| 1 | /* |
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| 2 | * hal_kentry.S - exception/interrupt/syscall kernel entry point for MIPS32 |
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| 3 | * |
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| 4 | * AUthors Ghassan Almaless (2007,2008,2009,2010,2011,2012) |
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| 5 | * Mohamed Lamine Karaoui (2015) |
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| 6 | * Alain Greiner (2017) |
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| 7 | * |
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| 8 | * Copyright (c) UPMC Sorbonne Universites |
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| 9 | * |
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| 10 | * This file is part of ALMOS-MKH. |
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| 11 | * |
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| 12 | * ALMOS-MKH is free software; you can redistribute it and/or modify it |
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| 13 | * under the terms of the GNU General Public License as published by |
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| 14 | * the Free Software Foundation; version 2.0 of the License. |
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| 15 | * |
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| 16 | * ALMOS-MKH is distributed in the hope that it will be useful, but |
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| 17 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 18 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 19 | * General Public License for more details. |
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| 20 | * |
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| 21 | * You should have received a copy of the GNU General Public License |
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| 22 | * along with ALMOS-MKH; if not, write to the Free Software Foundation, |
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| 23 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
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| 24 | */ |
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| 25 | |
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| 26 | #include <mips32_uzone.h> |
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| 27 | |
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| 28 | #--------------------------------------------------------------------------------- |
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| 29 | # This code is the unique kernel entry point in case of exception, interrupt, |
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| 30 | # or syscall for the TSAR_MIPS32 architecture. |
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| 31 | # |
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| 32 | # - If the core is in user mode: |
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| 33 | # . we desactivate the MMU. |
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| 34 | # . we save the context in the uzone of the calling thread descriptor. |
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| 35 | # . we increment the cores_in_kernel variable. |
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| 36 | # . we call the relevant exception/interrupt/syscall handler |
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| 37 | # |
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| 38 | # - If the core is already in kernel mode: |
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| 39 | # . we save the context in the kernel stack |
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| 40 | # . we call the relevant exception/interrupt/syscall handler |
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| 41 | # |
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| 42 | # - In both cases, when the handler returns: |
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| 43 | # . we restore the context |
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| 44 | # . we reactivate the MMU ??? |
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| 45 | #--------------------------------------------------------------------------------- |
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| 46 | |
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| 47 | .section .kentry,"ax",@progbits |
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| 48 | .extern cpu_do_interrupt |
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| 49 | .extern cpu_do_exception |
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| 50 | .extern cpu_do_syscall |
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| 51 | .extern cpu_kentry |
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| 52 | .extern cpu_kexit |
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| 53 | .org 0x180 |
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| 54 | .ent kentry |
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| 55 | .global kentry |
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| 56 | .global kentry_load |
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| 57 | .set noat |
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| 58 | .set noreorder |
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| 59 | |
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| 60 | #define SAVE_SIZE CPU_REGS_NR*4 |
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| 61 | #define LID_WIDTH 2 |
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| 62 | #define CXY_WIDTH 8 |
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| 63 | #define CXY_MASK 0xFF |
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| 64 | #define MMU_MODE_MASK 0xF |
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| 65 | #define GID_MASK 0x3FF |
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| 66 | #define LID_MASK 0x3 |
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| 67 | |
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| 68 | #--------------------------------------------------------------------------------- |
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| 69 | # Kernel Entry point |
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| 70 | #--------------------------------------------------------------------------------- |
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| 71 | |
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| 72 | kentry: |
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| 73 | mfc0 $26, $12 # read SR to test user/kernel mode |
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| 74 | andi $26, $26, 0x10 # User Mode bitmask |
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| 75 | beq $26, $0, kernel_mode |
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| 76 | ori $26, $0, 0x3 # $26 <= MMU OFF value |
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| 77 | |
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| 78 | #--------------------------------------------------------------------------------------- |
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| 79 | # this code is executed when the core is in user mode: |
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| 80 | # - we use the uzone defined in user thread descriptor. |
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| 81 | # - we set the MMU off, and save the CP2_MODE register to uzone. |
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| 82 | # - we save the user thread stack pointer to uzone and load the kernel stack pointer |
