On Tue, 24 Oct 2023 20:11:57 +0000 "Alessandro Carminati (Red Hat)" <alessandro.carminati@xxxxxxxxx> wrote: > In the kernel environment, scenarios often arise where identical names > are shared among symbols within core image or modules. > While this poses no complications for the kernel's binary itself, it > creates challenges when conducting trace or probe operations using tools > like kprobe. > > A solution has been introduced, referred to as "kas_alias." > During the kernel's build process, an extensive scan of all objects is > performed, encompassing both core kernel components and modules, to > collect comprehensive symbol information. > Subsequently, for all duplicate symbolsthe process enriches symbol names > by appending meaningful suffixes derived from source files and line > numbers. > These freshly generated aliases simplify interaction with symbols. > > The procedure is executed as follows. > During the kernel's build phase, an exhaustive search for duplicates among > symbols that share the same name in both kernel image and all modules > object files. > For the kernel core image, a new nem data file is created and alias for > all duplicate symbols is added. > For modules, the lib objects the ELF symtable is modified with the > addition of the alias for the duplicate symbols. > > Consider the symbol "device_show", you can expect an output like the > following: > > ~ # cat /proc/kallsyms | grep " device_show" > ffffffff963cd2a0 t device_show > ffffffff963cd2a0 t device_show@drivers_pci_pci_sysfs_c_49 > ffffffff96454b60 t device_show > ffffffff96454b60 t device_show@drivers_virtio_virtio_c_16 > ffffffff966e1700 T device_show_ulong > ffffffff966e1740 T device_show_int > ffffffff966e1770 T device_show_bool > ffffffffc04e10a0 t device_show [mmc_core] > ffffffffc04e10a0 t device_show@drivers_mmc_core_sdio_bus_c_45 [mmc_core] > > Signed-off-by: Alessandro Carminati (Red Hat) <alessandro.carminati@xxxxxxxxx> > Thanks for update. I tested that. Tested-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> BTW, on my environment, the suffix path is not relative but absolute path (including /home/<user> etc.) I guess it is because I use O= option. This is another concerning point to fix. > NOTE1: > About the symbols name duplication that happens as consequence of the > inclusion compat_binfmt_elf.c does, it is evident that this corner is > inherently challenging the addr2line approach. > Attempting to conceal this limitation would be counterproductive. > > compat_binfmt_elf.c includes directly binfmt_elf.c, addr2line can't help > but report all functions and data declared by that file, coming from > binfmt_elf.c. Hmm, indeed. If we find such symbols we may need to add a suffix number to distinguish it, but it may confuse user that which symbol is for binfmt_elf or compat_binfmt_elf... > > My position is that, rather than producing a more complicated pipeline > to handle this corner case, it is better to fix the compat_binfmt_elf.c > anomaly. Agreed. > > This patch does not deal with the two potentially problematic symbols > defined by compat_binfmt_elf.c I think it is OK in this step. > > NOTE2: > The current implementation does not offer a solution for out-of-tree modules. > My stance is that these modules fall outside the scope, but I welcome any > comments or feedback regarding this matter. Can the out-of-tree developers run the kas_alias.py by themselves? Ah, we need to give them a table of all symbols (including other modules). If we do this in 2 phases, collect symbols, and inject aliases, then we can leave the tables of existing symbols as a file, and those out-of-tree module developers can reuse that file. BTW, to hide the below changelogs (and above notes too?) from the commit, please put a '---' only line before that. Thank you! > > Changes from v1: > * Integrated changes requested by Masami to exclude symbols with prefixes > "_cfi" and "_pfx". > * Introduced a small framework to handle patterns that need to be excluded > from the alias production. > * Excluded other symbols using the framework. > * Introduced the ability to discriminate between text and data symbols. > * Added two new config symbols in this version: > CONFIG_KALLSYMS_ALIAS_DATA, which allows data for data, and > CONFIG_KALLSYMS_ALIAS_DATA_ALL, which excludes all filters and provides > an alias for each duplicated