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2023-06-29modpost: define more R_ARM_* for old distributionsMasahiro Yamada
On CentOS 7, the following build error occurs. scripts/mod/modpost.c: In function 'addend_arm_rel': scripts/mod/modpost.c:1312:7: error: 'R_ARM_MOVW_ABS_NC' undeclared (first use in this function); did you mean 'R_ARM_THM_ABS5'? case R_ARM_MOVW_ABS_NC: ^~~~~~~~~~~~~~~~~ R_ARM_THM_ABS5 scripts/mod/modpost.c:1312:7: note: each undeclared identifier is reported only once for each function it appears in scripts/mod/modpost.c:1313:7: error: 'R_ARM_MOVT_ABS' undeclared (first use in this function); did you mean 'R_ARM_THM_ABS5'? case R_ARM_MOVT_ABS: ^~~~~~~~~~~~~~ R_ARM_THM_ABS5 scripts/mod/modpost.c:1326:7: error: 'R_ARM_THM_MOVW_ABS_NC' undeclared (first use in this function); did you mean 'R_ARM_THM_ABS5'? case R_ARM_THM_MOVW_ABS_NC: ^~~~~~~~~~~~~~~~~~~~~ R_ARM_THM_ABS5 scripts/mod/modpost.c:1327:7: error: 'R_ARM_THM_MOVT_ABS' undeclared (first use in this function); did you mean 'R_ARM_THM_ABS5'? case R_ARM_THM_MOVT_ABS: ^~~~~~~~~~~~~~~~~~ R_ARM_THM_ABS5 Fixes: 12ca2c67d742 ("modpost: detect section mismatch for R_ARM_{MOVW_ABS_NC,MOVT_ABS}") Fixes: cd1824fb7a37 ("modpost: detect section mismatch for R_ARM_THM_{MOVW_ABS_NC,MOVT_ABS}") Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-28kbuild: revive "Entering directory" for Make >= 4.4.1Masahiro Yamada
With commit 9da0763bdd82 ("kbuild: Use relative path when building in a subdir of the source tree"), compiler messages in out-of-tree builds include relative paths, which are relative to the build directory, not the directory where make was started. To help IDEs/editors find the source files, Kbuild lets GNU Make print "Entering directory ..." when it changes the working directory. It has been working fine for a long time, but David reported it is broken with the latest GNU Make. The behavior was changed by GNU Make commit 8f9e7722ff0f ("[SV 63537] Fix setting -w in makefiles"). Previously, setting --no-print-directory to MAKEFLAGS only affected child makes, but it is now interpreted in the current make as soon as it is set. [test code] $ cat /tmp/Makefile ifneq ($(SUBMAKE),1) MAKEFLAGS += --no-print-directory all: ; $(MAKE) SUBMAKE=1 else all: ; : endif [before 8f9e7722ff0f] $ make -C /tmp make: Entering directory '/tmp' make SUBMAKE=1 : make: Leaving directory '/tmp' [after 8f9e7722ff0f] $ make -C /tmp make SUBMAKE=1 : Previously, the effect of --no-print-directory was delayed until Kbuild started the directory descending, but it is no longer true with GNU Make 4.4.1. This commit adds one more recursion to cater to GNU Make >= 4.4.1. When Kbuild needs to change the working directory, __submake will be executed twice. __submake without --no-print-directory --> show "Entering directory ..." __submake with --no-print-directory --> parse the rest of Makefile We end up with one more recursion than needed for GNU Make < 4.4.1, but I do not want to complicate the version check. Reported-by: David Howells <dhowells@redhat.com> Closes: https://lore.kernel.org/all/2427604.1686237298@warthog.procyon.org.uk/ Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Nicolas Schier <n.schier@avm.de>
2023-06-28kbuild: set correct abs_srctree and abs_objtree for package buildsMasahiro Yamada
When you run 'make rpm-pkg', the rpmbuild tool builds the kernel in rpmbuild/BUILD, but $(abs_srctree) and $(abs_objtree) point to the directory path where make was started, not the kernel is actually being built. The same applies to 'make snap-pkg'. Fix it. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-27scripts/mksysmap: Ignore prefixed KCFI symbolsPierre-Clément Tosi
The (relatively) new KCFI feature in LLVM/Clang encodes type information for C functions by generating symbols named __kcfi_typeid_<fname>, which can then be referenced from assembly. However, some custom build rules (e.g. nVHE or early PIE on arm64) use objcopy to add a prefix to all the symbols in their object files, making mksysmap's ignore filter miss those KCFI symbols. Therefore, explicitly list those twice-prefixed KCFI symbols as ignored. Alternatively, this could also be achieved in a less verbose way by ignoring any symbol containing the string "__kcfi_typeid_". However, listing the combined prefixes explicitly saves us from running the small risk of ignoring symbols that should be kept. Signed-off-by: Pierre-Clément Tosi <ptosi@google.com> Reviewed-by: Sami Tolvanen <samitolvanen@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-27kbuild: deb-pkg: remove the CONFIG_MODULES check in buildebMasahiro Yamada
When CONFIG_MODULES is disabled for ARCH=um, 'make (bin)deb-pkg' fails with an error like follows: cp: cannot create regular file 'debian/linux-image/usr/lib/uml/modules/6.4.0-rc2+/System.map': No such file or directory Remove the CONFIG_MODULES check completely so ${pdir}/usr/lib/uml/modules will always be created and modules.builtin.(modinfo) will be installed under it for ARCH=um. Fixes: b611daae5efc ("kbuild: deb-pkg: split image and debug objects staging out into functions") Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-27kbuild: builddeb: always make modules_install, to install modules.builtin*Josh Triplett
