+++ /dev/null
-; -*- fundamental -*-
-; Low level interrupt/thread handling code for GeekOS.
-; Copyright (c) 2001,2003,2004 David H. Hovemeyer <daveho@cs.umd.edu>
-; Copyright (c) 2003, Jeffrey K. Hollingsworth <hollings@cs.umd.edu>
-; $Revision: 1.1 $
-
-; This is free software. You are permitted to use,
-; redistribute, and modify it as specified in the file "COPYING".
-
-; This is 32 bit code to be linked into the kernel.
-; It defines low level interrupt handler entry points that we'll use
-; to populate the IDT. It also contains the interrupt handling
-; and thread context switch code.
-
-%include "defs.asm"
-%include "symbol.asm"
-%include "util.asm"
-
-
-[BITS 32]
-
-; ----------------------------------------------------------------------
-; Definitions
-; ----------------------------------------------------------------------
-
-; This is the size of the Interrupt_State struct in int.h
-INTERRUPT_STATE_SIZE equ 64
-
-; Save registers prior to calling a handler function.
-; This must be kept up to date with:
-; - Interrupt_State struct in int.h
-; - Setup_Initial_Thread_Context() in kthread.c
-%macro Save_Registers 0
- push eax
- push ebx
- push ecx
- push edx
- push esi
- push edi
- push ebp
- push ds
- push es
- push fs
- push gs
-%endmacro
-
-; Restore registers and clean up the stack after calling a handler function
-; (i.e., just before we return from the interrupt via an iret instruction).
-%macro Restore_Registers 0
- pop gs
- pop fs
- pop es
- pop ds
- pop ebp
- pop edi
- pop esi
- pop edx
- pop ecx
- pop ebx
- pop eax
- add esp, 8 ; skip int num and error code
-%endmacro
-
-; Code to activate a new user context (if necessary), before returning
-; to executing a thread. Should be called just before restoring
-; registers (because the interrupt context is used).
-%macro Activate_User_Context 0
- ; If the new thread has a user context which is not the current
- ; one, activate it.
- push esp ; Interrupt_State pointer
- push dword [g_currentThread] ; Kernel_Thread pointer
-; call Switch_To_User_Context
- add esp, 8 ; clear 2 arguments
-%endmacro
-
-; Number of bytes between the top of the stack and
-; the interrupt number after the general-purpose and segment
-; registers have been saved.
-REG_SKIP equ (11*4)
-
-; Template for entry point code for interrupts that have
-; an explicit processor-generated error code.
-; The argument is the interrupt number.
-%macro Int_With_Err 1
-align 8
- push dword %1 ; push interrupt number
- jmp Handle_Interrupt ; jump to common handler
-%endmacro
-
-; Template for entry point code for interrupts that do not
-; generate an explicit error code. We push a dummy error
-; code on the stack, so the stack layout is the same
-; for all interrupts.
-%macro Int_No_Err 1
-align 8
- push dword 0 ; fake error code
- push dword %1 ; push interrupt number
- jmp Handle_Interrupt ; jump to common handler
-%endmacro
-
-
-; ----------------------------------------------------------------------
-; Symbol imports and exports
-; ----------------------------------------------------------------------
-
-; This symbol is defined in idt.c, and is a table of addresses
-; of C handler functions for interrupts.
-IMPORT g_interruptTable
-
-; Global variable pointing to context struct for current thread.
-IMPORT g_currentThread
-
-; Set to non-zero when we need to choose a new thread
-; in the interrupt return code.
-IMPORT g_needReschedule
-
-; Set to non-zero when preemption is disabled.
-IMPORT g_preemptionDisabled
-
-; This is the function that returns the next runnable thread.
-IMPORT Get_Next_Runnable
-
-; Function to put a thread on the run queue.
-IMPORT Make_Runnable
-
-; Function to activate a new user context (if needed).
-IMPORT Switch_To_User_Context
-
-; Sizes of interrupt handler entry points for interrupts with
-; and without error codes. The code in idt.c uses this
-; information to infer the layout of the table of interrupt
-; handler entry points, without needing a separate linker
-; symbol for each one (which is quite tedious to type :-)
-EXPORT g_handlerSizeNoErr
-EXPORT g_handlerSizeErr
-
-; Simple functions to load the IDTR, GDTR, and LDTR.
-EXPORT Load_IDTR
-EXPORT Load_GDTR
-EXPORT Load_LDTR
-
-; Beginning and end of the table of interrupt entry points.
-EXPORT g_entryPointTableStart
-EXPORT g_entryPointTableEnd
-
-; Thread context switch function.
-EXPORT Switch_To_Thread
-
-; Return current value of eflags register.
-EXPORT Get_Current_EFLAGS
-
-; Return the return address
-EXPORT Get_EIP
-; ESP
-EXPORT Get_ESP
-; EBP
-EXPORT Get_EBP
-
-; Virtual memory support.
