/*
* Copyright (c) 2018-2020 Atmosphère-NX
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see .
*/
#include
#define SAVE_THREAD_CONTEXT(ctx, tmp0, tmp1, done_label) \
/* Save the callee save registers + SP and cpacr. */ \
mov tmp0, sp; \
mrs tmp1, cpacr_el1; \
stp x19, x20, [ctx, #(THREAD_CONTEXT_X19_X20)]; \
stp x21, x22, [ctx, #(THREAD_CONTEXT_X21_X22)]; \
stp x23, x24, [ctx, #(THREAD_CONTEXT_X23_X24)]; \
stp x25, x26, [ctx, #(THREAD_CONTEXT_X25_X26)]; \
stp x27, x28, [ctx, #(THREAD_CONTEXT_X27_X28)]; \
stp x29, x30, [ctx, #(THREAD_CONTEXT_X29_X30)]; \
\
stp tmp0, tmp1, [ctx, #(THREAD_CONTEXT_SP_CPACR)]; \
\
/* Check whether the FPU is enabled. */ \
/* If it isn't, skip saving FPU state. */ \
and tmp1, tmp1, #0x300000; \
cbz tmp1, done_label; \
\
/* Save fpcr and fpsr. */ \
mrs tmp0, fpcr; \
mrs tmp1, fpsr; \
stp tmp0, tmp1, [ctx, #(THREAD_CONTEXT_FPCR_FPSR)]; \
\
/* Save the FPU registers. */ \
stp q0, q1, [ctx, #(16 * 0 + THREAD_CONTEXT_FPU_REGISTERS)]; \
stp q2, q3, [ctx, #(16 * 2 + THREAD_CONTEXT_FPU_REGISTERS)]; \
stp q4, q5, [ctx, #(16 * 4 + THREAD_CONTEXT_FPU_REGISTERS)]; \
stp q6, q7, [ctx, #(16 * 6 + THREAD_CONTEXT_FPU_REGISTERS)]; \
stp q8, q9, [ctx, #(16 * 8 + THREAD_CONTEXT_FPU_REGISTERS)]; \
stp q10, q11, [ctx, #(16 * 10 + THREAD_CONTEXT_FPU_REGISTERS)]; \
stp q12, q13, [ctx, #(16 * 12 + THREAD_CONTEXT_FPU_REGISTERS)]; \
stp q14, q15, [ctx, #(16 * 14 + THREAD_CONTEXT_FPU_REGISTERS)]; \
stp q16, q17, [ctx, #(16 * 16 + THREAD_CONTEXT_FPU_REGISTERS)]; \
stp q18, q19, [ctx, #(16 * 18 + THREAD_CONTEXT_FPU_REGISTERS)]; \
stp q20, q21, [ctx, #(16 * 20 + THREAD_CONTEXT_FPU_REGISTERS)]; \
stp q22, q23, [ctx, #(16 * 22 + THREAD_CONTEXT_FPU_REGISTERS)]; \
stp q24, q25, [ctx, #(16 * 24 + THREAD_CONTEXT_FPU_REGISTERS)]; \
stp q26, q27, [ctx, #(16 * 26 + THREAD_CONTEXT_FPU_REGISTERS)]; \
stp q28, q29, [ctx, #(16 * 28 + THREAD_CONTEXT_FPU_REGISTERS)]; \
stp q30, q31, [ctx, #(16 * 30 + THREAD_CONTEXT_FPU_REGISTERS)];
#define RESTORE_THREAD_CONTEXT(ctx, tmp0, tmp1, done_label) \
/* Restore the callee save registers + SP and cpacr. */ \
ldp tmp0, tmp1, [ctx, #(THREAD_CONTEXT_SP_CPACR)]; \
mov sp, tmp0; \
ldp x19, x20, [ctx, #(THREAD_CONTEXT_X19_X20)]; \
ldp x21, x22, [ctx, #(THREAD_CONTEXT_X21_X22)]; \
ldp x23, x24, [ctx, #(THREAD_CONTEXT_X23_X24)]; \
ldp x25, x26, [ctx, #(THREAD_CONTEXT_X25_X26)]; \
ldp x27, x28, [ctx, #(THREAD_CONTEXT_X27_X28)]; \
ldp x29, x30, [ctx, #(THREAD_CONTEXT_X29_X30)]; \
\
msr cpacr_el1, tmp1; \
isb; \
\
/* Check whether the FPU is enabled. */ \
/* If it isn't, skip saving FPU state. */ \
and tmp1, tmp1, #0x300000; \
cbz tmp1, done_label; \
\
/* Save fpcr and fpsr. */ \
ldp tmp0, tmp1, [ctx, #(THREAD_CONTEXT_FPCR_FPSR)]; \
msr fpcr, tmp0; \
msr fpsr, tmp1; \
\
/* Save the FPU registers. */ \
ldp q0, q1, [ctx, #(16 * 0 + THREAD_CONTEXT_FPU_REGISTERS)]; \
ldp q2, q3, [ctx, #(16 * 2 + THREAD_CONTEXT_FPU_REGISTERS)]; \
ldp q4, q5, [ctx, #(16 * 4 + THREAD_CONTEXT_FPU_REGISTERS)]; \
ldp q6, q7, [ctx, #(16 * 6 + THREAD_CONTEXT_FPU_REGISTERS)]; \
ldp q8, q9, [ctx, #(16 * 8 + THREAD_CONTEXT_FPU_REGISTERS)]; \
ldp q10, q11, [ctx, #(16 * 10 + THREAD_CONTEXT_FPU_REGISTERS)]; \
ldp q12, q13, [ctx, #(16 * 12 + THREAD_CONTEXT_FPU_REGISTERS)]; \
ldp q14, q15, [ctx, #(16 * 14 + THREAD_CONTEXT_FPU_REGISTERS)]; \
