syscall.c

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#include "syscall.h"
#include "hal/cpu/core.h"
#include "hal/cpu/interrupt.h"
#include "hal/cpu/msr.h"
#include "hal/cpu/paging.h"
#include "init/init.h"
#include "libk/serial.h"
#include "sys/err_no.h"
 
// prototype
extern void syscall_dispatch(interrupt_stack_frame_t* rsp);
extern void syscall_entry(void);
 
static const char* get_syscall_name(int rax);
void syscall_init(void) {
    uint64_t efer = vxRDMSR(MSR_EFER);
    vxWRSR(MSR_EFER, efer | 1); // SCE bit
 
    vxWRSR(MSR_LSTAR, (uint64_t)syscall_entry);
 
    uint64_t star = 0;
    star |= (uint64_t)0x0028 << 32; // kernel CS (0x28), kernel SS (0x30)
    star |= (uint64_t)0x003B << 48; // user base for SYSRET (CS32 = 0x38, SS
                                    // = +8 = 0x40, CS64 = +16 = 0x48)
    vxWRSR(MSR_STAR, star);
 
    vxWRSR(MSR_FMASK, (1 << 9)); // IF bit
}
 
extern void syscall_dispatch(interrupt_stack_frame_t* rsp) {
    // #DEBUG
    if (rsp->rax != SYSCALL_EXIT)
        LOG2_DEBUG("syscall", "called %d (%s) 0x%x 0x%x %d", rsp->rax,
                   get_syscall_name((int)rsp->rax), rsp->rdi, rsp->rsi,
                   rsp->rdx);
 
    auto int_no = rsp->rax;
 
 
    // TODO: refactor this using array of linker section
    switch (int_no) {
    case SYSCALL_READ:
        rsp->rax = (uint64_t)syscall_read(
            (int)rsp->rdi, (void*)rsp->rsi, (int)rsp->rdx);
        break;
    case SYSCALL_WRITE: {
        rsp->rax = (uint64_t)syscall_write(
            (int)rsp->rdi, (void*)rsp->rsi, (int)rsp->rdx);
        break;
    }
    case SYSCALL_OPEN: {
        rsp->rax = (uint64_t)syscall_open((const char*)rsp->rdi,
                                          (int)rsp->rsi, (int)rsp->rdx);
        break;
    }
    case SYSCALL_CLOSE: {
        rsp->rax = 0;
        break;
    }
    case SYSCALL_ARCH_PRCTL: {
        rsp->rax = (uint64_t)syscall_arch_prctl(
            (int)rsp->rdi, (unsigned long)rsp->rsi);
        break;
    }
    case SYSCALL_SET_TID: {
        rsp->rax = (uint64_t)syscall_set_tid((uint32_t)rsp->rdi);
        break;
    }
    case SYSCALL_EXIT: {
        auto thr = get_current_core_data()->active_thread;
        thr->state = THREAD_STATE_TERMINATED;
        *thr->clear_child_tid = 0;
        // TODO: clear allocated memory on heap and mmap
        break;
    }
    case SYSCALL_IOCTL: {
        rsp->rax = (uint64_t)syscall_ioctl((int)rsp->rdi, (uint32_t)rsp->rsi,
                                   (void*)rsp->rdx);
        break;
    }
    case SYSCALL_WRITEV: {
        rsp->rax = (uint64_t)syscall_writev(
            (int)rsp->rdi, (const struct iovec*)rsp->rsi,
            (int)rsp->rdx);
        break;
    }
    case SYSCALL_BRK: {
        rsp->rax = (uint64_t)syscall_brk((void*)rsp->rdi);
        break;
    }
    case SYSCALL_MMAP: {
        rsp->rax = (uint64_t)syscall_mmap(
            (void*)rsp->rdi, (size_t)rsp->rsi, (int)rsp->rdx, (int)rsp->r10,
            (int)rsp->r8, (int)rsp->r9);
        break;
    }
    case SYSCALL_MPORTECT: {
        rsp->rax = (uint64_t)syscall_mprotect(
            (void*)rsp->rdi, (size_t)rsp->rsi, (int)rsp->rdx);
        break;
    }
    case SYSCALL_EXIT_GROUP: {
        syscall_exit_group((int)rsp->rdi);
        break;
    }
    default:
        serial2_printf("unknown syscall %d\n", int_no);
        rsp->rax = (uint64_t)-ENOSYS;
        break;
    }
}
 
INIT(Syscall) { syscall_init(); }
 
extern const char* syscall_names[335];
static const char* get_syscall_name(int rax) {
    int max_syscalls = sizeof(syscall_names) / sizeof(syscall_names[0]);
 
    if (rax >= 0 && rax < max_syscalls && syscall_names[rax] != NULL) {
        return syscall_names[rax];
    }
    return "UNKNOWN_SYSCALL / NOT_IMPLEMENTED";
}