On Wed, Aug 21, 2024 at 1:11 PM Kris Van Hees <kris.van.hees@xxxxxxxxxx> wrote: > > Create file module.builtin.ranges that can be used to find where > built-in modules are located by their addresses. This will be useful for > tracing tools to find what functions are for various built-in modules. > > The offset range data for builtin modules is generated using: > - modules.builtin: associates object files with module names > - vmlinux.map: provides load order of sections and offset of first member > per section > - vmlinux.o.map: provides offset of object file content per section > - .*.cmd: build cmd file with KBUILD_MODFILE > > The generated data will look like: > > .text 00000000-00000000 = _text > .text 0000baf0-0000cb10 amd_uncore > .text 0009bd10-0009c8e0 iosf_mbi > ... > .text 00b9f080-00ba011a intel_skl_int3472_discrete > .text 00ba0120-00ba03c0 intel_skl_int3472_discrete intel_skl_int3472_tps68470 > .text 00ba03c0-00ba08d6 intel_skl_int3472_tps68470 > ... > .data 00000000-00000000 = _sdata > .data 0000f020-0000f680 amd_uncore > > For each ELF section, it lists the offset of the first symbol. This can > be used to determine the base address of the section at runtime. > > Next, it lists (in strict ascending order) offset ranges in that section > that cover the symbols of one or more builtin modules. Multiple ranges > can apply to a single module, and ranges can be shared between modules. > > The CONFIG_BUILTIN_MODULE_RANGES option controls whether offset range data > is generated for kernel modules that are built into the kernel image. > > How it works: > > 1. The modules.builtin file is parsed to obtain a list of built-in > module names and their associated object names (the .ko file that > the module would be in if it were a loadable module, hereafter > referred to as <kmodfile>). This object name can be used to > identify objects in the kernel compile because any C or assembler > code that ends up into a built-in module will have the option > -DKBUILD_MODFILE=<kmodfile> present in its build command, and those > can be found in the .<obj>.cmd file in the kernel build tree. > > If an object is part of multiple modules, they will all be listed > in the KBUILD_MODFILE option argument. > > This allows us to conclusively determine whether an object in the > kernel build belong to any modules, and which. > > 2. The vmlinux.map is parsed next to determine the base address of each > top level section so that all addresses into the section can be > turned into offsets. This makes it possible to handle sections > getting loaded at different addresses at system boot. > > We also determine an 'anchor' symbol at the beginning of each > section to make it possible to calculate the true base address of > a section at runtime (i.e. symbol address - symbol offset). > > We collect start addresses of sections that are included in the top > level section. This is used when vmlinux is linked using vmlinux.o, > because in that case, we need to look at the vmlinux.o linker map to > know what object a symbol is found in. > > And finally, we process each symbol that is listed in vmlinux.map > (or vmlinux.o.map) based on the following structure: > > vmlinux linked from vmlinux.a: > > vmlinux.map: > <top level section> > <included section> -- might be same as top level section) > <object> -- built-in association known > <symbol> -- belongs to module(s) object belongs to > ... > > vmlinux linked from vmlinux.o: > > vmlinux.map: > <top level section> > <included section> -- might be same as top level section) > vmlinux.o -- need to use vmlinux.o.map > <symbol> -- ignored > ... > > vmlinux.o.map: > <section> > <object> -- built-in association known > <symbol> -- belongs to module(s) object belongs to > ... > > 3. As sections, objects, and symbols are processed, offset ranges are > constructed in a striaght-forward way: > > - If the symbol belongs to one or more built-in modules: > - If we were working on the same module(s), extend the range > to include this object > - If we were working on another module(s), close that range, > and start the new one > - If the symbol does not belong to any built-in modules: > - If we were working on a module(s) range, close that range > > Signed-off-by: Kris Van Hees <kris.van.hees@xxxxxxxxxx> > Reviewed-by: Nick Alcock <nick.alcock@xxxxxxxxxx> > Reviewed-by: Alan Maguire <alan.maguire@xxxxxxxxxx> > Reviewed-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> > --- > Changes since v6: > - Applied Masahiro Yamada's suggestions (Kconfig, makefile, script). > > Changes since v5: > - Removed unnecessary compatibility info from option description. > > Changes since v4: > - Improved commit description