ldp q16, q17, [ctx, #(16 * 16 + THREAD_CONTEXT_FPU_REGISTERS)]; \
ldp q18, q19, [ctx, #(16 * 18 + THREAD_CONTEXT_FPU_REGISTERS)]; \
ldp q20, q21, [ctx, #(16 * 20 + THREAD_CONTEXT_FPU_REGISTERS)]; \
ldp q22, q23, [ctx, #(16 * 22 + THREAD_CONTEXT_FPU_REGISTERS)]; \
ldp q24, q25, [ctx, #(16 * 24 + THREAD_CONTEXT_FPU_REGISTERS)]; \
ldp q26, q27, [ctx, #(16 * 26 + THREAD_CONTEXT_FPU_REGISTERS)]; \
ldp q28, q29, [ctx, #(16 * 28 + THREAD_CONTEXT_FPU_REGISTERS)]; \
ldp q30, q31, [ctx, #(16 * 30 + THREAD_CONTEXT_FPU_REGISTERS)];
/* ams::kern::KScheduler::ScheduleImpl() */
.section .text._ZN3ams4kern10KScheduler12ScheduleImplEv, "ax", %progbits
.global _ZN3ams4kern10KScheduler12ScheduleImplEv
.type _ZN3ams4kern10KScheduler12ScheduleImplEv, %function
/* Ensure ScheduleImpl is aligned to 0x40 bytes. */
.balign 0x40
_ZN3ams4kern10KScheduler12ScheduleImplEv:
/* Right now, x0 contains (this). We want x1 to point to the scheduling state, */
/* KScheduler layout has state at +0x0, this is guaranteed statically by assembly offsets. */
mov x1, x0
/* First, clear the need's scheduling bool (and dmb ish after, as it's an atomic). */
/* TODO: Should this be a stlrb? Nintendo does not do one. */
strb wzr, [x1]
dmb ish
/* Check whether there are runnable interrupt tasks. */
ldrb w8, [x1, #(KSCHEDULER_INTERRUPT_TASK_RUNNABLE)]
cbnz w8, 0f
/* If it isn't, we want to check if the highest priority thread is the same as the current thread. */
ldr x7, [x1, #(KSCHEDULER_HIGHEST_PRIORITY_THREAD)]
cmp x7, x18
b.ne 1f
/* If they're the same, then we can just return as there's nothing to do. */
ret
0: /* The interrupt task thread is runnable. */
/* We want to switch to the interrupt task/idle thread. */
mov x7, #0
1: /* The highest priority thread is not the same as the current thread. */
/* Get a reference to the current thread's stack parameters. */
add x2, sp, #0x1000
and x2, x2, #~(0x1000-1)
/* Check if the thread has terminated. We can do this by checking the DPC flags for DpcFlag_Terminated. */
ldurb w3, [x2, #-(THREAD_STACK_PARAMETERS_SIZE - THREAD_STACK_PARAMETERS_DPC_FLAGS)]
tbnz w3, #1, 3f
/* The current thread hasn't terminated, so we want to save its context. */
ldur x2, [x2, #-(THREAD_STACK_PARAMETERS_SIZE - THREAD_STACK_PARAMETERS_CONTEXT)]
SAVE_THREAD_CONTEXT(x2, x4, x5, 2f)
2: /* We're done saving this thread's context, so we need to unlock it. */
/* We can just do an atomic write to the relevant KThreadContext member. */
add x2, x2, #(THREAD_CONTEXT_LOCKED)
stlrb wzr, [x2]
3: /* The current thread's context has been entirely taken care of. */
/* Now we want to loop until we successfully switch the thread context. */
/* Start by saving all the values we care about in callee-save registers. */
mov x19, x0 /* this */
mov x20, x1 /* this->state */
mov x21, x7 /* highest priority thread */
/* Set our stack to the idle thread stack. */
ldr x3, [x20, #(KSCHEDULER_IDLE_THREAD_STACK)]
mov sp, x3
b 5f
4: /* We failed to successfully do the context switch, and need to retry. */
/* Clear the exclusive monitor. */
clrex
/* Clear the need's scheduling bool (and dmb ish after, as it's an atomic). */
/* TODO: Should this be a stlrb? Nintendo does not do one. */
strb wzr, [x20]
dmb ish
/* Refresh the highest priority thread. */
ldr x21, [x20, #(KSCHEDULER_HIGHEST_PRIORITY_THREAD)]
