On Fri, Sep 20, 2024 at 2:07 AM Daniel Gomez <da.gomez@xxxxxxxxxxx> wrote: > > On Fri, Sep 06, 2024 at 10:45:03AM -0400, Kris Van Hees 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> > > --- > > > > Notes: > > Changes since v9: > > - Reverted support for build directory as optional 4th argument. > > - Added modules.builtin.ranges and vmlinux.o.map to CLEAN_FILES. > > - Fixed support for sparc64. > > > > Changes since v8: > > - Added support for built-in Rust modules. > > - Added optional 4th argument to specify kernel build directory. > > > > Changes since v7: > > - Removed extra close(fn). > > - Make CONFIG_BUILTIN_MODULE_RANGES depend on !lTO. > > > > 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 + > > Makefile | 1 + > > lib/Kconfig.debug | 15 + > > scripts/Makefile.vmlinux | 18 + > > scripts/Makefile.vmlinux_o | 3 + > > scripts/generate_builtin_ranges.awk | 508 ++++++++++++++++++++++++++++ > > 6 files changed, 552 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/Makefile b/Makefile > > index d57cfc6896b8..ec98a1e5b257 100644 > > --- a/Makefile > > +++ b/Makefile > > @@ -1482,6 +1482,7 @@ endif # CONFIG_MODULES > > # Directories & files removed with 'make clean' > > CLEAN_FILES += vmlinux.symvers modules-only.symvers \ > > modules.builtin modules.builtin.modinfo modules.nsdeps \ > > + modules.builtin.ranges vmlinux.o.map \ > > compile_commands.json rust/test \ > > rust-project.json .vmlinux.objs .vmlinux.export.c > > > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > > index a30c03a66172..5e2f30921cb2 100644 > > --- a/lib/Kconfig.debug > > +++ b/lib/Kconfig.debug > > @@ -571,6 +571,21 @@ 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 > > + depends on VMLINUX_MAP > > + help > > + When modules are built into the kernel, there will be no module name > > + associated with its symbols in /proc/kallsyms. Tracers may want to > > + identify symbols by module name and symbol name regardless of whether > > + the module is configured as loadable or not. > > + > > + This option generates modules.builtin.ranges in the build tree with > > + offset ranges (per ELF section) for the module(s) they belong to. > > + It also records an anchor symbol to determine the load address of the > > + section. > > + > > config DEBUG_FORCE_WEAK_PER_CPU > > bool "Force weak per-cpu definitions" > > depends on DEBUG_KERNEL > > diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux > > index 5ceecbed31eb..dfb408aa19c6 100644 > > --- a/scripts/Makefile.vmlinux > > +++ b/scripts/Makefile.vmlinux > > @@ -33,6 +33,24 @@ targets += vmlinux > > vmlinux: scripts/link-vmlinux.sh vmlinux.o $(KBUILD_LDS) FORCE > > +$(call if_changed_dep,link_vmlinux) > > > > +# module.builtin.ranges > > +# --------------------------------------------------------------------------- > > +ifdef CONFIG_BUILTIN_MODULE_RANGES > > +__default: modules.builtin.ranges > > + > > +quiet_cmd_modules_builtin_ranges = GEN $@ > > + cmd_modules_builtin_ranges = $(real-prereqs) > $@ > > + > > +targets += modules.builtin.ranges > > +modules.builtin.ranges: $(srctree)/scripts/generate_builtin_ranges.awk \ > > + modules.builtin vmlinux.map vmlinux.o.map FORCE > > + $(call if_changed,modules_builtin_ranges) > > + > > +vmlinux.map: vmlinux > > + @: > > + > > +endif > > + > > # Add FORCE to the prerequisites of a target to force it to be always rebuilt. > > # --------------------------------------------------------------------------- > > > > diff --git a/scripts/Makefile.vmlinux_o b/scripts/Makefile.vmlinux_o > > index d64070b6b4bc..0b6e2ebf60dc 100644 > > --- a/scripts/Makefile.vmlinux_o > > +++ b/scripts/Makefile.vmlinux_o > > @@ -45,9 +45,12 @@ objtool-args = $(vmlinux-objtool-args-y) --link > > # Link of vmlinux.o used for section mismatch analysis > > # --------------------------------------------------------------------------- > > > > +vmlinux-o-ld-args-$(CONFIG_BUILTIN_MODULE_RANGES) += -Map=$@.map > > + > > quiet_cmd_ld_vmlinux.o = LD $@ > > cmd_ld_vmlinux.o = \ > > $(LD) ${KBUILD_LDFLAGS} -r -o $@ \ > > + $(vmlinux-o-ld-args-y) \ > > $(addprefix -T , $(initcalls-lds)) \ > > --whole-archive vmlinux.a --no-whole-archive \ > > --start-group $(KBUILD_VMLINUX_LIBS) --end-group \ > > diff --git a/scripts/generate_builtin_ranges.awk b/scripts/generate_builtin_ranges.awk > > new file mode 100755 > > index 000000000000..b9ec761b3bef > > --- /dev/null > > +++ b/scripts/generate_builtin_ranges.awk > > @@ -0,0 +1,508 @@ > > +#!/usr/bin/gawk -f > > This forces the gawk to be found always in /usr/bin. For systems where gawk can > be located in other places, can we change the Shebang to: > > diff --git a/scripts/generate_builtin_ranges.awk b/scripts/generate_builtin_ranges.awk > index b9ec761b3bef..886251c8d3f7 100755 > --- a/scripts/generate_builtin_ranges.awk > +++ b/scripts/generate_builtin_ranges.awk > @@ -1,4 +1,4 @@ > -#!/usr/bin/gawk -f > +#!/usr/bin/env 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> No. We cannot fix it this way. I already pointed out this shebang issue. https://lore.kernel.org/lkml/CAK7LNASLc=ik9QdX4K_XuN=cg+1VcUBk-y5EnQEtOG+qOWaY=Q@xxxxxxxxxxxxxx/ I thought Kris would send a fix up, but perhaps people tend to be busy with LPC this week. > Not sure if it's too late? in that case I can send a patch to change this. I can locally fix it up. Kris agreed with this fix. diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux index dfb408aa19c6..1284f05555b9 100644 --- a/scripts/Makefile.vmlinux +++ b/scripts/Makefile.vmlinux @@ -39,7 +39,7 @@ ifdef CONFIG_BUILTIN_MODULE_RANGES __default: modules.builtin.ranges quiet_cmd_modules_builtin_ranges = GEN $@ - cmd_modules_builtin_ranges = $(real-prereqs) > $@ + cmd_modules_builtin_ranges = gawk -f $(real-prereqs) > $@ targets += modules.builtin.ranges modules.builtin.ranges: $(srctree)/scripts/generate_builtin_ranges.awk \ -- Best Regards Masahiro Yamada
