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Implement loading of linked ELF executables.

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This took me a couple hours. :^)

The ELF loading code now allocates a single region for the entire
file and creates virtual memory mappings for the sections as needed.

Very nice!
This commit is contained in:
Andreas Kling 2018-10-27 14:56:52 +02:00
parent 99ee6acd69
commit 9a71c7759a
16 changed files with 258 additions and 57 deletions
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76
Kernel/MemoryManager.cpp
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@ -8,7 +8,7 @@
static MemoryManager* s_the;
MemoryManager& MemoryManager::the()
MemoryManager& MM
{
return *s_the;
}
@ -43,8 +43,8 @@ void MemoryManager::initializePaging()
identityMap(LinearAddress(4096), 4 * MB);
// Put pages between 4MB and 16MB in the page freelist.
for (size_t i = (4 * MB) + 1024; i < (16 * MB); i += PAGE_SIZE) {
// Put pages between 4MB and 8MB in the page freelist.
for (size_t i = (4 * MB) + PAGE_SIZE; i < (8 * MB); i += PAGE_SIZE) {
m_freePages.append(PhysicalAddress(i));
}
@ -56,6 +56,14 @@ void MemoryManager::initializePaging()
);
}
void* MemoryManager::allocatePageTable()
{
auto ppages = allocatePhysicalPages(1);
dword address = ppages[0].get();
identityMap(LinearAddress(address), 4096);
return (void*)address;
}
auto MemoryManager::ensurePTE(LinearAddress linearAddress) -> PageTableEntry
{
ASSERT_INTERRUPTS_DISABLED();
@ -76,8 +84,13 @@ auto MemoryManager::ensurePTE(LinearAddress linearAddress) -> PageTableEntry
pde.setPresent(true);
pde.setWritable(true);
} else {
// FIXME: We need an allocator!
ASSERT_NOT_REACHED();
auto* pageTable = allocatePageTable();
kprintf("allocated page table %u (for laddr=%p) at %p\n", pageDirectoryIndex, linearAddress.get(), pageTable);
memset(pageTable, 0, 4096);
pde.setPageTableBase((dword)pageTable);
pde.setUserAllowed(true);
pde.setPresent(true);
pde.setWritable(true);
}
}
return PageTableEntry(&pde.pageTableBase()[pageTableIndex]);
@ -190,7 +203,27 @@ bool MemoryManager::unmapRegion(Task& task, Task::Region& region)
pte.setWritable(false);
pte.setUserAllowed(false);
flushTLB(laddr);
// kprintf("MM: >> Unmapped L%x => P%x <<\n", laddr, zone.m_pages[i].get());
//kprintf("MM: >> Unmapped L%x => P%x <<\n", laddr, zone.m_pages[i].get());
}
return true;
}
bool MemoryManager::unmapSubregion(Task& task, Task::Subregion& subregion)
{
InterruptDisabler disabler;
auto& region = *subregion.region;
auto& zone = *region.zone;
size_t numPages = subregion.size / 4096;
ASSERT(numPages);
for (size_t i = 0; i < numPages; ++i) {
auto laddr = subregion.linearAddress.offset(i * PAGE_SIZE);
auto pte = ensurePTE(laddr);
pte.setPhysicalPageBase(0);
pte.setPresent(false);
pte.setWritable(false);
pte.setUserAllowed(false);
flushTLB(laddr);
//kprintf("MM: >> Unmapped subregion %s L%x => P%x <<\n", subregion.name.characters(), laddr, zone.m_pages[i].get());
}
return true;
}
@ -202,6 +235,31 @@ bool MemoryManager::unmapRegionsForTask(Task& task)
if (!unmapRegion(task, *region))
return false;
}
for (auto& subregion : task.m_subregions) {
if (!unmapSubregion(task, *subregion))
return false;
}
return true;
}
bool MemoryManager::mapSubregion(Task& task, Task::Subregion& subregion)
{
InterruptDisabler disabler;
auto& region = *subregion.region;
auto& zone = *region.zone;
size_t firstPage = subregion.offset / 4096;
size_t numPages = subregion.size / 4096;
ASSERT(numPages);
for (size_t i = 0; i < numPages; ++i) {
auto laddr = subregion.linearAddress.offset(i * PAGE_SIZE);
auto pte = ensurePTE(laddr);
pte.setPhysicalPageBase(zone.m_pages[firstPage + i].get());
pte.setPresent(true);
pte.setWritable(true);
pte.setUserAllowed(!task.isRing0());
flushTLB(laddr);
//kprintf("MM: >> Mapped subregion %s L%x => P%x (%u into region)<<\n", subregion.name.characters(), laddr, zone.m_pages[firstPage + i].get(), subregion.offset);
}
return true;
}
@ -229,6 +287,10 @@ bool MemoryManager::mapRegionsForTask(Task& task)
if (!mapRegion(task, *region))
return false;
}
for (auto& subregion : task.m_subregions) {
if (!mapSubregion(task, *subregion))
return false;
}
return true;
}
@ -243,7 +305,7 @@ bool copyToZone(Zone& zone, const void* data, size_t size)
auto* dataptr = (const byte*)data;
size_t remaining = size;
for (size_t i = 0; i < zone.m_pages.size(); ++i) {
byte* dest = MemoryManager::the().quickMapOnePage(zone.m_pages[i]);
byte* dest = MM.quickMapOnePage(zone.m_pages[i]);
kprintf("memcpy(%p, %p, %u)\n", dest, dataptr, min(PAGE_SIZE, remaining));
memcpy(dest, dataptr, min(PAGE_SIZE, remaining));
dataptr += PAGE_SIZE;