Even for a non-modular kernel, the kernel builds modules.builtin and modules.builtin.modinfo, with information about the built-in modules. Tools such as initramfs-tools need these files to build a working initramfs on some systems, such as those requiring firmware. Now that `make modules_install` works even in non-modular kernels and installs these files, unconditionally invoke it when building a Debian package. Signed-off-by: Josh Triplett <josh@joshtriplett.org> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-25modpost: continue even with unknown relocation typeMasahiro Yamada
Currently, unknown relocation types are just skipped. The value of r_addend is only needed to get the symbol name in case is_valid_name(elf, sym) returns false. Even if we do not know how to calculate r_addend, we should continue. At worst, we will get "(unknown)" as the symbol name, but it is better than failing to detect section mismatches. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-25modpost: factor out Elf_Sym pointer calculation to section_rel()Masahiro Yamada
Pass the Elf_Sym pointer to addend_arm_rel() as well as to check_section_mismatch(). Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2023-06-25modpost: factor out inst location calculation to section_rel()Masahiro Yamada
All the addend_*_rel() functions calculate the instruction location in the same way. Factor out the similar code to the caller. Squash reloc_location() too. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-25kbuild: Disable GCOV for *.mod.oSami Tolvanen
With GCOV_PROFILE_ALL, Clang injects __llvm_gcov_* functions to each object file, including the *.mod.o. As we filter out CC_FLAGS_CFI for *.mod.o, the compiler won't generate type hashes for the injected functions, and therefore indirectly calling them during module loading trips indirect call checking. Enabling CFI for *.mod.o isn't sufficient to fix this issue after commit 0c3e806ec0f9 ("x86/cfi: Add boot time hash randomization"), as *.mod.o aren't processed by objtool, which means any hashes emitted there won't be randomized. Therefore, in addition to disabling CFI for *.mod.o, also disable GCOV, as the object files don't otherwise contain any executable code. Fixes: cf68fffb66d6 ("add support for Clang CFI") Reported-by: Joe Fradley <joefradley@google.com> Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-25kbuild: Fix CFI failures with GCOVSami Tolvanen
With GCOV_PROFILE_ALL, Clang injects __llvm_gcov_* functions to each object file, and the functions are indirectly called during boot. However, when code is injected to object files that are not part of vmlinux.o, it's also not processed by objtool, which breaks CFI hash randomization as the hashes in these files won't be included in the .cfi_sites section and thus won't be randomized. Similarly to commit 42633ed852de ("kbuild: Fix CFI hash randomization with KASAN"), disable GCOV for .vmlinux.export.o and init/version-timestamp.o to avoid emitting unnecessary functions to object files that don't otherwise have executable code. Fixes: 0c3e806ec0f9 ("x86/cfi: Add boot time hash randomization") Reported-by: Joe Fradley <joefradley@google.com> Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-25kbuild: make clean rule robust against too long argument errorMasahiro Yamada
Commit cd968b97c492 ("kbuild: make built-in.a rule robust against too long argument error") made a build rule robust against "Argument list too long" error. Eugeniu Rosca reported the same error occurred when cleaning an external module. The $(obj)/ prefix can be a very long path for external modules. Apply a similar solution to 'make clean'. Reported-by: Eugeniu Rosca <erosca@de.adit-jv.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Eugeniu Rosca <erosca@de.adit-jv.com> Tested-by: Eugeniu Rosca <erosca@de.adit-jv.com>
2023-06-24script: modpost: emit a warning when the description is missingVincenzo Palazzo
Emit a warning when the mod description is missed and only when the W=1 is enabled. Reported-by: Roland Kletzing <devzero@web.de> Link: https://bugzilla.kernel.org/show_bug.cgi?id=10770 Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com> Tested-by: Nicolas Schier <n.schier@avm.de> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-24kbuild: make modules_install copy modules.builtin(.modinfo)Masahiro Yamada
Josh Triplett reports that initramfs-tools needs modules.builtin and modules.builtin.modinfo to create a working initramfs for a non-modular kernel. If this is a general tooling issue not limited to Debian, I think it makes sense to change modules_install. This commit changes the targets as follows when CONFIG_MODULES=n. In-tree builds: make modules -> no-op make modules_install -> install modules.builtin(.modinfo) External module builds: make modules -> show error message like before make modules_install -> show error message like before Link: https://lore.kernel.org/lkml/36a4014c73a52af27d930d3ca31d362b60f4461c.1686356364.git.josh@joshtriplett.org/ Reported-by: Josh Triplett <josh@joshtriplett.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu> Tested-by: Nicolas Schier <nicolas@fjasle.eu> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Tested-by: Josh Triplett <josh@joshtriplett.org>
