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Diffstat (limited to 'core/riscv-rv32i/switch.S')
| -rw-r--r-- | core/riscv-rv32i/switch.S | 171 |
1 files changed, 0 insertions, 171 deletions
diff --git a/core/riscv-rv32i/switch.S b/core/riscv-rv32i/switch.S deleted file mode 100644 index 8760667c6b..0000000000 --- a/core/riscv-rv32i/switch.S +++ /dev/null @@ -1,171 +0,0 @@ -/* Copyright 2019 The Chromium OS Authors. All rights reserved. - * Use of this source code is governed by a BSD-style license that can be - * found in the LICENSE file. - * - * Context switching - */ - -#include "config.h" -#include "cpu.h" - -#ifdef __RAM_CODE_SECTION_NAME -.section __RAM_CODE_SECTION_NAME -#endif - -/** - * Task context switching - * - * Change the task scheduled after returning from an interruption. - * - * This function must be called in interrupt context. - * - * Save the registers of the current task below the interrupt context on - * its task, then restore the live registers of the next task and set the - * process stack pointer to the new stack. - * - * the structure of the saved context on the stack is : - * ra, a0-a7, t0-t6 (caller saved) , s0-s11 (callee saved), mepc - * interrupt entry frame <|> additional registers - * if enabling the FPU: - * ra, a0-a7, t0-t6, ft0-ft11, fa0-fa7, and fcsr <|> - * s0-s11, fs0-fs11, and mepc - * - */ -.global __switch_task -__switch_task: - /* get the (new) highest priority task pointer in a0 */ - jal next_sched_task - /* pointer to the current task (which are switching from) */ - la t1, current_task - lw t0, 0(t1) - /* reset the re-scheduling request */ - la t2, need_resched - sw zero, 0(t2) - /* Nothing to do: let's return to keep the same task scheduled */ - beq a0, t0, __irq_exit - /* save our new scheduled task */ - sw a0, 0(t1) - /* save our current location in system stack so we can restore at end */ - add t3, sp, zero - /* restore current process stack pointer */ - csrr sp, mscratch - /* get the task program counter saved at exception entry */ - csrr t5, mepc - /* save s0-s11 on the current process stack */ - sw s11, -12*4(sp) - sw s10, -11*4(sp) - sw s9, -10*4(sp) - sw s8, -9*4(sp) - sw s7, -8*4(sp) - sw s6, -7*4(sp) - sw s5, -6*4(sp) - sw s4, -5*4(sp) - sw s3, -4*4(sp) - sw s2, -3*4(sp) - sw s1, -2*4(sp) - sw s0, -1*4(sp) -#ifdef CONFIG_FPU - /* save fs0-fs11 on the current process stack */ - fsw fs11, -24*4(sp) - fsw fs10, -23*4(sp) - fsw fs9, -22*4(sp) - fsw fs8, -21*4(sp) - fsw fs7, -20*4(sp) - fsw fs6, -19*4(sp) - fsw fs5, -18*4(sp) - fsw fs4, -17*4(sp) - fsw fs3, -16*4(sp) - fsw fs2, -15*4(sp) - fsw fs1, -14*4(sp) - fsw fs0, -13*4(sp) - /* save program counter on the current process stack */ - sw t5, -25*4(sp) - /* - * Note: we never execute on this stack frame, so it does not need to - * be 16-byte aligned. - */ - addi sp, sp, -25*4 -#else - /* save program counter on the current process stack */ - sw t5, -13*4(sp) - /* - * Note: we never execute on this stack frame, so it does not need to - * be 16-byte aligned. - */ - addi sp, sp, -13*4 -#endif - /* save the task stack pointer in its context */ - sw sp, 0(t0) - /* get the new scheduled task stack pointer */ - lw sp, 0(a0) -#ifdef CONFIG_FPU - addi sp, sp, 25*4 - /* get mepc */ - lw t0, -25*4(sp) - /* restore FP registers (fs0-fs11) from the next stack context */ - flw fs11, -24*4(sp) - flw fs10, -23*4(sp) - flw fs9, -22*4(sp) - flw fs8, -21*4(sp) - flw fs7, -20*4(sp) - flw fs6, -19*4(sp) - flw fs5, -18*4(sp) - flw fs4, -17*4(sp) - flw fs3, -16*4(sp) - flw fs2, -15*4(sp) - flw fs1, -14*4(sp) - flw fs0, -13*4(sp) -#else - addi sp, sp, 13*4 - /* get mepc */ - lw t0, -13*4(sp) -#endif - /* restore program counter from the next stack context */ - csrw mepc, t0 - /* restore registers from the next stack context */ - lw s11, -12*4(sp) - lw s10, -11*4(sp) - lw s9, -10*4(sp) - lw s8, -9*4(sp) - lw s7, -8*4(sp) - lw s6, -7*4(sp) - lw s5, -6*4(sp) - lw s4, -5*4(sp) - lw s3, -4*4(sp) - lw s2, -3*4(sp) - lw s1, -2*4(sp) - lw s0, -1*4(sp) - /* - * save sp to scratch register and switch to system stack. - * __irq_exit will restore sp from scratch register again before mret. - */ - csrw mscratch, sp - /* restore system stack */ - add sp, t3, zero - j __irq_exit - -.text -/** - * Start the task scheduling. - */ -.global __task_start -__task_start: - csrci mstatus, 0x8 - /* area used as thread stack for the first switch */ - la a3, scratchpad - li a4, 1 - li a2, 0 /* system call 3rd parameter : not an IRQ emulation */ - li a1, 0 /* system call 2nd parameter : re-schedule nothing */ - li a0, 0 /* system call 1st parameter : de-schedule nothing */ - /* put the stack pointer at the top of the stack in scratchpad */ - addi sp, a3, 4 * TASK_SCRATCHPAD_SIZE - /* we are ready to re-schedule */ - la t0, need_resched - sw a4, 0(t0) - la t0, start_called - sw a4, 0(t0) - csrsi mstatus, 0x8 - /* trigger scheduling to execute the task with the highest priority */ - ecall - /* we should never return here */ - j . |