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| 83 | # - we store the uzone pointer in $27 |
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| 84 | |
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| 85 | user_mode: |
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| 86 | mtc2 $26, $1 # set MMU OFF |
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| 87 | nop |
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| 88 | |
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| 89 | mfc0 $26, $4, 2 # $26 <= thread pointer |
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| 90 | lw $26, 0($26) # $26 <= uzone pointer |
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| 91 | |
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| 92 | sw $29, (UZ_SP*4)($26) # save user stack to uzone |
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| 93 | lw $29, (UZ_KSP*4)($26) # load kernel stack from uzone |
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| 94 | |
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| 95 | ori $27, $0, 0xF # MMU old value: assumed ON |
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| 96 | sw $27, (UZ_MODE*4)($26) # save MMU MODE to uzone |
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| 97 | |
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| 98 | j unified_mode |
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| 99 | or $27, $0, $26 # $27 <= uzone |
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| 100 | |
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| 101 | #--------------------------------------------------------------------------------------- |
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| 102 | # this code is executed when the core is in kernel mode: |
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| 103 | # - we use an uzone allocated in kernel stack. |
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| 104 | # - we set the MMU off, set the MMU data_paddr extension to local_cxy, |
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| 105 | # and save the CP2_MODE and CP2_DEXT to uzone. |
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| 106 | # - we save the kernel stack pointer to uzone and load the new kernel stack pointer |
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| 107 | # - we store the uzone pointer in $27 |
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| 108 | |
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| 109 | kernel_mode: |
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| 110 | mfc2 $26, $24 |
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| 111 | andi $26, $26, CXY_MASK # $26 <= CP2_DEXT |
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| 112 | |
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| 113 | mfc0 $27, $15, 1 |
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| 114 | andi $27, $27, GID_MASK # $27 <= core_gid (4/4/2 format) |
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| 115 | |
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| 116 | srl $27, $27, LID_WIDTH # $27 <= local_cxy |
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| 117 | mtc2 $27, $24 # set local_cxy to CP2_DEXT |
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| 118 | |
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| 119 | # use $26 to save both CP2_MODE (4 bits) and CP2_DEXT (8 bits) values |
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| 120 | |
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| 121 | mfc2 $27, $1 |
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| 122 | andi $27, $27, MMU_MODE_MASK # $27 <= CP2_MODE |
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| 123 | sll $27, $27, CXY_WIDTH # $27 <= 0x00000M00 |
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| 124 | or $26, $26, $27 # $26 <= 0x00000MXY |
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| 125 | |
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| 126 | ori $27, $0, 0x3 |
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| 127 | mtc2 $27, $1 # set MMU OFF |
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| 128 | |
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| 129 | # save old SP, CP2_MODE and CP2_DEXT in uzone allocated in kernel stack |
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| 130 | |
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| 131 | addiu $27, $29, -(SAVE_SIZE) # allocate an uzone in stack (use $27 as KSP) |
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| 132 | sw $29, (UZ_SP*4)($27) # save old KSP in this uzone |
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| 133 | |
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| 134 | srl $29, $26, CXY_WIDTH |
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| 135 | sw $29, (UZ_MODE*4)($27) # save CP2_MODE in this uzone |
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| 136 | |
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| 137 | andi $26, $26, CXY_MASK |
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| 138 | sw $26, (UZ_DEXT*4)($27) # save CP2_DEXT in this uzone |
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| 139 | |
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| 140 | or $29, $27, $0 # load new kernel stack pointer |
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| 141 | |
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| 142 | #-------------------------------------------------------------------------------------- |
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| 143 | # this code is executed in both modes, with the two following assumptions: |
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| 144 | # - $27 contains the pointer on uzone to save the cpu registers |
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| 145 | # - $29 contains the kernel stack pointer |
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| 146 | |
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| 147 | unified_mode: |
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| 148 | sw $1, (UZ_AT*4)($27) |
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| 149 | sw $2, (UZ_V0*4)($27) |
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| 150 | sw $3, (UZ_V1*4)($27) |
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| 151 | sw $4, (UZ_A0*4)($27) |
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| 152 | sw $5, (UZ_A1*4)($27) |
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| 153 | sw $6, (UZ_A2*4)($27) |
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| 154 | sw $7, (UZ_A3*4)($27) |
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| 155 | sw $8, (UZ_T0*4)($27) |
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| 156 | sw $9, (UZ_T1*4)($27) |
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| 157 | sw $10, (UZ_T2*4)($27) |
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| 158 | sw $11, (UZ_T3*4)($27) |
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| 159 | sw $12, (UZ_T4*4)($27) |
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| 160 | sw $13, (UZ_T5*4)($27) |
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| 161 | sw $14, (UZ_T6*4)($27) |
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| 162 | sw $15, (UZ_T7*4)($27) |
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| 163 | sw $16, (UZ_S0*4)($27) |
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| 164 | sw $17, (UZ_S1*4)($27) |
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| 165 | sw $18, (UZ_S2*4)($27) |