-EXPORT Enable_Paging
-EXPORT Set_PDBR
-EXPORT Get_PDBR
-EXPORT Flush_TLB
-
-; CPUID functions
-EXPORT cpuid_ecx
-EXPORT cpuid_eax
-
-; Utility Functions
-EXPORT Set_MSR
-EXPORT Get_MSR
-
-EXPORT Get_CR2
-
-
-EXPORT Proc_test
-
-; ----------------------------------------------------------------------
-; Code
-; ----------------------------------------------------------------------
-
-[SECTION .text]
-
-; Load IDTR with 6-byte pointer whose address is passed as
-; the parameter.
-align 8
-Load_IDTR:
- mov eax, [esp+4]
- lidt [eax]
- ret
-
-; Load the GDTR with 6-byte pointer whose address is
-; passed as the parameter. Assumes that interrupts
-; are disabled.
-align 8
-Load_GDTR:
- mov eax, [esp+4]
- lgdt [eax]
- ; Reload segment registers
- mov ax, KERNEL_DS
- mov ds, ax
- mov es, ax
- mov fs, ax
- mov gs, ax
- mov ss, ax
- jmp KERNEL_CS:.here
-.here:
- ret
-
-; Load the LDT whose selector is passed as a parameter.
-align 8
-Load_LDTR:
- mov eax, [esp+4]
- lldt ax
- ret
-
-;
-; Start paging
-; load crt3 with the passed page directory pointer
-; enable paging bit in cr2
-align 8
-Enable_Paging:
- push ebp
- mov ebp, esp
- push eax
- push ebx
- mov eax, [ebp+8]
- mov cr3, eax
- mov eax, cr3
- mov cr3, eax
- mov ebx, cr0
- or ebx, 0x80000000
- mov cr0, ebx
- pop ebx
- pop eax
- pop ebp
- ret
-
-
-
-
-
-;
-; Change PDBR
-; load cr3 with the passed page directory pointer
-align 8
-Set_PDBR:
- mov eax, [esp+4]
- mov cr3, eax
- ret
-
-;
-; Get the current PDBR.
-; This is useful for lazily switching address spaces;
-; only switch if the new thread has a different address space.
-;
-align 8
-Get_PDBR:
- mov eax, cr3
- ret
-
-;
-; Flush TLB - just need to re-load cr3 to force this to happen
-;
-align 8
-Flush_TLB:
- mov eax, cr3
- mov cr3, eax
- ret
-
-
-;
-; cpuid_ecx - return the ecx register from cpuid
-;
-align 8
-cpuid_ecx:
- push ebp
- mov ebp, esp
- push ecx
- mov eax, [ebp + 8]
- cpuid
- mov eax, ecx
- pop ecx
- pop ebp
- ret
-
-;
-; cpuid_eax - return the eax register from cpuid
-;
-align 8
-cpuid_eax:
- mov eax, [esp+4]
- cpuid
- ret
-
-;
-; Set_MSR - Set the value of a given MSR
-;
-align 8
-Set_MSR:
- push ebp
- mov ebp, esp
- pusha
- mov eax, [ebp+16]
- mov edx, [ebp+12]
- mov ecx, [ebp+8]
- wrmsr
- popa
- pop ebp
- ret
-
-
-
-;
-; Get_MSR - Get the value of a given MSR
-; void Get_MSR(int MSR, void * high_byte, void * low_byte);
-;
-align 8
-Get_MSR:
- push ebp
- mov ebp, esp
- pusha
- mov ecx, [ebp+8]
- rdmsr
- mov ebx, [ebp+12]
- mov [ebx], edx
- mov ebx, [ebp+16]
- mov [ebx], eax
- popa
- pop ebp
- ret
-
-
-
-align 8
-Get_CR2:
- mov eax, cr2
- ret
-
-
-align 8
-Proc_test:
- push ebp
- mov ebp, esp
- push ebx
- mov ebx, [ebp + 8]
- mov eax, [ebp + 12]
-
- add eax, ebx
- pop ebx
- pop ebp
- ret
-
-
-; Common interrupt handling code.
-; Save registers, call C handler function,
-; possibly choose a new thread to run, restore
-; registers, return from the interrupt.
-align 8
-Handle_Interrupt:
- ; Save registers (general purpose and segment)
- Save_Registers
-
- ; Ensure that we're using the kernel data segment
- mov ax, KERNEL_DS
- mov ds, ax
- mov es, ax
-
- ; Get the address of the C handler function from the
- ; table of handler functions.
- mov eax, g_interruptTable ; get address of handler table
- mov esi, [esp+REG_SKIP] ; get interrupt number
- mov ebx, [eax+esi*4] ; get address of handler function
-
- ; Call the handler.
- ; The argument passed is a pointer to an Interrupt_State struct,
- ; which describes the stack layout for all interrupts.
- push esp
- call ebx
- add esp, 4 ; clear 1 argument
-
- ; If preemption is disabled, then the current thread
- ; keeps running.
- cmp [g_preemptionDisabled], dword 0
- jne .restore
-
- ; See if we need to choose a new thread to run.
- cmp [g_needReschedule], dword 0
- je .restore
-
- ; Put current thread back on the run queue
- push dword [g_currentThread]
- call Make_Runnable
- add esp, 4 ; clear 1 argument
-
- ; Save stack pointer in current thread context, and
- ; clear numTicks field.
