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-rw-r--r--arch/riscv/trap/extable.cc92
-rw-r--r--arch/riscv/trap/fpu.S103
-rw-r--r--arch/riscv/trap/swtch.S96
-rw-r--r--arch/riscv/trap/trap_md.cc241
-rw-r--r--arch/riscv/trap/trap_vector.S283
5 files changed, 0 insertions, 815 deletions
diff --git a/arch/riscv/trap/extable.cc b/arch/riscv/trap/extable.cc
deleted file mode 100644
index 57a3dc1..0000000
--- a/arch/riscv/trap/extable.cc
+++ /dev/null
@@ -1,92 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
-/* Copyright (C) 2026 Richard Qin */
-
-#include <arch/extable.h>
-#include <lume/types.h>
-
-extern struct ExceptionTableEntry __extable_start[];
-extern struct ExceptionTableEntry __extable_end[];
-
-static void swap_extable_entries(struct ExceptionTableEntry *a, struct ExceptionTableEntry *b) {
- uint64 a_insn = reinterpret_cast<uint64>(&a->insn) + a->insn;
- uint64 a_fixup = reinterpret_cast<uint64>(&a->fixup) + a->fixup;
- uint64 b_insn = reinterpret_cast<uint64>(&b->insn) + b->insn;
- uint64 b_fixup = reinterpret_cast<uint64>(&b->fixup) + b->fixup;
-
- a->insn = static_cast<int32>(b_insn - reinterpret_cast<uint64>(&a->insn));
- a->fixup = static_cast<int32>(b_fixup - reinterpret_cast<uint64>(&a->fixup));
- b->insn = static_cast<int32>(a_insn - reinterpret_cast<uint64>(&b->insn));
- b->fixup = static_cast<int32>(a_fixup - reinterpret_cast<uint64>(&b->fixup));
-}
-
-static void sort_extable(size_t left, size_t right) {
- if (left >= right) return;
-
- size_t mid_idx = left + (right - left) / 2;
- struct ExceptionTableEntry *pivot = &__extable_start[mid_idx];
- uint64 pivot_val = reinterpret_cast<uint64>(&pivot->insn) + pivot->insn;
-
- size_t i = left;
- size_t j = right;
-
- while (i <= j) {
- while ((reinterpret_cast<uint64>(&__extable_start[i].insn) + __extable_start[i].insn) < pivot_val) {
- i++;
- }
- while ((reinterpret_cast<uint64>(&__extable_start[j].insn) + __extable_start[j].insn) > pivot_val) {
- if (j == 0) {
- break;
- }
- j--;
- }
- if (i <= j) {
- swap_extable_entries(&__extable_start[i], &__extable_start[j]);
- i++;
- if (j == 0) {
- break;
- }
- j--;
- }
- }
-
- if (j > left) {
- sort_extable(left, j);
- }
- if (i < right) {
- sort_extable(i, right);
- }
-}
-
-void extable_init() {
- size_t count = __extable_end - __extable_start;
- if (count <= 1) return;
- sort_extable(0, count - 1);
-}
-
-uint64 search_extable(uint64 pc) {
- size_t count = __extable_end - __extable_start;
- if (count == 0) return 0;
-
- size_t left = 0;
- size_t right = count - 1;
-
- /* Binary search */
- while (left <= right) {
- size_t mid = left + (right - left) / 2;
- const struct ExceptionTableEntry *entry = &__extable_start[mid];
- uint64 mid_pc = reinterpret_cast<uint64>(&entry->insn) + entry->insn;
-
- if (mid_pc == pc) {
- return reinterpret_cast<uint64>(&entry->fixup) + entry->fixup;
- }
-
- if (mid_pc < pc) {
- left = mid + 1;
- } else {
- if (mid == 0) break;
- right = mid - 1;
- }
- }
-
- return 0;
-}
diff --git a/arch/riscv/trap/fpu.S b/arch/riscv/trap/fpu.S
deleted file mode 100644
index 90d96d9..0000000
--- a/arch/riscv/trap/fpu.S
+++ /dev/null
@@ -1,103 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
-/* Copyright (C) 2026 Richard Qin */
-
-/*
- * FPU Save / Restore (RISC-V D extension)
- *
- * void fpu_save(FpState* state);
- * Saves f0-f31 and fcsr to the FpState structure.
- *
- * void fpu_restore(FpState* state);
- * Restores f0-f31 and fcsr from the FpState structure.
