[be4284d0] | 1 | /* dlentry.s |
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| 2 | * |
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| 3 | * This file contains the entry code for RTEMS programs starting |
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| 4 | * after download to RAM |
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| 5 | * |
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| 6 | * Author: Thomas Doerfler <td@imd.m.isar.de> |
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| 7 | * IMD Ingenieurbuero fuer Microcomputertechnik |
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| 8 | * |
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| 9 | * COPYRIGHT (c) 1998 by IMD |
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| 10 | * |
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| 11 | * Changes from IMD are covered by the original distributions terms. |
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| 12 | * This file has been derived from the papyrus BSP: |
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| 13 | * |
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| 14 | * This file contains the entry veneer for RTEMS programs |
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| 15 | * downloaded to Papyrus. |
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| 16 | * |
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| 17 | * Author: Andrew Bray <andy@i-cubed.co.uk> |
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| 18 | * |
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| 19 | * COPYRIGHT (c) 1995 by i-cubed ltd. |
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| 20 | * |
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| 21 | * To anyone who acknowledges that this file is provided "AS IS" |
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| 22 | * without any express or implied warranty: |
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| 23 | * permission to use, copy, modify, and distribute this file |
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| 24 | * for any purpose is hereby granted without fee, provided that |
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| 25 | * the above copyright notice and this notice appears in all |
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| 26 | * copies, and that the name of i-cubed limited not be used in |
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| 27 | * advertising or publicity pertaining to distribution of the |
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| 28 | * software without specific, written prior permission. |
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| 29 | * i-cubed limited makes no representations about the suitability |
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| 30 | * of this software for any purpose. |
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| 31 | * |
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| 32 | * $Id$ |
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| 33 | */ |
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| 34 | |
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| 35 | #include "asm.h" |
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| 36 | |
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| 37 | /* |
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| 38 | * The helas403 ELF link scripts support three special sections: |
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| 39 | * .entry The actual entry point |
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| 40 | * .vectors The section containing the interrupt entry veneers. |
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| 41 | */ |
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| 42 | |
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| 43 | /* |
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| 44 | * Downloaded code loads the vectors separately to 0x00000100, |
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| 45 | * so .entry can be over 256 bytes. |
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| 46 | * |
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| 47 | * The other sections are linked in the following order: |
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| 48 | * .entry |
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| 49 | * .text |
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| 50 | * .data |
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| 51 | * .bss |
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| 52 | * see linker command file for section placement |
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| 53 | * |
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| 54 | * The initial stack is set to stack.end |
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| 55 | * |
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| 56 | * All the entry veneer has to do is to clear the BSS. |
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| 57 | */ |
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| 58 | |
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| 59 | /* |
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| 60 | * GDB likes to have debugging information for the entry veneer. |
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| 61 | * Here was some DWARF information. IMD removed it, because we |
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| 62 | * could not check, whether it was still correct. Sorry. |
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| 63 | |
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| 64 | */ |
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| 65 | |
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| 66 | #if PPC_ASM == PPC_ASM_ELF |
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| 67 | .section .entry |
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| 68 | #else |
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| 69 | .csect .text[PR] |
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| 70 | #endif |
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| 71 | |
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| 72 | PUBLIC_VAR (download_entry) |
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| 73 | SYM(download_entry): |
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| 74 | bl .startup |
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| 75 | base_addr: |
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| 76 | |
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| 77 | /*--------------------------------------------------------------------------- |
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| 78 | * Parameters from linker |
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| 79 | *--------------------------------------------------------------------------*/ |
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| 80 | toc_pointer: |
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| 81 | #if PPC_ASM == PPC_ASM_ELF |
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| 82 | .long s.got |
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| 83 | #else |
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| 84 | .long TOC[tc0] |
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| 85 | #endif |
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| 86 | bss_length: |
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| 87 | .long bss.size |
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| 88 | bss_addr: |
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| 89 | .long bss.start |
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| 90 | stack_top: |
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| 91 | .long stack.end |
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| 92 | /*--------------------------------------------------------------------------- |
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| 93 | * Reset_entry. |
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| 94 | *--------------------------------------------------------------------------*/ |
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| 95 | .startup: |
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| 96 | /* Get start address, stack grows down from here... */ |
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| 97 | mflr r1 |
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| 98 | |
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| 99 | /* Assume Bank regs set up..., cache etc. */ |
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| 100 | bl bssclr |
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| 101 | |
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| 102 | .extern SYM(__vectors) |
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| 103 | |
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| 104 | lis r2,__vectors@h /* set EVPR exc. vector prefix */ |
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| 105 | mtspr evpr,r2 |
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| 106 | |
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| 107 | /*------------------------------------------------------------------- |
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| 108 | * C_setup. |
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| 109 | *------------------------------------------------------------------*/ |
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| 110 | lwz r2,toc_pointer-base_addr(r1) /* set r2 to toc */ |
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| 111 | lwz r1,stack_top-base_addr(r1) /* set r1 to stack_top */ |
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| 112 | |
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| 113 | addi r1,r1,-56-4 /* start stack at text_addr - 56 */ |
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| 114 | addi r3,r0,0x0 /* clear r3 */ |
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| 115 | stw r3, 0(r1) /* Clear stack chain */ |
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| 116 | stw r3, 4(r1) |
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| 117 | stw r3, 8(r1) |
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| 118 | stw r3, 12(r1) |
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| 119 | .extern SYM (boot_card) |
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| 120 | b SYM (boot_card) /* call the first C routine */ |
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| 121 | |
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| 122 | /*--------------------------------------------------------------------------- |
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| 123 | * bssclr. |
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| 124 | *--------------------------------------------------------------------------*/ |
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| 125 | bssclr: |
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| 126 | /*------------------------------------------------------------------- |
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| 127 | * Data move finished, zero out bss. |
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| 128 | *------------------------------------------------------------------*/ |
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| 129 | lwz r2,bss_addr-base_addr(r1) /* start of bss set by loader */ |
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| 130 | lwz r3,bss_length-base_addr(r1) /* bss length */ |
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| 131 | rlwinm. r3,r3,30,0x3FFFFFFF /* form length/4 */ |
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| 132 | beqlr /* no bss */ |
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| 133 | mtctr r3 /* set ctr reg */ |
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| 134 | xor r6,r6,r6 /* r6 = 0 */ |
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| 135 | clear_bss: |
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| 136 | stswi r6,r2,0x4 /* store r6 */ |
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| 137 | addi r2,r2,0x4 /* update r2 */ |
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| 138 | bdnz clear_bss /* decrement counter and loop */ |
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| 139 | blr /* return */ |
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| 140 | .L_text_e: |
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| 141 | |
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| 142 | #if PPC_ABI == PPC_ABI_POWEROPEN |
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| 143 | DESCRIPTOR (startup) |
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| 144 | #endif |
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