2023-06-22linux/export.h: rename 'sec' argument to 'license'Masahiro Yamada
Now, EXPORT_SYMBOL() is populated in two stages. In the first stage, all of EXPORT_SYMBOL/EXPORT_SYMBOL_GPL go into the same section, '.export_symbol'. 'sec' does not make sense any more. Rename it to 'license'. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2023-06-22modpost: show offset from symbol for section mismatch warningsMasahiro Yamada
Currently, modpost only shows the symbol names and section names, so it repeats the same message if there are multiple relocations in the same symbol. It is common the relocation spans across multiple instructions. It is better to show the offset from the symbol. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2023-06-22modpost: merge two similar section mismatch warningsMasahiro Yamada
In case of section mismatch, modpost shows slightly different messages. For extable section mismatch: "%s(%s+0x%lx): Section mismatch in reference to the %s:%s\n" For the other cases: "%s: section mismatch in reference: %s (section: %s) -> %s (section: %s)\n" They are similar. Merge them. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2023-06-22kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without recursionMasahiro Yamada
When CONFIG_TRIM_UNUSED_KSYMS is enabled, Kbuild recursively traverses the directory tree to determine which EXPORT_SYMBOL to trim. If an EXPORT_SYMBOL turns out to be unused by anyone, Kbuild begins the second traverse, where some source files are recompiled with their EXPORT_SYMBOL() tuned into a no-op. Linus stated negative opinions about this slowness in commits: - 5cf0fd591f2e ("Kbuild: disable TRIM_UNUSED_KSYMS option") - a555bdd0c58c ("Kbuild: enable TRIM_UNUSED_KSYMS again, with some guarding") We can do this better now. The final data structures of EXPORT_SYMBOL are generated by the modpost stage, so modpost can selectively emit KSYMTAB entries that are really used by modules. Commit f73edc8951b2 ("kbuild: unify two modpost invocations") is another ground-work to do this in a one-pass algorithm. With the list of modules, modpost sets sym->used if it is used by a module. modpost emits KSYMTAB only for symbols with sym->used==true. BTW, Nicolas explained why the trimming was implemented with recursion: https://lore.kernel.org/all/2o2rpn97-79nq-p7s2-nq5-8p83391473r@syhkavp.arg/ Actually, we never achieved that level of optimization where the chain reaction of trimming comes into play because: - CONFIG_LTO_CLANG cannot remove any unused symbols - CONFIG_LD_DEAD_CODE_DATA_ELIMINATION is enabled only for vmlinux, but not modules If deeper trimming is required, we need to revisit this, but I guess that is unlikely to happen. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-22modpost: use null string instead of NULL pointer for default namespaceMasahiro Yamada
The default namespace is the null string, "". When set, the null string "" is converted to NULL: s->namespace = namespace[0] ? NOFAIL(strdup(namespace)) : NULL; When printed, the NULL pointer is get back to the null string: sym->namespace ?: "" This saves 1 byte memory allocated for "", but loses the readability. In kernel-space, we strive to save memory, but modpost is a userspace tool used to build the kernel. On modern systems, such small piece of memory is not a big deal. Handle the namespace string as is. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2023-06-22modpost: squash sym_update_namespace() into sym_add_exported()Masahiro Yamada
Pass a set of the name, license, and namespace to sym_add_exported(). sym_update_namespace() is unneeded. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2023-06-22modpost: check static EXPORT_SYMBOL* by modpost againMasahiro Yamada
Commit 31cb50b5590f ("kbuild: check static EXPORT_SYMBOL* by script instead of modpost") moved the static EXPORT_SYMBOL* check from the mostpost to a shell script because I thought it must be checked per compilation unit to avoid false negatives. I came up with an idea to do this in modpost, against combined ELF files. The relocation entries in ELF will find the correct exported symbol even if there exist symbols with the same name in different compilation units. Again, the same sample code. Makefile: obj-y += foo1.o foo2.o foo1.c: #include <linux/export.h> static void foo(void) {} EXPORT_SYMBOL(foo); foo2.c: void foo(void) {} Then, modpost can catch it correctly. MODPOST Module.symvers ERROR: modpost: vmlinux: local symbol 'foo' was exported Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2023-06-22ia64,export.h: replace EXPORT_DATA_SYMBOL* with EXPORT_SYMBOL*Masahiro Yamada
With the previous refactoring, you can always use EXPORT_SYMBOL*. Replace two instances in ia64, then remove EXPORT_DATA_SYMBOL*. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2023-06-22kbuild: generate KSYMTAB entries by modpostMasahiro Yamada
