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* | modpost: pass r_type to addend_*_rel()Masahiro Yamada2023-07-311-13/+11
| | | | | | | | | | | | | | | | | | All of addend_*_rel() need the Elf_Rela pointer just for calculating ELF_R_TYPE(r->r_info). You can do it on the caller to de-duplicate the code. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
* | modpost: change return type of addend_*_rel()Masahiro Yamada2023-07-311-39/+24
| | | | | | | | | | | | | | Now that none of addend_*_rel() returns a meaningful value (the return value is always 0), change all of them to return the value of r_addend. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
* | linux/export.h: make <linux/export.h> independent of CONFIG_MODULESMasahiro Yamada2023-07-251-2/+6
|/ | | | | | | | | | | | | | Currently, all files with EXPORT_SYMBOL() are rebuilt when CONFIG_MODULES is flipped due to <linux/export.h> depending on CONFIG_MODULES. Now that modpost can make a final decision about export symbols, <linux/export.h> does not need to make EXPORT_SYMBOL() no-op. Instead, modpost can skip emitting KSYMTAB when CONFIG_MODULES is unset. This commit will reduce the number of recompilation when CONFIG_MODULES is toggled. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
* Merge tag 'kbuild-v6.5' of ↵Linus Torvalds2023-07-012-418/+373
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild Pull Kbuild updates from Masahiro Yamada: - Remove the deprecated rule to build *.dtbo from *.dts - Refactor section mismatch detection in modpost - Fix bogus ARM section mismatch detections - Fix error of 'make gtags' with O= option - Add Clang's target triple to KBUILD_CPPFLAGS to fix a build error with the latest LLVM version - Rebuild the built-in initrd when KBUILD_BUILD_TIMESTAMP is changed - Ignore more compiler-generated symbols for kallsyms - Fix 'make local*config' to handle the ${CONFIG_FOO} form in Makefiles - Enable more kernel-doc warnings with W=2 - Refactor <linux/export.h> by generating KSYMTAB data by modpost - Deprecate <asm/export.h> and <asm-generic/export.h> - Remove the EXPORT_DATA_SYMBOL macro - Move the check for static EXPORT_SYMBOL back to modpost, which makes the build faster - Re-implement CONFIG_TRIM_UNUSED_KSYMS with one-pass algorithm - Warn missing MODULE_DESCRIPTION when building modules with W=1 - Make 'make clean' robust against too long argument error - Exclude more objects from GCOV to fix CFI failures with GCOV - Allow 'make modules_install' to install modules.builtin and modules.builtin.modinfo even when CONFIG_MODULES is disabled - Include modules.builtin and modules.builtin.modinfo in the linux-image Debian package even when CONFIG_MODULES is disabled - Revive "Entering directory" logging for the latest Make version * tag 'kbuild-v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (72 commits) modpost: define more R_ARM_* for old distributions kbuild: revive "Entering directory" for Make >= 4.4.1 kbuild: set correct abs_srctree and abs_objtree for package builds scripts/mksysmap: Ignore prefixed KCFI symbols kbuild: deb-pkg: remove the CONFIG_MODULES check in buildeb kbuild: builddeb: always make modules_install, to install modules.builtin* modpost: continue even with unknown relocation type modpost: factor out Elf_Sym pointer calculation to section_rel() modpost: factor out inst location calculation to section_rel() kbuild: Disable GCOV for *.mod.o kbuild: Fix CFI failures with GCOV kbuild: make clean rule robust against too long argument error script: modpost: emit a warning when the description is missing kbuild: make modules_install copy modules.builtin(.modinfo) linux/export.h: rename 'sec' argument to 'license' modpost: show offset from symbol for section mismatch warnings modpost: merge two similar section mismatch warnings kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without recursion modpost: use null string instead of NULL pointer for default namespace modpost: squash sym_update_namespace() into sym_add_exported() ...