- *
- * FpState layout: f[0..31] at offset 0 (each 8 bytes), fcsr at offset 256.
- *
- * Called from schedule() when switching between tasks that have
- * used the FPU (sstatus.FS == Dirty on save path).
- */
-
- .section .text
-
-/* ======================================================================
- * void fpu_save(FpState* state); // a0 = state pointer
- * ====================================================================== */
- .globl fpu_save
- .align 2
-fpu_save:
- fsd f0, 0(a0)
- fsd f1, 8(a0)
- fsd f2, 16(a0)
- fsd f3, 24(a0)
- fsd f4, 32(a0)
- fsd f5, 40(a0)
- fsd f6, 48(a0)
- fsd f7, 56(a0)
- fsd f8, 64(a0)
- fsd f9, 72(a0)
- fsd f10, 80(a0)
- fsd f11, 88(a0)
- fsd f12, 96(a0)
- fsd f13, 104(a0)
- fsd f14, 112(a0)
- fsd f15, 120(a0)
- fsd f16, 128(a0)
- fsd f17, 136(a0)
- fsd f18, 144(a0)
- fsd f19, 152(a0)
- fsd f20, 160(a0)
- fsd f21, 168(a0)
- fsd f22, 176(a0)
- fsd f23, 184(a0)
- fsd f24, 192(a0)
- fsd f25, 200(a0)
- fsd f26, 208(a0)
- fsd f27, 216(a0)
- fsd f28, 224(a0)
- fsd f29, 232(a0)
- fsd f30, 240(a0)
- fsd f31, 248(a0)
- frcsr t0
- sw t0, 256(a0)
- ret
-
-/* ======================================================================
- * void fpu_restore(FpState* state); // a0 = state pointer
- * ====================================================================== */
- .globl fpu_restore
- .align 2
-fpu_restore:
- fld f0, 0(a0)
- fld f1, 8(a0)
- fld f2, 16(a0)
- fld f3, 24(a0)
- fld f4, 32(a0)
- fld f5, 40(a0)
- fld f6, 48(a0)
- fld f7, 56(a0)
- fld f8, 64(a0)
- fld f9, 72(a0)
- fld f10, 80(a0)
- fld f11, 88(a0)
- fld f12, 96(a0)
- fld f13, 104(a0)
- fld f14, 112(a0)
- fld f15, 120(a0)
- fld f16, 128(a0)
- fld f17, 136(a0)
- fld f18, 144(a0)
- fld f19, 152(a0)
- fld f20, 160(a0)
- fld f21, 168(a0)
- fld f22, 176(a0)
- fld f23, 184(a0)
- fld f24, 192(a0)
- fld f25, 200(a0)
- fld f26, 208(a0)
- fld f27, 216(a0)
- fld f28, 224(a0)
- fld f29, 232(a0)
- fld f30, 240(a0)
- fld f31, 248(a0)
- lw t0, 256(a0)
- fscsr t0
- ret
diff --git a/arch/riscv/trap/swtch.S b/arch/riscv/trap/swtch.S
deleted file mode 100644
index dbae43d..0000000
--- a/arch/riscv/trap/swtch.S
+++ /dev/null
@@ -1,96 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
-/* Copyright (C) 2026 Richard Qin */
-
-/*
- * Context Switch & Kernel Thread Trampoline (RISC-V 64)
- *
- * context_switch: saves/restores callee-saved registers.
- * kthread_entry_trampoline: entry point for newly created kernel threads.
- * After context_switch loads the new Context, execution lands here via
- * Context.ra = kthread_entry_trampoline. The entry function and argument
- * are in s0 and s1 respectively, set by sched_init/create_tcb.
- *
- * The trampoline calls the MI-layer kthread_entry(entry, arg).
