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Wrap IRQ, Exception, cpu_context to be ready for user

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Fix ASM where ebp was push 2 times.
One by pushw ebp
One by pushal later
This commit is contained in:
Mathieu Maret 2021-10-25 23:25:31 +02:00
parent 8f6f6cf471
commit 75dbbdb53b
11 changed files with 260 additions and 42 deletions
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7
Makefile
View File

@ -12,12 +12,13 @@ QEMU_OPT += -hda disk.img
ARCH?=x86
SUBDIRS := core drivers tests arch/$(ARCH)
CPPFLAGS += $(foreach dir, $(SUBDIRS), -I$(dir))
INCDIRS += $(foreach dir, $(SUBDIRS), -I$(dir))
CPPFLAGS += $(INCDIRS)
asmsrc=$(wildcard arch/$(ARCH)/boot/*.asm)
asmobj=$(asmsrc:%.asm=%.o)
csrc=$(shell find $(SUBDIRS) -type f -name "*.c")# $(wildcard *.c)
cobj=$(csrc:%.c=%.o) arch/$(ARCH)/cpu_context_switch.o arch/$(ARCH)/irq_pit.o arch/$(ARCH)/irq_wrappers.o arch/$(ARCH)/exception_wrappers.o
cobj=$(csrc:%.c=%.o) arch/$(ARCH)/cpu_context_switch.o arch/$(ARCH)/irq_pit.o arch/$(ARCH)/irq_wrappers.o arch/$(ARCH)/exception_wrappers.o arch/$(ARCH)/syscall_wrappers.o
deps = $(csrc:%.c=%.d)
kernel kernel.sym &: $(asmobj) $(cobj) linker.ld
@ -38,7 +39,7 @@ disk.img:
$(AS) $(ASFLAGS) -o $@ $<
%.o: %.S
$(CC) "-I$(PWD)" -c "$<" $(CFLAGS) -o "$@"
$(CC) $(INCDIRS) -c "$<" $(CFLAGS) -o "$@"
test: CFLAGS += -DRUN_TEST

3
arch/x86/cpu_context.c
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@ -38,12 +38,11 @@ struct cpu_state {
uint16_t alignment_padding; /* unused */
uint32_t edi;
uint32_t esi;
uint32_t esp;
uint32_t ebp;
uint32_t ebx;
uint32_t edx;
uint32_t ecx;
uint32_t eax;
uint32_t ebp;
/* MUST NEVER CHANGE (dependent on the IA32 iret instruction) */
uint32_t error_code;

39
arch/x86/cpu_context_switch.S
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@ -24,7 +24,13 @@ cpu_context_switch:
pushl %cs // (cs) esp+52
pushl $resume_pc // (ip) esp+48
pushl $0 // (error code) esp+12+8x4
pushal // (general reg) esp+12
pushl %ebp
pushl %eax
pushl %ecx
pushl %edx
pushl %ebx
pushl %esi
pushl %edi
subl $2, %esp // (alignment) esp+10
pushw %ss // esp+8
pushw %ds // esp+6
@ -37,11 +43,11 @@ cpu_context_switch:
*/
/* Store the address of the saved context */
movl 64(%esp), %ebx
movl 60(%esp), %ebx
movl %esp, (%ebx)
/* This is the proper context switch ! We change the stack here */
movl 68(%esp), %esp
movl 64(%esp), %esp
/* Prepare kernel TSS in case we are switching to a user thread: we
make sure that we will come back into the kernel at a correct
@ -49,9 +55,8 @@ cpu_context_switch:
pushl %esp /* Pass the location of the context we are
restoring to the function */
call cpu_context_update_kernel_tss
addl $4, %esp
/* Restore the CPU context */
popw %gs
popw %fs
@ -59,7 +64,13 @@ cpu_context_switch:
popw %ds
popw %ss
addl $2,%esp
popal
popl %edi
popl %esi
popl %ebx
popl %edx
popl %ecx
popl %eax
popl %ebp
addl $4, %esp /* Ignore "error code" */
/* This restores the eflags, the cs and the eip registers */
@ -95,6 +106,14 @@ cpu_context_exit_to:
call *8(%eax)
addl $4, %esp
/* Prepare kernel TSS in case we are switching to a user thread: we
make sure that we will come back into the kernel at a correct
stack location */
pushl %esp /* Pass the location of the context we are
restoring to the function */
call cpu_context_update_kernel_tss
addl $4, %esp
/* Restore the CPU context */
popw %gs
popw %fs
@ -102,7 +121,13 @@ cpu_context_exit_to:
popw %ds
popw %ss
addl $2,%esp
popal
popl %edi
popl %esi
popl %ebx
popl %edx
popl %ecx
popl %eax
popl %ebp
addl $4, %esp /* Ignore "error code" */
/* This restores the eflags, the cs and the eip registers */

