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The Kernel now executes and jumps to userspace for a single application.
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Which makes it now... a kernel! Happy Programmer's Day.

An Environment contains the code used to execute the application. The
Scheduler picks a new environment to execute. There is some architecture
specific context information that is called naively a PageTable.

The Loader creates an environment by asking the scheduler for a context
and then it allocates space for the code and copies it there. It then
reports to the Environment where it lives and where the entry point is.
The Environment will then set up the initial context. The Kernel will
run the environment by jumping to the entry point with an iret.

It uses interrupts (iretq) to jump to userspace. Only interrupts can
preempt the application. System calls are non-blocking (and not
functional as of yet).

Signed-off-by: James Larkby-Lahet <transmethyl@gmail.com>
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@wilkie @wolfwood
wilkie authored and wolfwood committed Sep 15, 2009
1 parent 8c71f8f commit a00b793
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Showing 19 changed files with 754 additions and 188 deletions.
2 changes: 1 addition & 1 deletion build/iso/boot/grub/menu.lst
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Expand Up @@ -126,4 +126,4 @@ hiddenmenu
title XOmB
kernel /boot/xomb
#module /your/module
### END PITTGEEKS AUTOMAGIC KERNELS LIST
module /boot/testapp
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21 changes: 13 additions & 8 deletions kernel/arch/x86_64/core/lapic.d
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Expand Up @@ -28,7 +28,7 @@ public:

install();

startAPs();
// startAPs();

return ErrorVal.Success;
}
Expand Down Expand Up @@ -79,19 +79,24 @@ private:
// Map in the register space
apicRegisters = cast(ApicRegisterSpace*)Paging.mapRegion(localAPICAddr, ApicRegisterSpace.sizeof);

// Map in the first megabyte of space
ubyte* bootRange;

bootRange = cast(ubyte*)Paging.mapRegion(cast(void*)0x0, 0x100000);

// Write the trampoline code where it needs to be

uint trampolineLength = cast(ulong)LinkerScript.etrampoline - cast(ulong)LinkerScript.trampoline;
ubyte* trampolineCode = cast(ubyte*)LinkerScript.trampoline + cast(ulong)System.kernel.virtualStart;

kprintfln!("trampolineLength: {} trampolineCode: {x} trampoline: {x} Kernel: {x}")(trampolineLength, trampolineCode, LinkerScript.trampoline, System.kernel.start);
// Map in the first megabyte of space
ubyte* bootRange;
bootRange = cast(ubyte*)Paging.mapRegion(cast(void*)0x0, trampolineLength);

bootRange[0..trampolineLength] = trampolineCode[0..trampolineLength];
kprintfln!("bootRange: {} trampolineLength: {} trampolineCode: {x} trampoline: {x} Kernel: {x}")(bootRange, trampolineLength, trampolineCode, LinkerScript.trampoline, System.kernel.start);

for(uint i; i < trampolineLength; i++) {
*bootRange = *trampolineCode;
bootRange++;
trampolineCode++;
}
// bootRange[0..trampolineLength] = trampolineCode[0..trampolineLength];
kprintfln!("Trampoline copied")();
}

void EOI() {
Expand Down
181 changes: 125 additions & 56 deletions kernel/arch/x86_64/core/paging.d
View file
Expand Up @@ -34,8 +34,7 @@ import kernel.dev.console;
// - devices
// - misc

struct Paging
{
struct Paging {
static:
public:

Expand Down Expand Up @@ -83,30 +82,13 @@ public:
// We need to map the kernel
kernelAddress = heapAddress;

ulong curPhysAddr = cast(ulong)System.kernel.start;
ulong regionLength = System.kernel.length + Heap.length + (curPhysAddr % PAGESIZE);
curPhysAddr -= (curPhysAddr % PAGESIZE);

// Set the new starting address
void* physAddr = cast(void*)curPhysAddr;

// Get the end address
curPhysAddr += regionLength;

// Align the end address
if ((curPhysAddr % PAGESIZE) > 0)
{
curPhysAddr += PAGESIZE - (curPhysAddr % PAGESIZE);
}

// Define the end address
void* endAddr = cast(void*)curPhysAddr;

// This region will be located at the current heapAddress
void* location = heapAddress;
mapRegion(System.kernel.start, System.kernel.length);

// Do the actual mapping
heapMap!(true)(physAddr, endAddr);
void* bitmapLocation = heapAddress;

// Map Heap bitmap
kprintfln!("Heap: {x}")(*(cast(ulong*)Heap.start));
mapRegion(Heap.start, Heap.length);

// We now have the kernel mapped
kernelMapped = true;
Expand All @@ -119,21 +101,29 @@ public:

// Restart the console driver to look at the right place
Console.initialize();
kprintfln!("bitmapLocation: {x}")(bitmapLocation);
Heap.virtualStart = bitmapLocation;