Commit 7b4537199a4a ("kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS") made modpost output CRCs in the same way whether the EXPORT_SYMBOL() is placed in *.c or *.S. For further cleanups, this commit applies a similar approach to the entire data structure of EXPORT_SYMBOL(). The EXPORT_SYMBOL() compilation is split into two stages. When a source file is compiled, EXPORT_SYMBOL() will be converted into a dummy symbol in the .export_symbol section. For example, EXPORT_SYMBOL(foo); EXPORT_SYMBOL_NS_GPL(bar, BAR_NAMESPACE); will be encoded into the following assembly code: .section ".export_symbol","a" __export_symbol_foo: .asciz "" /* license */ .asciz "" /* name space */ .balign 8 .quad foo /* symbol reference */ .previous .section ".export_symbol","a" __export_symbol_bar: .asciz "GPL" /* license */ .asciz "BAR_NAMESPACE" /* name space */ .balign 8 .quad bar /* symbol reference */ .previous They are mere markers to tell modpost the name, license, and namespace of the symbols. They will be dropped from the final vmlinux and modules because the *(.export_symbol) will go into /DISCARD/ in the linker script. Then, modpost extracts all the information about EXPORT_SYMBOL() from the .export_symbol section, and generates the final C code: KSYMTAB_FUNC(foo, "", ""); KSYMTAB_FUNC(bar, "_gpl", "BAR_NAMESPACE"); KSYMTAB_FUNC() (or KSYMTAB_DATA() if it is data) is expanded to struct kernel_symbol that will be linked to the vmlinux or a module. With this change, EXPORT_SYMBOL() works in the same way for *.c and *.S files, providing the following benefits. [1] Deprecate EXPORT_DATA_SYMBOL() In the old days, EXPORT_SYMBOL() was only available in C files. To export a symbol in *.S, EXPORT_SYMBOL() was placed in a separate *.c file. arch/arm/kernel/armksyms.c is one example written in the classic manner. Commit 22823ab419d8 ("EXPORT_SYMBOL() for asm") removed this limitation. Since then, EXPORT_SYMBOL() can be placed close to the symbol definition in *.S files. It was a nice improvement. However, as that commit mentioned, you need to use EXPORT_DATA_SYMBOL() for data objects on some architectures. In the new approach, modpost checks symbol's type (STT_FUNC or not), and outputs KSYMTAB_FUNC() or KSYMTAB_DATA() accordingly. There are only two users of EXPORT_DATA_SYMBOL: EXPORT_DATA_SYMBOL_GPL(empty_zero_page) (arch/ia64/kernel/head.S) EXPORT_DATA_SYMBOL(ia64_ivt) (arch/ia64/kernel/ivt.S) They are transformed as follows and output into .vmlinux.export.c KSYMTAB_DATA(empty_zero_page, "_gpl", ""); KSYMTAB_DATA(ia64_ivt, "", ""); The other EXPORT_SYMBOL users in ia64 assembly are output as KSYMTAB_FUNC(). EXPORT_DATA_SYMBOL() is now deprecated. [2] merge <linux/export.h> and <asm-generic/export.h> There are two similar header implementations: include/linux/export.h for .c files include/asm-generic/export.h for .S files Ideally, the functionality should be consistent between them, but they tend to diverge. Commit 8651ec01daed ("module: add support for symbol namespaces.") did not support the namespace for *.S files. This commit shifts the essential implementation part to C, which supports EXPORT_SYMBOL_NS() for *.S files. <asm/export.h> and <asm-generic/export.h> will remain as a wrapper of <linux/export.h> for a while. They will be removed after #include <asm/export.h> directives are all replaced with #include <linux/export.h>. [3] Implement CONFIG_TRIM_UNUSED_KSYMS in one-pass algorithm (by a later commit) When CONFIG_TRIM_UNUSED_KSYMS is enabled, Kbuild recursively traverses the directory tree to determine which EXPORT_SYMBOL to trim. If an EXPORT_SYMBOL turns out to be unused by anyone, Kbuild begins the second traverse, where some source files are recompiled with their EXPORT_SYMBOL() tuned into a no-op. We can do this better now; modpost can selectively emit KSYMTAB entries that are really used by modules. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2023-06-15modpost: pass struct module pointer to check_section_mismatch()Masahiro Yamada
The next commit will use it. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2023-06-15ARC: define ASM_NL and __ALIGN(_STR) outside #ifdef __ASSEMBLY__ guardMasahiro Yamada
ASM_NL is useful not only in *.S files but also in .c files for using inline assembler in C code. On ARC, however, ASM_NL is evaluated inconsistently. It is expanded to a backquote (`) in *.S files, but a semicolon (;) in *.c files because arch/arc/include/asm/linkage.h defines it inside #ifdef __ASSEMBLY__, so the definition for C code falls back to the default value defined in include/linux/linkage.h. If ASM_NL is used in inline assembler in .c files, it will result in wrong assembly code because a semicolon is not an instruction separator, but the start of a comment for ARC. Move ASM_NL (also __ALIGN and __ALIGN_STR) out of the #ifdef. Fixes: 9df62f054406 ("arch: use ASM_NL instead of ';' for assembler new line character in the macro") Fixes: 8d92e992a785 ("ARC: define __ALIGN_STR and __ALIGN symbols for ARC") Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-15scripts/kallsyms: remove KSYM_NAME_LEN_BUFFERMasahiro Yamada
You do not need to decide the buffer size statically. Use getline() to grow the line buffer as needed. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nicolas Schier <n.schier@avm.de>
2023-06-15scripts/kallsyms: constify long_optionsMasahiro Yamada
getopt_long() does not modify this. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nicolas Schier <n.schier@avm.de>
2023-06-15Revert "[PATCH] uml: export symbols added by GCC hardened"Masahiro Yamada
