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[kernel] Hide kernel symbols by default

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Using `-fvisibility=hidden` when building the kernel, and then
`--discard-all` when stripping it, we shave almost 100KiB off of the
resulting ELF file.

Also dropped some unused symbols from the linker script, and rearranged
the sections so that the file is able to be mapped directly into memory
instead of having each section copied.
This commit is contained in:
Justin C. Miller
2023-01-29 19:36:20 -08:00
parent e2e1696b7e
commit 5ea5978ee8
17 changed files with 126 additions and 120 deletions
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2
src/boot/allocator.cpp
View File

@@ -155,7 +155,7 @@ allocator::memset(void *start, size_t size, uint8_t value)
}
void
allocator::copy(void *to, void *from, size_t size)
allocator::copy(void *to, const void *from, size_t size)
{
m_bs.copy_mem(to, from, size);
}

2
src/boot/allocator.h
View File

@@ -35,7 +35,7 @@ public:
module * allocate_module();
void memset(void *start, size_t size, uint8_t value);
void copy(void *to, void *from, size_t size);
void copy(void *to, const void *from, size_t size);
inline void zero(void *start, size_t size) { memset(start, size, 0); }

64
src/boot/loader.cpp
View File

@@ -35,15 +35,42 @@ load_file(
return b;
}
void
verify_kernel_header(elf::file &kernel, util::const_buffer data)
{
status_line status {L"Verifying kernel header"};
// The header should be the first non-null section
const elf::section_header &sect = kernel.sections()[1];
const bootproto::header *header =
reinterpret_cast<const bootproto::header *>(
util::offset_pointer(data.pointer, sect.offset));
if (header->magic != bootproto::header_magic)
error::raise(uefi::status::load_error, L"Bad kernel magic number");
if (header->length < sizeof(bootproto::header))
error::raise(uefi::status::load_error, L"Bad kernel header length");
if (header->version < bootproto::min_header_version)
error::raise(uefi::status::unsupported, L"Kernel header version not supported");
console::print(L" Loaded kernel vserion: %d.%d.%d %x\r\n",
header->version_major, header->version_minor, header->version_patch,
header->version_gitsha);
}
bootproto::program *
load_program(
fs::file &disk,
const wchar_t *name,
const descriptor &desc)
const descriptor &desc,
bool verify)
{
status_line status(L"Loading program", name);
util::buffer data = load_file(disk, desc.path);
util::const_buffer data = load_file(disk, desc.path);
elf::file program(data.pointer, data.count);
if (!program.valid()) {
@@ -60,6 +87,9 @@ load_program(
error::raise(uefi::status::load_error, L"ELF file not valid");
}
if (verify)
verify_kernel_header(program, data);
size_t num_sections = 0;
for (auto &seg : program.programs()) {
if (seg.type == elf::segment_type::load)
@@ -85,7 +115,7 @@ load_program(
size_t page_count = memory::bytes_to_pages(mem_size);
void *pages = g_alloc.allocate_pages(page_count, alloc_type::program, true);
void *source = util::offset_pointer(data.pointer, seg.offset);
const void *source = util::offset_pointer(data.pointer, seg.offset);
g_alloc.copy(util::offset_pointer(pages, prelude), source, seg.file_size);
section.phys_addr = reinterpret_cast<uintptr_t>(pages);
section.virt_addr = virt_addr;
@@ -116,33 +146,5 @@ load_module(
mod->data = load_file(disk, path);
}
void
verify_kernel_header(bootproto::program &program)
{
status_line status(L"Verifying kernel header");
const bootproto::header *header =
reinterpret_cast<const bootproto::header *>(program.sections[0].phys_addr);
if (header->magic != bootproto::header_magic)
error::raise(uefi::status::load_error, L"Bad kernel magic number");
if (header->length < sizeof(bootproto::header))
error::raise(uefi::status::load_error, L"Bad kernel header length");
if (header->version < bootproto::min_header_version)
error::raise(uefi::status::unsupported, L"Kernel header version not supported");
console::print(L" Loaded kernel vserion: %d.%d.%d %x\r\n",
header->version_major, header->version_minor, header->version_patch,
header->version_gitsha);
/*
for (auto &section : program.sections)
console::print(L" Section: p:0x%lx v:0x%lx fs:0x%x ms:0x%x\r\n",
section.phys_addr, section.virt_addr, section.file_size, section.mem_size);
*/
}
} // namespace loader
} // namespace boot

15
src/boot/loader.h
View File

@@ -28,14 +28,16 @@ load_file(
const wchar_t *path);
/// Parse and load an ELF file in memory into a loaded image.
/// \arg disk The opened UEFI filesystem to load from
/// \arg desc The descriptor identifying the program
/// \arg name The human-readable name of the program to load
/// \arg disk The opened UEFI filesystem to load from
/// \arg desc The descriptor identifying the program
/// \arg name The human-readable name of the program to load
/// \arg verify If this is the kernel and should have its header verified
bootproto::program *
load_program(
fs::file &disk,
const wchar_t *name,
const descriptor &desc);
const descriptor &desc,
bool verify = false);
/// Load a file from disk into memory, creating an init args module
/// \arg disk The opened UEFI filesystem to load from
@@ -51,10 +53,5 @@ load_module(
bootproto::module_type type,
uint16_t subtype);
/// Verify that a loaded ELF has the j6 kernel header
/// \arg program The program to check for a header
void
verify_kernel_header(bootproto::program &program);
} // namespace loader
} // namespace boot

4
src/boot/main.cpp
View File

@@ -75,7 +75,7 @@ load_resources(bootproto::args *args, video::screen *screen, uefi::handle image,
fs::file bc_data = disk.open(L"jsix\\boot.conf");
bootconfig bc {bc_data.load(), bs};
args->kernel = loader::load_program(disk, L"kernel", bc.kernel());
args->kernel = loader::load_program(disk, L"kernel", bc.kernel(), true);
args->init = loader::load_program(disk, L"init server", bc.init());
args->flags = static_cast<bootproto::boot_flags>(bc.flags());
@@ -106,8 +106,6 @@ load_resources(bootproto::args *args, video::screen *screen, uefi::handle image,
}
}
}
loader::verify_kernel_header(*args->kernel);
}
memory::efi_mem_map