to explain the why and how. > - Documented dependency on GNU AWK for CONFIG_BUILTIN_MODULE_RANGES. > - Improved comments in generate_builtin_ranges.awk > - Improved logic in generate_builtin_ranges.awk to handle incorrect > object size information in linker maps > > Changes since v3: > - Consolidated patches 2 through 5 into a single patch > - Move CONFIG_BUILTIN_MODULE_RANGES to Kconfig.debug > - Make CONFIG_BUILTIN_MODULE_RANGES select CONFIG_VMLINUX_MAP > - Disable CONFIG_BUILTIN_MODULE_RANGES if CONFIG_LTO_CLANG_(FULL|THIN)=y > - Support LLVM (lld) compiles in generate_builtin_ranges.awk > - Support CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=y > > Changes since v2: > - Add explicit dependency on FTRACE for CONFIG_BUILTIN_MODULE_RANGES > - 1st arg to generate_builtin_ranges.awk is now modules.builtin.modinfo > - Switched from using modules.builtin.objs to parsing .*.cmd files > - Parse data from .*.cmd in generate_builtin_ranges.awk > - Use $(real-prereqs) rather than $(filter-out ...) > --- > Documentation/process/changes.rst | 7 + > lib/Kconfig.debug | 16 + > scripts/Makefile.vmlinux | 18 + > scripts/Makefile.vmlinux_o | 3 + > scripts/generate_builtin_ranges.awk | 506 ++++++++++++++++++++++++++++ > 5 files changed, 550 insertions(+) > create mode 100755 scripts/generate_builtin_ranges.awk > > diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst > index 3fc63f27c226..00f1ed7c59c3 100644 > --- a/Documentation/process/changes.rst > +++ b/Documentation/process/changes.rst > @@ -64,6 +64,7 @@ GNU tar 1.28 tar --version > gtags (optional) 6.6.5 gtags --version > mkimage (optional) 2017.01 mkimage --version > Python (optional) 3.5.x python3 --version > +GNU AWK (optional) 5.1.0 gawk --version > ====================== =============== ======================================== > > .. [#f1] Sphinx is needed only to build the Kernel documentation > @@ -192,6 +193,12 @@ platforms. The tool is available via the ``u-boot-tools`` package or can be > built from the U-Boot source code. See the instructions at > https://docs.u-boot.org/en/latest/build/tools.html#building-tools-for-linux > > +GNU AWK > +------- > + > +GNU AWK is needed if you want kernel builds to generate address range data for > +builtin modules (CONFIG_BUILTIN_MODULE_RANGES). > + > System utilities > **************** > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index a30c03a66172..f087dc3da321 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -571,6 +571,22 @@ config VMLINUX_MAP > pieces of code get eliminated with > CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. > > +config BUILTIN_MODULE_RANGES > + bool "Generate address range information for builtin modules" > + depends on !LTO_CLANG_FULL > + depends on !LTO_CLANG_THIN Forgot to mention this. These two lines can be replaced with depends on !LTO > diff --git a/scripts/generate_builtin_ranges.awk b/scripts/generate_builtin_ranges.awk > new file mode 100755 > index 000000000000..865cb7ac4970 > --- /dev/null > +++ b/scripts/generate_builtin_ranges.awk > @@ -0,0 +1,506 @@ > +#!/usr/bin/gawk -f > +# SPDX-License-Identifier: GPL-2.0 > +# generate_builtin_ranges.awk: Generate address range data for builtin modules > +# Written by Kris Van Hees <kris.van.hees@xxxxxxxxxx> > +# > +# Usage: generate_builtin_ranges.awk modules.builtin vmlinux.map \ > +# vmlinux.o.map > modules.builtin.ranges > +# > + > +# Return the module name(s) (if any) associated with the given object. > +# > +# If we have seen this object before, return information from the cache. > +# Otherwise, retrieve it from the corresponding .cmd file. > +# > +function get_module_info(fn, mod, obj, s) { > + if (fn in omod) > + return omod[fn]; > + > + if (match(fn, /\/[^/]+$/) == 0) > + return ""; > + > + obj = fn; > + mod = ""; > + fn = substr(fn, 1, RSTART) "." substr(fn, RSTART + 1) ".cmd"; > + if (getline s <fn == 1) { > + if (match(s, /DKBUILD_MODFILE=['"]+[^'"]+/) > 0) { > + mod = substr(s, RSTART + 16, RLENGTH - 16); > + gsub(/['"]/, "", mod); > + } > + } > + close(fn); > + > + # A single module (common case) also reflects objects that are not part > + # of a module. Some of those objects have names that are also a module > + # name (e.g. core). We check the associated module file name, and if > + # they do not match, the object is not part of a module. > + if (mod !~ / /) { > + if (!(mod in mods)) > + mod = ""; > + } > + > + gsub(/([^/ ]*\/)+/, "", mod); > + gsub(/-/, "_", mod); > + > + # At this point, mod is a single (valid) module name, or a list of > + # module names (that do not need validation). > + omod[obj] = mod; > + close(fn); I still see the second close(fn). -- Best Regards Masahiro Yamada
