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Diffstat (limited to 'arch/riscv/kernel/signal.cc')
| -rw-r--r-- | arch/riscv/kernel/signal.cc | 163 |
1 files changed, 0 insertions, 163 deletions
diff --git a/arch/riscv/kernel/signal.cc b/arch/riscv/kernel/signal.cc deleted file mode 100644 index 39fe34e..0000000 --- a/arch/riscv/kernel/signal.cc +++ /dev/null @@ -1,163 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0-or-later */ -/* Copyright (C) 2026 Richard Qin */ - -/* - * arch/riscv/signal.cc — Signal frame construction and sigreturn - * - * Constructs a signal frame on the user stack before returning to - * the user signal handler. On sigreturn, restores the original - * registers from the saved frame. - * - * Frame layout on user stack (grows downward): - * - * +-----------------------+ <- original sp - * | sigset_t saved_mask | 8 bytes - * | TrapFrame saved_regs | 296 bytes - * | kernel_siginfo info | 128 bytes - * +-----------------------+ <- new sp (16-byte aligned) - * - * Reference: Linux arch/riscv/kernel/signal.c - */ - -#include <lume/signal.h> -#include <lume/signal_types.h> -#include <lume/signal_nr.h> -#include <lume/task.h> -#include <lume/uaccess.h> -#include <lume/errno.h> -#include <lume/klog.h> -#include <arch/trapframe.h> - -/* ================================================================== */ -/* Signal frame layout */ -/* ================================================================== */ - -struct rt_sigframe { - kernel_siginfo info; /* siginfo for SA_SIGINFO handlers */ - arch::TrapFrame saved_regs; /* saved register state */ - sigset_t saved_mask; /* blocked mask to restore on sigreturn */ -}; - -/* ================================================================== */ -/* Signal trampoline (written to user stack) */ -/* ================================================================== */ - -/* - * When the user's signal handler returns (via `ret`), ra points here. - * This tiny code sequence invokes sys_rt_sigreturn to restore the - * original execution context. - * - * RISC-V instructions (8 bytes): - * li a7, 139 → addi a7, zero, 139 → 0x08b00893 - * ecall → 0x00000073 - */ -static constexpr uint32 sigreturn_trampoline[2] = { - 0x08b00893, /* li a7, 139 (SYS_rt_sigreturn) */ - 0x00000073, /* ecall */ -}; - -/* ================================================================== */ -/* setup_signal_frame */ -/* ================================================================== */ - -int setup_signal_frame(arch::TrapFrame* tf, int signo, - kernel_sigaction* ka, kernel_siginfo* info) -{ - TaskControlBlock* curr = current_task(); - if (!curr) return -EINVAL; - - /* Calculate frame location on user stack */ - uint64 sp = tf->sp; - - /* Reserve space for the trampoline below the frame */ - sp -= sizeof(sigreturn_trampoline); - sp &= ~15ULL; /* 16-byte align */ - uint64 trampoline_addr = sp; - - /* Reserve space for the signal frame */ - sp -= sizeof(rt_sigframe); - sp &= ~15ULL; /* 16-byte align */ - uint64 frame_addr = sp; - - /* Build the frame in kernel memory, then copy to user stack */ - rt_sigframe frame{}; - if (info) { - frame.info = *info; - } - frame.saved_regs = *tf; - frame.saved_mask = curr->blocked; - - /* Copy frame to user stack */ - int err = copy_to_user(frame_addr, &frame, sizeof(frame)); - if (err < 0) return -EFAULT; - - /* Copy trampoline to user stack */ - err = copy_to_user(trampoline_addr, sigreturn_trampoline, - sizeof(sigreturn_trampoline)); - if (err < 0) return -EFAULT; - - /* Set up the trap frame to execute the signal handler */ - tf->epc = ka->sa_handler; - tf->sp = frame_addr; - - /* Arguments to the handler: handler(int signo, siginfo_t*, ucontext_t*) */ - tf->a[0] = static_cast<uint64>(signo); - - if (ka->sa_flags & SA_SIGINFO) { - /* SA_SIGINFO: pass siginfo and ucontext pointers */ - tf->a[1] = frame_addr; /* &info */ - tf->a[2] = frame_addr + sizeof(kernel_siginfo); /* &saved_regs (as ucontext) */ - } else { - tf->a[1] = 0; - tf->a[2] = 0; - } - - /* Return address: when the handler does `ret`, jump to trampoline */ - if (ka->sa_flags & SA_RESTORER) { - tf->ra = ka->sa_restorer; - } else { - tf->ra = trampoline_addr; - } - - return 0; -} - -/* ================================================================== */ -/* arch_sigreturn — restore state from signal frame */ -/* ================================================================== */ - -int64 arch_sigreturn(arch::TrapFrame* tf) -{ - TaskControlBlock* curr = current_task(); - if (!curr) return -EINVAL; - - /* - * The signal frame is located at the current sp. - * We need to read it back and restore the original state. - */ - uint64 frame_addr = tf->sp; - - rt_sigframe frame{}; - int err = copy_from_user(&frame, frame_addr, sizeof(frame)); - if (err < 0) { - printk(KERN_ERR "sigreturn: failed to read signal frame at %llx\n", - frame_addr); - task_kill_current(SIGSEGV); - return -EFAULT; - } - - /* Restore the saved register state */ - *tf = frame.saved_regs; - - /* Restore the blocked mask */ - curr->blocked = frame.saved_mask; - curr->blocked.del(SIGKILL); - curr->blocked.del(SIGSTOP); - - /* - * Return value: we return the saved a0 from the original context. - * The syscall dispatch will NOT overwrite a0 because sigreturn - * is special — it returns via the restored trap frame directly. - */ - return tf->a[0]; -} |