This reverts commit cead61a6717a9873426b08d73a34a325e3546f5d. It exported __stack_smash_handler and __guard, while they may not be defined by anyone. The code *declares* __stack_smash_handler and __guard. It does not create weak symbols. If no external library is linked, they are left undefined, but yet exported. If a loadable module tries to access non-existing symbols, bad things (a page fault, NULL pointer dereference, etc.) will happen. So, the current code is wrong and dangerous. If the code were written as follows, it would *define* them as weak symbols so modules would be able to get access to them. void (*__stack_smash_handler)(void *) __attribute__((weak)); EXPORT_SYMBOL(__stack_smash_handler); long __guard __attribute__((weak)); EXPORT_SYMBOL(__guard); In fact, modpost forbids exporting undefined symbols. It shows an error message if it detects such a mistake. ERROR: modpost: "..." [...] was exported without definition Unfortunately, it is checked only when the code is built as modular. The problem described above has been unnoticed for a long time because arch/um/os-Linux/user_syms.c is always built-in. With a planned change in Kbuild, exporting undefined symbols will always result in a build error instead of a run-time error. It is a good thing, but we need to fix the breakage in advance. One fix is to define weak symbols as shown above. An alternative is to export them conditionally as follows: #ifdef CONFIG_STACKPROTECTOR extern void __stack_smash_handler(void *); EXPORT_SYMBOL(__stack_smash_handler); external long __guard; EXPORT_SYMBOL(__guard); #endif This is what other architectures do; EXPORT_SYMBOL(__stack_chk_guard) is guarded by #ifdef CONFIG_STACKPROTECTOR. However, adding the #ifdef guard is not sensible because UML cannot enable the stack-protector in the first place! (Please note UML does not select HAVE_STACKPROTECTOR in Kconfig.) So, the code is already broken (and unused) in multiple ways. Just remove. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2023-06-10kbuild: enable kernel-doc -Wall for W=2Johannes Berg
For W=2, we can enable more kernel-doc warnings, such as missing return value descriptions etc. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-10kernel-doc: don't let V=1 change outcomeJohannes Berg
The kernel-doc script currently reports a number of issues only in "verbose" mode, but that's initialized from V=1 (via KBUILD_VERBOSE), so if you use KDOC_WERROR=1 then adding V=1 might actually break the build. This is rather unexpected. Change kernel-doc to not change its behaviour wrt. errors (or warnings) when verbose mode is enabled, but rather add separate warning flags (and -Wall) for it. Allow enabling those flags via environment/make variables in the kernel's build system for easier user use, but to not have to parse them in the script itself. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Acked-by: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-08modpost: fix off by one in is_executable_section()Dan Carpenter
The > comparison should be >= to prevent an out of bounds array access. Fixes: 52dc0595d540 ("modpost: handle relocations mismatch in __ex_table.") Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-08streamline_config.pl: handle also ${CONFIG_FOO}Jiri Slaby
streamline_config.pl currently searches for CONFIG options in Kconfig files as $(CONFIG_FOO). But some Kconfigs (e.g. thunderbolt) use ${CONFIG_FOO}. So fix up the regex to accept both. This fixes: $ make LSMOD=`pwd/`/lsmod localmodconfig using config: '.config' thunderbolt config not found!! Signed-off-by: Jiri Slaby <jslaby@suse.cz> Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com> Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-07kbuild: Add KBUILD_CPPFLAGS to as-option invocationNathan Chancellor
After commit feb843a469fb ("kbuild: add $(CLANG_FLAGS) to KBUILD_CPPFLAGS"), there is an error while building certain PowerPC assembly files with clang: arch/powerpc/lib/copypage_power7.S: Assembler messages: arch/powerpc/lib/copypage_power7.S:34: Error: junk at end of line: `0b01000' arch/powerpc/lib/copypage_power7.S:35: Error: junk at end of line: `0b01010' arch/powerpc/lib/copypage_power7.S:37: Error: junk at end of line: `0b01000' arch/powerpc/lib/copypage_power7.S:38: Error: junk at end of line: `0b01010' arch/powerpc/lib/copypage_power7.S:40: Error: junk at end of line: `0b01010' clang: error: assembler command failed with exit code 1 (use -v to see invocation) as-option only uses KBUILD_AFLAGS, so after removing CLANG_FLAGS from KBUILD_AFLAGS, there is no more '--target=' or '--prefix=' flags. As a result of those missing flags, the host target will be tested during as-option calls and likely fail, meaning necessary flags may not get added when building assembly files, resulting in errors like seen above. Add KBUILD_CPPFLAGS to as-option invocations to clear up the errors. This should have been done in commit d5c8d6e0fa61 ("kbuild: Update assembler calls to use proper flags and language target"), which switched from using the assembler target to the assembler-with-cpp target, so flags that affect preprocessing are passed along in all relevant tests. as-option now mirrors cc-option. Fixes: feb843a469fb ("kbuild: add $(CLANG_FLAGS) to KBUILD_CPPFLAGS") Reported-by: Linux Kernel Functional Testing <lkft@linaro.org> Closes: https://lore.kernel.org/CA+G9fYs=koW9WardsTtora+nMgLR3raHz-LSLr58tgX4T5Mxag@mail.gmail.com/ Signed-off-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-07scripts/mksysmap: Ignore __pi_ local arm64 symbolsPierre-Clément Tosi