- mov eax, [g_currentThread]
- mov [eax+0], esp ; esp field
- mov [eax+4], dword 0 ; numTicks field
-
- ; Pick a new thread to run, and switch to its stack
- call Get_Next_Runnable
- mov [g_currentThread], eax
- mov esp, [eax+0] ; esp field
-
- ; Clear "need reschedule" flag
- mov [g_needReschedule], dword 0
-
-.restore:
- ; Activate the user context, if necessary.
- Activate_User_Context
-
- ; Restore registers
- Restore_Registers
-
- ; Return from the interrupt.
- iret
-
-; ----------------------------------------------------------------------
-; Switch_To_Thread()
-; Save context of currently executing thread, and activate
-; the thread whose context object is passed as a parameter.
-;
-; Parameter:
-; - ptr to Kernel_Thread whose state should be restored and made active
-;
-; Notes:
-; Called with interrupts disabled.
-; This must be kept up to date with definition of Kernel_Thread
-; struct, in kthread.h.
-; ----------------------------------------------------------------------
-align 16
-Switch_To_Thread:
- ; Modify the stack to allow a later return via an iret instruction.
- ; We start with a stack that looks like this:
- ;
- ; thread_ptr
- ; esp --> return addr
- ;
- ; We change it to look like this:
- ;
- ; thread_ptr
- ; eflags
- ; cs
- ; esp --> return addr
-
- push eax ; save eax
- mov eax, [esp+4] ; get return address
- mov [esp-4], eax ; move return addr down 8 bytes from orig loc
- add esp, 8 ; move stack ptr up
- pushfd ; put eflags where return address was
- mov eax, [esp-4] ; restore saved value of eax
- push dword KERNEL_CS ; push cs selector
- sub esp, 4 ; point stack ptr at return address
-
- ; Push fake error code and interrupt number
- push dword 0
- push dword 0
-
- ; Save general purpose registers.
- Save_Registers
-
- ; Save stack pointer in the thread context struct (at offset 0).
- mov eax, [g_currentThread]
- mov [eax+0], esp
-
- ; Clear numTicks field in thread context, since this
- ; thread is being suspended.
- mov [eax+4], dword 0
-
- ; Load the pointer to the new thread context into eax.
- ; We skip over the Interrupt_State struct on the stack to
- ; get the parameter.
- mov eax, [esp+INTERRUPT_STATE_SIZE]
-
- ; Make the new thread current, and switch to its stack.
- mov [g_currentThread], eax
- mov esp, [eax+0]
-
- ; Activate the user context, if necessary.
- Activate_User_Context
-
- ; Restore general purpose and segment registers, and clear interrupt
- ; number and error code.
- Restore_Registers
-
- ; We'll return to the place where the thread was
- ; executing last.
- iret
-
-; Return current contents of eflags register.
-align 16
-Get_Current_EFLAGS:
- pushfd ; push eflags
- pop eax ; pop contents into eax
- ret
-
-
-
-; Return the eip of the next instruction after the caller
-align 16
-Get_EIP:
- mov eax, [esp]
- ret
-
-; Return the current esp in the procedure
-align 16
-Get_ESP:
- mov eax, esp
- ret
-
-; Return the current ebp in the procedure
-align 16
-Get_EBP:
- mov eax, ebp
- ret
-
-
-
-; ----------------------------------------------------------------------
-; Generate interrupt-specific entry points for all interrupts.
-; We also define symbols to indicate the extend of the table
-; of entry points, and the size of individual entry points.
-; ----------------------------------------------------------------------
-align 8
-g_entryPointTableStart:
-
-; Handlers for processor-generated exceptions, as defined by
-; Intel 486 manual.
-Int_No_Err 0
-align 8
-Before_No_Err:
-Int_No_Err 1
-align 8
-After_No_Err:
-Int_No_Err 2 ; FIXME: not described in 486 manual
-Int_No_Err 3
-Int_No_Err 4
-Int_No_Err 5
-Int_No_Err 6
-Int_No_Err 7
-align 8
-Before_Err:
-Int_With_Err 8
-align 8
-After_Err:
-Int_No_Err 9 ; FIXME: not described in 486 manual
-Int_With_Err 10
-Int_With_Err 11
-Int_With_Err 12
-Int_With_Err 13
-Int_With_Err 14
-Int_No_Err 15 ; FIXME: not described in 486 manual
-Int_No_Err 16
-Int_With_Err 17
-
-; The remaining interrupts (18 - 255) do not have error codes.
-; We can generate them all in one go with nasm's %rep construct.
-%assign intNum 18
-%rep (256 - 18)
-Int_No_Err intNum
-%assign intNum intNum+1
-%endrep
-
-align 8
-g_entryPointTableEnd:
-
-[SECTION .data]
-
-; Exported symbols defining the size of handler entry points
-; (both with and without error codes).
-align 4
-g_handlerSizeNoErr: dd (After_No_Err - Before_No_Err)
-align 4
-g_handlerSizeErr: dd (After_Err - Before_Err)