symbol. > > https://lore.kernel.org/all/20230711151925.1092080-1-alessandro.carminati@xxxxxxxxx/ > > Changes from v2: > * Alias tags are created by querying DWARF information from the vmlinux. > * The filename + line number is normalized and appended to the original > name. > * The tag begins with '@' to indicate the symbol source. > * Not a change, but worth mentioning, since the alias is added to the > existing list, the old duplicated name is preserved, and the livepatch > way of dealing with duplicates is maintained. > * Acknowledging the existence of scenarios where inlined functions > declared in header files may result in multiple copies due to compiler > behavior, though it is not actionable as it does not pose an operational > issue. > * Highlighting a single exception where the same name refers to different > functions: the case of "compat_binfmt_elf.c," which directly includes > "binfmt_elf.c" producing identical function copies in two separate > modules. > > https://lore.kernel.org/all/20230714150326.1152359-1-alessandro.carminati@xxxxxxxxx/ > > Changes from v3: > * kas_alias was rewritten in Python to create a more concise and > maintainable codebase. > * The previous automation process used by kas_alias to locate the vmlinux > and the addr2line has been replaced with an explicit command-line switch > for specifying these requirements. > * addr2line has been added into the main Makefile. > * A new command-line switch has been introduced, enabling users to extend > the alias to global data names. > > https://lore.kernel.org/all/20230828080423.3539686-1-alessandro.carminati@xxxxxxxxx/ > > Changes from v4: > * Fixed the O=<build dir> build issue > * The tool halts execution upon encountering major issues, thereby ensuring > the pipeline is interrupted. > * A cmdline option to specify the source directory added. > * Minor code adjusments. > * Tested on mips32 and i386 > > https://lore.kernel.org/all/20230919193948.465340-1-alessandro.carminati@xxxxxxxxx/ > > Changes from v5: > * Regex filter extended to all symbols > * Alias creation extended to module objects > * Code cleaned and commented > * kas_alias verbose execution via KAS_ALIAS_DEBUG env variable > * CONFIG_KALLSYMS_ALIAS_SRCLINE selects KBUILD_BUILTIN to ensure no races > during modules build > * Tested on x86_64, aarch64 and i386 > > https://lore.kernel.org/all/20230927173516.1456594-1-alessandro.carminati@xxxxxxxxx/ > --- > Makefile | 14 +- > init/Kconfig | 22 ++ > scripts/Makefile.modfinal | 10 +- > scripts/kas_alias.py | 545 ++++++++++++++++++++++++++++++++++++++ > scripts/link-vmlinux.sh | 26 +- > 5 files changed, 613 insertions(+), 4 deletions(-) > create mode 100755 scripts/kas_alias.py > > diff --git a/Makefile b/Makefile > index 4f283d915e54..f2c51340fa52 100644 > --- a/Makefile > +++ b/Makefile > @@ -488,6 +488,7 @@ OBJCOPY = $(LLVM_PREFIX)llvm-objcopy$(LLVM_SUFFIX) > OBJDUMP = $(LLVM_PREFIX)llvm-objdump$(LLVM_SUFFIX) > READELF = $(LLVM_PREFIX)llvm-readelf$(LLVM_SUFFIX) > STRIP = $(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX) > +ADDR2LINE = $(LLVM_PREFIX)llvm-addr2line$(LLVM_SUFFIX) > else > CC = $(CROSS_COMPILE)gcc > LD = $(CROSS_COMPILE)ld > @@ -497,6 +498,7 @@ OBJCOPY = $(CROSS_COMPILE)objcopy > OBJDUMP = $(CROSS_COMPILE)objdump > READELF = $(CROSS_COMPILE)readelf > STRIP = $(CROSS_COMPILE)strip > +ADDR2LINE = $(CROSS_COMPILE)addr2line > endif > RUSTC = rustc > RUSTDOC = rustdoc > @@ -611,7 +613,7 @@ export RUSTC_BOOTSTRAP := 1 > export ARCH SRCARCH CONFIG_SHELL BASH HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE LD CC HOSTPKG_CONFIG > export RUSTC RUSTDOC RUSTFMT RUSTC_OR_CLIPPY_QUIET RUSTC_OR_CLIPPY BINDGEN CARGO > export HOSTRUSTC KBUILD_HOSTRUSTFLAGS > -export CPP AR NM STRIP OBJCOPY OBJDUMP READELF PAHOLE RESOLVE_BTFIDS LEX YACC AWK INSTALLKERNEL > +export CPP AR NM STRIP OBJCOPY OBJDUMP READELF ADDR2LINE PAHOLE RESOLVE_BTFIDS LEX YACC AWK INSTALLKERNEL > export PERL PYTHON3 CHECK CHECKFLAGS MAKE UTS_MACHINE HOSTCXX > export KGZIP KBZIP2 KLZOP LZMA LZ4 XZ ZSTD > export KBUILD_HOSTCXXFLAGS KBUILD_HOSTLDFLAGS KBUILD_HOSTLDLIBS LDFLAGS_MODULE > @@ -1542,6 +1544,16 @@ KBUILD_BUILTIN := 1 > modules: vmlinux > endif > > +# *.ko are usually independent of vmlinux, but CONFIG_KALLSYMS_ALIAS_SRCLINE > +# is another exception. > +# At the time when vmlinux is being linked, kas_alias operates on both vmlinux > +# and modules. To prevent races with modules, kas_alias needs to pause