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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 | /* * arch/sh64/kernel/switchto.S * * sh64 context switch * * Copyright (C) 2004 Richard Curnow * * This file is subject to the terms and conditions of the GNU General Public * License. See the file "COPYING" in the main directory of this archive * for more details. */ .section .text..SHmedia32,"ax" .little .balign 32 .type sh64_switch_to,@function .global sh64_switch_to .global __sh64_switch_to_end sh64_switch_to: /* Incoming args r2 - prev r3 - &prev->thread r4 - next r5 - &next->thread Outgoing results r2 - last (=prev) : this just stays in r2 throughout Want to create a full (struct pt_regs) on the stack to allow backtracing functions to work. However, we only need to populate the callee-save register slots in this structure; since we're a function our ancestors must have themselves preserved all caller saved state in the stack. This saves some wasted effort since we won't need to look at the values. In particular, all caller-save registers are immediately available for scratch use. */ #define FRAME_SIZE (76*8 + 8) movi FRAME_SIZE, r0 sub.l r15, r0, r15 ! Do normal-style register save to support backtrace st.l r15, 0, r18 ! save link reg st.l r15, 4, r14 ! save fp add.l r15, r63, r14 ! setup frame pointer ! hopefully this looks normal to the backtrace now. addi.l r15, 8, r1 ! base of pt_regs addi.l r1, 24, r0 ! base of pt_regs.regs addi.l r0, (63*8), r8 ! base of pt_regs.trregs /* Note : to be fixed? struct pt_regs is really designed for holding the state on entry to an exception, i.e. pc,sr,regs etc. However, for the context switch state, some of this is not required. But the unwinder takes struct pt_regs * as an arg so we have to build this structure to allow unwinding switched tasks in show_state() */ st.q r0, ( 9*8), r9 st.q r0, (10*8), r10 st.q r0, (11*8), r11 st.q r0, (12*8), r12 st.q r0, (13*8), r13 st.q r0, (14*8), r14 ! for unwind, want to look as though we took a trap at ! the point where the process is left in suspended animation, i.e. current ! fp here, not the saved one. st.q r0, (16*8), r16 st.q r0, (24*8), r24 st.q r0, (25*8), r25 st.q r0, (26*8), r26 st.q r0, (27*8), r27 st.q r0, (28*8), r28 st.q r0, (29*8), r29 st.q r0, (30*8), r30 st.q r0, (31*8), r31 st.q r0, (32*8), r32 st.q r0, (33*8), r33 st.q r0, (34*8), r34 st.q r0, (35*8), r35 st.q r0, (44*8), r44 st.q r0, (45*8), r45 st.q r0, (46*8), r46 st.q r0, (47*8), r47 st.q r0, (48*8), r48 st.q r0, (49*8), r49 st.q r0, (50*8), r50 st.q r0, (51*8), r51 st.q r0, (52*8), r52 st.q r0, (53*8), r53 st.q r0, (54*8), r54 st.q r0, (55*8), r55 st.q r0, (56*8), r56 st.q r0, (57*8), r57 st.q r0, (58*8), r58 st.q r0, (59*8), r59 ! do this early as pta->gettr has no pipeline forwarding (=> 5 cycle latency) ! Use a local label to avoid creating a symbol that will confuse the ! ! backtrace pta .Lsave_pc, tr0 gettr tr5, r45 gettr tr6, r46 gettr tr7, r47 st.q r8, (5*8), r45 st.q r8, (6*8), r46 st.q r8, (7*8), r47 ! Now switch context gettr tr0, r9 st.l r3, 0, r15 ! prev->thread.sp st.l r3, 8, r1 ! prev->thread.kregs st.l r3, 4, r9 ! prev->thread.pc st.q r1, 0, r9 ! save prev->thread.pc into pt_regs->pc ! Load PC for next task (init value or save_pc later) ld.l r5, 4, r18 ! next->thread.pc ! Switch stacks ld.l r5, 0, r15 ! next->thread.sp ptabs r18, tr0 ! Update current ld.l r4, 4, r9 ! next->thread_info (2nd element of next task_struct) putcon r9, kcr0 ! current = next->thread_info ! go to save_pc for a reschedule, or the initial thread.pc for a new process blink tr0, r63 ! Restore (when we come back to a previously saved task) .Lsave_pc: addi.l r15, 32, r0 ! r0 = next's regs addi.l r0, (63*8), r8 ! r8 = next's tr_regs ld.q r8, (5*8), r45 ld.q r8, (6*8), r46 ld.q r8, (7*8), r47 ptabs r45, tr5 ptabs r46, tr6 ptabs r47, tr7 ld.q r0, ( 9*8), r9 ld.q r0, (10*8), r10 ld.q r0, (11*8), r11 ld.q r0, (12*8), r12 ld.q r0, (13*8), r13 ld.q r0, (14*8), r14 ld.q r0, (16*8), r16 ld.q r0, (24*8), r24 ld.q r0, (25*8), r25 ld.q r0, (26*8), r26 ld.q r0, (27*8), r27 ld.q r0, (28*8), r28 ld.q r0, (29*8), r29 ld.q r0, (30*8), r30 ld.q r0, (31*8), r31 ld.q r0, (32*8), r32 ld.q r0, (33*8), r33 ld.q r0, (34*8), r34 ld.q r0, (35*8), r35 ld.q r0, (44*8), r44 ld.q r0, (45*8), r45 ld.q r0, (46*8), r46 ld.q r0, (47*8), r47 ld.q r0, (48*8), r48 ld.q r0, (49*8), r49 ld.q r0, (50*8), r50 ld.q r0, (51*8), r51 ld.q r0, (52*8), r52 ld.q r0, (53*8), r53 ld.q r0, (54*8), r54 ld.q r0, (55*8), r55 ld.q r0, (56*8), r56 ld.q r0, (57*8), r57 ld.q r0, (58*8), r58 ld.q r0, (59*8), r59 ! epilogue ld.l r15, 0, r18 ld.l r15, 4, r14 ptabs r18, tr0 movi FRAME_SIZE, r0 add r15, r0, r15 blink tr0, r63 __sh64_switch_to_end: .LFE1: .size sh64_switch_to,.LFE1-sh64_switch_to |