Kernel: Add basic fixed width allocator for userspace

We have to move process stacks to the general heap and maybe map
kernel to higher half.
This commit is contained in:
Bananymous 2023-05-06 18:10:38 +03:00
parent 9c07add00f
commit bcfd838131
10 changed files with 267 additions and 9 deletions

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@ -25,6 +25,7 @@ set(KERNEL_SOURCES
kernel/Input/PS2Keymap.cpp kernel/Input/PS2Keymap.cpp
kernel/InterruptController.cpp kernel/InterruptController.cpp
kernel/kernel.cpp kernel/kernel.cpp
kernel/Memory/FixedWidthAllocator.cpp
kernel/Memory/Heap.cpp kernel/Memory/Heap.cpp
kernel/Memory/kmalloc.cpp kernel/Memory/kmalloc.cpp
kernel/Panic.cpp kernel/Panic.cpp

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@ -0,0 +1,48 @@
#pragma once
#include <kernel/Memory/Heap.h>
namespace Kernel
{
class Process;
class FixedWidthAllocator
{
BAN_NON_COPYABLE(FixedWidthAllocator);
public:
FixedWidthAllocator(Process*, uint32_t);
FixedWidthAllocator(FixedWidthAllocator&&);
~FixedWidthAllocator();
vaddr_t allocate();
void deallocate(vaddr_t);
uint32_t allocation_size() const { return m_allocation_size; }
private:
struct node
{
node* prev { nullptr };
node* next { nullptr };
};
vaddr_t address_of(const node*) const;
void allocate_page_for_node_if_needed(const node*);
private:
static constexpr uint32_t m_min_allocation_size = 16;
Process* m_process;
const uint32_t m_allocation_size;
vaddr_t m_nodes_page { 0 };
vaddr_t m_allocated_pages { 0 };
node* m_free_list { nullptr };
node* m_used_list { nullptr };
uint32_t m_allocated { 0 };
};
}

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@ -4,6 +4,7 @@
#include <BAN/StringView.h> #include <BAN/StringView.h>
#include <BAN/Vector.h> #include <BAN/Vector.h>
#include <kernel/FS/Inode.h> #include <kernel/FS/Inode.h>
#include <kernel/Memory/FixedWidthAllocator.h>
#include <kernel/Memory/Heap.h> #include <kernel/Memory/Heap.h>
#include <kernel/Memory/MMU.h> #include <kernel/Memory/MMU.h>
#include <kernel/SpinLock.h> #include <kernel/SpinLock.h>
@ -55,6 +56,8 @@ namespace Kernel
BAN::ErrorOr<BAN::String> working_directory() const; BAN::ErrorOr<BAN::String> working_directory() const;
BAN::ErrorOr<void> set_working_directory(BAN::StringView); BAN::ErrorOr<void> set_working_directory(BAN::StringView);
BAN::ErrorOr<void*> allocate(size_t);
void termid(char*) const; void termid(char*) const;
static Process& current() { return Thread::current().process(); } static Process& current() { return Thread::current().process(); }
@ -90,6 +93,8 @@ namespace Kernel
BAN::String m_working_directory; BAN::String m_working_directory;
BAN::Vector<Thread*> m_threads; BAN::Vector<Thread*> m_threads;
BAN::Vector<FixedWidthAllocator> m_fixed_width_allocators;
MMU* m_mmu { nullptr }; MMU* m_mmu { nullptr };
TTY* m_tty { nullptr }; TTY* m_tty { nullptr };
}; };

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@ -7,6 +7,7 @@
#define SYS_CLOSE 5 #define SYS_CLOSE 5
#define SYS_SEEK 6 #define SYS_SEEK 6
#define SYS_OPEN 7 #define SYS_OPEN 7
#define SYS_ALLOC 8
#include <stdint.h> #include <stdint.h>