- *
- * Reference: docs/specs/scheduler.md §6
- */
-
- .section .text
-
-/* ========================================================================
- * void context_switch(Context* old_ctx, Context* next_ctx);
- * a0 = old_ctx_ptr, a1 = next_ctx_ptr
- * ======================================================================== */
- .globl context_switch
- .align 2
-context_switch:
- sd ra, 0(a0)
- sd sp, 8(a0)
- sd s0, 16(a0)
- sd s1, 24(a0)
- sd s2, 32(a0)
- sd s3, 40(a0)
- sd s4, 48(a0)
- sd s5, 56(a0)
- sd s6, 64(a0)
- sd s7, 72(a0)
- sd s8, 80(a0)
- sd s9, 88(a0)
- sd s10, 96(a0)
- sd s11, 104(a0)
-
- ld ra, 0(a1)
- ld sp, 8(a1)
- ld s0, 16(a1)
- ld s1, 24(a1)
- ld s2, 32(a1)
- ld s3, 40(a1)
- ld s4, 48(a1)
- ld s5, 56(a1)
- ld s6, 64(a1)
- ld s7, 72(a1)
- ld s8, 80(a1)
- ld s9, 88(a1)
- ld s10, 96(a1)
- ld s11, 104(a1)
-
- ret
-
-/* ========================================================================
- * kthread_entry_trampoline
- *
- * Reached via context_switch when a new kthread is first scheduled.
- * Context was set up by create_tcb():
- * s0 = entry function pointer
- * s1 = argument pointer
- *
- * Calls the MI-layer C++ function:
- * void kthread_entry(void (*entry)(void*), void* arg);
- * ======================================================================== */
- .globl kthread_entry_trampoline
- .align 2
-kthread_entry_trampoline:
- mv a0, s0 /* a0 = entry function */
- mv a1, s1 /* a1 = argument */
- call kthread_entry /* MI-layer C++ function */
-
- /* kthread_entry should never return, but if it does: */
- wfi
- j kthread_entry_trampoline + 12 /* loop on wfi */
-
-/* ========================================================================
- * ret_from_fork
- *
- * Trampoline for newly forked processes.
- * Context is set up by fork() so that s0 contains the TrapFrame pointer.
- *
- * Calls the MI-layer C++ function:
- * void fork_child_entry(TrapFrame* tf);
- * ======================================================================== */
- .globl ret_from_fork
- .align 2
-ret_from_fork:
- mv a0, s0 /* a0 = TrapFrame pointer */
- call fork_child_entry /* does not return, eventually calls userret */
- wfi
- j ret_from_fork + 8 \ No newline at end of file
diff --git a/arch/riscv/trap/trap_md.cc b/arch/riscv/trap/trap_md.cc
deleted file mode 100644
index e30aea6..0000000
--- a/arch/riscv/trap/trap_md.cc
+++ /dev/null
@@ -1,241 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
-/* Copyright (C) 2026 Richard Qin */
-
-/*
- * Trap MD Layer (RISC-V 64)
- *
- * All architecture-specific trap logic lives here:
- * - scause/stval reading (CSR access)
- * - scause → MI TrapCause translation
- * - RISC-V specific fixups (ecall epc += 4, ebreak epc += 2)
- * - stvec setup (trap_init / trap_init_ap)
- * - kernel_trap_handler (traps from S-mode)
- *
- * MI layer (kernel/trap.cc) contains ZERO arch-specific code.
- *
- * Reference: docs/specs/trap.md §7
- */
-
-#include <lume/trap.h>
-#include <lume/irq.h>
-#include <lume/klog.h>
-#include <lume/console.h>
-#include <lume/kprintf.h>
-#include <lume/sched.h>
-#include <lume/task.h>
-#include <arch/trap.h>
-#include <arch/trapframe.h>
-#include <arch/cpu.h>
-#include <arch/extable.h>
-
-/* PLIC interface (drivers/plic.cc) */
-uint32 plic_claim();
-void plic_complete(uint32 irq);
-
-/* trap_vector.S: assembly entry point */
-extern "C" void trap_vector();
-
-/* ========================================================================
- * scause → TrapCause translation (RISC-V specific)
- * ======================================================================== */
-
-static TrapCause scause_to_trap_cause(uint64 scause)
-{
- if (arch::trap::is_interrupt(scause)) {
- switch (arch::trap::cause_code(scause)) {
- case IRQ_S_TIMER: return TrapCause::IrqTimer;
- case IRQ_S_SOFTWARE: return TrapCause::IrqSoftware;
- case IRQ_S_EXTERNAL: return TrapCause::IrqExternal;
- default: return TrapCause::Unknown;
- }
- }
-
- /* Exception (synchronous) */
