From 0ce5139fd96e9d415d3faaef1c575e238f9bbd67 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Thu, 18 Sep 2025 10:05:46 +0200 Subject: kbuild: always create intermediate vmlinux.unstripped Generate the intermediate vmlinux.unstripped regardless of CONFIG_ARCH_VMLINUX_NEEDS_RELOCS. If CONFIG_ARCH_VMLINUX_NEEDS_RELOCS is unset, vmlinux.unstripped and vmlinux are identiacal. This simplifies the build rule, and allows to strip more sections by adding them to remove-section-y. Signed-off-by: Masahiro Yamada Reviewed-by: Nicolas Schier Link: https://patch.msgid.link/a48ca543fa2305bd17324f41606dcaed9b19f2d4.1758182101.git.legion@kernel.org Signed-off-by: Nathan Chancellor --- scripts/Makefile.vmlinux | 45 ++++++++++++++++++++++----------------------- 1 file changed, 22 insertions(+), 23 deletions(-) (limited to 'scripts/Makefile.vmlinux') diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux index b64862dc6f08..4f2d4c3fb737 100644 --- a/scripts/Makefile.vmlinux +++ b/scripts/Makefile.vmlinux @@ -9,20 +9,6 @@ include $(srctree)/scripts/Makefile.lib targets := -ifdef CONFIG_ARCH_VMLINUX_NEEDS_RELOCS -vmlinux-final := vmlinux.unstripped - -quiet_cmd_strip_relocs = RSTRIP $@ - cmd_strip_relocs = $(OBJCOPY) --remove-section='.rel*' --remove-section=!'.rel*.dyn' $< $@ - -vmlinux: $(vmlinux-final) FORCE - $(call if_changed,strip_relocs) - -targets += vmlinux -else -vmlinux-final := vmlinux -endif - %.o: %.c FORCE $(call if_changed_rule,cc_o_c) @@ -61,19 +47,19 @@ targets += .builtin-dtbs-list ifdef CONFIG_GENERIC_BUILTIN_DTB targets += .builtin-dtbs.S .builtin-dtbs.o -$(vmlinux-final): .builtin-dtbs.o +vmlinux.unstripped: .builtin-dtbs.o endif -# vmlinux +# vmlinux.unstripped # --------------------------------------------------------------------------- ifdef CONFIG_MODULES targets += .vmlinux.export.o -$(vmlinux-final): .vmlinux.export.o +vmlinux.unstripped: .vmlinux.export.o endif ifdef CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX -$(vmlinux-final): arch/$(SRCARCH)/tools/vmlinux.arch.o +vmlinux.unstripped: arch/$(SRCARCH)/tools/vmlinux.arch.o arch/$(SRCARCH)/tools/vmlinux.arch.o: vmlinux.o FORCE $(Q)$(MAKE) $(build)=arch/$(SRCARCH)/tools $@ @@ -86,17 +72,30 @@ cmd_link_vmlinux = \ $< "$(LD)" "$(KBUILD_LDFLAGS)" "$(LDFLAGS_vmlinux)" "$@"; \ $(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true) -targets += $(vmlinux-final) -$(vmlinux-final): scripts/link-vmlinux.sh vmlinux.o $(KBUILD_LDS) FORCE +targets += vmlinux.unstripped +vmlinux.unstripped: scripts/link-vmlinux.sh vmlinux.o $(KBUILD_LDS) FORCE +$(call if_changed_dep,link_vmlinux) ifdef CONFIG_DEBUG_INFO_BTF -$(vmlinux-final): $(RESOLVE_BTFIDS) +vmlinux.unstripped: $(RESOLVE_BTFIDS) endif ifdef CONFIG_BUILDTIME_TABLE_SORT -$(vmlinux-final): scripts/sorttable +vmlinux.unstripped: scripts/sorttable endif +# vmlinux +# --------------------------------------------------------------------------- + +remove-section-y := +remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel*' + +quiet_cmd_strip_relocs = OBJCOPY $@ + cmd_strip_relocs = $(OBJCOPY) $(addprefix --remove-section=,$(remove-section-y)) $< $@ + +targets += vmlinux +vmlinux: vmlinux.unstripped FORCE + $(call if_changed,strip_relocs) + # modules.builtin.ranges # --------------------------------------------------------------------------- ifdef CONFIG_BUILTIN_MODULE_RANGES @@ -110,7 +109,7 @@ 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-final) +vmlinux.map: vmlinux.unstripped @: endif -- cgit v1.2.3 From 3e86e4d74c0490e5fc5a7f8de8f29e7579c9ffe5 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Thu, 18 Sep 2025 10:05:47 +0200 Subject: kbuild: keep .modinfo section in vmlinux.unstripped Keep the .modinfo section during linking, but strip it from the final vmlinux. Adjust scripts/mksysmap to exclude modinfo symbols from kallsyms. This change will allow the next commit to extract the .modinfo section from the vmlinux.unstripped intermediate. Signed-off-by: Masahiro Yamada Signed-off-by: Alexey Gladkov Reviewed-by: Nicolas Schier Link: https://patch.msgid.link/aaf67c07447215463300fccaa758904bac42f992.1758182101.git.legion@kernel.org Signed-off-by: Nathan Chancellor --- include/asm-generic/vmlinux.lds.h | 2 +- scripts/Makefile.vmlinux | 7 +++++-- scripts/mksysmap | 3 +++ 3 files changed, 9 insertions(+), 3 deletions(-) (limited to 'scripts/Makefile.vmlinux') diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index ae2d2359b79e..cfa63860dfd4 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -831,6 +831,7 @@ defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG) /* Required sections not related to debugging. */ #define ELF_DETAILS \ + .modinfo : { *(.modinfo) } \ .comment 0 : { *(.comment) } \ .symtab 0 : { *(.symtab) } \ .strtab 0 : { *(.strtab) } \ @@ -1044,7 +1045,6 @@ defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG) *(.discard.*) \ *(.export_symbol) \ *(.no_trim_symbol) \ - *(.modinfo) \ /* ld.bfd warns about .gnu.version* even when not emitted */ \ *(.gnu.version*) \ diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux index 4f2d4c3fb737..70856dab0f54 100644 --- a/scripts/Makefile.vmlinux +++ b/scripts/Makefile.vmlinux @@ -86,11 +86,14 @@ endif # vmlinux # --------------------------------------------------------------------------- -remove-section-y := +remove-section-y := .modinfo remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel*' +# To avoid warnings: "empty loadable segment detected at ..." from GNU objcopy, +# it is necessary to remove the PT_LOAD flag from the segment. quiet_cmd_strip_relocs = OBJCOPY $@ - cmd_strip_relocs = $(OBJCOPY) $(addprefix --remove-section=,$(remove-section-y)) $< $@ + cmd_strip_relocs = $(OBJCOPY) $(patsubst %,--set-section-flags %=noload,$(remove-section-y)) $< $@; \ + $(OBJCOPY) $(addprefix --remove-section=,$(remove-section-y)) $@ targets += vmlinux vmlinux: vmlinux.unstripped FORCE diff --git a/scripts/mksysmap b/scripts/mksysmap index 3accbdb269ac..a607a0059d11 100755 --- a/scripts/mksysmap +++ b/scripts/mksysmap @@ -79,6 +79,9 @@ / _SDA_BASE_$/d / _SDA2_BASE_$/d +# MODULE_INFO() +/ __UNIQUE_ID_modinfo[0-9]*$/d + # --------------------------------------------------------------------------- # Ignored patterns # (symbols that contain the pattern are ignored) -- cgit v1.2.3 From 39cfd5b12160be4f57df1c3ba60139741c827616 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Thu, 18 Sep 2025 10:05:48 +0200 Subject: kbuild: extract modules.builtin.modinfo from vmlinux.unstripped Currently, we assume all the data for modules.builtin.modinfo are available in vmlinux.o. This makes it impossible for modpost, which is invoked