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@ -0,0 +1,145 @@
#include <kernel/CriticalScope.h>
#include <kernel/Memory/FixedWidthAllocator.h>
#include <kernel/Memory/MMU.h>
#include <kernel/Process.h>
namespace Kernel
{
FixedWidthAllocator::FixedWidthAllocator(Process* process, uint32_t allocation_size)
: m_process(process)
, m_allocation_size(BAN::Math::max(allocation_size, m_min_allocation_size))
{
ASSERT(BAN::Math::is_power_of_two(allocation_size));
paddr_t nodes_paddr = Heap::get().take_free_page();
m_nodes_page = m_process->mmu().get_free_page();
m_process->mmu().map_page_at(nodes_paddr, m_nodes_page, MMU::Flags::ReadWrite | MMU::Flags::Present);
paddr_t allocated_pages_paddr = Heap::get().take_free_page();
m_allocated_pages = m_process->mmu().get_free_page();
m_process->mmu().map_page_at(allocated_pages_paddr, m_allocated_pages, MMU::Flags::ReadWrite | MMU::Flags::Present);
CriticalScope _;
m_process->mmu().load();
memset((void*)m_nodes_page, 0, PAGE_SIZE);
memset((void*)m_allocated_pages, 0, PAGE_SIZE);
node* node_table = (node*)m_nodes_page;
for (uint32_t i = 0; i < PAGE_SIZE / sizeof(node); i++)
{
node_table[i].next = &node_table[i + 1];
node_table[i].prev = &node_table[i - 1];
}
node_table[0].prev = nullptr;
node_table[PAGE_SIZE / sizeof(node) - 1].next = nullptr;
m_free_list = node_table;
m_used_list = nullptr;
Process::current().mmu().load();
}
FixedWidthAllocator::FixedWidthAllocator(FixedWidthAllocator&& other)
: m_process(other.m_process)
, m_allocation_size(other.m_allocation_size)
, m_nodes_page(other.m_nodes_page)
, m_allocated_pages(other.m_allocated_pages)
, m_free_list(other.m_free_list)
, m_used_list(other.m_used_list)
, m_allocated(other.m_allocated)
{
other.m_process = nullptr;
}
FixedWidthAllocator::~FixedWidthAllocator()
{
if (m_process == nullptr)
return;
Heap::get().release_page(m_process->mmu().physical_address_of(m_nodes_page));
m_process->mmu().unmap_page(m_nodes_page);
for (uint32_t page_index = 0; page_index < PAGE_SIZE / sizeof(vaddr_t); page_index++)
{
vaddr_t page_vaddr = ((vaddr_t*)m_allocated_pages)[page_index];
if (page_vaddr == 0)
continue;
ASSERT(!m_process->mmu().is_page_free(page_vaddr));
paddr_t page_paddr = m_process->mmu().physical_address_of(page_vaddr);
Heap::get().release_page(page_paddr);
m_process->mmu().unmap_page(page_vaddr);
}
Heap::get().release_page(m_process->mmu().physical_address_of(m_allocated_pages));
m_process->mmu().unmap_page(m_allocated_pages);
}
paddr_t FixedWidthAllocator::allocate()
{
// FIXME: We should get allocate more memory if we run out of
// nodes in free list.
ASSERT(m_free_list);
node* node = m_free_list;
m_free_list = node->next;
if (m_free_list)
m_free_list->prev = nullptr;
node->next = m_used_list;
node->prev = nullptr;
if (m_used_list)
m_used_list->prev = node;
m_used_list = node;
m_allocated++;
allocate_page_for_node_if_needed(node);
return address_of(node);
}
void FixedWidthAllocator::deallocate(paddr_t addr)
{
(void)addr;
ASSERT_NOT_REACHED();
}
vaddr_t FixedWidthAllocator::address_of(const node* node) const
{
uint32_t index = node - (struct node*)m_nodes_page;
uint32_t page_index = index / (PAGE_SIZE / sizeof(struct node));
ASSERT(page_index < PAGE_SIZE / sizeof(vaddr_t));
uint32_t offset = index % (PAGE_SIZE / sizeof(struct node));
vaddr_t page_begin = ((vaddr_t*)m_allocated_pages)[page_index];
ASSERT(page_begin);
return page_begin + offset * m_allocation_size;
}
void FixedWidthAllocator::allocate_page_for_node_if_needed(const node* node)
{
uint32_t index = node - (struct node*)m_nodes_page;
uint32_t page_index = index / (PAGE_SIZE / sizeof(struct node));
ASSERT(page_index < PAGE_SIZE / sizeof(vaddr_t));
vaddr_t& page_vaddr = ((vaddr_t*)m_allocated_pages)[page_index];
if (page_vaddr)
return;
paddr_t page_paddr = Heap::get().take_free_page();
ASSERT(page_paddr);
page_vaddr = m_process->mmu().get_free_page();
m_process->mmu().map_page_at(page_paddr, page_vaddr, MMU::Flags::UserSupervisor | MMU::Flags::ReadWrite | MMU::Flags::Present);
}
}