- switch (scause) {
- case EXC_INST_PAGE_FAULT: return TrapCause::PageFaultExec;
- case EXC_LOAD_PAGE_FAULT: return TrapCause::PageFaultLoad;
- case EXC_STORE_PAGE_FAULT: return TrapCause::PageFaultStore;
- case EXC_ECALL_FROM_U: return TrapCause::Syscall;
- case EXC_ILLEGAL_INST: return TrapCause::IllegalInst;
- case EXC_BREAKPOINT: return TrapCause::Breakpoint;
-
- case EXC_INST_ACCESS_FAULT:
- case EXC_LOAD_ACCESS_FAULT:
- case EXC_STORE_ACCESS_FAULT:
- return TrapCause::AccessFault;
-
- case EXC_INST_MISALIGNED:
- case EXC_LOAD_MISALIGNED:
- case EXC_STORE_MISALIGNED:
- return TrapCause::AlignFault;
-
- default:
- return TrapCause::Unknown;
- }
-}
-
-TrapCause trap_translate_scause(uint64 scause)
-{
- return scause_to_trap_cause(scause);
-}
-
-static TrapOrigin origin_from_sstatus(uint64 sstatus)
-{
- constexpr uint64 kSstatusSPP = (1ULL << 8);
- return (sstatus & kSstatusSPP) ? TrapOrigin::FromKernel
- : TrapOrigin::FromUser;
-}
-
-static TrapClass classify_trap(uint64 scause, TrapCause cause)
-{
- if (arch::trap::is_interrupt(scause)) {
- return TrapClass::Interrupt;
- }
- if (cause == TrapCause::Syscall) {
- return TrapClass::Syscall;
- }
- if (cause == TrapCause::Unknown) {
- return TrapClass::Unknown;
- }
- return TrapClass::Exception;
-}
-
-static TrapInfo build_trap_info(arch::TrapFrame* tf,
- uint64 scause,
- uint64 stval,
- TrapOrigin origin)
-{
- TrapInfo info{};
- info.cause = scause_to_trap_cause(scause);
- info.cls = classify_trap(scause, info.cause);
- info.origin = origin;
- info.val = stval;
- info.epc = tf ? tf->epc : 0;
- info.scause = scause;
- return info;
-}
-
-/* ========================================================================
- * trap_dispatch — user-mode trap entry (called from trap_vector.S)
- *
- * Reads RISC-V CSRs, translates to MI TrapCause, applies arch-specific
- * fixups, then calls MI trap_handle().
- *
- * After trap_handle returns, we must return to user mode via userret().
- * The assembly jalr t3 that called us has NO return-to-user code after it,
- * so trap_dispatch must never return normally.
- * ======================================================================== */
-
-extern "C" void userret(arch::TrapFrame* tf);
-
-extern "C" [[noreturn]] void trap_dispatch(arch::TrapFrame* tf)
-{
- /* Switch stvec to kernelvec immediately so that any traps during
- * kernel execution (timer IRQs, page faults from copy_from_user)
- * go through the kernel trap entry, not the user trap entry.
- * This matches Linux which sets stvec to handle_exception (kernel)
- * at the top of the user trap path. */
- extern void kernelvec();
- arch::trap::set_vector(reinterpret_cast<uint64>(&kernelvec));
-
- /* Enable SUM so S-mode can access user pages (PTE_U).
- * Without this, any dereference of user-space pointers in syscall
- * handlers (sys_write buf, sys_read buf, etc.) would page fault. */
- arch::trap::enable_sum();
-
- uint64 scause = arch::trap::get_cause();
- uint64 stval = arch::trap::get_value();
-
- TrapOrigin origin = origin_from_sstatus(tf->sstatus);
- TrapInfo info = build_trap_info(tf, scause, stval, origin);
-
- /* Per-trap trace from user mode. Stored at KLOG_DEBUG / KLOG_SUBSYS_TRAP
- * so it lives in the ring buffer for postmortem but stays off the console
- * by default. No more in-band 20-trap window — flip console_level or
- * dump the ring on demand instead. */
- if (origin == TrapOrigin::FromUser) {
- pr_debug_s(KLOG_SUBSYS_TRAP,
- "trap: cause=%u epc=%llx val=%llx\n",
- static_cast<unsigned>(info.cause), info.epc, info.val);
- }
-
- /* Save trapframe in TCB for syscall handlers (like fork) */
- TaskControlBlock* curr = current_task();
- if (curr) {
- curr->trapframe = tf;
- }
-
- /* RISC-V ecall fix: ecall does not increment sepc.
- * Advance epc so sret returns to the instruction AFTER ecall. */
- if (info.cause == TrapCause::Syscall) {
- tf->epc += 4;
- info.epc = tf->epc;
- }
-
- /* RISC-V ebreak fix: advance past the C.EBREAK instruction (2 bytes).