operations > +# while it is executed. > +ifdef CONFIG_KALLSYMS_ALIAS_SRCLINE > +KBUILD_BUILTIN := 1 > +modules: vmlinux > +endif > + > modules: modules_prepare > > # Target to prepare building external modules > diff --git a/init/Kconfig b/init/Kconfig > index 6d35728b94b2..d45dd423e1ec 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -1738,6 +1738,28 @@ config KALLSYMS_BASE_RELATIVE > time constants, and no relocation pass is required at runtime to fix > up the entries based on the runtime load address of the kernel. > > +config KALLSYMS_ALIAS_SRCLINE > + bool "Produces alias for duplicated text symbols" if EXPERT > + depends on KALLSYMS && DEBUG_INFO && !DEBUG_INFO_SPLIT > + help > + It is not uncommon for drivers or modules related to similar > + peripherals to have symbols with the exact same name. > + While this is not a problem for the kernel's binary itself, it > + becomes an issue when attempting to trace or probe specific > + functions using infrastructure like ftrace or kprobe. > + > + This option addresses this challenge, producing alias for text > + symbol names that include the file name and line where the symbols > + are defined in the source code. > + > +config KALLSYMS_ALIAS_SRCLINE_DATA > + bool "Produces alias also for global variables names" > + depends on KALLSYMS_ALIAS_SRCLINE > + help > + Sometimes it can be useful to refer to global vars by name. Since > + they suffer the same issue as text symbols, this config option > + allows having aliases for global variables names too. > + > # end of the "standard kernel features (expert users)" menu > > # syscall, maps, verifier > diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal > index b3a6aa8fbe8c..3d9756a6eb3e 100644 > --- a/scripts/Makefile.modfinal > +++ b/scripts/Makefile.modfinal > @@ -15,6 +15,14 @@ include $(srctree)/scripts/Makefile.lib > # find all modules listed in modules.order > modules := $(call read-file, $(MODORDER)) > > +ifeq ($(KBUILD_BUILTIN),y) > + ifeq ($(or $(CONFIG_DEBUG_INFO_BTF_MODULES),$(CONFIG_KALLSYMS_ALIAS_SRCLINE)),y) > + VMLINUX_DEP := vmlinux > + endif > +endif > + > +VMLINUX_DEP ?= > + > __modfinal: $(modules:%.o=%.ko) > @: > > @@ -55,7 +63,7 @@ if_changed_except = $(if $(call newer_prereqs_except,$(2))$(cmd-check), \ > printf '%s\n' 'savedcmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:) > > # Re-generate module BTFs if either module's .ko or vmlinux changed > -%.ko: %.o %.mod.o scripts/module.lds $(and $(CONFIG_DEBUG_INFO_BTF_MODULES),$(KBUILD_BUILTIN),vmlinux) FORCE > +%.ko: %.o %.mod.o scripts/module.lds $(VMLINUX_DEP) FORCE > +$(call if_changed_except,ld_ko_o,vmlinux) > ifdef CONFIG_DEBUG_INFO_BTF_MODULES > +$(if $(newer-prereqs),$(call cmd,btf_ko)) > diff --git a/scripts/kas_alias.py b/scripts/kas_alias.py > new file mode 100755 > index 000000000000..bc930039867b > --- /dev/null > +++ b/scripts/kas_alias.py > @@ -0,0 +1,545 @@ > +#!/usr/bin/env python3 > +# SPDX-License-Identifier: GPL-2.0-only > +# > +# Copyright (C) 2023 Red Hat, Inc. Alessandro Carminati <alessandro.carminati@xxxxxxxxx> > +# > +# kas_alias: Adds alias to duplicate symbols for the kallsyms output. > + > +import os > +import re > +import argparse > +import subprocess > +from enum import Enum > +from collections import namedtuple > + > +# Regex representing symbols that needs no alias > +regex_filter = [ > + "^__compound_literal\\.[0-9]+$", > + "^__[wm]*key\\.[0-9]+$", > + "^_*TRACE_SYSTEM.*$", > + "^__already_done\\.[0-9]+$", > + "^__msg\\.[0-9]+$", > + "^__func__\\.[0-9]+$", > + "^CSWTCH\\.[0-9]+$", > + "^_rs\\.[0-9]+$", > + "^___tp_str\\.[0-9]+$", > + "^__flags\\.[0-9]+$", > + "^___done\\.[0-9]+$", > + "^__print_once\\.[0-9]+$", > + "^___once_key\\.[0-9]+$", > + "^__pfx_.*$", > + "^__cfi_.*$", > + "^\\.LC[0-9]+$", > + "^\\.L[0-9]+.[0-9]+$", > + "^__UNIQUE_ID_.*$", > + "^symbols\\.