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@ -1,4 +1,5 @@
#include <BAN/StringView.h> #include <BAN/StringView.h>
#include <kernel/CriticalScope.h>
#include <kernel/FS/VirtualFileSystem.h> #include <kernel/FS/VirtualFileSystem.h>
#include <kernel/LockGuard.h> #include <kernel/LockGuard.h>
#include <kernel/Memory/Heap.h> #include <kernel/Memory/Heap.h>
@ -69,10 +70,10 @@ namespace Kernel
break; break;
case LibELF::PT_LOAD: case LibELF::PT_LOAD:
{ {
// TODO: Do some relocations? // TODO: Do some relocations or map kernel to higher half?
ASSERT(process->mmu().is_range_free(elf_program_header.p_vaddr, elf_program_header.p_memsz)); ASSERT(process->mmu().is_range_free(elf_program_header.p_vaddr, elf_program_header.p_memsz));
uint8_t flags = MMU::Flags::UserSupervisor | MMU::Flags::Present; MMU::flags_t flags = MMU::Flags::UserSupervisor | MMU::Flags::Present;
if (elf_program_header.p_flags & LibELF::PF_W) if (elf_program_header.p_flags & LibELF::PF_W)
flags |= MMU::Flags::ReadWrite; flags |= MMU::Flags::ReadWrite;
size_t page_start = elf_program_header.p_vaddr / PAGE_SIZE; size_t page_start = elf_program_header.p_vaddr / PAGE_SIZE;
@ -82,12 +83,16 @@ namespace Kernel
{ {
auto paddr = Heap::get().take_free_page(); auto paddr = Heap::get().take_free_page();
MUST(process->m_allocated_pages.push_back(paddr)); MUST(process->m_allocated_pages.push_back(paddr));
process->m_mmu->map_page_at(paddr, page * PAGE_SIZE, flags); process->mmu().map_page_at(paddr, page * PAGE_SIZE, flags);
} }
process->m_mmu->load();
{
CriticalScope _;
process->mmu().load();
memcpy((void*)elf_program_header.p_vaddr, elf->data() + elf_program_header.p_offset, elf_program_header.p_filesz); memcpy((void*)elf_program_header.p_vaddr, elf->data() + elf_program_header.p_offset, elf_program_header.p_filesz);
memset((void*)(elf_program_header.p_vaddr + elf_program_header.p_filesz), 0, elf_program_header.p_memsz - elf_program_header.p_filesz); memset((void*)(elf_program_header.p_vaddr + elf_program_header.p_filesz), 0, elf_program_header.p_memsz - elf_program_header.p_filesz);
Process::current().mmu().load(); Process::current().mmu().load();
}
break; break;
} }
default: default:
@ -100,6 +105,11 @@ namespace Kernel
delete elf; delete elf;
MUST(process->m_fixed_width_allocators.emplace_back(process, 64));
MUST(process->m_fixed_width_allocators.emplace_back(process, 256));
MUST(process->m_fixed_width_allocators.emplace_back(process, 1024));
MUST(process->m_fixed_width_allocators.emplace_back(process, 4096));
register_process(process); register_process(process);
return process; return process;
} }
@ -112,6 +122,7 @@ namespace Kernel
Process::~Process() Process::~Process()
{ {
ASSERT(m_threads.empty()); ASSERT(m_threads.empty());
ASSERT(m_fixed_width_allocators.empty());
if (m_mmu) if (m_mmu)
{ {
MMU::get().load(); MMU::get().load();
@ -144,6 +155,9 @@ namespace Kernel
for (auto& open_fd : m_open_files) for (auto& open_fd : m_open_files)
open_fd.inode = nullptr; open_fd.inode = nullptr;
// NOTE: We must clear allocators while the mmu is still alive
m_fixed_width_allocators.clear();
dprintln("process {} exit", pid()); dprintln("process {} exit", pid());
s_process_lock.lock(); s_process_lock.lock();
for (size_t i = 0; i < s_processes.size(); i++) for (size_t i = 0; i < s_processes.size(); i++)
@ -364,6 +378,14 @@ namespace Kernel
return {}; return {};
} }
BAN::ErrorOr<void*> Process::allocate(size_t bytes)
{
for (auto& allocator : m_fixed_width_allocators)
if (bytes <= allocator.allocation_size())
return (void*)allocator.allocate();
return BAN::Error::from_errno(ENOMEM);
}
void Process::termid(char* buffer) const void Process::termid(char* buffer) const
{ {
if (m_tty == nullptr) if (m_tty == nullptr)

