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Implement fork()!

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This is quite cool! The syscall entry point plumbs the register dump
down to sys$fork(), which uses it to set up the child process's TSS
in order to resume execution right after the int 0x80 fork() call. :^)

This works pretty well, although there is some problem with the kernel
alias mappings used to clone the parent process's regions. If I disable
the MM::release_page_directory() code, there's no problem. Probably there's
a premature freeing of a physical page somehow.
This commit is contained in:
Andreas Kling 2018-11-02 20:41:58 +01:00
parent 10b666f69a
commit 8accc92c3c
16 changed files with 228 additions and 78 deletions
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10
Kernel/kmalloc.cpp
View file

@ -26,6 +26,8 @@ typedef struct
#define ETERNAL_BASE_PHYSICAL 0x200000
#define BASE_PHYS 0x100000
#define RANGE_SIZE 0x100000
PRIVATE BYTE alloc_map[POOL_SIZE / CHUNK_SIZE / 8];
volatile DWORD sum_alloc = 0;
@ -36,6 +38,9 @@ volatile size_t kmalloc_sum_page_aligned = 0;
static byte* s_next_eternal_ptr;
static byte* s_next_page_aligned_ptr;
static byte* s_end_of_eternal_range;
static byte* s_end_of_page_aligned_range;
bool is_kmalloc_address(void* ptr)
{
if (ptr >= (byte*)ETERNAL_BASE_PHYSICAL && ptr < s_next_eternal_ptr)
@ -58,12 +63,16 @@ kmalloc_init()
s_next_eternal_ptr = (byte*)ETERNAL_BASE_PHYSICAL;
s_next_page_aligned_ptr = (byte*)PAGE_ALIGNED_BASE_PHYSICAL;
s_end_of_eternal_range = s_next_eternal_ptr + RANGE_SIZE;
s_end_of_page_aligned_range = s_next_page_aligned_ptr + RANGE_SIZE;
}
void* kmalloc_eternal(size_t size)
{
void* ptr = s_next_eternal_ptr;
s_next_eternal_ptr += size;
ASSERT(s_next_eternal_ptr < s_end_of_eternal_range);
kmalloc_sum_eternal += size;
return ptr;
}
@ -73,6 +82,7 @@ void* kmalloc_page_aligned(size_t size)
ASSERT((size % 4096) == 0);
void* ptr = s_next_page_aligned_ptr;
s_next_page_aligned_ptr += size;
ASSERT(s_next_page_aligned_ptr < s_end_of_page_aligned_range);
kmalloc_sum_page_aligned += size;
return ptr;
}