Similarly to "__kvm_nvhe_", filter out any local symbol that was prefixed with "__pi_" (generated when CONFIG_RANDOMIZE_BASE=y) when compiling System.map and in kallsyms. Signed-off-by: Pierre-Clément Tosi <ptosi@google.com> Acked-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-07scripts/mksysmap: Fix badly escaped '$'Pierre-Clément Tosi
The backslash characters escaping '$' in the command to sed (intended to prevent it from interpreting '$' as "end-of-line") are currently being consumed by the Shell (where they mean that sh should not evaluate what follows '$' as a variable name). This means that sed -e "/ \$/d" executes the script / $/d instead of the intended / \$/d So escape twice in mksysmap any '$' that actually needs to reach sed escaped so that the backslash survives the Shell. Fixes: c4802044a0a7 ("scripts/mksysmap: use sed with in-line comments") Fixes: 320e7c9d4494 ("scripts/kallsyms: move compiler-generated symbol patterns to mksysmap") Signed-off-by: Pierre-Clément Tosi <ptosi@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-07modpost: propagate W=1 build option to modpostMasahiro Yamada
"No build warning" is a strong requirement these days, so you must fix all issues before enabling a new warning flag. We often add a new warning to W=1 first so that the kbuild test robot blocks new breakages. This commit allows modpost to show extra warnings only when W=1 (or KBUILD_EXTRA_WARN=1) is given. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2023-06-06initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMPBenjamin Gray
gen_initramfs.sh has an internal dependency on KBUILD_BUILD_TIMESTAMP for generating file mtimes that is not exposed to make, so changing KBUILD_BUILD_TIMESTAMP will not trigger a rebuild of the archive. Declare the mtime date as a new parameter to gen_initramfs.sh to encode KBUILD_BUILD_TIMESTAMP in the shell command, thereby making make aware of the dependency. It will rebuild if KBUILD_BUILD_TIMESTAMP changes or is newly set/unset. It will _not_ rebuild if KBUILD_BUILD_TIMESTAMP is unset before and after. This should be fine for anyone who doesn't care about setting specific build times in the first place. Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com> Tested-by: Andrew Donnellan <ajd@linux.ibm.com> Signed-off-by: Benjamin Gray <bgray@linux.ibm.com> Reviewed-by: Nicolas Schier <n.schier@avm.de> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-05kbuild: add $(CLANG_FLAGS) to KBUILD_CPPFLAGSMasahiro Yamada
When preprocessing arch/*/kernel/vmlinux.lds.S, the target triple is not passed to $(CPP) because we add it only to KBUILD_{C,A}FLAGS. As a result, the linker script is preprocessed with predefined macros for the build host instead of the target. Assuming you use an x86 build machine, compare the following: $ clang -dM -E -x c /dev/null $ clang -dM -E -x c /dev/null -target aarch64-linux-gnu There is no actual problem presumably because our linker scripts do not rely on such predefined macros, but it is better to define correct ones. Move $(CLANG_FLAGS) to KBUILD_CPPFLAGS, so that all *.c, *.S, *.lds.S will be processed with the proper target triple. [Note] After the patch submission, we got an actual problem that needs this commit. (CBL issue 1859) Link: https://github.com/ClangBuiltLinux/linux/issues/1859 Reported-by: Tom Rini <trini@konsulko.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org>
2023-06-05kbuild: Add CLANG_FLAGS to as-instrNathan Chancellor
A future change will move CLANG_FLAGS from KBUILD_{A,C}FLAGS to KBUILD_CPPFLAGS so that '--target' is available while preprocessing. When that occurs, the following errors appear multiple times when building ARCH=powerpc powernv_defconfig: ld.lld: error: vmlinux.a(arch/powerpc/kernel/head_64.o):(.text+0x12d4): relocation R_PPC64_ADDR16_HI out of range: -4611686018409717520 is not in [-2147483648, 2147483647]; references '__start___soft_mask_table' ld.lld: error: vmlinux.a(arch/powerpc/kernel/head_64.o):(.text+0x12e8): relocation R_PPC64_ADDR16_HI out of range: -4611686018409717392 is not in [-2147483648, 2147483647]; references '__stop___soft_mask_table' Diffing the .o.cmd files reveals that -DHAVE_AS_ATHIGH=1 is not present anymore, because as-instr only uses KBUILD_AFLAGS, which will no longer contain '--target'. Mirror Kconfig's as-instr and add CLANG_FLAGS explicitly to the invocation to ensure the target information is always present. Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-05powerpc/vdso: Include CLANG_FLAGS explicitly in ldflags-yNathan Chancellor
A future change will move CLANG_FLAGS from KBUILD_{A,C}FLAGS to KBUILD_CPPFLAGS so that '--target' is available while preprocessing. When that occurs, the following error appears when building the compat PowerPC vDSO: clang: error: unsupported option '-mbig-endian' for target 'x86_64-pc-linux-gnu' make[3]: *** [.../arch/powerpc/kernel/vdso/Makefile:76: arch/powerpc/kernel/vdso/vdso32.so.dbg] Error 1 Explicitly add CLANG_FLAGS to ldflags-y, so that '--target' will always be present. Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-05mips: Include KBUILD_CPPFLAGS in CHECKFLAGS invocationNathan Chancellor