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@ -55,6 +55,14 @@ namespace Kernel
return res.value(); return res.value();
} }
long sys_alloc(size_t bytes)
{
auto res = Process::current().allocate(bytes);
if (res.is_error())
return -res.error().get_error_code();
return (long)res.value();
}
extern "C" long cpp_syscall_handler(int syscall, void* arg1, void* arg2, void* arg3) extern "C" long cpp_syscall_handler(int syscall, void* arg1, void* arg2, void* arg3)
{ {
Thread::current().set_in_syscall(true); Thread::current().set_in_syscall(true);
@ -85,6 +93,9 @@ namespace Kernel
case SYS_OPEN: case SYS_OPEN:
ret = sys_open((const char*)arg1, (int)(uintptr_t)arg2); ret = sys_open((const char*)arg1, (int)(uintptr_t)arg2);
break; break;
case SYS_ALLOC:
ret = sys_alloc((size_t)arg1);
break;
default: default:
Kernel::panic("Unknown syscall {}", syscall); Kernel::panic("Unknown syscall {}", syscall);
} }

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@ -1,8 +1,10 @@
#include <BAN/Assert.h> #include <BAN/Assert.h>
#include <ctype.h> #include <ctype.h>
#include <errno.h>
#include <stdio.h> #include <stdio.h>
#include <stdlib.h> #include <stdlib.h>
#include <string.h> #include <string.h>
#include <sys/syscall.h>
#include <unistd.h> #include <unistd.h>
extern "C" void _fini(); extern "C" void _fini();
@ -55,10 +57,16 @@ char* getenv(const char*)
return nullptr; return nullptr;
} }
void* malloc(size_t) void* malloc(size_t bytes)
{ {
long ret = syscall(SYS_ALLOC, bytes);
if (ret < 0)
{
errno = -ret;
return nullptr; return nullptr;
} }
return (void*)ret;
}
void* calloc(size_t nmemb, size_t size) void* calloc(size_t nmemb, size_t size)
{ {

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@ -68,6 +68,12 @@ long syscall(long syscall, ...)
ret = Kernel::syscall(SYS_OPEN, path, oflags); ret = Kernel::syscall(SYS_OPEN, path, oflags);
break; break;
} }
case SYS_ALLOC:
{
size_t bytes = va_arg(args, size_t);
ret = Kernel::syscall(SYS_ALLOC, bytes);
break;
}
default: default:
puts("LibC: Unhandeled syscall"); puts("LibC: Unhandeled syscall");
} }

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@ -1,7 +1,18 @@
#include <stdio.h> #include <stdio.h>
#include <stdlib.h>
int main() int main()
{ {
void* ptr = malloc(10);
if (ptr == NULL)
{
perror("malloc");
return 1;
}
*(int*)ptr = 5;
putc('0' + *(int*)ptr, stdout);
return 0;
FILE* fp = fopen("/boot/grub/grub.cfg", "r"); FILE* fp = fopen("/boot/grub/grub.cfg", "r");
if (fp == NULL) if (fp == NULL)
{ {