- * This is arch-specific because instruction size depends on the ISA. */
- if (info.cause == TrapCause::Breakpoint) {
- tf->epc += 2;
- info.epc = tf->epc;
- }
-
- /* Call MI-layer dispatcher (zero inline assembly from here on) */
- trap_handle(tf, info);
-
- /* Return to user mode.
- * Set stvec back to trap_vector for the next user-mode trap,
- * then jump to userret which restores registers and does sret. */
- arch::trap::set_vector(reinterpret_cast<uint64>(&trap_vector));
- userret(tf);
- __builtin_unreachable();
-}
-
-/* ========================================================================
- * kernel_trap_handler — traps taken while already in S-mode
- *
- * For Phase 2, only timer and external interrupts are expected.
- * Exceptions in S-mode are always fatal.
- *
- * This belongs in MD because it reads scause directly.
- * ======================================================================== */
-
-extern "C" void kernel_trap_handler(arch::TrapFrame* tf)
-{
- uint64 scause = arch::trap::get_cause();
- uint64 stval = arch::trap::get_value();
-
- if (scause == EXC_LOAD_PAGE_FAULT || scause == EXC_STORE_PAGE_FAULT) {
- uint64 fixup = search_extable(tf->epc);
- if (fixup != 0) {
- /* Exception table entry found: redirect execution to fixup code */
- tf->epc = fixup;
- return;
- }
- }
-
- TrapInfo info = build_trap_info(tf, scause, stval, TrapOrigin::FromKernel);
- trap_handle(tf, info);
-}
-
-/* kernelvec assembly is in trap_vector.S */
-extern "C" void kernelvec();
-
-/* ========================================================================
- * trap_init() — BSP: set stvec, init IrqManager
- * ======================================================================== */
-
-void trap_init()
-{
- g_irq_manager.init();
- arch::trap::set_vector(reinterpret_cast<uint64>(&kernelvec));
-}
-
-/* ========================================================================
- * trap_init_ap() — AP: set this CPU's stvec
- * ======================================================================== */
-
-void trap_init_ap()
-{
- arch::trap::set_vector(reinterpret_cast<uint64>(&kernelvec));
-}
-
diff --git a/arch/riscv/trap/trap_vector.S b/arch/riscv/trap/trap_vector.S
deleted file mode 100644
index 8e45cae..0000000
--- a/arch/riscv/trap/trap_vector.S
+++ /dev/null
@@ -1,283 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
-/* Copyright (C) 2026 Richard Qin */
-
-/*
- * Trap Vector Entry / Exit (RISC-V 64, S-mode)
- *
- * On trap entry (interrupt / exception / ecall):
- * sscratch holds the TrapFrame pointer (set up by kernel before sret).
- * We swap sscratch <-> tp, save all 31 GPRs + sstatus + sepc into TrapFrame,
- * then load kernel metadata (sp, satp, tp, trap handler) and jump to C++.
- *
- * On trap return (userret):
- * Restore all GPRs + sstatus + sepc from TrapFrame, swap sscratch <-> tp,
- * then sret back to user mode.
