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https://github.com/Mathewnd/Astral.git
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Matheus
52 lines
1.1 KiB
C
52 lines
1.1 KiB
C
#include <arch/cpu.h>
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#include <arch/msr.h>
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#include <cpuid.h>
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#include <arch/cls.h>
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#include <stdio.h>
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// initialises things like
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// syscall, sse, etc
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// for the current cpu
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extern void asm_syscall_entry();
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void cpu_state_init(){
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// syscall
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// does it exist
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int eax,ebx,ecx,edx;
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__get_cpuid(0x80000001, &eax, &ebx, &ecx, &edx);
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if(edx & (1 << 11)){ // check for the syscall bit
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uint64_t efer = rdmsr(MSR_EFER);
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efer |= 1; // set syscall enable bit
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wrmsr(MSR_EFER, efer);
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uint64_t star = 0;
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star |= (uint64_t)0x28 << 48;
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star |= (uint64_t)0x28 << 32;
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wrmsr(MSR_STAR, star);
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wrmsr(MSR_LSTAR, asm_syscall_entry);
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wrmsr(MSR_CSTAR, 0); // no compat mode syscall handler
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wrmsr(MSR_FMASK, 0x200); // disable interrupts on syscall
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}
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// undefined opcode exception will handle system calls then
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else printf("CPU%lu: syscall instruction not supported\n", arch_getcls()->lapicid);
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// enable SSE
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asm volatile(
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"mov %%cr0, %%rax;"
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"and $0xFFFB, %%ax;"
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"or $2, %%eax;"
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"mov %%rax, %%cr0;"
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"mov %%cr4, %%rax;"
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"or $0b11000000000, %%rax;"
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"mov %%rax, %%cr4;"
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: : : "rax");
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}
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