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| 166 | sw $19, (UZ_S3*4)($27) |
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| 167 | sw $20, (UZ_S4*4)($27) |
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| 168 | sw $21, (UZ_S5*4)($27) |
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| 169 | sw $22, (UZ_S6*4)($27) |
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| 170 | sw $23, (UZ_S7*4)($27) |
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| 171 | sw $24, (UZ_T8*4)($27) |
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| 172 | sw $25, (UZ_T9*4)($27) |
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| 173 | sw $28, (UZ_GP*4)($27) |
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| 174 | sw $30, (UZ_S8*4)($27) |
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| 175 | sw $31, (UZ_RA*4)($27) |
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| 176 | |
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| 177 | mfc0 $16, $14 |
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| 178 | sw $16, (UZ_EPC*4)($27) # Save EPC |
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| 179 | mflo $14 |
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| 180 | sw $14, (UZ_LO*4)($27) # save LO |
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| 181 | mfhi $15 |
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| 182 | sw $15, (UZ_HI*4)($27) # save HI |
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| 183 | mfc0 $18, $12 |
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| 184 | sw $18, (UZ_SR*4)($27) # Save SR |
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| 185 | mfc0 $17, $13 |
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| 186 | sw $17, (UZ_CR*4)($27) # Save CR |
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| 187 | |
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| 188 | srl $3, $18, 5 # put SR in kernel mode, IRQ disabled, clear exl |
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| 189 | sll $3, $3, 5 |
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| 190 | mtc0 $3, $12 # Set new SR |
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| 191 | |
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| 192 | andi $1, $17, 0x3F # $1 <= XCODE (from CR) |
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| 193 | |
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| 194 | # signal that core enters kernel |
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| 195 | jal cluster_core_kernel_enter |
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| 196 | nop |
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| 197 | |
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| 198 | #--------------------------------------------------------------------------------------- |
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| 199 | # Depending on XCODE (in $1) , call the apropriate handler. The three called |
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| 200 | # functions take the same two arguments: thread pointer and uzone pointer. |
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| 201 | |
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| 202 | mfc0 $4, $4, 2 # $4 <= thread pointer (first arg) |
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| 203 | or $5, $0, $27 # $5 <= uzone pointer (second arg) |
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| 204 | or $19, $0, $27 # $19 <= &uzone (for kentry_exit) |
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| 205 | |
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| 206 | ori $8, $0, 0x20 # $8 <= cause syscall |
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| 207 | beq $8, $1, cause_sys |
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| 208 | nop |
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| 209 | beq $1, $0, cause_int |
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| 210 | nop |
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| 211 | |
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| 212 | cause_excp: |
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| 213 | la $1, hal_do_exception |
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| 214 | jalr $1 # call exception handler |
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| 215 | addiu $29, $29, -8 # hal_do_exception has 2 args |
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| 216 | addiu $29, $29, 8 |
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| 217 | j kentry_exit # jump to kentry_exit |
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| 218 | nop |
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| 219 | |
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| 220 | cause_sys: |
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| 221 | la $1, hal_do_syscall |
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| 222 | jalr $1 # call syscall handler |
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| 223 | addiu $29, $29, -8 # hal_do_syscall has 2 args |
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| 224 | addiu $29, $29, 8 |
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| 225 | j kentry_exit # jump to kentry_exit |
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| 226 | or $19, $0, $2 |
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| 227 | |
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| 228 | cause_int: |
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| 229 | la $1, hal_do_interrupt |
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| 230 | jalr $1 # call interrupt handler |
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| 231 | addiu $29, $29, -8 # hal_do_interrupt has 2 args |
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| 232 | addiu $29, $29, 8 |
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| 233 | |
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| 234 | # ----------------------------------------------------------------------------------- |
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| 235 | # Kentry exit |
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| 236 | # ----------------------------------------------------------------------------------- |
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| 237 | kentry_exit: |
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| 238 | |
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| 239 | # signal that core exit kernel |
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| 240 | jal cluster_core_kernel_exit |
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| 241 | |
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| 242 | # restore context from uzone |
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| 243 | or $27, $0, $19 # $27 <= &uzone |
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| 244 | |
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| 245 | lw $29, (UZ_SP*4)($27) # restore SP from uzone |
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| 246 | lw $16, (UZ_EPC*4)($27) |
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| 247 | mtc0 $16, $14 # restore EPC from uzone |
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| 248 | lw $16, (UZ_HI*4)($27) |
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| 249 | mthi $16 # restore HI from uzone |
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| 250 | lw $16, (UZ_LO*4)($27) |
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| 251 | mtlo $16 # restore LO from uzone |
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| 252 | |