after vmlinux.o, to add additional module info. This commit moves the modules.builtin.modinfo rule after modpost. Signed-off-by: Masahiro Yamada Signed-off-by: Alexey Gladkov Reviewed-by: Nicolas Schier Link: https://patch.msgid.link/cdb3e5b9a739666b755cd0097dc34ab69c350e51.1758182101.git.legion@kernel.org Signed-off-by: Nathan Chancellor --- scripts/Makefile.vmlinux | 26 ++++++++++++++++++++++++++ scripts/Makefile.vmlinux_o | 26 +------------------------- 2 files changed, 27 insertions(+), 25 deletions(-) (limited to 'scripts/Makefile.vmlinux') diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux index 70856dab0f54..ce7946171497 100644 --- a/scripts/Makefile.vmlinux +++ b/scripts/Makefile.vmlinux @@ -99,6 +99,32 @@ targets += vmlinux vmlinux: vmlinux.unstripped FORCE $(call if_changed,strip_relocs) +# modules.builtin.modinfo +# --------------------------------------------------------------------------- + +OBJCOPYFLAGS_modules.builtin.modinfo := -j .modinfo -O binary + +targets += modules.builtin.modinfo +modules.builtin.modinfo: vmlinux.unstripped FORCE + $(call if_changed,objcopy) + +# modules.builtin +# --------------------------------------------------------------------------- + +__default: modules.builtin + +# The second line aids cases where multiple modules share the same object. + +quiet_cmd_modules_builtin = GEN $@ + cmd_modules_builtin = \ + tr '\0' '\n' < $< | \ + sed -n 's/^[[:alnum:]:_]*\.file=//p' | \ + tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$$/.ko/' > $@ + +targets += modules.builtin +modules.builtin: modules.builtin.modinfo FORCE + $(call if_changed,modules_builtin) + # modules.builtin.ranges # --------------------------------------------------------------------------- ifdef CONFIG_BUILTIN_MODULE_RANGES diff --git a/scripts/Makefile.vmlinux_o b/scripts/Makefile.vmlinux_o index b024ffb3e201..23c8751285d7 100644 --- a/scripts/Makefile.vmlinux_o +++ b/scripts/Makefile.vmlinux_o @@ -1,7 +1,7 @@ # SPDX-License-Identifier: GPL-2.0-only PHONY := __default -__default: vmlinux.o modules.builtin.modinfo modules.builtin +__default: vmlinux.o include include/config/auto.conf include $(srctree)/scripts/Kbuild.include @@ -73,30 +73,6 @@ vmlinux.o: $(initcalls-lds) vmlinux.a $(KBUILD_VMLINUX_LIBS) FORCE targets += vmlinux.o -# modules.builtin.modinfo -# --------------------------------------------------------------------------- - -OBJCOPYFLAGS_modules.builtin.modinfo := -j .modinfo -O binary - -targets += modules.builtin.modinfo -modules.builtin.modinfo: vmlinux.o FORCE - $(call if_changed,objcopy) - -# modules.builtin -# --------------------------------------------------------------------------- - -# The second line aids cases where multiple modules share the same object. - -quiet_cmd_modules_builtin = GEN $@ - cmd_modules_builtin = \ - tr '\0' '\n' < $< | \ - sed -n 's/^[[:alnum:]:_]*\.file=//p' | \ - tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$$/.ko/' > $@ - -targets += modules.builtin -modules.builtin: modules.builtin.modinfo FORCE - $(call if_changed,modules_builtin) - # Add FORCE to the prerequisites of a target to force it to be always rebuilt. # --------------------------------------------------------------------------- -- cgit v1.2.3 From 5ab23c7923a1d2ae1890026866a2d8506b010a4a Mon Sep 17 00:00:00 2001 From: Alexey Gladkov Date: Thu, 18 Sep 2025 10:05:51 +0200 Subject: modpost: Create modalias for builtin modules For some modules, modalias is generated using the modpost utility and the section is added to the module file. When a module is added inside vmlinux, modpost does not generate modalias for such modules and the information is lost. As a result kmod (which uses modules.builtin.modinfo in userspace) cannot determine that modalias is handled by a builtin kernel module. $ cat /sys/devices/pci0000:00/0000:00:14.0/modalias pci:v00008086d0000A36Dsv00001043sd00008694bc0Csc03i30 $ modinfo xhci_pci name: xhci_pci filename: (builtin) license: GPL file: drivers/usb/host/xhci-pci description: xHCI PCI Host Controller Driver Missing modalias "pci:v*d*sv*sd*bc0Csc03i30*" which will be generated by modpost if the module is built separately. To fix this it is necessary to generate the same modalias for vmlinux as for the individual modules. Fortunately '.vmlinux.export.o' is already generated from which '.modinfo' can be extracted in the same way as for vmlinux.o. Signed-off-by: Masahiro Yamada Signed-off-by: Alexey Gladkov Tested-by: Stephen Rothwell Reviewed-by: Nicolas Schier Link: https://patch.msgid.link/28d4da3b0e3fc8474142746bcf469e03752c3208.1758182101.git.legion@kernel.org Signed-off-by: Nathan Chancellor --- include/linux/module.h | 4 ---- scripts/Makefile.vmlinux | 4 +++- scripts/mksysmap | 3 +++ scripts/mod/file2alias.c | 19 ++++++++++++++++++- scripts/mod/modpost.c | 15 +++++++++++++++ scripts/mod/modpost.h | 2 ++ 6 files changed, 41 insertions(+), 6 deletions(-) (limited to 'scripts/Makefile.vmlinux') diff --git a/include/linux/module.h b/include/linux/module.h index e31ee29fac6b..e135cc79acee 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -256,14 +256,10 @@ struct module_kobject *lookup_or_create_module_kobject(const char *name); __PASTE(type, \ __PASTE(__, name))))) -#ifdef MODULE /* Creates an alias so file2alias.c can find device table. */ #define MODULE_DEVICE_TABLE(type, name) \ static typeof(name) __mod_device_table(type, name) \ __attribute__ ((used, alias(__stringify(name)))) -#else /* !MODULE */ -#define MODULE_DEVICE_TABLE(type, name) -#endif /* Version of form [:][-]. * Or for CVS/RCS ID version, everything but the number is stripped. diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux index ce7946171497..1e5e37aadcd0 100644 --- a/scripts/Makefile.vmlinux +++ b/scripts/Makefile.vmlinux @@ -89,11 +89,13 @@ endif remove-section-y := .modinfo remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel*' +remove-symbols := -w --strip-symbol='__mod_device_table__*' + # To avoid warnings: "empty loadable segment detected at ..." from GNU objcopy, # it is necessary to remove the PT_LOAD flag from the segment. quiet_cmd_strip_relocs = OBJCOPY $@ cmd_strip_relocs = $(OBJCOPY) $(patsubst %,--set-section-flags %=noload,$(remove-section-y)) $< $@; \ - $(OBJCOPY) $(addprefix --remove-section=,$(remove-section-y)) $@ + $(OBJCOPY) $(addprefix --remove-section=,$(remove-section-y)) $(remove-symbols) $@ targets += vmlinux vmlinux: vmlinux.unstripped FORCE diff --git a/scripts/mksysmap b/scripts/mksysmap index a607a0059d11..c4531eacde20 100755 --- a/scripts/mksysmap +++ b/scripts/mksysmap @@ -59,6 +59,9 @@ # EXPORT_SYMBOL (namespace) / __kstrtabns_/d +# MODULE_DEVICE_TABLE (symbol name) +/ __mod_device_table__/d + # --------------------------------------------------------------------------- # Ignored suffixes # (do not forget '$' after each pattern) diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c index 1260bc2287fb..7da9735e7ab3 100644 --- a/scripts/mod/file2alias.c +++ b/scripts/mod/file2alias.c @@ -1477,7 +1477,7 @@ void handle_moddevtable(struct module *mod, struct elf_info *info, void *symval; char *zeros = NULL; const char *type, *name, *modname; - size_t typelen; + size_t typelen, modnamelen; static const char *prefix = "__mod_device_table__"; /* We're looking for a section relative symbol */ @@ -1500,6 +1500,7 @@ void handle_moddevtable(struct module *mod, struct elf_info *info, type = strstr(modname, "__"); if (!type) return; + modnamelen = type - modname; type += strlen("__"); name = strstr(type, "__"); @@ -1526,5 +1527,21 @@ void handle_moddevtable(struct module *mod, struct elf_info *info, } } + if (mod->is_vmlinux) { + struct module_alias *alias; + + /* + * If this is vmlinux, record the name of the builtin module. + * Traverse the linked list in the reverse order, and set the + * builtin_modname unless it has already been set in the + * previous call. + */ + list_for_each_entry_reverse(alias, &mod->aliases, node) { + if (alias->builtin_modname) + break; + alias->builtin_modname = xstrndup(modname, modnamelen); + } + } + free(zeros); } diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 5ca7c268294e..47c8aa2a6939 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -2067,11 +2067,26 @@ static void write_if_changed(struct buffer *b, const char *fname) static void write_vmlinux_export_c_file(struct module *mod) { struct buffer buf = { }; + struct module_alias *alias, *next; buf_printf(&buf, "#include \n"); add_exported_symbols(&buf, mod); + + buf_printf(&buf, + "#include \n" + "#undef __MODULE_INFO_PREFIX\n" + "#define __MODULE_INFO_PREFIX\n"); + + list_for_each_entry_safe(alias, next, &mod->aliases, node) { + buf_printf(&buf, "MODULE_INFO(%s.alias, \"%s\");\n", + alias->builtin_modname, alias->str); + list_del(&alias->node); + free(alias->builtin_modname); + free(alias); + } + write_if_changed(&buf, ".vmlinux.export.c"); free(buf.p); } diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h index 9133e4c3803f..2aecb8f25c87 100644 --- a/scripts/mod/modpost.h +++ b/scripts/mod/modpost.h @@ -99,10 +99,12 @@ buf_write(struct buffer *buf, const char *s, int len); * struct module_alias - auto-generated MODULE_ALIAS() * * @node: linked to module::aliases + * @modname: name of the builtin module (only for vmlinux) * @str: a string for MODULE_ALIAS() */ struct module_alias { struct list_head node; + char *builtin_modname; char str[]; }; -- cgit v1.2.3 From 3328d39a8dca2d6ed27197a0025df7540b99adf2 Mon Sep 17 00:00:00 2001 From: Alexey Gladkov Date: Thu, 18 Sep 2025 10:05:52 +0200 Subject: kbuild: vmlinux.unstripped should always depend on .vmlinux.export.o Since .vmlinux.export.c is used to add generated by modpost modaliases for builtin modules the .vmlinux.export.o is no longer optional and should always be created. The generation of this file is not dependent on CONFIG_MODULES. Signed-off-by: Alexey Gladkov Reviewed-by: Nicolas Schier Link: https://patch.msgid.link/0e63a9c7741fe8217e4fd7c60afcf057ffa2ef5a.1758182101.git.legion@kernel.org Signed-off-by: Nathan Chancellor --- scripts/Makefile.vmlinux | 9 ++------- scripts/link-vmlinux.sh | 5 +---- 2 files changed, 3 insertions(+), 11 deletions(-) (limited to 'scripts/Makefile.vmlinux') diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux index 1e5e37aadcd0..7c6ae9886f8f 100644 --- a/scripts/Makefile.vmlinux +++ b/scripts/Makefile.vmlinux @@ -53,11 +53,6 @@ endif # vmlinux.unstripped # --------------------------------------------------------------------------- -ifdef CONFIG_MODULES -targets += .vmlinux.export.o -vmlinux.unstripped: .vmlinux.export.o -endif - ifdef CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX vmlinux.unstripped: arch/$(SRCARCH)/tools/vmlinux.arch.o @@ -72,8 +67,8 @@ cmd_link_vmlinux = \ $< "$(LD)" "$(KBUILD_LDFLAGS)" "$(LDFLAGS_vmlinux)" "$@"; \ $(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true) -targets += vmlinux.unstripped -vmlinux.unstripped: scripts/link-vmlinux.sh vmlinux.o $(KBUILD_LDS) FORCE +targets += vmlinux.unstripped .vmlinux.export.o +vmlinux.unstripped: scripts/link-vmlinux.sh vmlinux.o .vmlinux.export.o $(KBUILD_LDS) FORCE +$(call if_changed_dep,link_vmlinux) ifdef CONFIG_DEBUG_INFO_BTF vmlinux.unstripped: $(RESOLVE_BTFIDS) diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index 51367c2bfc21..433849ff7529 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -73,10 +73,7 @@ vmlinux_link() objs="${objs} .builtin-dtbs.o" fi - if is_enabled CONFIG_MODULES; then - objs="${objs} .vmlinux.export.o" - fi - + objs="${objs} .vmlinux.export.o" objs="${objs} init/version-timestamp.o" if [ "${SRCARCH}" = "um" ]; then -- cgit v1.2.3 From 4b47a3aefb29c523ca66f0d28de8db15a10f9352 Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Wed, 8 Oct 2025 15:46:44 -0700 Subject: kbuild: Restore pattern to avoid stripping .rela.dyn from vmlinux Commit 0ce5139fd96e ("kbuild: always create intermediate vmlinux.unstripped") removed the pattern to avoid stripping .rela.dyn sections added by commit e9d86b8e17e7 ("scripts: Do not strip .rela.dyn section"). Restore it so that .rela.dyn sections remain in the final vmlinux. Fixes: 0ce5139fd96e ("kbuild: always create intermediate vmlinux.unstripped") Acked-by: Ard Biesheuvel Acked-by: Alexey Gladkov Acked-by: Nicolas Schier Link: https://patch.msgid.link/20251008-kbuild-fix-modinfo-regressions-v1-1-9fc776c5887c@kernel.org Signed-off-by: Nathan Chancellor --- scripts/Makefile.vmlinux | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'scripts/Makefile.vmlinux') diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux index 7c6ae9886f8f..a62639982be5 100644 --- a/scripts/Makefile.vmlinux +++ b/scripts/Makefile.vmlinux @@ -82,7 +82,7 @@ endif # --------------------------------------------------------------------------- remove-section-y := .modinfo -remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel*' +remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel*' '!.rel*.dyn' remove-symbols := -w --strip-symbol='__mod_device_table__*' -- cgit v1.2.3 From 8ec3af916fe3954381cf3555ea03dc5adf4d0e8e Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Wed, 8 Oct 2025 15:46:45 -0700 Subject: kbuild: Add '.rel.*' strip pattern for vmlinux Prior to binutils commit c12d9fa2afe ("Support objcopy --remove-section=.relaFOO") [1] in 2.32, stripping relocation sections required the trailing period (i.e., '.rel.