[0-9]+$", > + "^_note_[0-9]+$" > + ] > + > +class DebugLevel(Enum): > + PRODUCTION = 0 > + INFO = 1 > + DEBUG_BASIC = 2 > + DEBUG_MODULES = 3 > + DEBUG_ALL = 4 > + > +class SeparatorType: > + def __call__(self, separator): > + if len(separator) != 1: > + raise argparse.ArgumentTypeError("Separator must be a single character") > + return separator > + > +class Addr2LineError(Exception): > + pass > + > +debug = DebugLevel.PRODUCTION > + > +Line = namedtuple('Line', ['address', 'type', 'name']) > + > +def parse_nm_lines(lines, name_occurrences=None): > + """ > + Parses a given nm output and returns the symbol list along with a hash of > + symbol occurrences. > + Args: > + lines: List of tuples representing one nm line. > + name_occurrences: Hash having the name as key, used to count names' > + occurrences. > + Returns: > + Creates a new line list proper for the nm output it parsed and, updates > + the occurrences hash. > + """ > + if debug >= DebugLevel.DEBUG_BASIC.value: > + print("parse_nm_lines: parse start") > + > + if name_occurrences is None: > + name_occurrences = {} > + > + symbol_list = [] > + > + for line in lines: > + fields = line.strip().split() > + > + if len(fields) >= 3: > + address, type, name = fields[0], fields[1], ' '.join(fields[2:]) > + symbol_list.append(Line(address, type, name)) > + name_occurrences[name] = name_occurrences.get(name, 0) + 1 > + > + return symbol_list, name_occurrences > + > +def start_addr2line_process(binary_file, addr2line_file): > + """ > + Initializes an addr2line server process operating on the given ELF object. > + Args: > + binary_file: String representing the binary file name object of addr2line > + queries. > + addr2line_file: String representing the addr2line executable name. > + Returns: > + Returns addr2line process descriptor. > + """ > + if debug >= DebugLevel.DEBUG_BASIC.value: > + print(f"start_addr2line_process: Starting addr2line process on {binary_file}") > + > + try: > + addr2line_process = subprocess.Popen([addr2line_file, '-fe', > + binary_file], > + stdin=subprocess.PIPE, > + stdout=subprocess.PIPE, > + stderr=subprocess.PIPE, > + text=True) > + return addr2line_process > + except Exception as e: > + raise SystemExit(f"Fatal: Can't start addr2line resolver: {e}") > + > + > +def addr2line_fetch_address(addr2line_process, address): > + """ > + Queries a specific address using the active addr2line process. > + Args: > + addr2line_process: Descriptor of the addr2line process that is wanted to > + handle the query. > + address: The address of the symbol that needs to be resolved. > + Returns: > + Returns a string representing the file and line number where the symbol > + at the specified address has been defined. The address is normalized > + before being returned. > + """ > + if debug >= DebugLevel.DEBUG_ALL.value: > + print(f"addr2line_fetch_address: Resolving {address}") > + > + try: > + addr2line_process.stdin.write(address + '\n') > + addr2line_process.stdin.flush() > + addr2line_process.stdout.readline().strip() > + output = addr2line_process.stdout.readline().strip() > + > + return os.path.normpath(output) > + except Exception as e: > + raise SystemExit( > + "Fatal: Error communicating with" > + f" the addr2line resolver: {e}." > + ) > + > +def process_line(line, process_data_sym, init_section_info): > + """ > + Determines whether a duplicate item requires an alias or not. > + Args: > + line: nm line object that needs to be checked. > + process_data_sym: Flag indicating that the script requires to produce alias > + also for data symbols. > + Returns: > + Returns true if the line needs to be processed, false otherwise. > + """ > + if debug >= DebugLevel.DEBUG_ALL.value: > + print(f"process_line: Processing {line.address} {line.type} {line.name}") > + > + # The module contains symbols that were discarded after being loaded. Typically, > + # these symbols belong to the initialization function. These symbols have their > + # address in the init section addresses, so this check prevents these symbols > + # from being assigned aliases. > + if init_section_info != None: > + if (int(line.address, 16) >= init_section_info["address"] and > + int(line.address, 16) <= init_section_info["address"] + init_section_info["size"]): > + if debug >= DebugLevel.DEBUG_ALL.value: > + print(f"process_line: Skip {line.name} since its address is .init.text") > + return False > + > + if process_data_sym: > + return not (any(re.match(regex, line.name) for regex in regex_filter)) > + else: > + return (line.type in {"T", "t"}) and ( > + not (any(re.match(regex, line.name) for regex in regex_filter))) > + > +def fetch_file_lines(filename): > + """ > + Reads a text file and retrieves its content. > + Args: > + filename: String representing the name of the file that needs to be read. > + Returns: > + Returns a string list representing the lines read in the file. > + """ > + if debug >= DebugLevel.DEBUG_BASIC.value: > + print(f"fetch_file_lines: Fetch {filename}") > + > + try: > + with open(filename, 'r') as file: > + lines = [line.strip() for line in file.readlines()] > + return lines > + except FileNotFoundError: > + raise SystemExit(f"Fatal: File not found: {filename}") > + > +def do_nm(filename, nm_executable): > + """ > + Runs the nm command on a specified file. > + Args: > + filename: String representing the name of the file on which nm should > + run against. > + nm_executable: String representing the nm executable filename. > + Returns: > + Returns a strings list representing the nm output. > + """ > + # Later, during processing, objcopy cannot modify files in place when > + # adding new alias symbols. It requires a source file and a destination > + # file. > + # After this operation, there is an object file ".o" with the aliases and > + # a ".k{0,1}o.orig" file, which is the old intended object and serves as the > + # source for objcopy. > + # In a fresh build, the state is just fine. > + # However, in a second build without clean, an issue arises. > + # The ".k{0,1}o" file already contain the alias, and reprocessing it, do > + # corrupt the final result. To address this, do_nm must check if the file > + # ".k{0,1}o.orig" already exists. > + # If it does, that's the target for nm and must be renamed in ".k{0,1}o" > + # to restore the intended state. If not, it's a fresh build, and nm can > + # proceed with the ".k{0,1}o" file. > + backup_file = filename + '.orig' > + if os.path.exists(backup_file): > + print(f"do_nm: {filename} is not clean, restore {backup_file} to {filename}") > + os.rename(backup_file, filename) > + > + if debug >= DebugLevel.DEBUG_BASIC.value: > + print(f"do_nm: executing {nm_executable} -n {filename}") > + > + try: > + nm_output = subprocess.check_output([nm_executable, '-n', filename], > + universal_newlines=True, stderr=subprocess.STDOUT).splitlines() > + return nm_output > + except subprocess.CalledProcessError as e: > + raise SystemExit(f"Fatal: Error executing nm: {e}") > + > +def make_objcpy_arg(line, decoration, elf_section_names): > + """ > + Produces an objcopy argument statement for a single alias to be added in a > + module. > + Args: > + line: nm line object target for this iteration. > + decoration: String representing the decoration (normalized addr2line > + output) to be added at the symbol name to have the alias. > + elf_section_names: List of the section names that can be used by objcopy > + to add a symbol to the ELF symbol table. > + Returns: > + Returns a string that directly maps the argument string objcopy should > + use to add the alias. > + """ > + try: > + section = ( > + elf_section_names[".text"] if line.type.upper() == "T" else ( > + elf_section_names[".data"] if line.type.upper() == "D" else ( > + elf_section_names[".rodata"] if line.type.upper() == "R" else ".bss" > + ) > + ) > + ) > + flag = "global" if line.type.isupper() else "local" > + > + if debug >= DebugLevel.DEBUG_MODULES.value: > + print("make_objcpy_arg: " > + f"{line.name + decoration}={section}:0x{line.address},{flag}") > + > + > + return ( > + "--add-symbol " > + f"{line.name + decoration}={section}:0x{line.address},{flag} " > + ) > + except Exception: > + print( > + f"make_objcpy_arg warning: Skip alias for {line.name}" > + f" type {line.type} because no corresponding section found.") > + return "" > + > +def execute_objcopy(objcopy_executable, objcopy_args, object_file): > + """ > + Uses objcopy to add aliases to a given module object file. > + Since objcopy can't operate in place, the original object file is renamed > + before operating on it. At function end, a new object file having the old > + object's name is carrying the aliases for the duplicate symbols. > + Args: > + objcopy_executable: String representing the object copy executable file. > + objcopy_args: Arguments (aliases to add to the object file) to be used > + in the objcopy execution command line. > + object_file: Target object file (module object file) against which objcopy is executed. > + Returns: > + Nothing is returned, but as a side effect of this function execution, > + the module's object file contains the aliases for duplicated symbols. > + """ > + # Rename the original object file by adding a suffix > + backup_file = object_file + '.orig' > + if debug >= DebugLevel.DEBUG_MODULES.value: > + print("execute_objcopy: " > + f"rename {object_file} to {backup_file}") > + os.rename(object_file, backup_file) > + > + full_command = ( > + f"{objcopy_executable} " > + f"{objcopy_args} {backup_file} {object_file}" > + ) > + if debug >= DebugLevel.DEBUG_MODULES.value: > + print(f"execute_objcopy: executing {full_command}") > + > + try: > + subprocess.run(full_command, shell=True, check=True) > + except subprocess.CalledProcessError as e: > + os.rename(backup_file, object_file) > + raise SystemExit(f"Fatal: Error executing objcopy: {e}") > + > +def generate_decoration(line, config, addr2line_process): > + """ > + Generates symbol decoration to be used to make the alias name, by > + querying addr2line. > + Args: > + line: nm line object that needs an alias. > + config: Object containing command line configuration. > + addr2line_process: Descriptor of the addr2line process that serves > + the binary object where the symbol belongs. > + Returns: > + Returns a string representing the decoration for the given symbol, > + or empty string if this can not be done. E.g., addr2line can't find > + the point where the symbol is defined. > + """ > + output = addr2line_fetch_address(addr2line_process, line.address) > + decoration = config.separator + "".join( > + "_" if not c.isalnum() else c for c in output.replace(config.linux_base_dir, "") > + ) > + # The addr2line can emit the special string "?:??" when addr2line can not find the > + # specified address in the DWARF section that after normalization it becomes "____". > + # In such cases, emitting an alias wouldn't make sense, so it is skipped. > + if decoration != config.separator + "____": > + return decoration > + return "" > + > +def get_objdump_text(objdump_executable, file_to_operate): > + """ > + objdump output is needed for a couple of functions revolving around > + modules. This function kust query objdump to emit sections info and > + return its output. > + Args: > + objdump_executable: String representing the objdump executable. > + file_to_operate: file whose section names are wanted. > + Returns: > + Returns objdump output. > + """ > + try: > + output = subprocess.check_output( > + [objdump_executable, '-h', file_to_operate], > + universal_newlines=True) > + > + except Exception as e: > + raise SystemExit( > + "Fatal: Can't find section names" > + f" for {file_to_operate}. Error: {e}" > + ) > + return output > + > +def get_init_text_info(objdump_lines): > + """ > + Recovers info on the .init.text section. > + Args: > + objdump_lines: output from objdump -h command. > + Returns: > + Returns a map containing the size and address of the .init.text section > + None if it is not there. > + """ > + section_info = None > + section_name_pattern = re.compile(r'^\s*\d+') > + > + for line in objdump_lines.strip().splitlines(): > + if section_name_pattern.match(line): > + parts = line.split() > + if len(parts) >= 2: > + current_section_name = parts[1] > + if current_section_name == ".init.text": > + size = int(parts[2], 16) > + address = int(parts[3], 16) > + section_info = {"size": size, "address": address} > + break > + > + return section_info > + > +def get_section_names(objdump_lines): > + """ > + objcopy needs to refer to a section name to assign the symbol type. > + Unfortunately, not always all the section are present into a given > + object file exist, for example, ".rodata" can not exist, and a [Rr] > + symbol my refer to some other section e.g., ".rodata.str1". > + For this reason this function tries to recover the exact names to use > + in an objcopy statement. > + Args: > + objdump_lines: output from objdump -h command. > + Returns: > + Returns a map containing four string indexed with typical section > + names. > + """ > + section_names = [] > + lines = objdump_lines.strip().splitlines() > + section_name_pattern = re.compile(r'^\s*\d+') > + for line in lines: > + if section_name_pattern.match(line): > + parts = line.split() > + if len(parts) >= 2: > + section_name = parts[1] > + section_names.append(section_name) > + > + best_matches = [".text", ".rodata", ".data", ".bss"] > + result = {} > + > + for match in best_matches: > + for section_name in section_names: > + if re.match(match+".