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Map address 0x0 to an empty page

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This commit is contained in:
Alex 2022-12-06 01:26:17 +02:00
parent 8288de53a9
commit 4188a465d2
Signed by untrusted user who does not match committer: enderice2
GPG Key ID: EACC3AD603BAB4DD
1 changed files with 20 additions and 9 deletions
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29
Core/Memory/Memory.cpp
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@ -37,14 +37,26 @@ __no_instrument_function void tracepagetable(PageTable4 *pt)
__no_instrument_function void MapFromZero(PageTable4 *PT, BootInfo *Info) __no_instrument_function void MapFromZero(PageTable4 *PT, BootInfo *Info)
{ {
Virtual va = Virtual(PT); static int once = 0;
uint64_t VirtualOffsetNormalVMA = NORMAL_VMA_OFFSET; if (!once++)
uint64_t MemSize = Info->Memory.Size;
for (uint64_t t = 0; t < MemSize; t += PAGE_SIZE)
{ {
va.Map((void *)t, (void *)t, PTFlag::RW /* | PTFlag::US */); Virtual va = Virtual(PT);
va.Map((void *)VirtualOffsetNormalVMA, (void *)t, PTFlag::RW /* | PTFlag::US */); void *NullAddress = KernelAllocator.RequestPage();
VirtualOffsetNormalVMA += PAGE_SIZE; memset(NullAddress, 0, PAGE_SIZE); // TODO: If the CPU instruction pointer hits this page, there should be function to handle it. (memcpy assembly code?)
va.Map((void *)0, (void *)NullAddress, PTFlag::RW | PTFlag::US);
uint64_t VirtualOffsetNormalVMA = NORMAL_VMA_OFFSET;
uint64_t MemSize = Info->Memory.Size;
for (uint64_t t = 0; t < MemSize; t += PAGE_SIZE)
{
va.Map((void *)t, (void *)t, PTFlag::RW /* | PTFlag::US */);
va.Map((void *)VirtualOffsetNormalVMA, (void *)t, PTFlag::RW /* | PTFlag::US */);
VirtualOffsetNormalVMA += PAGE_SIZE;
}
}
else
{
error("MapFromZero() called more than once!");
CPU::Stop();
} }
} }
@ -180,8 +192,7 @@ __no_instrument_function void InitializeMemoryManagement(BootInfo *Info)
debug("Mapping from 0x0 to %#llx", Info->Memory.Size); debug("Mapping from 0x0 to %#llx", Info->Memory.Size);
MapFromZero(KernelPageTable, Info); MapFromZero(KernelPageTable, Info);
debug("Mapping from 0x0 %#llx for Userspace Page Table", Info->Memory.Size); debug("Mapping from 0x0 %#llx for Userspace Page Table", Info->Memory.Size);
UserspaceKernelOnlyPageTable[0] = KernelPageTable[0]; // TODO: This is a hack to speed up the boot process UserspaceKernelOnlyPageTable[0] = KernelPageTable[0];
// MapFromZero(UserspaceKernelOnlyPageTable, Info);
/* Mapping Framebuffer address */ /* Mapping Framebuffer address */
debug("Mapping Framebuffer"); debug("Mapping Framebuffer");