DynamicLoader: Use file backed mmap when possible

kernel/kernel/Memory/FileBackedRegion.cpp

@@ -189,9 +189,39 @@ namespace Kernel
 		return true;
 	}
 
-	BAN::ErrorOr<BAN::UniqPtr<MemoryRegion>> FileBackedRegion::clone(PageTable&)
+	BAN::ErrorOr<BAN::UniqPtr<MemoryRegion>> FileBackedRegion::clone(PageTable& page_table)
 	{
-		ASSERT_NOT_REACHED();
+		const size_t aligned_size = (m_size + PAGE_SIZE - 1) & PAGE_ADDR_MASK;
+		auto result = TRY(FileBackedRegion::create(m_inode, page_table, m_offset, m_size, { .start = m_vaddr, .end = m_vaddr + aligned_size }, m_type, m_flags));
+
+		// shared regions can just go through demand paging
+		if (m_type == Type::SHARED)
+			return BAN::UniqPtr<MemoryRegion>(BAN::move(result));
+
+		ASSERT(m_type == Type::PRIVATE);
+
+		for (size_t offset = 0; offset < m_size; offset += PAGE_SIZE)
+		{
+			const vaddr_t vaddr = m_vaddr + offset;
+			if (m_page_table.physical_address_of(vaddr) == 0)
+				continue;
+
+			ASSERT(&PageTable::current() == &m_page_table);
+
+			const paddr_t paddr = Heap::get().take_free_page();
+			if (paddr == 0)
+				return BAN::Error::from_errno(ENOMEM);
+
+			page_table.map_page_at(paddr, vaddr, m_flags);
+
+			const size_t to_copy = BAN::Math::min<size_t>(PAGE_SIZE, m_size - offset);
+			PageTable::with_fast_page(paddr, [&] {
+				memcpy(PageTable::fast_page_as_ptr(), reinterpret_cast<void*>(vaddr), to_copy);
+				memset(PageTable::fast_page_as_ptr(to_copy), 0, PAGE_SIZE - to_copy);
+			});
+		}
+
+		return BAN::UniqPtr<MemoryRegion>(BAN::move(result));
 	}
 
 }

userspace/programs/DynamicLoader/main.cpp

@@ -622,98 +622,57 @@ static void load_program_header(const ElfNativeProgramHeader& program_header, in
 			return result;
 		}();
 
-	const uintptr_t aligned_vaddr = program_header.p_vaddr & ~(uintptr_t)0xFFF;
+	if ((program_header.p_vaddr & 0xFFF) || (program_header.p_offset & 0xFFF))
+	{
+		const uintptr_t aligned_addr = program_header.p_vaddr & ~(uintptr_t)0xFFF;
 
+		// unaligned addresses, cannot use file mmap
 		sys_mmap_t mmap_args;
-	mmap_args.addr = reinterpret_cast<void*>(aligned_vaddr);
+		mmap_args.addr = reinterpret_cast<void*>(aligned_addr);
 		mmap_args.fildes = -1;
 		mmap_args.flags = MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED;
-	mmap_args.len = (program_header.p_vaddr + program_header.p_memsz) - aligned_vaddr;
+		mmap_args.len = (program_header.p_vaddr + program_header.p_memsz) - aligned_addr;
 		mmap_args.off = 0;
 		mmap_args.prot = prot | PROT_WRITE;
 
-	if (auto ret = syscall(SYS_MMAP, &mmap_args); ret != static_cast<long>(aligned_vaddr))
-		print_error_and_exit("could not load program header", ret);
-	if (auto ret = syscall(SYS_PREAD, fd, program_header.p_vaddr, program_header.p_filesz, program_header.p_offset); ret != static_cast<long>(program_header.p_filesz))
+		if (auto ret = syscall(SYS_MMAP, &mmap_args); ret != static_cast<long>(aligned_addr))
 			print_error_and_exit("could not load program header", ret);
 
-	return;
+		const uintptr_t addr = program_header.p_vaddr;
+		const uintptr_t size = program_header.p_filesz;
+		const size_t offset = program_header.p_offset;
+		if (auto ret = syscall(SYS_PREAD, fd, addr, size, offset); ret != static_cast<long>(size))
+			print_error_and_exit("could not load program header", ret);
+	}
+	else
+	{
+		// aligned addresses, use file mmap
+		sys_mmap_t mmap_args;
+		mmap_args.addr = reinterpret_cast<void*>(program_header.p_vaddr);
+		mmap_args.fildes = fd;
+		mmap_args.flags = MAP_PRIVATE | MAP_FIXED;
+		mmap_args.len = program_header.p_memsz;
+		mmap_args.off = program_header.p_offset;
+		mmap_args.prot = prot | PROT_WRITE;
 