// This is the virtual address for the page table
root = cast(PageLevel4*)0xFFFFFFFF_FFFFF000;
kprintfln!("root: {x}")(root);
kprintfln!("root: {x} : {x}")(root, rootPhysical);
kprintfln!("heap: {x}")(Heap.virtualStart);

// All is well.
return ErrorVal.Success;
}

void install() {
kprintfln!("Installing...")();
ulong rootAddr = cast(ulong)rootPhysical;
kprintfln!("Installing........")();
asm {
mov RAX, rootAddr;
mov CR3, RAX;
}
kprintfln!("Installed")();
kprintfln!("Heap: {x}")(*(cast(ulong*)Heap.virtualStart));

}

// This function will get the physical address that is mapped from the
Expand Down Expand Up @@ -161,7 +151,6 @@ public:
out ulong indexLevel4)
{
ulong vAddr = cast(ulong)virtAddress;
kprintfln!("addr {x}")(virtAddress);

vAddr >>= 12;
indexLevel1 = vAddr & 0x1ff;
Expand Down Expand Up @@ -203,12 +192,55 @@ public:
// This region will be located at the current heapAddress
void* location = heapAddress;

doHeapMap(physAddr, endAddr);
if (kernelMapped) {
doHeapMap(physAddr, endAddr);
}
else {
heapMap!(true)(physAddr, endAddr);
}

// Return the position of this region
return location;
}

void* mapRegion(PageLevel4* rootTable, void* physAddr, ulong regionLength, void* virtAddr = null) {
if (virtAddr is null) {
virtAddr = physAddr;
}
// Sanitize inputs

// physAddr should be floored to the page boundary
// regionLength should be ceilinged to the page boundary
ulong curPhysAddr = cast(ulong)physAddr;
regionLength += (curPhysAddr % PAGESIZE);
curPhysAddr -= (curPhysAddr % PAGESIZE);

// Set the new starting address
physAddr = cast(void*)curPhysAddr;

// Get the end address
curPhysAddr += regionLength;

// Align the end address
if ((curPhysAddr % PAGESIZE) > 0)
{
curPhysAddr += PAGESIZE - (curPhysAddr % PAGESIZE);
}

// Define the end address
void* endAddr = cast(void*)curPhysAddr;

kprintfln!("virtaddr: {x}")(virtAddr);

heapMap!(false, false)(physAddr, endAddr, virtAddr);

return virtAddr;
}

PageLevel4* kernelPageTable() {
return cast(PageLevel4*)0xfffffffffffff000;
}

private:


Expand Down Expand Up @@ -236,10 +268,9 @@ private:

// -- Mapping Functions -- //

template heapMap(bool initialMapping = false, bool kernelLevel = true) {
void heapMap(void* physAddr, void* endAddr, void* virtAddr = heapAddress) {

template heapMap(bool initialMapping = false) {
void heapMap(void* physAddr, void* endAddr)
{
// Do the mapping
PageLevel3* pl3;
PageLevel2* pl2;
Expand All @@ -249,60 +280,92 @@ private:
void* startAddr = physAddr;

// Find the initial page
translateAddress(heapAddress, indexL1, indexL2, indexL3, indexL4);
translateAddress(virtAddr, indexL1, indexL2, indexL3, indexL4);

// From there, map the region
ulong done = 0;
for ( ; indexL4 < 512 && physAddr < endAddr ; indexL4++ )
{
// get the L3 table
static if (initialMapping) {
pl3 = cast(PageLevel3*)Heap.allocPageNoMap();
*pl3 = PageLevel3.init;
root.entries[indexL4].pml = cast(ulong)pl3;
root.entries[indexL4].present = 1;
root.entries[indexL4].rw = 1;
if (root.entries[indexL4].present) {
pl3 = cast(PageLevel3*)(root.entries[indexL4].address << 12);
}
else {
pl3 = cast(PageLevel3*)Heap.allocPageNoMap();
*pl3 = PageLevel3.init;
root.entries[indexL4].pml = cast(ulong)pl3;
root.entries[indexL4].present = 1;
root.entries[indexL4].rw = 1;
static if (!kernelLevel) {
root.entries[indexL4].us = 1;
}
}
}
else {
pl3 = root.getOrCreateTable(indexL4);
pl3 = root.getOrCreateTable(indexL4, !kernelLevel);
}

for ( ; indexL3 < 512 ; indexL3++ )
{
// get the L2 table
static if (initialMapping) {
pl2 = cast(PageLevel2*)Heap.allocPageNoMap();
*pl2 = PageLevel2.init;
pl3.entries[indexL3].pml = cast(ulong)pl2;
pl3.entries[indexL3].present = 1;
pl3.entries[indexL3].rw = 1;
if (pl3.entries[indexL3].present) {
pl2 = cast(PageLevel2*)(pl3.entries[indexL3].address << 12);
}
else {
pl2 = cast(PageLevel2*)Heap.allocPageNoMap();
*pl2 = PageLevel2.init;
pl3.entries[indexL3].pml = cast(ulong)pl2;
pl3.entries[indexL3].present = 1;
pl3.entries[indexL3].rw = 1;
static if (!kernelLevel) {
pl3.entries[indexL3].us = 1;
}
}
}
else {
pl2 = pl3.getOrCreateTable(indexL3);
pl2 = pl3.getOrCreateTable(indexL3, !kernelLevel);
}