*') to work properly. After commit 3e86e4d74c04 ("kbuild: keep .modinfo section in vmlinux.unstripped"), there is an error with binutils 2.31.1 or earlier because these sections are not properly removed: s390-linux-objcopy: st6tO8Ev: symbol `.modinfo' required but not present s390-linux-objcopy:st6tO8Ev: no symbols Add the old pattern to resolve this issue (along with a comment to allow cleaning this when binutils 2.32 or newer is the minimum supported version). While the aforementioned kbuild change exposes this, the pattern was originally changed by commit 71d815bf5dfd ("kbuild: Strip runtime const RELA sections correctly"), where it would still be incorrect with binutils older than 2.32. Fixes: 71d815bf5dfd ("kbuild: Strip runtime const RELA sections correctly") Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=c12d9fa2afe7abcbe407a00e15719e1a1350c2a7 [1] Reported-by: Linux Kernel Functional Testing Closes: https://lore.kernel.org/CA+G9fYvVktRhFtZXdNgVOL8j+ArsJDpvMLgCitaQvQmCx=hwOQ@mail.gmail.com/ Acked-by: Ard Biesheuvel Acked-by: Alexey Gladkov Acked-by: Nicolas Schier Link: https://patch.msgid.link/20251008-kbuild-fix-modinfo-regressions-v1-2-9fc776c5887c@kernel.org Signed-off-by: Nathan Chancellor --- scripts/Makefile.vmlinux | 3 +++ 1 file changed, 3 insertions(+) (limited to 'scripts/Makefile.vmlinux') diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux index a62639982be5..c02f85c2e241 100644 --- a/scripts/Makefile.vmlinux +++ b/scripts/Makefile.vmlinux @@ -83,6 +83,9 @@ endif remove-section-y := .modinfo remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel*' '!.rel*.dyn' +# for compatibility with binutils < 2.32 +# https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=c12d9fa2afe7abcbe407a00e15719e1a1350c2a7 +remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel.*' remove-symbols := -w --strip-symbol='__mod_device_table__*' -- cgit v1.2.3 From b0f2942a16017f88395d768afedd7373860968ce Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Fri, 10 Oct 2025 14:49:27 -0700 Subject: kbuild: Use '--strip-unneeded-symbol' for removing module device table symbols After commit 5ab23c7923a1 ("modpost: Create modalias for builtin modules"), relocatable RISC-V kernels with CONFIG_KASAN=y start failing when attempting to strip the module device table symbols: riscv64-linux-objcopy: not stripping symbol `__mod_device_table__kmod_irq_starfive_jh8100_intc__of__starfive_intc_irqchip_match_table' because it is named in a relocation make[4]: *** [scripts/Makefile.vmlinux:97: vmlinux] Error 1 The relocation appears to come from .LASANLOC5 in .data.rel.local: $ llvm-objdump --disassemble-symbols=.LASANLOC5 --disassemble-all -r drivers/irqchip/irq-starfive-jh8100-intc.o drivers/irqchip/irq-starfive-jh8100-intc.o: file format elf64-littleriscv Disassembly of section .data.rel.local: 0000000000000180 <.LASANLOC5>: ... 1d0: 0000 unimp 00000000000001d0: R_RISCV_64 __mod_device_table__kmod_irq_starfive_jh8100_intc__of__starfive_intc_irqchip_match_table ... This section appears to come from GCC for including additional information about global variables that may be protected by KASAN. There appears to be no way to opt out of the generation of these symbols through either a flag or attribute. Attempting to remove '.LASANLOC*' with '--strip-symbol' results in the same error as above because these symbols may refer to (thus have relocation between) each other. Avoid this build breakage by switching to '--strip-unneeded-symbol' for removing __mod_device_table__ symbols, as it will only remove the symbol when there is no relocation pointing to it. While this may result in a little more bloat in the symbol table in certain configurations, it is not as bad as outright build failures. Fixes: 5ab23c7923a1 ("modpost: Create modalias for builtin modules") Reported-by: Charles Mirabile Closes: https://lore.kernel.org/20251007011637.2512413-1-cmirabil@redhat.com/ Suggested-by: Alexey Gladkov Tested-by: Nicolas Schier Signed-off-by: Nathan Chancellor --- scripts/Makefile.vmlinux | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'scripts/Makefile.vmlinux') diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux index c02f85c2e241..ced4379550d7 100644 --- a/scripts/Makefile.vmlinux +++ b/scripts/Makefile.vmlinux @@ -87,7 +87,7 @@ remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel*' '!.rel*.dyn' # https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=c12d9fa2afe7abcbe407a00e15719e1a1350c2a7 remove-section-$(CONFIG_ARCH_VMLINUX_NEEDS_RELOCS) += '.rel.*' -remove-symbols := -w --strip-symbol='__mod_device_table__*' +remove-symbols := -w --strip-unneeded-symbol='__mod_device_table__*' # To avoid warnings: "empty loadable segment detected at ..." from GNU objcopy, # it is necessary to remove the PT_LOAD flag from the segment. -- cgit v1.2.3 From a26a6c93edfeee82cb73f55e87d995eea59ddfe8 Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Wed, 5 Nov 2025 15:30:27 -0700 Subject: kbuild: Strip trailing padding bytes from modules.builtin.modinfo After commit d50f21091358 ("kbuild: align modinfo section for Secureboot Authenticode EDK2 compat"), running modules_install with certain versions of kmod (such as 29.1 in Ubuntu Jammy) in certain configurations may fail with: depmod: ERROR: kmod_builtin_iter_next: unexpected string without modname prefix The additional padding bytes to ensure .modinfo is aligned within vmlinux.unstripped are unexpected by kmod, as this section has always just been null-terminated strings. Strip the trailing padding bytes from modules.builtin.modinfo after it has been extracted from vmlinux.unstripped to restore the format that kmod expects while keeping .modinfo aligned within vmlinux.unstripped to avoid regressing the Authenticode calculation fix for EDK2. Cc: stable@vger.kernel.org Fixes: d50f21091358 ("kbuild: align modinfo section for Secureboot Authenticode EDK2 compat") Reported-by: Omar Sandoval Reported-by: Samir M Reported-by: Venkat Rao Bagalkote Closes: https://lore.kernel.org/7fef7507-ad64-4e51-9bb8-c9fb6532e51e@linux.ibm.com/ Tested-by: Omar Sandoval Tested-by: Samir M Tested-by: Venkat Rao Bagalkote Reviewed-by: Nicolas Schier Link: https://patch.msgid.link/20251105-kbuild-fix-builtin-modinfo-for-kmod-v1-1-b419d8ad4606@kernel.org Signed-off-by: Nathan Chancellor --- scripts/Makefile.vmlinux | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) (limited to 'scripts/Makefile.vmlinux') diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux index ced4379550d7..cd788cac9d91 100644 --- a/scripts/Makefile.vmlinux +++ b/scripts/Makefile.vmlinux @@ -102,11 +102,24 @@ vmlinux: vmlinux.unstripped FORCE # modules.builtin.modinfo # --------------------------------------------------------------------------- +# .modinfo in vmlinux.unstripped is aligned to 8 bytes for compatibility with +# tools that expect vmlinux to have sufficiently aligned sections but the +# additional bytes used for padding .modinfo to satisfy this requirement break +# certain versions of kmod with +# +# depmod: ERROR: kmod_builtin_iter_next: unexpected string without modname prefix +# +# Strip the trailing padding bytes after extracting .modinfo to comply with +# what kmod expects to parse. +quiet_cmd_modules_builtin_modinfo = GEN $@ + cmd_modules_builtin_modinfo = $(cmd_objcopy); \ + sed -i 's/\x00\+$$/\x00/g' $@ + OBJCOPYFLAGS_modules.builtin.modinfo := -j .modinfo -O binary targets += modules.builtin.modinfo modules.builtin.modinfo: vmlinux.unstripped FORCE - $(call if_changed,objcopy) + $(call if_changed,modules_builtin_modinfo) # modules.builtin # --------------------------------------------------------------------------- -- cgit v1.2.3 From 522397d05e7d4a7c30b91841492360336b24f833 Mon Sep 17 00:00:00 2001 From: Ihor Solodrai Date: Fri, 19 Dec 2025 10:18:25 -0800 Subject: resolve_btfids: Change in-place update with raw binary output Currently resolve_btfids updates .BTF_ids section of an ELF file in-place, based on the contents of provided BTF, usually within the same input file, and optionally a BTF base. Change resolve_btfids behavior to enable BTF transformations as part of its main operation. To achieve this, in-place ELF write in resolve_btfids is replaced with generation of the following binaries: * ${1}.BTF with .BTF section data * ${1}.BTF_ids with .BTF_ids section data if it existed in ${1} * ${1}.BTF.base with .BTF.base section data for out-of-tree modules The execution of resolve_btfids and consumption of its output is orchestrated by scripts/gen-btf.sh introduced in this patch. The motivation for emitting binary data is that it allows simplifying resolve_btfids implementation by delegating ELF update to the $OBJCOPY tool [1], which is already widely used across the codebase. There are two distinct paths for BTF generation and resolve_btfids application in the kernel build: for vmlinux and for kernel modules. For the vmlinux binary a .BTF section is added in a roundabout way to ensure correct linking. The patch doesn't change this approach, only the implementation is a little different. Before this patch it worked as follows: * pahole consumed .tmp_vmlinux1 [2] and added .BTF section with llvm-objcopy [3] to it * then everything except the .BTF section was stripped from .tmp_vmlinux1 into a .tmp_vmlinux1.bpf.o object [2], later linked into vmlinux * resolve_btfids was executed later on vmlinux.unstripped [4], updating it in-place After this patch gen-btf.sh implements the following: * pahole consumes .tmp_vmlinux1 and produces a *detached* file with raw BTF data * resolve_btfids consumes .tmp_vmlinux1 and detached BTF to produce (potentially modified) .BTF, and .BTF_ids sections data * a .tmp_vmlinux1.bpf.o object is then produced with objcopy copying BTF output of resolve_btfids * .BTF_ids data gets embedded into vmlinux.unstripped in link-vmlinux.sh by objcopy --update-section For kernel modules, creating a special .bpf.o file is not necessary, and so embedding of sections data produced by resolve_btfids is straightforward with objcopy. With this patch an ELF file becomes effectively read-only within resolve_btfids, which allows deleting elf_update() call and satellite code (like compressed_section_fix [5]). Endianness handling of .BTF_ids data is also changed. Previously the "flags" part of the section was bswapped in sets_patch() [6], and then Elf_Type was modified before elf_update() to signal to libelf that bswap may be necessary. With this patch we explicitly bswap entire data buffer on load and on dump. [1] https://lore.kernel.org/bpf/131b4190-9c49-4f79-a99d-c00fac97fa44@linux.dev/ [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/link-vmlinux.sh?h=v6.18#n110 [3] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/tree/btf_encoder.c?h=v1.31#n1803 [4] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/link-vmlinux.sh?h=v6.18#n284 [5] https://lore.kernel.org/bpf/20200819092342.259004-1-jolsa@kernel.org/ [6] https://lore.kernel.org/bpf/cover.1707223196.git.vmalik@redhat.com/ Signed-off-by: Ihor Solodrai Signed-off-by: Andrii Nakryiko Tested-by: Alan Maguire Acked-by: Eduard Zingerman Link: https://lore.kernel.org/bpf/20251219181825.1289460-3-ihor.solodrai@linux.dev --- MAINTAINERS | 1 + scripts/Makefile.btf | 12 +- scripts/Makefile.modfinal | 5 +- scripts/Makefile.vmlinux | 2 +- scripts/gen-btf.sh | 157 +++++++++++++++ scripts/link-vmlinux.sh | 42 +--- tools/bpf/resolve_btfids/main.c | 224 +++++++++++++-------- tools/testing/selftests/bpf/.gitignore | 3 + tools/testing/selftests/bpf/Makefile | 9 +- .../selftests/bpf/prog_tests/resolve_btfids.c | 4 +- 10 files changed, 328 insertions(+), 131 deletions(-) create mode 100755 scripts/gen-btf.sh (limited to 'scripts/Makefile.vmlinux') diff --git a/MAINTAINERS b/MAINTAINERS index 5b11839cba9d..cb1898a85b05 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -4766,6 +4766,7 @@ F: net/sched/act_bpf.c F: net/sched/cls_bpf.c F: samples/bpf/ F: scripts/bpf_doc.py +F: scripts/gen-btf.sh F: scripts/Makefile.btf F: scripts/pahole-version.sh F: tools/bpf/ diff --git a/scripts/Makefile.btf b/scripts/Makefile.btf index 840a55de42da..562a04b40e06 100644 --- a/scripts/Makefile.btf +++ b/scripts/Makefile.btf @@ -18,13 +18,15 @@ pahole-flags-$(call test-ge, $(pahole-ver), 126) = -j$(JOBS) --btf_features=enc pahole-flags-$(call test-ge, $(pahole-ver), 130) += --btf_features=attributes -ifneq ($(KBUILD_EXTMOD),) -module-pahole-flags-$(call test-ge, $(pahole-ver), 128) += --btf_features=distilled_base -endif - endif pahole-flags-$(CONFIG_PAHOLE_HAS_LANG_EXCLUDE) += --lang_exclude=rust export PAHOLE_FLAGS := $(pahole-flags-y) -export MODULE_PAHOLE_FLAGS := $(module-pahole-flags-y) + +resolve-btfids-flags-y := +resolve-btfids-flags-$(CONFIG_WERROR) += --fatal_warnings +resolve-btfids-flags-$(if $(KBUILD_EXTMOD),y) += --distill_base +resolve-btfids-flags-$(if $(KBUILD_VERBOSE),y) += --verbose + +export RESOLVE_BTFIDS_FLAGS := $(resolve-btfids-flags-y) diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal index 149e12ff5700..422c56dc878e 100644 --- a/scripts/Makefile.modfinal +++ b/scripts/Makefile.modfinal @@ -42,9 +42,8 @@ quiet_cmd_btf_ko = BTF [M] $@ cmd_btf_ko = \ if [ ! -f $(objtree)/vmlinux ]; then \ printf "Skipping BTF generation for %s due to unavailability of vmlinux\n" $@ 1>&2; \ - else \ - LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J $(PAHOLE_FLAGS) $(MODULE_PAHOLE_FLAGS) --btf_base $(objtree)/vmlinux $@; \ - $(RESOLVE_BTFIDS) -b $(objtree)/vmlinux $@; \ + else \ + $(srctree)/scripts/gen-btf.sh --btf_base $(objtree)/vmlinux $@; \ fi; # Same as newer-prereqs, but allows to exclude specified extra dependencies diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux index cd788cac9d91..20a988f4fe0c 100644 --- a/scripts/Makefile.vmlinux +++ b/scripts/Makefile.vmlinux @@ -71,7 +71,7 @@ targets += vmlinux.unstripped .vmlinux.export.o vmlinux.unstripped: scripts/link-vmlinux.sh vmlinux.o .vmlinux.export.o $(KBUILD_LDS) FORCE +$(call if_changed_dep,link_vmlinux) ifdef CONFIG_DEBUG_INFO_BTF -vmlinux.unstripped: $(RESOLVE_BTFIDS) +vmlinux.unstripped: $(RESOLVE_BTFIDS) $(srctree)/scripts/gen-btf.sh endif ifdef CONFIG_BUILDTIME_TABLE_SORT diff --git a/scripts/gen-btf.sh b/scripts/gen-btf.sh new file mode 100755 index 000000000000..06c6d8becaa2 --- /dev/null +++ b/scripts/gen-btf.sh @@ -0,0 +1,157 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# Copyright (c) 2025 Meta Platforms, Inc. and affiliates. +# +# This script generates BTF data for the provided ELF file. +# +# Kernel BTF generation involves these conceptual steps: +# 1. pahole generates BTF from DWARF data +# 2. resolve_btfids applies kernel-specific btf2btf +# transformations and computes data for .BTF_ids section +# 3. the result gets linked/objcopied into the target binary +# +# How step (3) should be done differs between vmlinux, and +# kernel modules, which is the primary reason for the existence +# of this script. +# +# For modules the script expects vmlinux passed in as --btf_base. +# Generated .BTF, .BTF.base and .BTF_ids sections become embedded +# into the input ELF file with objcopy. +# +# For vmlinux the input file remains unchanged and two files are produced: +# - ${1}.btf.o ready for linking into vmlinux +# - ${1}.BTF_ids with .BTF_ids data blob +# This output is consumed by scripts/link-vmlinux.sh + +set -e + +usage() +{ + echo "Usage: $0 [--btf_base ] " + exit 1 +} + +BTF_BASE="" + +while [ $# -gt 0 ]; do + case "$1" in + --btf_base) + BTF_BASE="$2" + shift 2 + ;; + -*) + echo "Unknown option: $1" >&2 + usage + ;; + *) + break + ;; + esac +done + +if [ $# -ne 1 ]; then + usage +fi + +ELF_FILE="$1" +shift + +is_enabled() { + grep -q "^$1=y" ${objtree}/include/config/auto.conf +} + +info() +{ + printf " %-7s %s\n" "${1}" "${2}" +} + +case "${KBUILD_VERBOSE}" in +*1*) + set -x + ;; +esac + + +gen_btf_data() +{ + info BTF "${ELF_FILE}" + btf1="${ELF_FILE}.BTF.1" + ${PAHOLE} -J ${PAHOLE_FLAGS} \ + ${BTF_BASE:+--btf_base ${BTF_BASE}} \ + --btf_encode_detached=${btf1} \ + "${ELF_FILE}" + + info BTFIDS "${ELF_FILE}" + ${RESOLVE_BTFIDS} ${RESOLVE_BTFIDS_FLAGS} \ + ${BTF_BASE:+--btf_base ${BTF_BASE}} \ + --btf ${btf1} "${ELF_FILE}" +} + +gen_btf_o() +{ + local btf_data=${ELF_FILE}.btf.o + + # Create ${btf_data} which contains just .BTF section but no symbols. Add + # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all + # deletes all symbols including __start_BTF and __stop_BTF, which will + # be redefined in the linker script. + info OBJCOPY "${btf_data}" + echo "" | ${CC} ${CLANG_FLAGS} -c -x c -o ${btf_data} - + ${OBJCOPY} --add-section .BTF=${ELF_FILE}.BTF \ + --set-section-flags .BTF=alloc,readonly ${btf_data} + ${OBJCOPY} --only-section=.BTF --strip-all ${btf_data} + + # Change e_type to ET_REL so that it can be used to link final vmlinux. + # GNU ld 2.35+ and lld do not allow an ET_EXEC input. + if is_enabled CONFIG_CPU_BIG_ENDIAN; then + et_rel='\0\1' + else + et_rel='\1\0' + fi + printf "${et_rel}" | dd of="${btf_data}" conv=notrunc bs=1 seek=16 status=none +} + +embed_btf_data() +{ + info OBJCOPY "${ELF_FILE}.BTF" + ${OBJCOPY} --add-section .BTF=${ELF_FILE}.BTF ${ELF_FILE} + + # a module might not have a .BTF_ids or .BTF.base section + local btf_base="${ELF_FILE}.BTF.base" + if [ -f "${btf_base}" ]; then + ${OBJCOPY} --add-section .BTF.base=${btf_base} ${ELF_FILE} + fi + local btf_ids="${ELF_FILE}.BTF_ids" + if [ -f "${btf_ids}" ]; then + ${OBJCOPY} --update-section .BTF_ids=${btf_ids} ${ELF_FILE} + fi +} + +cleanup() +{ + rm -f "${ELF_FILE}.BTF.1" + rm -f "${ELF_FILE}.BTF" + if [ "${BTFGEN_MODE}" = "module" ]; then + rm -f "${ELF_FILE}.BTF.base" + rm -f "${ELF_FILE}.BTF_ids" + fi +} +trap cleanup EXIT + +BTFGEN_MODE="vmlinux" +if [ -n "${BTF_BASE}" ]; then + BTFGEN_MODE="module" +fi + +gen_btf_data + +case "${BTFGEN_MODE}" in +vmlinux) + gen_btf_o + ;; +module) + embed_btf_data + ;; +esac + +exit 0 diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index 4ab44c73da4d..e2207e612ac3 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -106,34 +106,6 @@ vmlinux_link() ${kallsymso} ${btf_vmlinux_bin_o} ${arch_vmlinux_o} ${ldlibs} } -# generate .BTF typeinfo from DWARF debuginfo -# ${1} - vmlinux image -gen_btf() -{ - local btf_data=${1}.btf.o - - info BTF "${btf_data}" - LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1} - - # Create ${btf_data} which contains just .BTF section but no symbols. Add - # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all - # deletes all symbols including __start_BTF and __stop_BTF, which will - # be redefined in the linker script. Add 2>/dev/null to suppress GNU - # objcopy warnings: "empty loadable segment detected at ..." - ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ - --strip-all ${1} "${btf_data}" 2>/dev/null - # Change e_type to ET_REL so that it can be used to link final vmlinux. - # GNU ld 2.35+ and lld do not allow an ET_EXEC input. - if is_enabled CONFIG_CPU_BIG_ENDIAN; then - et_rel='\0\1' - else - et_rel='\1\0' - fi - printf "${et_rel}" | dd of="${btf_data}" conv=notrunc bs=1 seek=16 status=none - - btf_vmlinux_bin_o=${btf_data} -} - # Create ${2}.o file with all symbols from the ${1} object file kallsyms() { @@ -205,6 +177,7 @@ if is_enabled CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX; then fi btf_vmlinux_bin_o= +btfids_vmlinux= kallsymso= strip_debug= generate_map= @@ -232,11 +205,13 @@ if is_enabled CONFIG_KALLSYMS || is_enabled CONFIG_DEBUG_INFO_BTF; then fi if is_enabled CONFIG_DEBUG_INFO_BTF; then - if ! gen_btf .tmp_vmlinux1; then + if ! ${srctree}/scripts/gen-btf.sh .tmp_vmlinux1; then echo >&2 "Failed to generate BTF for vmlinux" echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" exit 1 fi + btf_vmlinux_bin_o=.tmp_vmlinux1.btf.o + btfids_vmlinux=.tmp_vmlinux1.BTF_ids fi if is_enabled CONFIG_KALLSYMS; then @@ -289,14 +264,9 @@ fi vmlinux_link "${VMLINUX}" -# fill in BTF IDs if is_enabled CONFIG_DEBUG_INFO_BTF; then - info BTFIDS "${VMLINUX}" - RESOLVE_BTFIDS_ARGS="" - if is_enabled CONFIG_WERROR; then - RESOLVE_BTFIDS_ARGS=" --fatal_warnings " - fi - ${RESOLVE_BTFIDS} ${RESOLVE_BTFIDS_ARGS} "${VMLINUX}" + info OBJCOPY ${btfids_vmlinux} + ${OBJCOPY} --update-section .BTF_ids=${btfids_vmlinux} ${VMLINUX} fi mksysmap "${VMLINUX}" System.map diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c index e721e20a2bbd..2cbc252259be 100644 --- a/tools/bpf/resolve_btfids/main.c +++ b/tools/bpf/resolve_btfids/main.c @@ -71,9 +71,11 @@ #include #include #include +#include #include #include #include +#include #include #include #include @@ -124,6 +126,7 @@ struct object { struct btf *btf; struct btf *base_btf; + bool distill_base; struct { int fd; @@ -324,42 +327,16 @@ static struct btf_id *add_symbol(struct rb_root *root, char *name, size_t size) return btf_id__add(root, id, BTF_ID_KIND_SYM); } -/* Older libelf.h and glibc elf.h might not yet define the ELF compression types. */ -#ifndef SHF_COMPRESSED -#define SHF_COMPRESSED (1 << 11) /* Section with compressed data. */ -#endif - -/* - * The data of compressed section should be aligned to 4 - * (for 32bit) or 8 (for 64 bit) bytes. The binutils ld - * sets sh_addralign to 1, which makes libelf fail with - * misaligned section error during the update: - * FAILED elf_update(WRITE): invalid section alignment - * - * While waiting for ld fix, we fix the compressed sections - * sh_addralign value manualy. - */ -static int compressed_section_fix(Elf *elf, Elf_Scn *scn, GElf_Shdr *sh) +static void bswap_32_data(void *data, u32 nr_bytes) { - int expected = gelf_getclass(elf) == ELFCLASS32 ? 4 : 8; - - if (!(sh->sh_flags & SHF_COMPRESSED)) - return 0; - - if (sh->sh_addralign == expected) - return 0; + u32 cnt, i; + u32 *ptr; - pr_debug2(" - fixing wrong alignment sh_addralign %u, expected %u\n", - sh->sh_addralign, expected); + cnt = nr_bytes / sizeof(u32); + ptr = data; - sh->sh_addralign = expected; - - if (gelf_update_shdr(scn, sh) == 0) { - pr_err("FAILED cannot update section header: %s\n", - elf_errmsg(-1)); - return -1; - } - return 0; + for (i = 0; i < cnt; i++) + ptr[i] = bswap_32(ptr[i]); } static int elf_collect(struct object *obj) @@ -380,7 +357,7 @@ static int elf_collect(struct object *obj) elf_version(EV_CURRENT); - elf = elf_begin(fd, ELF_C_RDWR_MMAP, NULL); + elf = elf_begin(fd, ELF_C_READ_MMAP_PRIVATE, NULL); if (!elf) { close(fd); pr_err("FAILED cannot create ELF descriptor: %s\n", @@ -443,21 +420,20 @@ static int elf_collect(struct object *obj) obj->efile.symbols_shndx = idx; obj->efile.strtabidx = sh.sh_link; } else if (!strcmp(name, BTF_IDS_SECTION)) { + /* + * If target endianness differs from host, we need to bswap32 + * the .BTF_ids section data on load, because .BTF_ids has + * Elf_Type = ELF_T_BYTE, and so libelf returns data buffer in + * the target endianness. We repeat this on dump. + */ + if (obj->efile.encoding != ELFDATANATIVE) { + pr_debug("bswap_32 .BTF_ids data from target to host endianness\n"); + bswap_32_data(data->d_buf, data->d_size); + } obj->efile.idlist = data; obj->efile.idlist_shndx = idx; obj->efile.idlist_addr = sh.sh_addr; - } else if (!strcmp(name, BTF_BASE_ELF_SEC)) { - /* If a .BTF.base section is found, do not resolve - * BTF ids relative to vmlinux; resolve relative - * to the .BTF.base section instead. btf__parse_split() - * will take care of this once the base BTF it is - * passed is NULL. - */ - obj->base_btf_path = NULL; } - - if (compressed_section_fix(elf, scn, &sh)) - return -1; } return 0; @@ -587,11 +563,26 @@ static int load_btf(struct object *obj) obj->base_btf = base_btf; obj->btf = btf; + if (obj->base_btf && obj->distill_base) { + err = btf__distill_base(obj->btf, &base_btf, &btf); + if (err) { + pr_err("FAILED to distill base BTF: %s\n", strerror(errno)); + goto out_err; + } + + btf__free(obj->base_btf); + btf__free(obj->btf); + obj->base_btf = base_btf; + obj->btf = btf; + } + return 0; out_err: btf__free(base_btf); btf__free(btf); + obj->base_btf = NULL; + obj->btf = NULL; return err; } @@ -760,24 +751,6 @@ static int sets_patch(struct object *obj) */ BUILD_BUG_ON((u32 *)set8->pairs != &set8->pairs[0].id); qsort(set8->pairs, set8->cnt, sizeof(set8->pairs[0]), cmp_id); - - /* - * When ELF endianness does not match endianness of the - * host, libelf will do the translation when updating - * the ELF. This, however, corrupts SET8 flags which are - * already in the target endianness. So, let's bswap - * them to the host endianness and libelf will then - * correctly translate everything. - */ - if (obj->efile.encoding != ELFDATANATIVE) { - int i; - - set8->flags = bswap_32(set8->flags); - for (i = 0; i < set8->cnt; i++) { - set8->pairs[i].flags = - bswap_32(set8->pairs[i].flags); - } - } break; default: pr_err("Unexpected btf_id_kind %d for set '%s'\n", id->kind, id->name); @@ -793,8 +766,6 @@ static int sets_patch(struct object *obj) static int symbols_patch(struct object *obj) { - off_t err; - if (__symbols_patch(obj, &obj->structs) || __symbols_patch(obj, &obj->unions) || __symbols_patch(obj, &obj->typedefs) || @@ -805,20 +776,90 @@ static int symbols_patch(struct object *obj) if (sets_patch(obj)) return -1; - /* Set type to ensure endian translation occurs. */ - obj->efile.idlist->d_type = ELF_T_WORD; + return 0; +} - elf_flagdata(obj->efile.idlist, ELF_C_SET, ELF_F_DIRTY); +static int dump_raw_data(const char *out_path, const void *data, u32 size) +{ + size_t written; + FILE *file; - err = elf_update(obj->efile.elf, ELF_C_WRITE); - if (err < 0) { - pr_err("FAILED elf_update(WRITE): %s\n", - elf_errmsg(-1)); + file = fopen(out_path, "wb"); + if (!file) { + pr_err("Couldn't open %s for writing\n", out_path); + return -1; + } + + written = fwrite(data, 1, size, file); + if (written != size) { + pr_err("Failed to write data to %s\n", out_path); + fclose(file); + unlink(out_path); + return -1; + } + + fclose(file); + pr_debug("Dumped %lu bytes of data to %s\n", size, out_path); + + return 0; +} + +static int dump_raw_btf_ids(struct object *obj, const char *out_path) +{ + Elf_Data *data = obj->efile.idlist; + int err; + + if (!data || !data->d_buf) { + pr_debug("%s has no BTF_ids data to dump\n", obj->path); + return 0; + } + + /* + * If target endianness differs from host, we need to bswap32 the + * .BTF_ids section data before dumping so that the output is in + * target endianness. + */ + if (obj->efile.encoding != ELFDATANATIVE) { + pr_debug("bswap_32 .BTF_ids data from host to target