-	uintptr_t filesz = program_header.p_filesz;
+		if (auto ret = syscall(SYS_MMAP, &mmap_args); ret != static_cast<long>(program_header.p_vaddr))
+			print_error_and_exit("could not load program header", ret);
+	}
 
 	if (program_header.p_filesz != program_header.p_memsz)
 	{
-		const uintptr_t data_end_vaddr = program_header.p_vaddr + program_header.p_filesz;
-		const uintptr_t zero_end_vaddr = program_header.p_vaddr + program_header.p_memsz;
-
-		uintptr_t start_vaddr = data_end_vaddr & ~(uintptr_t)0xFFF;
-		if (program_header.p_vaddr & 0xFFF)
-			start_vaddr = program_header.p_vaddr & ~(uintptr_t)0xFFF;
-
-		if (start_vaddr != data_end_vaddr)
-		{
-			const uintptr_t end_vaddr = (data_end_vaddr + 4095) & ~(uintptr_t)0xFFF;
-			const ptrdiff_t length = min(end_vaddr - start_vaddr, zero_end_vaddr - start_vaddr);
-
-			sys_mmap_t mmap_args;
-			mmap_args.addr = reinterpret_cast<void*>(start_vaddr);
-			mmap_args.fildes = -1;
-			mmap_args.flags = MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED;
-			mmap_args.len = length;
-			mmap_args.off = 0;
-			mmap_args.prot = prot | PROT_WRITE;
-
-			if (auto ret = syscall(SYS_MMAP, &mmap_args); ret != static_cast<long>(start_vaddr))
-				print_error_and_exit("could not load program header", ret);
-
-			uintptr_t dummy_bytes = program_header.p_vaddr - start_vaddr;
-			if (program_header.p_vaddr & 0xFFF)
-				dummy_bytes = 0;
-
-			const uintptr_t data_vaddr = program_header.p_vaddr + dummy_bytes;
-			const ptrdiff_t data_bytes = data_end_vaddr - data_vaddr;
-			const uintptr_t data_offset = program_header.p_offset + dummy_bytes;
-			if (auto ret = syscall(SYS_PREAD, fd, data_vaddr, data_bytes, data_offset); ret != data_bytes)
-				print_error_and_exit("could not load program header", ret);
+		memset(
+			reinterpret_cast<void*>(program_header.p_vaddr + program_header.p_filesz),
+			0x00,
+			program_header.p_memsz - program_header.p_filesz
+		);
+	}
 
 	if (!(prot & PROT_WRITE) && !needs_writable)
 	{
 		// FIXME: Implement mprotect so PROT_WRITE can be removed
 		//syscall(SYS_MPROTECT, start_vaddr, length, prot);
 	}
-
-			filesz -= data_bytes;
-			start_vaddr += 4096;
-		}
-
-		if (start_vaddr < zero_end_vaddr)
-		{
-			sys_mmap_t mmap_args;
-			mmap_args.addr = reinterpret_cast<void*>(start_vaddr);
-			mmap_args.fildes = -1;
-			mmap_args.flags = MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED;
-			mmap_args.len = zero_end_vaddr - start_vaddr;
-			mmap_args.off = 0;
-			mmap_args.prot = prot | (needs_writable ? PROT_WRITE : 0);
-
-			if (auto ret = syscall(SYS_MMAP, &mmap_args); ret != static_cast<long>(start_vaddr))
-				print_error_and_exit("could not load program header", ret);
-		}
-	}
-
-	if (filesz)
-	{
-		sys_mmap_t mmap_args;
-		mmap_args.addr = reinterpret_cast<void*>(program_header.p_vaddr);
-		mmap_args.fildes = fd;
-		mmap_args.flags = MAP_PRIVATE | MAP_FIXED;
-		mmap_args.len = filesz;
-		mmap_args.off = program_header.p_offset;
-		mmap_args.prot = prot | (needs_writable ? PROT_WRITE : 0);
-
-		if (auto ret = syscall(SYS_MMAP, &mmap_args); ret != static_cast<long>(program_header.p_vaddr))
-			print_error_and_exit("could not load program header", ret);
-	}
 }
 
 static LoadedElf s_loaded_files[128];

userspace/programs/DynamicLoader/utils.cpp

@@ -56,6 +56,14 @@ void* memcpy(void* __restrict dstp, const void* __restrict srcp, size_t n)
 	return dstp;
 }
 
+void* memset(void* s, int c, size_t n)
+{
+	unsigned char* p = static_cast<unsigned char*>(s);
+	for (size_t i = 0; i < n; i++)
+		p[i] = c;
+	return s;
+}
+
 static int s_random_fd;
 
 void init_random()

userspace/programs/DynamicLoader/utils.h

@@ -42,7 +42,9 @@ inline void print_uint(int fd, T val, uint8_t base = 10)
 
 int strcmp(const char* s1, const char* s2);
 char* strcpy(char* __restrict s1, const char* __restrict s2);
+
 void* memcpy(void* __restrict s1, const void* __restrict s2, size_t n);
+void* memset(void* s, int c, size_t n);
 
 void init_random();
 void fini_random();