- *
- * Layout must match arch::TrapFrame in arch/riscv/include/arch/trapframe.h
- * Reference: docs/specs/arch_abstraction.md §7.2
- */
-
-#include <arch/trapframe.h>
-
- .section .text
- .globl trap_vector
- .globl userret
- .align 4
-
-/*
- * trap_vector — unified S-mode trap entry point (Direct mode)
- *
- * Precondition: sscratch = pointer to current task's TrapFrame
- */
-trap_vector:
- /* Step 1: swap sscratch <-> tp. Now tp = TrapFrame*, sscratch = old tp */
- csrrw tp, sscratch, tp
-
- /* Step 2: save all 31 general-purpose registers into TrapFrame */
- sd ra, TF_RA(tp)
- sd sp, TF_SP(tp)
- sd gp, TF_GP(tp)
- /* tp (x4) is in sscratch — save it later */
- sd t0, TF_T0(tp)
- sd t1, TF_T1(tp)
- sd t2, TF_T2(tp)
- sd s0, TF_S0(tp)
- sd s1, TF_S1(tp)
- sd a0, TF_A0(tp)
- sd a1, TF_A1(tp)
- sd a2, TF_A2(tp)
- sd a3, TF_A3(tp)
- sd a4, TF_A4(tp)
- sd a5, TF_A5(tp)
- sd a6, TF_A6(tp)
- sd a7, TF_A7(tp)
- sd s2, TF_S2(tp)
- sd s3, TF_S3(tp)
- sd s4, TF_S4(tp)
- sd s5, TF_S5(tp)
- sd s6, TF_S6(tp)
- sd s7, TF_S7(tp)
- sd s8, TF_S8(tp)
- sd s9, TF_S9(tp)
- sd s10, TF_S10(tp)
- sd s11, TF_S11(tp)
- sd t3, TF_T3(tp)
- sd t4, TF_T4(tp)
- sd t5, TF_T5(tp)
- sd t6, TF_T6(tp)
-
- /* Save the real tp (user's tp) which is now in sscratch */
- csrr t0, sscratch
- sd t0, TF_TP(tp)
-
- /* Step 3: save sstatus */
- csrr t0, sstatus
- sd t0, TF_SSTATUS(tp)
-
- /* Step 4: save sepc (interrupted PC) */
- csrr t0, sepc
- sd t0, TF_EPC(tp)
-
- /* Step 5: load kernel context from TrapFrame metadata */
- ld sp, TF_KERNEL_SP(tp) /* switch to kernel stack */
- ld t1, TF_KERNEL_SATP(tp) /* kernel page table */
- ld t2, TF_KERNEL_CPUID(tp) /* CPU ID for tp */
- ld t3, TF_KERNEL_TRAP(tp) /* C++ trap_handler address */
-
- /* Switch to kernel page table */
- csrw satp, t1
-
- /* Step 6: flush TLB after page table switch */
- sfence.vma zero, zero
-
- /* Step 6.5: restore kernel gp (global pointer).
- * The compiler uses gp-relative addressing for global variable access
- * (e.g. ld reg, offset(gp)). User mode may have set gp to anything,
- * so we MUST reload it before entering any C++ code. */
-.option push
-.option norelax
- la gp, __global_pointer$
-.option pop
-
- /* Pass TrapFrame* to C++ handler (a0 = tf) */
- mv a0, tp
-
- /* Set tp = CPU ID (kernel convention) */
- mv tp, t2
-
- /* Step 7: jump to C++ trap_handler */
- jalr t3
-
-
-/* ========================================================================
- * kernelvec — unified S-mode trap entry point for traps FROM S-MODE
- *
- * Traps from S-mode already have a valid kernel stack pointer in sp.
- * We just allocate a TrapFrame on the stack and save registers.
- * ======================================================================== */
- .globl kernelvec
- .align 4
-kernelvec:
- /* Allocate TrapFrame on stack */
- addi sp, sp, -296
-
- /* Save all 31 general-purpose registers into TrapFrame */
- sd ra, TF_RA(sp)
- /* Save the OLD sp (before we subtracted 296) */
- addi t0, sp, 296
- sd t0, TF_SP(sp)
- sd gp, TF_GP(sp)
- sd tp, TF_TP(sp)
- sd t0, TF_T0(sp)
- sd t1, TF_T1(sp)
- sd t2, TF_T2(sp)
- sd s0, TF_S0(sp)
- sd s1, TF_S1(sp)
- sd a0, TF_A0(sp)
- sd a1, TF_A1(sp)
- sd a2, TF_A2(sp)
- sd a3, TF_A3(sp)
- sd a4, TF_A4(sp)