50
arch/x86/exception_wrappers.S
View File

@ -1,10 +1,19 @@
#define ASM_SOURCE 1
#include "segment.h"
.file "irq_wrappers.S"
.text
.extern exception_handler_wrap
.globl exception_handler_wrapper_array
/** Update the kernel TSS in case we are switching to a thread in user
mode in order to come back into the correct kernel stack */
.extern cpu_context_update_kernel_tss
/* The address of the function to call to set back the user thread's
MMU configuration upon return to user context */
.extern thread_prepare_exception_switch_back
.altmacro
@ -24,12 +33,12 @@
pushl %ebp
movl %esp, %ebp
pushl %edi
pushl %esi
pushl %edx
pushl %ecx
pushl %ebx
pushl %eax
pushl %ecx
pushl %edx
pushl %ebx
pushl %esi
pushl %edi
subl $2,%esp
pushw %ss
pushw %ds
@ -37,11 +46,31 @@
pushw %fs
pushw %gs
/* Set correct kernel segment descriptors' value */
movw $BUILD_SEGMENT_REG_VALUE(0, 0, SEG_KDATA), %di
pushw %di ; popw %ds
pushw %di ; popw %es
pushw %di ; popw %fs
pushw %di ; popw %gs
push %esp
pushl $\id
call exception_handler_wrap
addl $8, %esp
/* Reconfigure the MMU if needed */
pushl %esp /* cpu_ctxt */
call thread_prepare_exception_switch_back
addl $4, %esp /* Unallocate the stack */
/* Prepare kernel TSS in case we are switching to a
user thread: we make sure that we will come back
into the kernel at a correct stack location */
pushl %esp /* Pass the location of the context we are
restoring to the function */
call cpu_context_update_kernel_tss
addl $4, %esp
/* Restore the context */
popw %gs
popw %fs
@ -49,14 +78,13 @@
popw %ds
popw %ss
addl $2,%esp
popl %eax
popl %ebx
popl %ecx
popl %edx
popl %esi
popl %edi
popl %esi
popl %ebx
popl %edx
popl %ecx
popl %eax
popl %ebp
/* Remove fake error code */
addl $4, %esp

1
arch/x86/gdt.h
View File

@ -19,6 +19,7 @@
*/
#pragma once
#include "types.h"
#include "stdarg.h"
/**
* @file gdt.h
*

48
arch/x86/irq_wrappers.S
View File

@ -1,9 +1,17 @@
#define ASM_SOURCE 1
#include "segment.h"
.file "irq_wrappers.S"
.text
.extern interrupt_handler_pic
.globl irq_handler_wrapper_array
/** Update the kernel TSS in case we are switching to a thread in user
mode in order to come back into the correct kernel stack */
.extern cpu_context_update_kernel_tss
/* The address of the function to call to set back the user thread's
MMU configuration upon return to user context */
.extern thread_prepare_irq_switch_back
.altmacro
@ -24,12 +32,12 @@
pushl %ebp
movl %esp, %ebp
pushl %edi
pushl %esi
pushl %edx
pushl %ecx
pushl %ebx
pushl %eax
pushl %ecx
pushl %edx
pushl %ebx
pushl %esi
pushl %edi
subl $2,%esp
pushw %ss
pushw %ds
@ -37,11 +45,31 @@
pushw %fs
pushw %gs
/* Set correct kernel segment descriptors' value */
movw $BUILD_SEGMENT_REG_VALUE(0, 0, SEG_KDATA), %di
pushw %di ; popw %ds
pushw %di ; popw %es
pushw %di ; popw %fs
pushw %di ; popw %gs
push %esp
pushl $\irq
call interrupt_handler_pic
addl $8, %esp
/* Reconfigure the MMU if needed */
pushl %esp /* cpu_ctxt */
call thread_prepare_irq_switch_back
addl $4, %esp /* Unallocate the stack */
/* Prepare kernel TSS in case we are switching to a
user thread: we make sure that we will come back
into the kernel at a correct stack location */
pushl %esp /* Pass the location of the context we are
restoring to the function */
call cpu_context_update_kernel_tss
addl $4, %esp
/* Restore the context */
popw %gs
popw %fs
@ -49,12 +77,12 @@
popw %ds
popw %ss
addl $2,%esp
popl %eax
popl %ebx
popl %ecx
popl %edx
popl %esi
popl %edi
popl %esi
popl %ebx
popl %edx
popl %ecx
popl %eax
popl %ebp
/* Remove fake error code */