A future change will move CLANG_FLAGS from KBUILD_{A,C}FLAGS to KBUILD_CPPFLAGS so that '--target' is available while preprocessing. When that occurs, the following error appears when building ARCH=mips with clang (tip of tree error shown): clang: error: unsupported option '-mabi=' for target 'x86_64-pc-linux-gnu' Add KBUILD_CPPFLAGS in the CHECKFLAGS invocation to keep everything working after the move. Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-04modpost: detect section mismatch for R_ARM_REL32Masahiro Yamada
For ARM, modpost fails to detect some types of section mismatches. [test code] .section .init.data,"aw" bar: .long 0 .section .data,"aw" .globl foo foo: .long bar - . It is apparently a bad reference, but modpost does not report anything. The test code above produces the following relocations. Relocation section '.rel.data' at offset 0xe8 contains 1 entry: Offset Info Type Sym.Value Sym. Name 00000000 00000403 R_ARM_REL32 00000000 .init.data Currently, R_ARM_REL32 is just skipped. Handle it like R_ARM_ABS32. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-04modpost: fix section_mismatch message for R_ARM_THM_{CALL,JUMP24,JUMP19}Masahiro Yamada
addend_arm_rel() processes R_ARM_THM_CALL, R_ARM_THM_JUMP24, R_ARM_THM_JUMP19 in a wrong way. Here, test code. [test code for R_ARM_THM_JUMP24]   .section .init.text,"ax"   bar:           bx      lr   .section .text,"ax"   .globl foo   foo:           b       bar [test code for R_ARM_THM_CALL]   .section .init.text,"ax"   bar:           bx      lr   .section .text,"ax"   .globl foo   foo:           push    {lr}           bl      bar           pop     {pc} If you compile it with CONFIG_THUMB2_KERNEL=y, modpost will show the symbol name, (unknown).   WARNING: modpost: vmlinux.o: section mismatch in reference: foo (section: .text) -> (unknown) (section: .init.text) (You need to use GNU linker instead of LLD to reproduce it.) Fix the code to make modpost show the correct symbol name. I checked arch/arm/kernel/module.c to learn the encoding of R_ARM_THM_CALL and R_ARM_THM_JUMP24. The module does not support R_ARM_THM_JUMP19, but I checked its encoding in ARM ARM. The '+4' is the compensation for pc-relative instruction. It is documented in "ELF for the Arm Architecture" [1].   "If the relocation is pc-relative then compensation for the PC bias   (the PC value is 8 bytes ahead of the executing instruction in Arm   state and 4 bytes in Thumb state) must be encoded in the relocation   by the object producer." [1]: https://github.com/ARM-software/abi-aa/blob/main/aaelf32/aaelf32.rst Fixes: c9698e5cd6ad ("ARM: 7964/1: Detect section mismatches in thumb relocations") Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-04modpost: detect section mismatch for R_ARM_THM_{MOVW_ABS_NC,MOVT_ABS}Masahiro Yamada
When CONFIG_THUMB2_KERNEL is enabled, modpost fails to detect some types of section mismatches. [test code] #include <linux/init.h> int __initdata foo; int get_foo(void) { return foo; } It is apparently a bad reference, but modpost does not report anything. The test code above produces the following relocations. Relocation section '.rel.text' at offset 0x1e8 contains 2 entries: Offset Info Type Sym.Value Sym. Name 00000000 0000052f R_ARM_THM_MOVW_AB 00000000 .LANCHOR0 00000004 00000530 R_ARM_THM_MOVT_AB 00000000 .LANCHOR0 Currently, R_ARM_THM_MOVW_ABS_NC and R_ARM_THM_MOVT_ABS are just skipped. Add code to handle them. I checked arch/arm/kernel/module.c to learn how the offset is encoded in the instruction. One more thing to note for Thumb instructions - the st_value is an odd value, so you need to mask the bit 0 to get the offset. Otherwise, you will get an off-by-one error in the nearest symbol look-up. It is documented in "ELF for the ARM Architecture" [1]: In addition to the normal rules for symbol values the following rules shall also apply to symbols of type STT_FUNC: * If the symbol addresses an Arm instruction, its value is the address of the instruction (in a relocatable object, the offset of the instruction from the start of the section containing it). * If the symbol addresses a Thumb instruction, its value is the address of the instruction with bit zero set (in a relocatable object, the section offset with bit zero set). * For the purposes of relocation the value used shall be the address of the instruction (st_value & ~1). [1]: https://github.com/ARM-software/abi-aa/blob/main/aaelf32/aaelf32.rst Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-02modpost: refactor find_fromsym() and find_tosym()Masahiro Yamada
find_fromsym() and find_tosym() are similar - both of them iterate in the .symtab section and return the nearest symbol. The difference between them is that find_tosym() allows a negative distance, but the distance must be less than 20. Factor out the common part into find_nearest_sym(). Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2023-06-02modpost: detect section mismatch for R_ARM_{MOVW_ABS_NC,MOVT_ABS}Masahiro Yamada