| * modpost: define more R_ARM_* for old distributionsMasahiro Yamada2023-06-291-0/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * modpost: continue even with unknown relocation typeMasahiro Yamada2023-06-251-10/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * modpost: factor out Elf_Sym pointer calculation to section_rel()Masahiro Yamada2023-06-251-4/+5
| | | | | | | | | | | | | | | | 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>
| * modpost: factor out inst location calculation to section_rel()Masahiro Yamada2023-06-251-16/+12
| | | | | | | | | | | | | | | | | | 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>
| * script: modpost: emit a warning when the description is missingVincenzo Palazzo2023-06-241-0/+2
| | | | | | | | | | | | | | | | | | | | | | 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>
| * modpost: show offset from symbol for section mismatch warningsMasahiro Yamada2023-06-221-2/+2
| | | | | | | | | | | | | | | | | | | | | | 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>
| * modpost: merge two similar section mismatch warningsMasahiro Yamada2023-06-221-15/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without recursionMasahiro Yamada2023-06-221-5/+52
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * modpost: use null string instead of NULL pointer for default namespaceMasahiro Yamada2023-06-221-6/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * modpost: squash sym_update_namespace() into sym_add_exported()Masahiro Yamada2023-06-221-23/+4
| | | | | | | | | | | | | | | | | | 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>
| * modpost: check static EXPORT_SYMBOL* by modpost againMasahiro Yamada2023-06-221-0/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * kbuild: generate KSYMTAB entries by modpostMasahiro Yamada2023-06-222-33/+74
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * modpost: pass struct module pointer to check_section_mismatch()Masahiro Yamada2023-06-151-11/+11
| | | | | | | | | | | | | | The next commit will use it. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
| * modpost: fix off by one in is_executable_section()Dan Carpenter2023-06-081-1/+1
| | | | | | | | | | | | | | | | | | 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>
| * modpost: propagate W=1 build option to modpostMasahiro Yamada2023-06-071-1/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | "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>
| * modpost: detect section mismatch for R_ARM_REL32Masahiro Yamada2023-06-041-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * modpost: fix section_mismatch message for R_ARM_THM_{CALL,JUMP24,JUMP19}Masahiro Yamada2023-06-041-6/+47
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * modpost: detect section mismatch for R_ARM_THM_{MOVW_ABS_NC,MOVT_ABS}Masahiro Yamada2023-06-041-5/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * modpost: refactor find_fromsym() and find_tosym()Masahiro Yamada2023-06-021-56/+33
| | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * modpost: detect section mismatch for R_ARM_{MOVW_ABS_NC,MOVT_ABS}Masahiro Yamada2023-06-021-2/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * modpost: fix section mismatch message for R_ARM_{PC24,CALL,JUMP24}Masahiro Yamada2023-06-021-0/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * modpost: fix section mismatch message for R_ARM_ABS32Masahiro Yamada2023-06-021-3/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * modpost: remove *_sections[] arraysMasahiro Yamada2023-05-281-27/+9
| | | | | | | | | | | | Use PATTERNS() macros to remove unneeded array definitions. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
| * modpost: merge bad_tosec=ALL_EXIT_SECTIONS entries in sectioncheck tableMasahiro Yamada2023-05-281-11/+4
| | | | | | | | | | | | | | | | 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>
| * modpost: merge fromsec=DATA_SECTIONS entries in sectioncheck tableMasahiro Yamada2023-05-281-6/+1
| | | | | | | | | | | | | | You can merge these entries. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
| * modpost: remove is_shndx_special() check from section_rel(a)Masahiro Yamada2023-05-282-17/+4
| | | | | | | | | | | | | | | | | | | | This check is unneeded. Without it, sec_name() will returns the null string "", then section_mismatch() will return immediately. Anyway, special section indices rarely appear in these loops. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
| * modpost: replace r->r_offset, r->r_addend with faddr, taddrMasahiro Yamada2023-05-281-15/+19