91
arch/x86/syscall_wrappers.S Normal file
View File

@ -0,0 +1,91 @@
#define ASM_SOURCE
#include "segment.h"
.file "syscall_wrappers.S"
.text
/* The address of the real "C" syscall function */
.extern syscall_execute
/** Update the kernel TSS in case we are switching to a thread in user
mode in order to come back into the correct kernel stack */
.extern cpu_context_update_kernel_tss
/* The address of the function to call to set back the user thread's
MMU configuration upon return to user context */
.extern thread_prepare_syscall_switch_back
.p2align 2, 0x90
.globl syscallHandler
syscallHandler:
.type syscallHandler,@function
/* Fake error code */
pushl $0
/* Backup the context */
pushl %ebp
movl %esp, %ebp
pushl %eax
pushl %ecx
pushl %edx
pushl %ebx
pushl %esi
pushl %edi
subl $2,%esp
pushw %ss
pushw %ds
pushw %es
pushw %fs
pushw %gs
/* Set correct kernel segment descriptors' value */
movw $BUILD_SEGMENT_REG_VALUE(0, 0, SEG_KDATA), %di
pushw %di ; popw %ds
pushw %di ; popw %es
pushw %di ; popw %fs
pushw %di ; popw %gs
/* Prepare the call to do_syscall */
pushl %esp /* user_ctxt */
pushl %eax /* syscall ID */
call syscall_execute
/* Unallocate the stack used by the
do_syscall arguments */
addl $8, %esp
/* store the do_syscall return value into interrupted context */
movl %eax, 12(%esp)
/* Set the MMU configuration to that of the user thread's process */
pushl %esp /* user_ctxt */
call thread_prepare_syscall_switch_back
addl $4, %esp /* Unallocate the stack */
/* Prepare kernel TSS because we are switching back to a user
thread: we make sure that we will come back into the kernel at a
correct stack location */
pushl %esp /* Pass the location of the context we are
restoring to the function */
call cpu_context_update_kernel_tss
addl $4, %esp
/* Restore the user context */
popw %gs
popw %fs
popw %es
popw %ds
popw %ss
addl $2,%esp
popl %edi
popl %esi
popl %ebx
popl %edx
popl %ecx
popl %eax
popl %ebp
/* Remove fake error code */
addl $4, %esp
iret

13
core/kthread.c
View File

@ -258,3 +258,16 @@ int kthreadAddThread(struct kthread *th)
return 0;
}
void thread_prepare_syscall_switch_back(struct cpu_state *cpu_state){
(void)cpu_state;
return;
}
void thread_prepare_exception_switch_back(struct cpu_state *cpu_state){
(void)cpu_state;
return;
}
void thread_prepare_irq_switch_back(struct cpu_state *cpu_state){
(void)cpu_state;
return;
}

14
core/segment.h
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@ -1,4 +1,5 @@
/* Copyright (C) 2004 The SOS Team
/* Copyright (C) 2021 Mathieu Maret
Copyright (C) 2004 The SOS Team
Copyright (C) 1999 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or
@ -29,8 +30,6 @@
* @see Intel x86 doc, vol 3 chapter 3.
*/
#include "stdarg.h"
/*
* Global segment selectors (GDT) for SOS/x86.
*
@ -46,9 +45,16 @@
/**
* Helper macro that builds a segment register's value
*/
#ifdef ASM_SOURCE
#define BUILD_SEGMENT_REG_VALUE(desc_privilege,in_ldt,seg_index) \
( (((desc_privilege) & 0x3) << 0) \
| ((in_ldt & 1) << 2) \
| ((seg_index) << 3) )
#else
#define BUILD_SEGMENT_REG_VALUE(desc_privilege, in_ldt, seg_index) \
((((desc_privilege)&0x3) << 0) | (((in_ldt) ? 1 : 0) << 2) | ((seg_index) << 3))
#endif
/*
* Local segment selectors (LDT) for SOS/x86
*/

21
core/syscall.c Normal file
View File

@ -0,0 +1,21 @@
#include "syscall.h"
#include "irq.h"
#include "idt.h"
extern void syscallHandler();
int syscallSetup(){
uint32_t flags, ret;
disable_IRQs(flags);
ret = idt_set_handler(SYSCALL_INTR_NB, (vaddr_t)syscallHandler, 3);
restore_IRQs(flags);
return ret;
}
int syscall_execute(int syscallId, const struct cpu_state *user_ctx){
(void)syscallId;
(void)user_ctx;
return 0;
}

5
core/syscall.h Normal file
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@ -0,0 +1,5 @@
#pragma once
#define SYSCALL_INTR_NB 0x42
int syscallSetup();