5: /* We're starting to try to do the context switch. */
/* Check if the highest priority thread if null. */
/* If it is, we want to branch to a special idle thread loop. */
cbz x21, 11f
/* Get the highest priority thread's context, and save it. */
/* ams::kern::KThread::GetContextForSchedulerLoop() */
mov x0, x21
bl _ZN3ams4kern7KThread26GetContextForSchedulerLoopEv
mov x22, x0
/* Prepare to try to acquire the context lock. */
add x1, x22, #(THREAD_CONTEXT_LOCKED)
mov w2, #1
6: /* We want to try to lock the highest priority thread's context. */
/* Check if the lock is already held. */
ldaxrb w3, [x1]
cbnz w3, 7f
/* If it's not, try to take it. */
stxrb w3, w2, [x1]
cbnz w3, 6b
/* We hold the lock, so we can now switch the thread. */
b 8f
7: /* The highest priority thread's context is already locked. */
/* Check if we need scheduling. If we don't, we can retry directly. */
ldarb w3, [x20] // ldarb w3, [x20, #(KSCHEDULER_NEEDS_SCHEDULING)]
cbz w3, 6b
/* If we do, another core is interfering, and we must start from the top. */
b 4b
8: /* It's time to switch the thread. */
/* Switch to the highest priority thread. */
mov x0, x19
mov x1, x21
/* Call ams::kern::KScheduler::SwitchThread(ams::kern::KThread *) */
bl _ZN3ams4kern10KScheduler12SwitchThreadEPNS0_7KThreadE
/* Check if we need scheduling. If we don't, then we can't complete the switch and should retry. */
ldarb w1, [x20] // ldarb w1, [x20, #(KSCHEDULER_NEEDS_SCHEDULING)]
cbnz w1, 10f
/* Restore the thread context. */
mov x0, x22
RESTORE_THREAD_CONTEXT(x0, x1, x2, 9f)
9: /* Configure single-step, if we should. */
#if defined(MESOSPHERE_ENABLE_HARDWARE_SINGLE_STEP)
/* Get a reference to the new thread's stack parameters. */
add x2, sp, #0x1000
and x2, x2, #~(0x1000-1)
/* Read the single-step flag. */
ldurb w2, [x2, #-(THREAD_STACK_PARAMETERS_SIZE - THREAD_STACK_PARAMETERS_IS_SINGLE_STEP)]
/* Update the single-step bit in mdscr_el1. */
mrs x1, mdscr_el1
bic x1, x1, #1
orr x1, x1, x2
msr mdscr_el1, x1
isb
#endif
/* We're done restoring the thread context, and can return safely. */
ret
10: /* Our switch failed. */
/* We should unlock the thread context, and then retry. */
add x1, x22, #(THREAD_CONTEXT_LOCKED)
stlrb wzr, [x1]
b 4b
11: /* The next thread is nullptr! */
/* Switch to nullptr. This will actually switch to the idle thread. */
mov x0, x19
mov x1, #0
/* Call ams::kern::KScheduler::SwitchThread(ams::kern::KThread *) */
bl _ZN3ams4kern10KScheduler12SwitchThreadEPNS0_7KThreadE
12: /* We've switched to the idle thread, so we want to process interrupt tasks until we schedule a non-idle thread. */
/* Check whether there are runnable interrupt tasks. */
ldrb w3, [x20, #(KSCHEDULER_INTERRUPT_TASK_RUNNABLE)]
cbnz w3, 13f
/* Check if we need scheduling. */
ldarb w3, [x20] // ldarb w3, [x20, #(KSCHEDULER_NEEDS_SCHEDULING)]
cbnz w3, 4b
/* Clear the previous thread. */
str xzr, [x20, #(KSCHEDULER_PREVIOUS_THREAD)]
/* Wait for an interrupt and check again. */
wfi
msr daifclr, #2
msr daifset, #2
b 12b
13: /* We have interrupt tasks to execute! */
/* Execute any pending interrupt tasks. */
ldr x0, [x20, #(KSCHEDULER_INTERRUPT_TASK_MANAGER)]
bl _ZN3ams4kern21KInterruptTaskManager7DoTasksEv
/* Clear the interrupt task thread as runnable. */
strb wzr, [x20, #(KSCHEDULER_INTERRUPT_TASK_RUNNABLE)]
/* Retry the scheduling loop. */
b 4b