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https://github.com/rdmsr/zag.git
synced 2026-10-27 13:58:20 +00:00
build: rewrite ksyms script in zig
This commit is contained in:
Loïc Grégoire
@@ -36,11 +36,19 @@ pub fn build(b: *std.Build) void {
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.optimize = optimize,
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});
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// first pass
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const empty_cmd = b.addSystemCommand(&.{ "python3", "build/ksyms.py", "--empty" });
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empty_cmd.addArg("--output");
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const ksyms_exe = b.addExecutable(.{
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.name = "ksyms",
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.root_module = b.createModule(.{
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.root_source_file = b.path("build/ksyms.zig"),
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.target = b.graph.host,
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}),
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});
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const empty_cmd = b.addRunArtifact(ksyms_exe);
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const empty_ksyms_s = empty_cmd.addOutputFileArg("ksyms_empty.s");
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empty_cmd.stdio = .inherit;
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const rtl_module = b.createModule(.{
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.root_source_file = b.path("src/rtl/root.zig"),
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.optimize = optimize,
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@@ -69,12 +77,10 @@ pub fn build(b: *std.Build) void {
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b.step("kernel-nosym", "Build nosym kernel").dependOn(&kernel_nosym.step);
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// generate symbols
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const ksyms = b.addSystemCommand(&.{ "python3", "build/ksyms.py" });
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ksyms.addArg("--input");
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const ksyms = b.addRunArtifact(ksyms_exe);
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ksyms.step.dependOn(&kernel_nosym.step);
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ksyms.addFileArg(kernel_nosym.getEmittedBin());
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ksyms.addArg("--output");
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const ksyms_s = ksyms.addOutputFileArg("ksyms.s");
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ksyms.addFileArg(kernel_nosym.getEmittedBin());
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// second pass
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const kernel = addKernel(b, plat, optimize, config_module, ksyms_module, rtl_module, arch_module);
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@@ -1,89 +0,0 @@
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#!/usr/bin/env python3
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# Simple kernel symbol dumper
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# Usage: ksyms.py --input <kernel binary> --output <output file>
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import argparse
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import subprocess
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import sys
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excluded_symbols = [
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"text_start_addr",
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"text_end_addr",
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"rodata_start_addr",
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"rodata_end_addr",
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"data_start_addr",
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"data_end_addr",
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]
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def parse_nm_line(line: str):
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parts = line.split()
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if len(parts) < 3:
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return None
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addr_str, type, name = parts[0], parts[1], parts[2]
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# Only get symbols in text
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if type.lower() != "t":
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return None
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if name in excluded_symbols:
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return None
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addr = int(addr_str, 16)
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return addr, name
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def run_nm(binary: str):
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result = subprocess.run(["nm", "-n", binary], capture_output=True, text=True)
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if result.returncode != 0:
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raise RuntimeError(f"nm failed: {result.stderr}")
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return result.stdout.splitlines()
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parser = argparse.ArgumentParser(description="Generate kernel symbols from a binary")
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parser.add_argument("--input", help="Input kernel binary")
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parser.add_argument("--output", help="Output Assembly file (.s)")
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parser.add_argument("--empty", action="store_true", help="Generate empty ksyms")
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args = parser.parse_args()
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with open(args.output, "w") as f:
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f.write("/* Auto-generated by build/ksyms.py - do not edit */\n")
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f.write(".section .rodata\n")
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if args.empty:
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f.write(".global ksyms_array\n")
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f.write(".global ksyms_count\n")
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f.write(".align 8\n")
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f.write("ksyms_array:\n")
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f.write("ksyms_count:\n")
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f.write(" .quad 0\n")
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sys.exit(0)
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lines = run_nm(args.input)
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symbols = []
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for line in lines:
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parsed = parse_nm_line(line)
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if parsed:
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symbols.append(parsed)
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# Sort by address
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symbols.sort(key=lambda x: x[0])
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for i, (addr, name) in enumerate(symbols):
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escaped = name.replace("\\", "\\\\").replace('"', '\\"')
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f.write(f'.Lstr{i}: .asciz "{escaped}"\n')
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f.write("\n.global ksyms_array\n")
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f.write(".global ksyms_count\n")
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f.write(".align 8\n")
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f.write("ksyms_array:\n")
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for i, (addr, name) in enumerate(symbols):
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name_len = len(name.encode("utf-8"))
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f.write(f" .quad 0x{addr:016x}\n")
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f.write(f" .quad .Lstr{i}\n")
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f.write(f" .quad {name_len}\n")
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f.write("\nksyms_count:\n")
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f.write(f" .quad {len(symbols)}\n")
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+161
@@ -0,0 +1,161 @@
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//! Script to generate ksyms
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//! Usage: ksyms.zig <output> <input>
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const std = @import("std");
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const builtin = @import("builtin");
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const elf = std.elf;
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const Io = std.Io;
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const Allocator = std.mem.Allocator;
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const Symbol = struct {
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addr: usize,
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name: []const u8,
