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Kernel/riscv64: Implement Processor::switch_context

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This code is based on the aarch64 implementation.
This commit is contained in:
Sönke Holz 2024-02-06 21:04:01 +01:00 • committed by Andrew Kaster
parent 494e026ca7
commit 726865592c
1 changed files with 129 additions and 2 deletions
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131
Kernel/Arch/riscv64/Processor.cpp
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@ -198,9 +198,136 @@ void ProcessorBase<T>::initialize_context_switching(Thread& initial_thread)
}
template<typename T>
void ProcessorBase<T>::switch_context(Thread*&, Thread*&)
void ProcessorBase<T>::switch_context(Thread*& from_thread, Thread*& to_thread)
{
TODO_RISCV64();
VERIFY(!m_in_irq);
VERIFY(m_in_critical == 1);
dbgln_if(CONTEXT_SWITCH_DEBUG, "switch_context --> switching out of: {} {}", VirtualAddress(from_thread), *from_thread);
// m_in_critical is restored in enter_thread_context
from_thread->save_critical(m_in_critical);
// clang-format off
asm volatile(
// Store a RegisterState of from_thread on from_thread's stack
"addi sp, sp, -(34 * 8) \n"
"sd x1, 0*8(sp) \n"
// sp
"sd x3, 2*8(sp) \n"
"sd x4, 3*8(sp) \n"
"sd x5, 4*8(sp) \n"
"sd x6, 5*8(sp) \n"
"sd x7, 6*8(sp) \n"
"sd x8, 7*8(sp) \n"
"sd x9, 8*8(sp) \n"
"sd x10, 9*8(sp) \n"
"sd x11, 10*8(sp) \n"
"sd x12, 11*8(sp) \n"
"sd x13, 12*8(sp) \n"
"sd x14, 13*8(sp) \n"
"sd x15, 14*8(sp) \n"
"sd x16, 15*8(sp) \n"
"sd x17, 16*8(sp) \n"
"sd x18, 17*8(sp) \n"
"sd x19, 18*8(sp) \n"
"sd x20, 19*8(sp) \n"
"sd x21, 20*8(sp) \n"
"sd x22, 21*8(sp) \n"
"sd x23, 22*8(sp) \n"
"sd x24, 23*8(sp) \n"
"sd x25, 24*8(sp) \n"
"sd x26, 25*8(sp) \n"
"sd x27, 26*8(sp) \n"
"sd x28, 27*8(sp) \n"
"sd x29, 28*8(sp) \n"
"sd x30, 29*8(sp) \n"
"sd x31, 30*8(sp) \n"
// Store current sp as from_thread's sp.
"sd sp, %[from_sp] \n"
// Set from_thread's pc to label "1"
"la t0, 1f \n"
"sd t0, %[from_ip] \n"
// Switch to to_thread's stack
"ld sp, %[to_sp] \n"
// Store from_thread, to_thread, to_ip on to_thread's stack
"addi sp, sp, -(4 * 8) \n"
"ld a0, %[from_thread] \n"
"sd a0, 0*8(sp) \n"
"ld a1, %[to_thread] \n"
"sd a1, 1*8(sp) \n"
"ld s1, %[to_ip] \n"
"sd s1, 2*8(sp) \n"
// enter_thread_context(from_thread, to_thread)
"call enter_thread_context \n"
// Jump to to_ip
"jr s1 \n"
// A thread enters here when they were already scheduled at least once
"1: \n"
"addi sp, sp, (4 * 8) \n"
// Restore the RegisterState of to_thread
"ld x1, 0*8(sp) \n"
// sp
"ld x3, 2*8(sp) \n"
"ld x4, 3*8(sp) \n"
"ld x5, 4*8(sp) \n"
"ld x6, 5*8(sp) \n"
"ld x7, 6*8(sp) \n"
"ld x8, 7*8(sp) \n"
"ld x9, 8*8(sp) \n"
"ld x10, 9*8(sp) \n"
"ld x11, 10*8(sp) \n"
"ld x12, 11*8(sp) \n"
"ld x13, 12*8(sp) \n"
"ld x14, 13*8(sp) \n"
"ld x15, 14*8(sp) \n"
"ld x16, 15*8(sp) \n"
"ld x17, 16*8(sp) \n"
"ld x18, 17*8(sp) \n"
"ld x19, 18*8(sp) \n"
"ld x20, 19*8(sp) \n"
"ld x21, 20*8(sp) \n"
"ld x22, 21*8(sp) \n"
"ld x23, 22*8(sp) \n"
"ld x24, 23*8(sp) \n"
"ld x25, 24*8(sp) \n"
"ld x26, 25*8(sp) \n"
"ld x27, 26*8(sp) \n"
"ld x28, 27*8(sp) \n"
"ld x29, 28*8(sp) \n"
"ld x30, 29*8(sp) \n"
"ld x31, 30*8(sp) \n"
"addi sp, sp, -(4 * 8) \n"
"ld t0, 0*8(sp) \n"
"sd t0, %[from_thread] \n"
"ld t0, 1*8(sp) \n"
"sd t0, %[to_thread] \n"
"addi sp, sp, (34 * 8) + (4 * 8) \n"
:
[from_ip] "=m"(from_thread->regs().pc),
[from_sp] "=m"(from_thread->regs().x[1]),
"=m"(from_thread),
"=m"(to_thread)
: [to_ip] "m"(to_thread->regs().pc),
[to_sp] "m"(to_thread->regs().x[1]),
[from_thread] "m"(from_thread),
[to_thread] "m"(to_thread)
: "memory", "t0", "s1", "a0", "a1");
// clang-format on
dbgln_if(CONTEXT_SWITCH_DEBUG, "switch_context <-- from {} {} to {} {}", VirtualAddress(from_thread), *from_thread, VirtualAddress(to_thread), *to_thread);
}
extern "C" FlatPtr do_init_context(Thread*, u32)