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More work on system calls

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This commit is contained in:
Alex 2022-10-20 05:02:49 +03:00
parent 3dc83ad90f
commit cae9572cc1
Signed by untrusted user who does not match committer: enderice2
GPG Key ID: EACC3AD603BAB4DD
2 changed files with 124 additions and 6 deletions
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76
Architecture/amd64/SystemCalls.cpp
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@ -4,18 +4,82 @@
#include "cpu/gdt.hpp"
// https://supercip971.github.io/02-wingos-syscalls.html
using namespace CPU::x64;
extern "C" __attribute__((naked, used, no_stack_protector)) void SystemCallHandlerStub()
{
}
// "Core/SystemCalls.cpp"
extern "C" uint64_t SystemCallsHandler(SyscallsRegs *regs);
extern "C" void SystemCallHandlerStub();
extern "C" __attribute__((naked, used, no_stack_protector)) void SystemCallHandlerStub_broken()
{
// asmv(
// // "cmp $0x08, 0x8(%rsp)\n"
// // "je 1f\n"
// "swapgs\n"
// // "1:\n"
// "mov %rsp, 0x8(%gs)\n" // CPUData->TempStack
// "mov 0x0(%gs), %rsp\n" // CPUData->SystemCallStack
// "push $0x1b\n" // user data segment
// "push 0x8(%gs)\n" // saved stack
// "push %r11\n" // saved rflags
// "push $0x23\n" // user code segment
// "push %rcx\n" // Current RIP
// "push %rax\n"
// "push %rbx\n"
// "push %rcx\n"
// "push %rdx\n"
// "push %rsi\n"
// "push %rdi\n"
// "push %rbp\n"
// "push %r8\n"
// "push %r9\n"
// "push %r10\n"
// "push %r11\n"
// "push %r12\n"
// "push %r13\n"
// "push %r14\n"
// "push %r15\n"
// "mov %rsp, %rdi\n"
// "mov $0, %rbp\n"
// "call SystemCallsHandler\n"
// "pop %r15\n"
// "pop %r14\n"
// "pop %r13\n"
// "pop %r12\n"
// "pop %r11\n"
// "pop %r10\n"
// "pop %r9\n"
// "pop %r8\n"
// "pop %rbp\n"
// "pop %rdi\n"
// "pop %rsi\n"
// "pop %rdx\n"
// "pop %rcx\n"
// "pop %rbx\n"
// /* "pop %rax\n" */
// "mov 0x8(%gs), %rsp\n" // CPUData->TempStack
// // "cmp $0x08, 0x8(%rsp)\n"
// // "je 1f\n"
// "swapgs\n"
// // "1:\n"
// "sti\n"
// "sysretq\n");
}
void InitializeSystemCalls()
{
wrmsr(MSR_EFER, rdmsr(MSR_EFER) | 1);
wrmsr(MSR_STAR, ((uint64_t)(GDT_KERNEL_CODE) << 32) | ((uint64_t)(GDT_KERNEL_DATA | 3) << 48));
wrmsr(MSR_LSTAR, (uint64_t)SystemCallsHandler);
wrmsr(MSR_SYSCALL_MASK, 0);
wrmsr(MSR_LSTAR, (uint64_t)SystemCallHandlerStub);
wrmsr(MSR_SYSCALL_MASK, (uint64_t)(1 << 9));
}

54
Architecture/amd64/SystemCallsAssemblyStub.asm Normal file
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@ -0,0 +1,54 @@
[BITS 64]
ALIGN 4096
extern SystemCallsHandler
global SystemCallHandlerStub
SystemCallHandlerStub:
swapgs
mov [gs:0x8], rsp ; CPUData->TempStack
mov rsp, [gs:0x0] ; CPUData->SystemCallStack
push qword 0x23 ; user data segment
push qword [gs:0x8] ; saved stack
push r11 ; saved rflags
push qword 0x1b ; user code segment
push rcx ; Current RIP
push rax
push rbx
push rcx
push rdx
push rsi
push rdi
push rbp
push r8
push r9
push r10
push r11
push r12
push r13
push r14
push r15
mov rdi, rsp
mov rbp, 0
call SystemCallsHandler
pop r15
pop r14
pop r13
pop r12
pop r11
pop r10
pop r9
pop r8
pop rbp
pop rdi
pop rsi
pop rdx
pop rcx
pop rbx
mov rsp, [gs:0x8]
swapgs
sti
o64 sysret