| 1 | /*
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| 2 | * Copyright (c) 2007 Petr Stepan, Pavel Jancik
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| 3 | * All rights reserved.
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| 4 | *
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| 5 | * Redistribution and use in source and binary forms, with or without
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| 6 | * modification, are permitted provided that the following conditions
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| 7 | * are met:
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| 8 | *
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| 9 | * - Redistributions of source code must retain the above copyright
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| 10 | * notice, this list of conditions and the following disclaimer.
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| 11 | * - Redistributions in binary form must reproduce the above copyright
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| 12 | * notice, this list of conditions and the following disclaimer in the
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| 13 | * documentation and/or other materials provided with the distribution.
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| 14 | * - The name of the author may not be used to endorse or promote products
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| 15 | * derived from this software without specific prior written permission.
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| 16 | *
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| 17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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| 18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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| 19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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| 20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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| 22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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| 23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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| 24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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| 25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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| 26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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| 27 | */
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| 28 |
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| 29 | /** @addtogroup arm32
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| 30 | * @{
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| 31 | */
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| 32 | /** @file
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| 33 | * @brief Userspace switch.
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| 34 | */
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| 35 |
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| 36 | #include <userspace.h>
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| 37 | #include <arch/ras.h>
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| 38 |
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| 39 | /** Struct for holding all general purpose registers.
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| 40 | *
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| 41 | * Used to set registers when going to userspace.
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| 42 | */
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| 43 | typedef struct {
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| 44 | uint32_t r0;
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| 45 | uint32_t r1;
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| 46 | uint32_t r2;
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| 47 | uint32_t r3;
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| 48 | uint32_t r4;
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| 49 | uint32_t r5;
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| 50 | uint32_t r6;
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| 51 | uint32_t r7;
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| 52 | uint32_t r8;
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| 53 | uint32_t r9;
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| 54 | uint32_t r10;
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| 55 | uint32_t r11;
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| 56 | uint32_t r12;
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| 57 | uint32_t sp;
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| 58 | uint32_t lr;
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| 59 | uint32_t pc;
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| 60 | } ustate_t;
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| 61 |
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| 62 | /** Change processor mode
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| 63 | *
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| 64 | * @param kernel_uarg Userspace settings (entry point, stack, ...).
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| 65 | *
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| 66 | */
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| 67 | void userspace(uspace_arg_t *kernel_uarg)
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| 68 | {
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| 69 | volatile ustate_t ustate;
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| 70 |
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| 71 | /* set first parameter */
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| 72 | ustate.r0 = (uintptr_t) kernel_uarg->uspace_uarg;
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| 73 |
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| 74 | /* %r1 is defined to hold pcb_ptr - set it to 0 */
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| 75 | ustate.r1 = 0;
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| 76 |
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| 77 | /* pass the RAS page address in %r2 */
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| 78 | ustate.r2 = (uintptr_t) ras_page;
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| 79 |
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| 80 | /* clear other registers */
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| 81 | ustate.r3 = 0;
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| 82 | ustate.r4 = 0;
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| 83 | ustate.r5 = 0;
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| 84 | ustate.r6 = 0;
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| 85 | ustate.r7 = 0;
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| 86 | ustate.r8 = 0;
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| 87 | ustate.r9 = 0;
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| 88 | ustate.r10 = 0;
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| 89 | ustate.r11 = 0;
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| 90 | ustate.r12 = 0;
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| 91 | ustate.lr = 0;
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| 92 |
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| 93 | /* set user stack */
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| 94 | ustate.sp = ((uint32_t) kernel_uarg->uspace_stack) +
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| 95 | kernel_uarg->uspace_stack_size;
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| 96 |
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| 97 | /* set where uspace execution starts */
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| 98 | ustate.pc = (uintptr_t) kernel_uarg->uspace_entry;
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| 99 |
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| 100 | /* status register in user mode */
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| 101 | ipl_t user_mode = current_status_reg_read() &
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| 102 | (~STATUS_REG_MODE_MASK | USER_MODE);
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| 103 |
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| 104 | /* set user mode, set registers, jump */
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| 105 | asm volatile (
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| 106 | "mov sp, %[ustate]\n"
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| 107 | "msr spsr_c, %[user_mode]\n"
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| 108 | "ldmfd sp, {r0-r12, sp, lr}^\n"
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| 109 | "nop\n" /* Cannot access sp immediately after ldm(2) */
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| 110 | "add sp, sp, #(15*4)\n"
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| 111 | "ldmfd sp!, {pc}^\n"
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| 112 | :: [ustate] "r" (&ustate), [user_mode] "r" (user_mode)
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| 113 | );
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| 114 |
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| 115 | /* unreachable */
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| 116 | while(1)
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| 117 | ;
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| 118 | }
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| 119 |
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| 120 | /** @}
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| 121 | */
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