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};
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const file_hdr =
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\\/* Auto-generated by build/ksyms.zig - do not edit */
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\\.section .rodata
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\\.global ksyms_array
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\\.global ksyms_count
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\\.align 8
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\\
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;
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const empty_str = file_hdr ++
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\\ksyms_array:
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\\ksyms_count:
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\\.quad 0
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;
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fn getElfString(strtab: []const u8, offset: u32) []const u8 {
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const remainder = strtab[offset..];
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const str_ptr: [*:0]const u8 = @ptrCast(remainder.ptr);
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const len = std.mem.len(str_ptr);
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return remainder[0..len];
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}
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fn getSymbols(allocator: Allocator, bytes: []u8) !std.ArrayList(Symbol) {
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var reader = Io.Reader.fixed(bytes);
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const header = try std.elf.Header.read(&reader);
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const shstrhdr_addr = header.shoff + (header.shentsize * header.shstrndx);
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const shstrhdr = std.mem.bytesAsValue(elf.Shdr, bytes[shstrhdr_addr..]);
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const section_names: []const u8 = bytes[shstrhdr.sh_offset..];
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reader.seek = header.shoff;
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var text_section_index: usize = undefined;
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var symtab: elf.Shdr = undefined;
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const shdrs = std.mem.bytesAsSlice(
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elf.Shdr,
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bytes[header.shoff..][0 .. header.shnum * header.shentsize],
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);
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for (0..header.shnum) |i| {
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const name = getElfString(section_names, shdrs[i].sh_name);
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if (std.mem.eql(u8, name, ".text")) {
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text_section_index = i;
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} else if (shdrs[i].sh_type == elf.SHT_SYMTAB) {
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symtab = shdrs[i];
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}
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}
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const sym_strtab_shdr_addr = header.shoff + (header.shentsize * symtab.sh_link);
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const sym_strtab_shdr = std.mem.bytesAsValue(elf.Shdr, bytes[sym_strtab_shdr_addr..]);
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const symbol_names: []const u8 = bytes[sym_strtab_shdr.sh_offset..];
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const how_many = symtab.sh_size / symtab.sh_entsize;
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const symbols: [*]elf.Sym = @ptrCast(@alignCast(bytes[symtab.sh_offset..].ptr));
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var ret = try std.ArrayList(Symbol).initCapacity(allocator, how_many);
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for (0..how_many) |i| {
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const sym = symbols[i];
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if (sym.st_shndx == elf.SHN_UNDEF)
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continue;
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if (sym.st_name == 0)
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continue;
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if (sym.st_shndx != text_section_index) {
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continue;
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}
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const name = getElfString(symbol_names, sym.st_name);
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try ret.append(allocator, .{
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.addr = sym.st_value,
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.name = name,
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});
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}
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return ret;
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}
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fn lessThan(_: void, a: Symbol, b: Symbol) bool {
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return a.addr < b.addr;
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}
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fn generateSymbols(alloc: Allocator, file: []u8, writer: *Io.Writer) !void {
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const symbols = try getSymbols(alloc, file);
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std.mem.sort(Symbol, symbols.items, {}, lessThan);
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_ = try writer.write(file_hdr);
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_ = try writer.write("ksyms_array:\n");
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for (symbols.items, 0..) |sym, i| {
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try writer.print(".quad 0x{x}\n", .{sym.addr});
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try writer.print(".quad .Lstr{}\n", .{i});
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try writer.print(".quad {}\n", .{sym.name.len});
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}
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try writer.print("ksyms_count:\n .quad {}\n", .{symbols.items.len});
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for (symbols.items, 0..) |sym, i| {
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if (std.mem.indexOfScalar(u8, sym.name, '"') == null) {
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try writer.print(".Lstr{}: .asciz \"{s}\"\n", .{ i, sym.name });
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} else {
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const size = std.mem.replacementSize(u8, sym.name, "\"", "\\\"");
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const escaped = try alloc.alloc(u8, size);
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_ = std.mem.replace(u8, sym.name, "\"", "\\\"", escaped);
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try writer.print(".Lstr{}: .asciz \"{s}\" \n", .{ i, escaped });
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}
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}
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}
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pub fn main(init: std.process.Init) !void {
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const arena = init.arena.allocator();
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const io = init.io;
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const args = init.minimal.args;
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const args_slice = try args.toSlice(arena);
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const outfile = try std.Io.Dir.cwd().createFile(io, args_slice[1], .{});
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defer outfile.close(io);
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const write_buffer = try arena.alloc(u8, 64 * 1024);
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var writer = outfile.writer(io, write_buffer);
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if (args_slice.len == 2) {
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// Only output, generate an empty file.
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try writer.interface.writeAll(empty_str);
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}
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if (args_slice.len == 3) {
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// Got an input, parse the ELF.
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const buf = try std.Io.Dir.cwd().readFileAlloc(
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io,
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args_slice[2],
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arena,
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.unlimited,
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);
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try generateSymbols(arena, buf, &writer.interface);
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}
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try writer.flush();
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}
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