| /* |
| * 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 |
| |