
  30         PUSH    %r9
  31 .endm
  32
  33 .macro  SAVE_R1_TO_R24
  34         PUSH    %r1
  35         PUSH    %r2
  36         PUSH    %r3
  37         PUSH    %r4
  38         PUSH    %r5
  39         PUSH    %r6
  40         PUSH    %r7
  41         PUSH    %r8
  42         PUSH    %r9
  43         PUSH    %r10
  44         PUSH    %r11
  45         PUSH    %r12
  46         PUSH    %r13
  47         PUSH    %r14
  48         PUSH    %r15
  49         PUSH    %r16
  50         PUSH    %r17
  51         PUSH    %r18
  52         PUSH    %r19
  53         PUSH    %r20
  54         PUSH    %r21
  55         PUSH    %r22
  56         PUSH    %r23
  57         PUSH    %r24
  58 .endm
  59
  60 .macro SAVE_ALL_SYS
  61         /* saving %r0 to reg->r0 in advance since we read %ecr into it */
  62         st      %r0, [%sp, -8]
  63         lr      %r0, [%ecr]     /* all stack addressing is manual so far */
  64         st      %r0, [%sp]
  65         st      %sp, [%sp, -4]
  66         /* now move %sp to reg->r0 position so we can do "push" automatically */
  67         sub     %sp, %sp, 8
  68
  69         SAVE_R1_TO_R24
  70         PUSH    %r25
  71         PUSH    %gp
  72         PUSH    %fp
  73         PUSH    %blink
  74         PUSHAX  %eret
  75         PUSHAX  %erstatus
  76         PUSH    %lp_count
  77         PUSHAX  %lp_end
  78         PUSHAX  %lp_start
  79         PUSHAX  %erbta
  80 .endm
  81
  82 .macro SAVE_EXCEPTION_SOURCE
  83 #ifdef CONFIG_MMU
  84         /* If MMU exists exception faulting address is loaded in EFA reg */
  85         lr      %r0, [%efa]
  86 #else
  87         /* Otherwise in ERET (exception return) reg */
  88         lr      %r0, [%eret]
  89 #endif
  90 .endm
  91
  92 ENTRY(_start)
  93         /* Setup interrupt vector base that matches "__text_start" */
  94         sr      __ivt_start, [ARC_AUX_INTR_VEC_BASE]
  95
  96         /* Setup stack pointer */
  97         mov     %sp, CONFIG_SYS_INIT_SP_ADDR
  98         mov     %fp, %sp
  99
 100         /* Clear bss */
 101         mov     %r0, __bss_start
 102         mov     %r1, __bss_end
 103
 104 clear_bss:
 105         st.ab   0, [%r0, 4]
 106         brlt    %r0, %r1, clear_bss
 107
 108         /* Zero the one and only argument of "board_init_f" */
 109         mov_s   %r0, 0
 110         j       board_init_f
 111 ENDPROC(_start)
 112
 113 ENTRY(memory_error)
 114         SAVE_ALL_SYS
 115         SAVE_EXCEPTION_SOURCE
 116         mov     %r1, %sp
 117         j       do_memory_error
 118 ENDPROC(memory_error)
 119
 120 ENTRY(instruction_error)
 121         SAVE_ALL_SYS
 122         SAVE_EXCEPTION_SOURCE
 123         mov     %r1, %sp
 124         j       do_instruction_error
 125 ENDPROC(instruction_error)
 126
 127 ENTRY(interrupt_handler)
 128         /* Todo - save and restore CPU context when interrupts will be in use */
 129         bl      do_interrupt_handler
 130         rtie
 131 ENDPROC(interrupt_handler)
 132
 133 ENTRY(EV_MachineCheck)
 134         SAVE_ALL_SYS
 135         SAVE_EXCEPTION_SOURCE
 136         mov     %r1, %sp
 137         j       do_machine_check_fault
 138 ENDPROC(EV_MachineCheck)
 139
 140 ENTRY(EV_TLBMissI)
 141         SAVE_ALL_SYS
 142         mov     %r0, %sp
 143         j       do_itlb_miss
 144 ENDPROC(EV_TLBMissI)
 145
 146 ENTRY(EV_TLBMissD)
 147         SAVE_ALL_SYS