*", section_name): > + result[match] = section_name > + > + if debug >= DebugLevel.DEBUG_MODULES.value: > + for key, value in result.items(): > + print(f"get_section_names: sections {key} = {value}") > + > + return result > + > +def produce_output_modules(config, symbol_list, name_occurrences, > + module_file_name, addr2line_process): > + """ > + Computes the alias addition on a given module object file. > + Args: > + config: Object containing command line configuration. > + symbol_list: List of tuples representing nm lines for the given object > + file. > + name_occurrences: Hash that stores symbol occurreces for the build. > + module_file_name: String representing the target moule object file. > + addr2line_process: Descriptor of the addr2line process that is wanted to > + handle the query. > + Returns: > + Nothing is returned, but as a side effect of this function execution, > + the module's object file contains the aliases for duplicated symbols. > + """ > + objcopy_args = ""; > + args_cnt = 0 > + objdump_data = get_objdump_text(config.objdump_file, module_file_name) > + elf_section_names = get_section_names(objdump_data) > + init_text_section_data = get_init_text_info(objdump_data) > + for obj in symbol_list: > + if (name_occurrences[obj.name] > 1) and process_line(obj, config.process_data_sym, init_text_section_data): > + decoration = generate_decoration(obj, config, addr2line_process) > + if decoration != "": > + objcopy_args = objcopy_args + make_objcpy_arg(obj, decoration, elf_section_names) > + args_cnt = args_cnt + 1 > + if args_cnt > 50: > + if debug >= DebugLevel.DEBUG_MODULES.value: > + print("Produce_output_modules: Number of arguments high, split objcopy call into multiple statements.") > + execute_objcopy(config.objcopy_file, objcopy_args, module_file_name) > + args_cnt = 0 > + objcopy_args = "" > + > + execute_objcopy(config.objcopy_file, objcopy_args, module_file_name) > + > +def produce_output_vmlinux(config, symbol_list, name_occurrences, addr2line_process): > + """ > + Computes the alias addition for the core Linux on image. > + Args: > + config: Object containing command line configuration. > + symbol_list: List of tuples representing nm lines for the given object > + file. > + name_occurrences: Hash that stores symbol occurreces for the build. > + addr2line_process: Descriptor of the addr2line process that is wanted to > + handle the query. > + Returns: > + Nothing is returned, but as a side effect of this function execution, > + the core kernel image contains the aliases for duplicated symbols. > + """ > + with open(config.output_file, 'w') as output_file: > + for obj in symbol_list: > + output_file.write(f"{obj.address} {obj.type} {obj.name}\n") > + if (name_occurrences[obj.name] > 1) and process_line(obj, config.process_data_sym, None): > + decoration = generate_decoration(obj, config, addr2line_process) > + if decoration != "": > + output_file.write(f"{obj.address} {obj.type} {obj.name + decoration}\n") > + > +if __name__ == "__main__": > + # Handles command-line arguments and generates a config object > + parser = argparse.ArgumentParser(description='Add alias to multiple occurring symbols name in kallsyms') > + parser.add_argument('-a', "--addr2line", dest="addr2line_file", required=True, help="Set the addr2line executable to be used.") > + parser.add_argument('-b', "--basedir", dest="linux_base_dir", required=True, help="Set base directory of the source kernel code.") > + parser.add_argument('-c', "--objcopy", dest="objcopy_file", required=True, help="Set the objcopy executable to be used.") > + parser.add_argument('-d', "--process_data", dest="process_data_sym", required=False, help="Requires the tool to process data symbols along with text symbols.", action='store_true') > + parser.add_argument('-e', "--nm", dest="nm_file", required=True, help="Set the nm executable to be used.") > + parser.add_argument('-m', "--modules_list", dest="module_list", required=True, help="Set the file containing the list of the modules object files.") > + parser.add_argument('-n', "--nmdata", dest="nm_data_file", required=True, help="Set vmlinux nm output file to use for core image.") > + parser.add_argument('-o', "--outfile", dest="output_file", required=True, help="Set the vmlinux nm output file containing aliases.") > + parser.add_argument('-s', "--separator", dest="separator", required=False, help="Set separator, character that separates original name from the addr2line data in alias symbols.", default="@", type=SeparatorType()) > + parser.add_argument('-u', "--objdump", dest="objdump_file", required=True, help="Set objdump executable to be used.") > + parser.add_argument('-v', "--vmlinux", dest="vmlinux_file", required=True, help="Set the