diff options
Diffstat (limited to 'arch/sh64/kernel/switchto.S')
| -rw-r--r-- | arch/sh64/kernel/switchto.S | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/arch/sh64/kernel/switchto.S b/arch/sh64/kernel/switchto.S new file mode 100644 index 00000000000..45b2d90eed7 --- /dev/null +++ b/arch/sh64/kernel/switchto.S @@ -0,0 +1,198 @@ +/* + * 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 + |