On Fri, Aug 16, 2024 at 12:04 AM Kris Van Hees <kris.van.hees@xxxxxxxxxx> wrote:
The subject should be:
"kbuild: generate offset range data for builtin modules"
(Drop ", kconfig")
>
> 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 and KBUILD_MODNAME
I do not see "KBUILD_MODNAME" in the code.
It only checks "KUILD_MODFILE".
>
> The generated data will look like:
>
> .text 00000000-00000000 = _text
> .text 0000baf0-0000cb10 amd_uncore
> .text 0009bd10-0009c8e0 iosf_mbi
> ...
> .text 008e6660-008e9630 snd_soc_wcd_mbhc
> .text 008e9630-008ea610 snd_soc_wcd9335 snd_soc_wcd934x snd_soc_wcd938x
It is good to note that multiple module names appear
in one line, but the instance (snd_soc_wcd933*) no longer
occurs since 11b0b802f8e38d48ca74d520028add81263f003e.
I recommend to replace the output snippet with:
.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
This still happens when CONFIG_INTEL_SKL_INT3472=y.
> .text 008ea610-008ea780 snd_soc_wcd9335
> ...
> .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 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 ...)
> ---
> System utilities
> index a30c03a66172..dcdf14ffe031 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
> + select VMLINUX_MAP
I still got
"WARNING: unmet direct dependencies detected for VMLINUX_MAP"
I suggested "depends on VMLINUX_MAP" instead of "select VMLINUX_MAP".
https://lore.kernel.org/linux-kbuild/202405150623.lmS5sVhM-lkp@xxxxxxxxx/
https://lore.kernel.org/linux-kbuild/CAK7LNAST_SbaN9WQRM_k0xE1MUReJvn9AMSg4A1-9b9xotf67w@xxxxxxxxxxxxxx/
> + 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 49946cb96844..7e21162e9de1 100644
> --- a/scripts/Makefile.vmlinux
> +++ b/scripts/Makefile.vmlinux
> @@ -33,6 +33,22 @@ 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 = \
> + $(srctree)/scripts/generate_builtin_ranges.awk $(real-prereqs) > $@
> +
> +vmlinux.map: vmlinux
This should be:
vmlinux.map: vmlinux
@:
Otherwise, GNU Make would try to find a pattern rule
to update vmlinux.map.
> +
> +targets += modules.builtin.ranges
> +modules.builtin.ranges: modules.builtin vmlinux.map vmlinux.o.map FORCE
> + $(call if_changed,modules_builtin_ranges)
Presumably, modules.builtin.ranges should be regenerated when
scripts/generate_builtin_ranges.awk is changed.
Maybe, you can do this:
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)
> +endif
> +
> # Add FORCE to the prequisites of a target to force it to be always rebuilt.
> # ---------------------------------------------------------------------------
>
> diff --git a/scripts/Makefile.vmlinux_o b/scripts/Makefile.vmlinux_o
> index 6de297916ce6..252505505e0e 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 $(KBUILD_VMLINUX_LIBS) --end-group \
> diff --git a/scripts/generate_builtin_ranges.awk b/scripts/generate_builtin_ranges.awk
> new file mode 100755
> index 000000000000..9b647781d5fe
> --- /dev/null
> +++ b/scripts/generate_builtin_ranges.awk
> @@ -0,0 +1,515 @@
> +#!/usr/bin/gawk -f
> +# SPDX-License-Identifier: GPL-2.0
> +# generate_builtin_ranges.awk: Generate address range data for builtin modules
> +# Written by Kris Van Hees <kris.van.hees@xxxxxxxxxx>
> +#
> +# Usage: generate_builtin_ranges.awk modules.builtin vmlinux.map \
> +# vmlinux.o.map > modules.builtin.ranges
> +#
> +
> +# Return the module name(s) (if any) associated with the given object.
> +#
> +# If we have seen this object before, return information from the cache.
> +# Otherwise, retrieve it from the corresponding .cmd file.
> +#
> +function get_module_info(fn, mod, obj, mfn, s) {
> + if (fn in omod)
> + return omod[fn];
> +
> + if (match(fn, /\/[^/]+$/) == 0)
> + return "";
> +
> + obj = fn;
> + mod = "";
> + mfn = "";
> + fn = substr(fn, 1, RSTART) "." substr(fn, RSTART + 1) ".cmd";
> + if (getline s <fn == 1) {
> + if (match(s, /DKBUILD_MODFILE=['"]+[^'"]+/) > 0) {
> + mfn = substr(s, RSTART + 16, RLENGTH - 16);
> + gsub(/['"]/, "", mfn);
> +
> + mod = mfn;
> + gsub(/([^/ ]*\/)+/, "", mod);
> + 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 = "";
> + if (mods[mod] != mfn)
> + 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);
Is this "close(fn)" necessary?