 148         mov     %r0, %sp
 149         j       do_dtlb_miss
 150 ENDPROC(EV_TLBMissD)
 151
 152 ENTRY(EV_TLBProtV)
 153         SAVE_ALL_SYS
 154         SAVE_EXCEPTION_SOURCE
 155         mov     %r1, %sp
 156         j       do_tlb_prot_violation
 157 ENDPROC(EV_TLBProtV)
 158
 159 ENTRY(EV_PrivilegeV)
 160         SAVE_ALL_SYS
 161         mov     %r0, %sp
 162         j       do_privilege_violation
 163 ENDPROC(EV_PrivilegeV)
 164
 165 ENTRY(EV_Trap)
 166         SAVE_ALL_SYS
 167         mov     %r0, %sp
 168         j       do_trap
 169 ENDPROC(EV_Trap)
 170
 171 ENTRY(EV_Extension)
 172         SAVE_ALL_SYS
 173         mov     %r0, %sp
 174         j       do_extension
 175 ENDPROC(EV_Extension)
 176
 177 /*
 178  * void relocate_code (addr_sp, gd, addr_moni)
 179  *
 180  * This "function" does not return, instead it continues in RAM
 181  * after relocating the monitor code.
 182  *
 183  * r0 = start_addr_sp
 184  * r1 = new__gd
 185  * r2 = relocaddr
 186  */
 187 ENTRY(relocate_code)
 188         /*
 189          * r0-r12 might be clobbered by C functions
 190          * so we use r13-r16 for storage here
 191          */
 192         mov     %r13, %r0               /* save addr_sp */
 193         mov     %r14, %r1               /* save addr of gd */
 194         mov     %r15, %r2               /* save addr of destination */
 195
 196         mov     %r16, %r2               /* %r9 - relocation offset */
 197         sub     %r16, %r16, __image_copy_start
 198
 199 /* Set up the stack */
 200 stack_setup:
 201         mov     %sp, %r13
 202         mov     %fp, %sp
 203
 204 /* Check if monitor is loaded right in place for relocation */
 205         mov     %r0, __image_copy_start
 206         cmp     %r0, %r15               /* skip relocation if code loaded */
 207         bz      do_board_init_r         /* in target location already */
 208
 209 /* Copy data (__image_copy_start - __image_copy_end) to new location */
 210         mov     %r1, %r15
 211         mov     %r2, __image_copy_end
 212         sub     %r2, %r2, %r0           /* r3 <- amount of bytes to copy */
 213         asr     %r2, %r2, 2             /* r3 <- amount of words to copy */
 214         mov     %lp_count, %r2
 215         lp      copy_end
 216         ld.ab   %r2,[%r0,4]
 217         st.ab   %r2,[%r1,4]
 218 copy_end:
 219
 220 /* Fix relocations related issues */
 221         bl      do_elf_reloc_fixups
 222 #ifndef CONFIG_SYS_ICACHE_OFF
 223         bl      invalidate_icache_all
 224 #endif
 225 #ifndef CONFIG_SYS_DCACHE_OFF
 226         bl      flush_dcache_all
 227 #endif
 228
 229 /* Update position of intterupt vector table */
 230         lr      %r0, [ARC_AUX_INTR_VEC_BASE]    /* Read current position */
 231         add     %r0, %r0, %r16                  /* Update address */
 232         sr      %r0, [ARC_AUX_INTR_VEC_BASE]    /* Write new position */
 233
 234 do_board_init_r:
 235 /* Prepare for exection of "board_init_r" in relocated monitor */
 236         mov     %r2, board_init_r       /* old address of "board_init_r()" */
 237         add     %r2, %r2, %r16          /* new address of "board_init_r()" */
 238         mov     %r0, %r14               /* 1-st parameter: gd_t */
 239         mov     %r1, %r15               /* 2-nd parameter: dest_addr */
 240         j       [%r2]
 241 ENDPROC(relocate_code)