endianness\n"); + bswap_32_data(data->d_buf, data->d_size); + } + + err = dump_raw_data(out_path, data->d_buf, data->d_size); + if (err) + return -1; + + return 0; +} + +static int dump_raw_btf(struct btf *btf, const char *out_path) +{ + const void *raw_btf_data; + u32 raw_btf_size; + int err; + + raw_btf_data = btf__raw_data(btf, &raw_btf_size); + if (!raw_btf_data) { + pr_err("btf__raw_data() failed\n"); + return -1; } - pr_debug("update %s for %s\n", - err >= 0 ? "ok" : "failed", obj->path); - return err < 0 ? -1 : 0; + err = dump_raw_data(out_path, raw_btf_data, raw_btf_size); + if (err) + return -1; + + return 0; +} + +static inline int make_out_path(char *buf, u32 buf_sz, const char *in_path, const char *suffix) +{ + int len = snprintf(buf, buf_sz, "%s%s", in_path, suffix); + + if (len < 0 || len >= buf_sz) { + pr_err("Output path is too long: %s%s\n", in_path, suffix); + return -E2BIG; + } + + return 0; } static const char * const resolve_btfids_usage[] = { @@ -840,6 +881,8 @@ int main(int argc, const char **argv) .sets = RB_ROOT, }; bool fatal_warnings = false; + char out_path[PATH_MAX]; + struct option btfid_options[] = { OPT_INCR('v', "verbose", &verbose, "be more verbose (show errors, etc)"), @@ -849,6 +892,8 @@ int main(int argc, const char **argv) "path of file providing base BTF"), OPT_BOOLEAN(0, "fatal_warnings", &fatal_warnings, "turn warnings into errors"), + OPT_BOOLEAN(0, "distill_base", &obj.distill_base, + "distill --btf_base and emit .BTF.base section data"), OPT_END() }; int err = -1; @@ -860,6 +905,9 @@ int main(int argc, const char **argv) obj.path = argv[0]; + if (load_btf(&obj)) + goto out; + if (elf_collect(&obj)) goto out; @@ -869,23 +917,37 @@ int main(int argc, const char **argv) */ if (obj.efile.idlist_shndx == -1 || obj.efile.symbols_shndx == -1) { - pr_debug("Cannot find .BTF_ids or symbols sections, nothing to do\n"); - err = 0; - goto out; + pr_debug("Cannot find .BTF_ids or symbols sections, skip symbols resolution\n"); + goto dump_btf; } if (symbols_collect(&obj)) goto out; - if (load_btf(&obj)) - goto out; - if (symbols_resolve(&obj)) goto out; if (symbols_patch(&obj)) goto out; + err = make_out_path(out_path, sizeof(out_path), obj.path, BTF_IDS_SECTION); + err = err ?: dump_raw_btf_ids(&obj, out_path); + if (err) + goto out; + +dump_btf: + err = make_out_path(out_path, sizeof(out_path), obj.path, BTF_ELF_SEC); + err = err ?: dump_raw_btf(obj.btf, out_path); + if (err) + goto out; + + if (obj.base_btf && obj.distill_base) { + err = make_out_path(out_path, sizeof(out_path), obj.path, BTF_BASE_ELF_SEC); + err = err ?: dump_raw_btf(obj.base_btf, out_path); + if (err) + goto out; + } + if (!(fatal_warnings && warnings)) err = 0; out: diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore index 19c1638e312a..b8bf51b7a0b0 100644 --- a/tools/testing/selftests/bpf/.gitignore +++ b/tools/testing/selftests/bpf/.gitignore @@ -45,3 +45,6 @@ xdp_synproxy xdp_hw_metadata xdp_features verification_cert.h +*.BTF +*.BTF_ids +*.BTF.base diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index ffd0a4c354c7..f28a32b16ff0 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -4,6 +4,7 @@ include ../../../scripts/Makefile.arch include ../../../scripts/Makefile.include CXX ?= $(CROSS_COMPILE)g++ +OBJCOPY ?= $(CROSS_COMPILE)objcopy CURDIR := $(abspath .) TOOLSDIR := $(abspath ../../..) @@ -653,9 +654,10 @@ $(TRUNNER_TEST_OBJS): $(TRUNNER_OUTPUT)/%.test.o: \ | $(TRUNNER_OUTPUT)/%.test.d $$(call msg,TEST-OBJ,$(TRUNNER_BINARY),$$@) $(Q)cd $$(@D) && $$(CC) -I. $$(CFLAGS) -MMD -MT $$@ -c $(CURDIR)/$$< $$(LDLIBS) -o $$(@F) - $$(if $$(TEST_NEEDS_BTFIDS), \ - $$(call msg,BTFIDS,$(TRUNNER_BINARY),$$@) \ - $(RESOLVE_BTFIDS) --btf $(TRUNNER_OUTPUT)/btf_data.bpf.o $$@) + $$(if $$(TEST_NEEDS_BTFIDS), \ + $$(call msg,BTFIDS,$(TRUNNER_BINARY),$$@) \ + $(RESOLVE_BTFIDS) --btf $(TRUNNER_OUTPUT)/btf_data.bpf.o $$@; \ + $(OBJCOPY) --update-section .BTF_ids=$$@.BTF_ids $$@) $(TRUNNER_TEST_OBJS:.o=.d): $(TRUNNER_OUTPUT)/%.test.d: \ $(TRUNNER_TESTS_DIR)/%.c \ @@ -894,6 +896,7 @@ EXTRA_CLEAN := $(SCRATCH_DIR) $(HOST_SCRATCH_DIR) \ prog_tests/tests.h map_tests/tests.h verifier/tests.h \ feature bpftool $(TEST_KMOD_TARGETS) \ $(addprefix $(OUTPUT)/,*.o *.d *.skel.h *.lskel.h *.subskel.h \ + *.BTF *.BTF_ids *.BTF.base \ no_alu32 cpuv4 bpf_gcc \ liburandom_read.so) \ $(OUTPUT)/FEATURE-DUMP.selftests \ diff --git a/tools/testing/selftests/bpf/prog_tests/resolve_btfids.c b/tools/testing/selftests/bpf/prog_tests/resolve_btfids.c index 51544372f52e..41dfaaabb73f 100644 --- a/tools/testing/selftests/bpf/prog_tests/resolve_btfids.c +++ b/tools/testing/selftests/bpf/prog_tests/resolve_btfids.c @@ -101,9 +101,9 @@ static int resolve_symbols(void) int type_id; __u32 nr; - btf = btf__parse_elf("btf_data.bpf.o", NULL); + btf = btf__parse_raw("resolve_btfids.test.o.BTF"); if (CHECK(libbpf_get_error(btf), "resolve", - "Failed to load BTF from btf_data.bpf.o\n")) + "Failed to load BTF from resolve_btfids.test.o.BTF\n")) return -1; nr = btf__type_cnt(btf); -- cgit v1.2.3 From 6d60354ea2f90352b22039ed8371c4f4321df90e Mon Sep 17 00:00:00 2001 From: Ethan Zuo Date: Wed, 28 Jan 2026 14:37:51 +0800 Subject: kbuild: Fix permissions of modules.builtin.modinfo Currently, modules.builtin.modinfo is created with executable permissions (0755). This is because after commit 39cfd5b12160 ("kbuild: extract modules.builtin.modinfo from vmlinux.unstripped"), modules.builtin.modinfo is extracted from vmlinux.unstripped using objcopy. When extracting sections, objcopy inherits attributes from the source ELF file. Since modules.builtin.modinfo is a data file and not an executable, it should have regular file permissions (0644). The executable bit can trigger warnings in Debian's Lintian tool. Explicitly remove the executable bit after generation. Fixes: 39cfd5b12160 ("kbuild: extract modules.builtin.modinfo from vmlinux.unstripped") Signed-off-by: Ethan Zuo Link: https://patch.msgid.link/SY0P300MB0609F6916B24ADF65502940B9C91A@SY0P300MB0609.AUSP300.PROD.OUTLOOK.COM Signed-off-by: Nicolas Schier --- scripts/Makefile.vmlinux | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'scripts/Makefile.vmlinux') diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux index cd788cac9d91..276c3134a563 100644 --- a/scripts/Makefile.vmlinux +++ b/scripts/Makefile.vmlinux @@ -113,7 +113,8 @@ vmlinux: vmlinux.unstripped FORCE # what kmod expects to parse. quiet_cmd_modules_builtin_modinfo = GEN $@ cmd_modules_builtin_modinfo = $(cmd_objcopy); \ - sed -i 's/\x00\+$$/\x00/g' $@ + sed -i 's/\x00\+$$/\x00/g' $@; \ + chmod -x $@ OBJCOPYFLAGS_modules.builtin.modinfo := -j .modinfo -O binary -- cgit v1.2.3