- sd a5, TF_A5(sp)
- sd a6, TF_A6(sp)
- sd a7, TF_A7(sp)
- sd s2, TF_S2(sp)
- sd s3, TF_S3(sp)
- sd s4, TF_S4(sp)
- sd s5, TF_S5(sp)
- sd s6, TF_S6(sp)
- sd s7, TF_S7(sp)
- sd s8, TF_S8(sp)
- sd s9, TF_S9(sp)
- sd s10, TF_S10(sp)
- sd s11, TF_S11(sp)
- sd t3, TF_T3(sp)
- sd t4, TF_T4(sp)
- sd t5, TF_T5(sp)
- sd t6, TF_T6(sp)
-
- /* Save sstatus and sepc */
- csrr t0, sstatus
- sd t0, TF_SSTATUS(sp)
- csrr t0, sepc
- sd t0, TF_EPC(sp)
-
- /* Call C++ kernel_trap_handler(TrapFrame* tf) */
- mv a0, sp
- call kernel_trap_handler
-
- /* Restore sstatus and sepc */
- ld t0, TF_SSTATUS(sp)
- csrw sstatus, t0
- ld t0, TF_EPC(sp)
- csrw sepc, t0
-
- /* Restore all 31 general-purpose registers */
- ld ra, TF_RA(sp)
- ld gp, TF_GP(sp)
- ld tp, TF_TP(sp)
- ld t0, TF_T0(sp)
- ld t1, TF_T1(sp)
- ld t2, TF_T2(sp)
- ld s0, TF_S0(sp)
- ld s1, TF_S1(sp)
- ld a0, TF_A0(sp)
- ld a1, TF_A1(sp)
- ld a2, TF_A2(sp)
- ld a3, TF_A3(sp)
- ld a4, TF_A4(sp)
- ld a5, TF_A5(sp)
- ld a6, TF_A6(sp)
- ld a7, TF_A7(sp)
- ld s2, TF_S2(sp)
- ld s3, TF_S3(sp)
- ld s4, TF_S4(sp)
- ld s5, TF_S5(sp)
- ld s6, TF_S6(sp)
- ld s7, TF_S7(sp)
- ld s8, TF_S8(sp)
- ld s9, TF_S9(sp)
- ld s10, TF_S10(sp)
- ld s11, TF_S11(sp)
- ld t3, TF_T3(sp)
- ld t4, TF_T4(sp)
- ld t5, TF_T5(sp)
- ld t6, TF_T6(sp)
-
- /* Restore sp last */
- ld sp, TF_SP(sp)
-
- sret
-
-/*
- * userret — return to user mode
- *
- * Called from C++ as: userret(TrapFrame* tf)
- * a0 = pointer to TrapFrame (with user satp already written by caller)
- *
- * Precondition: interrupts must be disabled by caller.
- */
-userret:
- /* a0 = TrapFrame pointer, use it as base */
-
- /* Step 1: write back epc -> sepc */
- ld t0, TF_EPC(a0)
- csrw sepc, t0
-
- /* Step 2: write back sstatus */
- ld t0, TF_SSTATUS(a0)
- csrw sstatus, t0
-
- /* Step 3: caller is responsible for switching satp to user page table
- * and flushing TLB before calling userret. */
-
- /* Store TrapFrame address into sscratch for next trap entry */
- csrw sscratch, a0
-
- /* Use a0 as base to restore all registers */
- mv tp, a0
-
- /* Step 4: restore all 31 general-purpose registers */
- ld ra, TF_RA(tp)
- ld sp, TF_SP(tp)
- ld gp, TF_GP(tp)
- /* defer tp restore — we're using it as base */
- ld t0, TF_T0(tp)
- ld t1, TF_T1(tp)
- ld t2, TF_T2(tp)
- ld s0, TF_S0(tp)
- ld s1, TF_S1(tp)
- ld a0, TF_A0(tp)
- ld a1, TF_A1(tp)
- ld a2, TF_A2(tp)
- ld a3, TF_A3(tp)
- ld a4, TF_A4(tp)
- ld a5, TF_A5(tp)
- ld a6, TF_A6(tp)
- ld a7, TF_A7(tp)
- ld s2, TF_S2(tp)
- ld s3, TF_S3(tp)
- ld s4, TF_S4(tp)
- ld s5, TF_S5(tp)
- ld s6, TF_S6(tp)
- ld s7, TF_S7(tp)
- ld s8, TF_S8(tp)
- ld s9, TF_S9(tp)
- ld s10, TF_S10(tp)
- ld s11, TF_S11(tp)
- ld t3, TF_T3(tp)
- ld t4, TF_T4(tp)
- ld t5, TF_T5(tp)
- ld t6, TF_T6(tp)
-
- /* Step 5: restore user tp (swap sscratch <-> tp) */
- /* sscratch currently = TrapFrame address, tp = TrapFrame address */
- /* We need: tp = user's tp, sscratch = TrapFrame address */
- /* Load user tp from TrapFrame first, but we can't use any temp reg now.
- * Use the sscratch swap trick: */
- ld tp, TF_TP(tp)
-
- /* sscratch already holds TrapFrame address (set above with csrw) */
-
- /* Step 6: sret — return to user mode */
- sret
generated by cgit v1.2.3 (git 2.46.0) at 2026-10-29 03:42:27 +0000