I see it a few lines above too.
The code became way simpler since my previous review, but
I think this is still redundant.
You do not need to check both of modname and its path.
I attached a patch for code refactoring.
--
Best Regards
Masahiro Yamada
From fcdc459ce4c7eb84549e45cf06a3a44f90aa3cf9 Mon Sep 17 00:00:00 2001
From: Masahiro Yamada <masahiroy@xxxxxxxxxx>
Date: Fri, 16 Aug 2024 23:55:51 +0900
Subject: [PATCH] fixup modules.builtin.ranges
Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
---
lib/Kconfig.debug | 2 +-
scripts/Makefile.vmlinux | 12 +++++++-----
scripts/generate_builtin_ranges.awk | 25 ++++++++-----------------
3 files changed, 16 insertions(+), 23 deletions(-)
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index dcdf14ffe031..f087dc3da321 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -575,7 +575,7 @@ config BUILTIN_MODULE_RANGES
bool "Generate address range information for builtin modules"
depends on !LTO_CLANG_FULL
depends on !LTO_CLANG_THIN
- select VMLINUX_MAP
+ 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
diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux
index 7e21162e9de1..7e8b703799c8 100644
--- a/scripts/Makefile.vmlinux
+++ b/scripts/Makefile.vmlinux
@@ -39,14 +39,16 @@ ifdef CONFIG_BUILTIN_MODULE_RANGES
__default: modules.builtin.ranges
quiet_cmd_modules_builtin_ranges = GEN $@
- cmd_modules_builtin_ranges = \
- $(srctree)/scripts/generate_builtin_ranges.awk $(real-prereqs) > $@
-
-vmlinux.map: vmlinux
+ cmd_modules_builtin_ranges = $(real-prereqs) > $@
targets += modules.builtin.ranges
-modules.builtin.ranges: modules.builtin vmlinux.map vmlinux.o.map FORCE
+modules.builtin.ranges: $(srctree)/scripts/generate_builtin_ranges.awk \
+ modules.builtin vmlinux.map vmlinux.o.map FORCE
$(call if_changed,modules_builtin_ranges)
+
+vmlinux.map: vmlinux
+ @:
+
endif
# Add FORCE to the prequisites of a target to force it to be always rebuilt.
diff --git a/scripts/generate_builtin_ranges.awk b/scripts/generate_builtin_ranges.awk
index 9b647781d5fe..865cb7ac4970 100755
--- a/scripts/generate_builtin_ranges.awk
+++ b/scripts/generate_builtin_ranges.awk
@@ -12,7 +12,7 @@
# If we have seen this object before, return information from the cache.
# Otherwise, retrieve it from the corresponding .cmd file.
#
-function get_module_info(fn, mod, obj, mfn, s) {
+function get_module_info(fn, mod, obj, s) {
if (fn in omod)
return omod[fn];
@@ -21,16 +21,11 @@ function get_module_info(fn, mod, obj, mfn, s) {
obj = fn;
mod = "";
- mfn = "";
fn = substr(fn, 1, RSTART) "." substr(fn, RSTART + 1) ".cmd";
if (getline s <fn == 1) {
if (match(s, /DKBUILD_MODFILE=['"]+[^'"]+/) > 0) {
- mfn = substr(s, RSTART + 16, RLENGTH - 16);
- gsub(/['"]/, "", mfn);
-
- mod = mfn;
- gsub(/([^/ ]*\/)+/, "", mod);
- gsub(/-/, "_", mod);
+ mod = substr(s, RSTART + 16, RLENGTH - 16);
+ gsub(/['"]/, "", mod);
}
}
close(fn);
@@ -42,10 +37,11 @@ function get_module_info(fn, mod, obj, mfn, s) {
if (mod !~ / /) {
if (!(mod in mods))
mod = "";
- if (mods[mod] != mfn)
- mod = "";
}
+ gsub(/([^/ ]*\/)+/, "", mod);
+ gsub(/-/, "_", mod);
+
# At this point, mod is a single (valid) module name, or a list of
# module names (that do not need validation).
omod[obj] = mod;
@@ -76,18 +72,13 @@ function update_entry(osect, mod, soff, eoff, sect, idx) {
#
# Lines will be like:
# kernel/crypto/lzo-rle.ko
-# and we derive the built-in module name from this as "lzo_rle" and associate
-# it with object name "crypto/lzo-rle".
+# and we record the object name "crypto/lzo-rle".
#
ARGIND == 1 {
sub(/kernel\//, ""); # strip off "kernel/" prefix
sub(/\.ko$/, ""); # strip off .ko suffix
- mod = $1;
- sub(/([^/]*\/)+/, "", mod); # mod = basename($1)
- gsub(/-/, "_", mod); # Convert - to _
-
- mods[mod] = $1;
+ mods[$1] = 1;
next;
}
--
2.43.0