vmlinux core image file.") > + parser.add_argument('-z', "--debug", dest="debug", required=False, help="Set the debug level.", choices=[f"{level.value}" for level in DebugLevel], default="1" ) > + config = parser.parse_args() > + debug = int(config.debug) > + > + try: > + if debug >= DebugLevel.INFO.value: > + print("kas_alias: Start processing") > + > + # Determine kernel source code base directory > + config.linux_base_dir = os.path.normpath(os.getcwd() + "/" + config.linux_base_dir) + "/" > + > + if debug >= DebugLevel.INFO.value: > + print("kas_alias: Process nm data from vmlinux") > + > + # Process nm data from vmlinux > + vmlinux_nm_lines = fetch_file_lines(config.nm_data_file) > + vmlinux_symbol_list, name_occurrences = parse_nm_lines(vmlinux_nm_lines) > + > + if debug >= DebugLevel.INFO.value: > + print("kas_alias: Process nm data for modules") > + > + # Process nm data for modules > + module_list = fetch_file_lines(config.module_list) > + module_symbol_list = {} > + for module in module_list: > + module_nm_lines = do_nm(module, config.nm_file) > + module_symbol_list[module], name_occurrences = parse_nm_lines(module_nm_lines, name_occurrences) > + > + if debug >= DebugLevel.INFO.value: > + print("kas_alias: Produce file for vmlinux") > + > + # Produce file for vmlinux > + addr2line_process = start_addr2line_process(config.vmlinux_file, config.addr2line_file) > + produce_output_vmlinux(config, vmlinux_symbol_list, name_occurrences, addr2line_process) > + addr2line_process.stdin.close() > + addr2line_process.stdout.close() > + addr2line_process.stderr.close() > + addr2line_process.wait() > + > + # link-vmlinux.sh calls this two times: Avoid running kas_alias twice for efficiency and prevent duplicate aliases > + # in module processing by checking the last letter of the nm data file > + if config.vmlinux_file and config.vmlinux_file[-1] == '2': > + if debug >= DebugLevel.INFO.value: > + print("kas_alias: Add aliases to module files") > + > + # Add aliases to module files > + for module in module_list: > + addr2line_process = start_addr2line_process(module, config.addr2line_file) > + produce_output_modules(config, module_symbol_list[module], name_occurrences, module, addr2line_process) > + addr2line_process.stdin.close() > + addr2line_process.stdout.close() > + addr2line_process.stderr.close() > + addr2line_process.wait() > + else: > + if debug >= DebugLevel.INFO.value: > + print("kas_alias: Skip module processing if pass is not the second") > + > + > + except Exception as e: > + raise SystemExit(f"Script terminated due to an error: {e}") > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh > index a432b171be82..beb94f1f7961 100755 > --- a/scripts/link-vmlinux.sh > +++ b/scripts/link-vmlinux.sh > @@ -91,7 +91,12 @@ vmlinux_link() > > # The kallsyms linking does not need debug symbols included. > if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then > - ldflags="${ldflags} ${wl}--strip-debug" > + # The kallsyms linking does not need debug symbols included, > + # unless the KALLSYMS_ALIAS_SRCLINE. > + if ! is_enabled CONFIG_KALLSYMS_ALIAS_SRCLINE && \ > + [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then > + ldflags="${ldflags} ${wl}--strip-debug" > + fi > fi > > if is_enabled CONFIG_VMLINUX_MAP; then > @@ -161,7 +166,23 @@ kallsyms() > fi > > info KSYMS ${2} > - scripts/kallsyms ${kallsymopt} ${1} > ${2} > + ALIAS="" > + KAS_DATA="" > + if is_enabled CONFIG_KALLSYMS_ALIAS_SRCLINE_DATA; then > + KAS_DATA="--process_data" > + fi > + if is_enabled CONFIG_KALLSYMS_ALIAS_SRCLINE; then > + ALIAS=".alias" > + # You can use KAS_ALIAS_DEBUG=<debug level> in the make statements to enable > + # verbose execution for kas_alias. > + ${srctree}/scripts/kas_alias.py \ > + --addr2line ${ADDR2LINE} --vmlinux ${kallsyms_vmlinux} \ > + --nmdata ${1} --outfile ${1}${ALIAS} \ > + --modules_list ${MODORDER} --nm ${NM} --debug ${KAS_ALIAS_DEBUG:-0}\ > + --objdump ${OBJDUMP} --objcopy ${OBJCOPY} \ > + --basedir ${srctree} --separator @ ${KAS_DATA} > + fi > + scripts/kallsyms ${kallsymopt} ${1}${ALIAS} > ${2} > } > > # Perform one step in kallsyms generation, including temporary linking of > @@ -203,6 +224,7 @@ cleanup() > rm -f System.map > rm -f vmlinux > rm -f vmlinux.map > + find . -type f -name "*.orig" -exec rm {} \; > } > > # Use "make V=1" to debug this script > -- > 2.34.1 > -- Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