for ( ; indexL2 < 512 ; indexL2++ )
{
// get the L1 table
static if (initialMapping) {
pl1 = cast(PageLevel1*)Heap.allocPageNoMap();
*pl1 = PageLevel1.init;
pl2.entries[indexL2].pml = cast(ulong)pl1;
pl2.entries[indexL2].present = 1;
pl2.entries[indexL2].rw = 1;
if (pl2.entries[indexL2].present) {
pl1 = cast(PageLevel1*)(pl2.entries[indexL2].address << 12);
}
else {
pl1 = cast(PageLevel1*)Heap.allocPageNoMap();
*pl1 = PageLevel1.init;
pl2.entries[indexL2].pml = cast(ulong)pl1;
pl2.entries[indexL2].present = 1;
pl2.entries[indexL2].rw = 1;
static if (!kernelLevel) {
pl2.entries[indexL2].us = 1;
}
}
}
else {
pl1 = pl2.getOrCreateTable(indexL2);
pl1 = pl2.getOrCreateTable(indexL2, !kernelLevel);
}

for ( ; indexL1 < 512 ; indexL1++ )
{
// set the address
if (pl1.entries[indexL1].present) {
// Page already allocated
// XXX: Fail
}

pl1.entries[indexL1].pml = cast(ulong)physAddr;

pl1.entries[indexL1].present = 1;
pl1.entries[indexL1].rw = 1;
pl1.entries[indexL1].pat = 1;
static if (!kernelLevel) {
pl1.entries[indexL1].us = 1;
}

physAddr += PAGESIZE;
done += PAGESIZE;
Expand Down Expand Up @@ -334,14 +397,17 @@ private:
ulong regionLength = cast(ulong)endAddr - cast(ulong)startAddr;

// Relocate heap address
heapAddress += regionLength;
static if (kernelLevel) {
heapAddress += regionLength;
}
}
}

alias heapMap!(false) doHeapMap;

// -- Structures -- //
}

// -- Structures -- //

// The x86 implements a four level page table.
// We use the 4KB page size hierarchy
Expand Down Expand Up @@ -401,7 +467,7 @@ private:
return cast(PageLevel3*)(0xFFFFFF7F_BFE00000 + (idx << 12));
}

PageLevel3* getOrCreateTable(uint idx) {
PageLevel3* getOrCreateTable(uint idx, bool usermode = false) {
PageLevel3* ret = getTable(idx);

if (ret is null) {
Expand All @@ -412,6 +478,7 @@ private:
entries[idx].pml = cast(ulong)ret;
entries[idx].present = 1;
entries[idx].rw = 1;
entries[idx].us = usermode;

// Calculate virtual address
ret = cast(PageLevel3*)(0xFFFFFF7F_BFE00000 + (idx << 12));
Expand All @@ -437,7 +504,7 @@ private:
return cast(PageLevel2*)(0xFFFFFF7F_C0000000 + ((baseAddr + idx) << 12));
}

PageLevel2* getOrCreateTable(uint idx) {
PageLevel2* getOrCreateTable(uint idx, bool usermode = false) {
PageLevel2* ret = getTable(idx);

if (ret is null) {
Expand All @@ -448,6 +515,7 @@ private:
entries[idx].pml = cast(ulong)ret;
entries[idx].present = 1;
entries[idx].rw = 1;
entries[idx].us = usermode;

// Calculate virtual address
ulong baseAddr = cast(ulong)this;
Expand Down Expand Up @@ -476,7 +544,7 @@ private:
return cast(PageLevel1*)(0xFFFFFF80_00000000 + ((baseAddr + idx) << 12));
}

PageLevel1* getOrCreateTable(uint idx) {
PageLevel1* getOrCreateTable(uint idx, bool usermode = false) {
PageLevel1* ret = getTable(idx);

if (ret is null) {
Expand All @@ -487,6 +555,7 @@ private:
entries[idx].pml = cast(ulong)ret;
entries[idx].present = 1;
entries[idx].rw = 1;
entries[idx].us = usermode;

// Calculate virtual address
ulong baseAddr = cast(ulong)this;
Expand All @@ -508,4 +577,4 @@ private:
return cast(void*)(entries[idx].address << 12);
}
}
}

1 change: 1 addition & 0 deletions kernel/arch/x86_64/cpu.d
View file
Expand Up @@ -34,6 +34,7 @@ public:

// This module will conform to the interface
ErrorVal initialize() {
kprintfln!("Paging?")();

Paging.install();
printToLog("Enabling Paging", ErrorVal.Success);
Expand Down

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