mirror of
https://github.com/RGBCube/serenity
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82 lines
2.7 KiB
C++
82 lines
2.7 KiB
C++
/*
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* Copyright (c) 2021, Owen Smith <yeeetari@gmail.com>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <Kernel/Arch/x86/DescriptorTable.h>
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#include <Kernel/Arch/x86/Processor.h>
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#include <Kernel/Arch/x86/TrapFrame.h>
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extern "C" void syscall_entry();
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extern "C" [[gnu::naked]] void syscall_entry()
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{
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// clang-format off
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asm(
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// Store the user stack, then switch to the kernel stack.
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" movq %%rsp, %%gs:%c[user_stack] \n"
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" movq %%gs:%c[kernel_stack], %%rsp \n"
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// Build RegisterState.
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" pushq $0x1b \n" // User ss
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" pushq %%gs:%c[user_stack] \n" // User rsp
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" sti \n" // It's now safe to enable interrupts, but we can't index into gs after this point
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" pushq %%r11 \n" // The CPU preserves the user rflags in r11
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" pushq $0x23 \n" // User cs
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" pushq %%rcx \n" // The CPU preserves the user IP in rcx
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" pushq $0 \n"
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" pushq %%r15 \n"
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" pushq %%r14 \n"
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" pushq %%r13 \n"
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" pushq %%r12 \n"
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" pushq %%r11 \n"
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" pushq %%r10 \n"
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" pushq %%r9 \n"
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" pushq %%r8 \n"
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" pushq %%rax \n"
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" pushq %%rcx \n"
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" pushq %%rdx \n"
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" pushq %%rbx \n"
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" pushq %%rsp \n"
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" pushq %%rbp \n"
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" pushq %%rsi \n"
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" pushq %%rdi \n"
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" pushq %%rsp \n" // TrapFrame::regs
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" subq $" __STRINGIFY(TRAP_FRAME_SIZE - 8) ", %%rsp \n"
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" movq %%rsp, %%rdi \n"
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" call enter_trap_no_irq \n"
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" movq %%rsp, %%rdi \n"
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" call syscall_handler \n"
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" movq %%rsp, %%rdi \n"
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" call exit_trap \n"
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" addq $" __STRINGIFY(TRAP_FRAME_SIZE) ", %%rsp \n" // Pop TrapFrame
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" popq %%rdi \n"
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" popq %%rsi \n"
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" popq %%rbp \n"
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" addq $8, %%rsp \n" // Skip restoring kernel rsp
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" popq %%rbx \n"
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" popq %%rdx \n"
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" popq %%rcx \n"
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" popq %%rax \n"
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" popq %%r8 \n"
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" popq %%r9 \n"
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" popq %%r10 \n"
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" popq %%r11 \n"
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" popq %%r12 \n"
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" popq %%r13 \n"
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" popq %%r14 \n"
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" popq %%r15 \n"
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" addq $8, %%rsp \n"
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" popq %%rcx \n"
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" addq $16, %%rsp \n"
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// Disable interrupts before we restore the user stack pointer. sysret will re-enable interrupts when it restores
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// rflags.
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" cli \n"
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" popq %%rsp \n"
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" sysretq \n"
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:: [user_stack] "i"(Kernel::Processor::user_stack_offset()), [kernel_stack] "i"(Kernel::Processor::kernel_stack_offset()));
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// clang-format on
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}
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