For ARM defconfig (i.e. multi_v7_defconfig), modpost fails to detect some types of section mismatches. [test code] #include <linux/init.h> int __initdata foo; int get_foo(void) { return foo; } It is apparently a bad reference, but modpost does not report anything. The test code above produces the following relocations. Relocation section '.rel.text' at offset 0x200 contains 2 entries: Offset Info Type Sym.Value Sym. Name 00000000 0000062b R_ARM_MOVW_ABS_NC 00000000 .LANCHOR0 00000004 0000062c R_ARM_MOVT_ABS 00000000 .LANCHOR0 Currently, R_ARM_MOVW_ABS_NC and R_ARM_MOVT_ABS are just skipped. Add code to handle them. I checked arch/arm/kernel/module.c to learn how the offset is encoded in the instruction. The referenced symbol in relocation might be a local anchor. If is_valid_name() returns false, let's search for a better symbol name. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-02modpost: fix section mismatch message for R_ARM_{PC24,CALL,JUMP24}Masahiro Yamada
addend_arm_rel() processes R_ARM_PC24, R_ARM_CALL, R_ARM_JUMP24 in a wrong way. Here, test code. [test code for R_ARM_JUMP24] .section .init.text,"ax" bar: bx lr .section .text,"ax" .globl foo foo: b bar [test code for R_ARM_CALL] .section .init.text,"ax" bar: bx lr .section .text,"ax" .globl foo foo: push {lr} bl bar pop {pc} If you compile it with ARM multi_v7_defconfig, modpost will show the symbol name, (unknown). WARNING: modpost: vmlinux.o: section mismatch in reference: foo (section: .text) -> (unknown) (section: .init.text) (You need to use GNU linker instead of LLD to reproduce it.) Fix the code to make modpost show the correct symbol name. I imported (with adjustment) sign_extend32() from include/linux/bitops.h. The '+8' is the compensation for pc-relative instruction. It is documented in "ELF for the Arm Architecture" [1]. "If the relocation is pc-relative then compensation for the PC bias (the PC value is 8 bytes ahead of the executing instruction in Arm state and 4 bytes in Thumb state) must be encoded in the relocation by the object producer." [1]: https://github.com/ARM-software/abi-aa/blob/main/aaelf32/aaelf32.rst Fixes: 56a974fa2d59 ("kbuild: make better section mismatch reports on arm") Fixes: 6e2e340b59d2 ("ARM: 7324/1: modpost: Fix section warnings for ARM for many compilers") Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-06-02modpost: fix section mismatch message for R_ARM_ABS32Masahiro Yamada
addend_arm_rel() processes R_ARM_ABS32 in a wrong way. Here, test code. [test code 1] #include <linux/init.h> int __initdata foo; int get_foo(void) { return foo; } If you compile it with ARM versatile_defconfig, modpost will show the symbol name, (unknown). WARNING: modpost: vmlinux.o: section mismatch in reference: get_foo (section: .text) -> (unknown) (section: .init.data) (You need to use GNU linker instead of LLD to reproduce it.) If you compile it for other architectures, modpost will show the correct symbol name. WARNING: modpost: vmlinux.o: section mismatch in reference: get_foo (section: .text) -> foo (section: .init.data) For R_ARM_ABS32, addend_arm_rel() sets r->r_addend to a wrong value. I just mimicked the code in arch/arm/kernel/module.c. However, there is more difficulty for ARM. Here, test code. [test code 2] #include <linux/init.h> int __initdata foo; int get_foo(void) { return foo; } int __initdata bar; int get_bar(void) { return bar; } With this commit applied, modpost will show the following messages for ARM versatile_defconfig: WARNING: modpost: vmlinux.o: section mismatch in reference: get_foo (section: .text) -> foo (section: .init.data) WARNING: modpost: vmlinux.o: section mismatch in reference: get_bar (section: .text) -> foo (section: .init.data) The reference from 'get_bar' to 'foo' seems wrong. I have no solution for this because it is true in assembly level. In the following output, relocation at 0x1c is no longer associated with 'bar'. The two relocation entries point to the same symbol, and the offset to 'bar' is encoded in the instruction 'r0, [r3, #4]'. Disassembly of section .text: 00000000 <get_foo>: 0: e59f3004 ldr r3, [pc, #4] @ c <get_foo+0xc> 4: e5930000 ldr r0, [r3] 8: e12fff1e bx lr c: 00000000 .word 0x00000000 00000010 <get_bar>: 10: e59f3004 ldr r3, [pc, #4] @ 1c <get_bar+0xc> 14: e5930004 ldr r0, [r3, #4] 18: e12fff1e bx lr 1c: 00000000 .word 0x00000000 Relocation section '.rel.text' at offset 0x244 contains 2 entries: Offset Info Type Sym.Value Sym. Name 0000000c 00000c02 R_ARM_ABS32 00000000 .init.data 0000001c 00000c02 R_ARM_ABS32 00000000 .init.data When find_elf_symbol() gets into a situation where relsym->st_name is zero, there is no guarantee to get the symbol name as written in C. I am keeping the current logic because it is useful in many architectures, but the symbol name is not always correct depending on the optimization. I left some comments in find_tosym(). Fixes: 56a974fa2d59 ("kbuild: make better section mismatch reports on arm") Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-05-28modpost: remove *_sections[] arraysMasahiro Yamada
Use PATTERNS() macros to remove unneeded array definitions. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-05-28modpost: merge bad_tosec=ALL_EXIT_SECTIONS entries in sectioncheck tableMasahiro Yamada
There is no distinction between TEXT_TO_ANY_EXIT and DATA_TO_ANY_EXIT. Just merge them. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>