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| 253 | lw $17, (UZ_SR*4)($27) # get saved SR value from uzone |
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| 254 | andi $17, $17, 0x1F # keep only the 5 LSB bits |
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| 255 | mfc0 $26, $12 # get current SR value from CP0 |
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| 256 | or $26, $26, $17 # merge the two values |
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| 257 | mtc0 $26, $12 # setup new SR to CP0 |
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| 258 | |
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| 259 | lw $1, (UZ_AT*4)($27) |
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| 260 | lw $2, (UZ_V0*4)($27) |
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| 261 | lw $3, (UZ_V1*4)($27) |
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| 262 | lw $4, (UZ_A0*4)($27) |
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| 263 | lw $5, (UZ_A1*4)($27) |
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| 264 | lw $6, (UZ_A2*4)($27) |
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| 265 | lw $7, (UZ_A3*4)($27) |
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| 266 | lw $8, (UZ_T0*4)($27) |
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| 267 | lw $9, (UZ_T1*4)($27) |
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| 268 | lw $10, (UZ_T2*4)($27) |
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| 269 | lw $11, (UZ_T3*4)($27) |
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| 270 | lw $12, (UZ_T4*4)($27) |
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| 271 | lw $13, (UZ_T5*4)($27) |
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| 272 | lw $14, (UZ_T6*4)($27) |
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| 273 | lw $15, (UZ_T7*4)($27) |
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| 274 | lw $16, (UZ_S0*4)($27) |
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| 275 | lw $17, (UZ_S1*4)($27) |
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| 276 | lw $18, (UZ_S2*4)($27) |
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| 277 | lw $19, (UZ_S3*4)($27) |
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| 278 | lw $20, (UZ_S4*4)($27) |
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| 279 | lw $21, (UZ_S5*4)($27) |
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| 280 | lw $22, (UZ_S6*4)($27) |
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| 281 | lw $23, (UZ_S7*4)($27) |
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| 282 | lw $24, (UZ_T8*4)($27) |
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| 283 | lw $25, (UZ_T9*4)($27) |
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| 284 | lw $28, (UZ_GP*4)($27) |
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| 285 | lw $30, (UZ_S8*4)($27) |
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| 286 | lw $31, (UZ_RA*4)($27) |
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| 287 | |
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| 288 | |
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| 289 | lw $26, (UZ_DEXT*4)($27) |
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| 290 | mtc2 $26, $24 # restore CP2_DEXT from uzone |
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| 291 | |
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| 292 | #TODO: optimize |
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| 293 | lw $26, (UZ_MODE*4)($27) # get saved CP2_MODE from uzone |
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| 294 | andi $26, $26, 0xc # keep only the TLBs controling bits |
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| 295 | beq $26, $0, out_mmu_3 # both MSB are 0 (the first two LSB are always set) |
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| 296 | andi $26, $26, 0x8 |
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| 297 | beq $26, $0, out_mmu_7 # first MSB is 0 (bit 2 is set) |
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| 298 | |
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| 299 | # Possible value for MMU_MODE |
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| 300 | # In kernel mode : 0x7/0x3 |
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| 301 | # In user mode : 0xF |
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| 302 | |
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| 303 | # DP_EXT can either be local or remote |
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| 304 | # Once these register set we can no longuer |
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| 305 | # access global data |
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| 306 | |
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| 307 | out_mmu_F: |
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| 308 | ori $26, $0, 0xF |
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| 309 | mtc2 $26, $1 # CP2_MODE <= 0xF |
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| 310 | j out_kentry |
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| 311 | nop |
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| 312 | |
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| 313 | out_mmu_7: |
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| 314 | ori $26, $0, 0x7 |
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| 315 | mtc2 $26, $1 # CP2_MODE <= 0x7 |
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| 316 | j out_kentry |
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| 317 | nop |
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| 318 | |
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| 319 | out_mmu_3: |
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| 320 | ori $26, $0, 0x3 |
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| 321 | mtc2 $26, $1 # CP2_MODE <= 0x3 |
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| 322 | |
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| 323 | out_kentry: |
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| 324 | nop |
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| 325 | eret |
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| 326 | |
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| 327 | .end kentry |
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| 328 | .set reorder |
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| 329 | .set at |
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| 330 | |
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| 331 | .ent kentry_load |
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| 332 | kentry_load: |
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| 333 | # theses nops are required to load the eret instruction |
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| 334 | # while we are in virtual mode (processor pipeline) ? |
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| 335 | mtc2 $26, $1 # set MMU MODE |
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| 336 | nop |
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| 337 | nop |
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| 338 | eret |
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| 339 | .end kentry_load |
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| 340 | |
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| 341 | #------------------------------------------------------------------------------- |
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| 342 | |
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