forked from PoliEcho-holding-org/kern
76 lines
2.1 KiB
C
76 lines
2.1 KiB
C
#ifndef SYSCALL_H
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#define SYSCALL_H
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#include <pit.h>
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// System call count
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#define MAX_SYSCALLS 2
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// Args: ebx - number of miliseconds
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void sys_sleep() {
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uint32_t ms;
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__asm__ volatile ("movl %%ebx, %0" : "=r"(ms));
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uint32_t requiredTicks = *timerTicks + ms;
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while (*timerTicks != requiredTicks) { // Wait...
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__asm__ volatile ("sti;hlt;cli;");
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}
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}
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// System call table
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void* syscalls[MAX_SYSCALLS] = {
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sys_sleep,
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};
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// int 0x80 - Syscall interrupt, handled by this function
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// eax : Syscall number
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__attribute__ ((naked)) // No prologue or epilogue, just assembly
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void syscallHandler(void) {
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// Interrupt - Stack should contain: ss, esp, eflags, cs, eip
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// We should also push these regs: ax, gs, fs, es, ds, bp, di, si, dx, cx, bx
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__asm__ volatile (
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".intel_syntax noprefix\n" // We use intel syntax
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".equ MAX_SYSCALLS, 2\n" // Define MAX_SYSCALLS again
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// Check if syscall exists
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"cmp eax, MAX_SYSCALLS - 1\n"
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"ja invalidSyscall\n"
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// Call the syscall
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"push eax\n" // Push required values
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"push gs\n"
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"push fs\n"
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"push es\n"
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"push ds\n"
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"push ebp\n"
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"push edi\n"
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"push esi\n"
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"push edx\n"
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"push ecx\n"
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"push ebx\n"
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"push esp\n" // Push stack pointer again (for variables and such idk)
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"call [syscalls + eax * 4]\n" // Call syscall from table. Syscall number should be in eax
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"add esp, 4\n"
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"pop ebx\n" // Pop pushed values
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"pop ecx\n"
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"pop edx\n"
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"pop esi\n"
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"pop edi\n"
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"pop ebp\n"
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"pop ds\n"
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"pop es\n"
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"pop fs\n"
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"pop gs\n"
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"add esp, 4\n" // Save eax value
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"iretd\n" // Return from interrupt
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// TODO: Send an error or something here
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"invalidSyscall:\n"
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"iretd\n"
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".att_syntax" // Switch back to Att Syntax (Just in case)
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);
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}
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#endif
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