On Thu, Sep 19, 2024 at 11:28:44PM +0900, Masahiro Yamada wrote: > Hi Kris, > > > > On Tue, Sep 10, 2024 at 4:43 AM Kris Van Hees <kris.van.hees@xxxxxxxxxx> wrote: > > > > On Sun, Sep 08, 2024 at 11:50:51AM +0900, Masahiro Yamada wrote: > > > On Fri, Sep 6, 2024 at 11:45???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 straight-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> > > > > Tested-by: Sam James <sam@xxxxxxxxxx> > > > > --- > > > > > > > > > If v10 is the final version, I offer to locally squash the following: > > > > Thanks! That would be great! v10 is indeed the final version (see bwlow). > > > > > diff --git a/.gitignore b/.gitignore > > > index c06a3ef6d6c6..625bf59ad845 100644 > > > --- a/.gitignore > > > +++ b/.gitignore > > > @@ -69,6 +69,7 @@ modules.order > > > /Module.markers > > > /modules.builtin > > > /modules.builtin.modinfo > > > +/modules.builtin.ranges > > > /modules.nsdeps > > > > > > # > > > diff --git a/Documentation/dontdiff b/Documentation/dontdiff > > > index 3c399f132e2d..a867aea95c40 100644 > > > --- a/Documentation/dontdiff > > > +++ b/Documentation/dontdiff > > > @@ -180,6 +180,7 @@ modpost > > > modules-only.symvers > > > modules.builtin > > > modules.builtin.modinfo > > > +modules.builtin.ranges > > > modules.nsdeps > > > modules.order > > > modversions.h* > > > > > If Sami reports more errors and you end up with v11, > > > please remember to fold it. > > > > Sami confirmed v10 [0]. Can you squash his reviewed-by and tested-by as well? > > > > Thanks for all the help! > > > > Kris > > > > [0] https://lore.kernel.org/lkml/20240909191801.GA398180@xxxxxxxxxx/ > > > > > > Can you please add a small explanation to > Documentation/kbuild/kbuild.rst ? > > > It documents modules.order, modules.builtin, modules.builtin.modinfo. > > Having modules.builtin.ranges there will keep the consistency. > > > > You do not need to re-submit the entire patch. > > If you provide a diff in a few days, > I will locally squash it. Thank you for offering to locally squash the diff. Kris diff --git a/Documentation/kbuild/kbuild.rst b/Documentation/kbuild/kbuild.rst index 9c8d1d046ea5..142be0c74761 100644 --- a/Documentation/kbuild/kbuild.rst +++ b/Documentation/kbuild/kbuild.rst @@ -22,6 +22,11 @@ modules.builtin.modinfo This file contains modinfo from all modules that are built into the kernel. Unlike modinfo of a separate module, all fields are prefixed with module name. +modules.builtin.ranges +---------------------- +This file contains address offset ranges (per ELF section) for all modules +that are built into the kernel. Together with System.map, it can be used +to associate module names with symbols. Environment variables =====================