| | | | | | | | | | | | | | | | | | | | | | r_offset/r_addend holds the offset address from/to which a symbol is referenced. It is unclear unless you are familiar with ELF. Rename them to faddr, taddr, respectively. The prefix 'f' means 'from', 't' means 'to'. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
| * modpost: unify 'sym' and 'to' in default_mismatch_handler()Masahiro Yamada2023-05-281-5/+4
| | | | | | | | | | | | | | | | | | find_tosym() takes 'sym' and stores the return value to another variable 'to'. You can use the same variable because we want to replace the original one when appropriate. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
| * modpost: remove unused argument from secref_whitelist()Masahiro Yamada2023-05-281-3/+2
| | | | | | | | | | | | | | secref_whitelist() does not use the argument 'mismatch'. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
| * Revert "modpost: skip ELF local symbols during section mismatch check"Masahiro Yamada2023-05-281-12/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This reverts commit a4d26f1a0958bb1c2b60c6f1e67c6f5d43e2647b. The variable 'fromsym' never starts with ".L" since commit 87e5b1e8f257 ("module: Sync code of is_arm_mapping_symbol()"). In other words, Pattern 6 is now dead code. Previously, the .LANCHOR1 hid the symbols listed in Pattern 2. 87e5b1e8f257 provided a better solution. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
| * modpost: rename find_elf_symbol() and find_elf_symbol2()Masahiro Yamada2023-05-221-6/+6
| | | | | | | | | | | | | | | | find_elf_symbol() and find_elf_symbol2() are not good names. Rename them to find_tosym(), find_fromsym(), respectively. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
| * modpost: pass section index to find_elf_symbol2()Masahiro Yamada2023-05-221-19/+15
| | | | | | | | | | | | | | | | | | | | find_elf_symbol2() converts the section index to the section name, then compares the two strings in each iteration. This is slow. It is faster to compare the section indices (i.e. integers) directly. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
| * modpost: pass 'tosec' down to default_mismatch_handler()Masahiro Yamada2023-05-221-4/+3
| | | | | | | | | | | | | | | | | | | | | | default_mismatch_handler() does not need to compute 'tosec' because it is calculated by the caller. Pass it down to default_mismatch_handler() instead of calling sec_name() twice. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
| * modpost: squash extable_mismatch_handler() into default_mismatch_handler()Masahiro Yamada2023-05-221-58/+26
| | | | | | | | | | | | | | | | Merging these two reduces several lines of code. The extable section mismatch is already distinguished by EXTABLE_TO_NON_TEXT. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
| * modpost: clean up is_executable_section()Masahiro Yamada2023-05-221-8/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | SHF_EXECINSTR is a bit flag (#define SHF_EXECINSTR 0x4). Compare the masked flag to '!= 0'. There is no good reason to stop modpost immediately even if a special section index is given. You will get a section mismatch error anyway. Also, change the return type to bool. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
| * modpost: squash report_sec_mismatch() into default_mismatch_handler()Masahiro Yamada2023-05-221-35/+20
| | | | | | | | | | | | | | | | report_sec_mismatch() and default_mismatch_handler() are small enough to be merged together. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
| * modpost: squash report_extable_warnings() into extable_mismatch_handler()Masahiro Yamada2023-05-221-26/+14
| | | | | | | | | | | | | | | | Collect relevant code into one place to clarify all the cases are covered by 'if () ... else if ... else ...'. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
| * modpost: remove get_prettyname()Masahiro Yamada2023-05-221-25/+2
| | | | | | | | | | | | | | | | This is the last user of get_pretty_name() - it is just used to distinguish whether the symbol is a function or not. It is not valuable information. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
| * modpost: remove fromsym info in __ex_table section mismatch warningMasahiro Yamada2023-05-221-9/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | report_extable_warnings() prints "from" in a pretty form, but we know it is always located in the __ex_table section, i.e. a collection of struct exception_table_entry. It is very likely to fail to get the symbol name and ends up with meaningless message: ... in reference from the (unknown reference) (unknown) to ... Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
| * modpost: remove broken calculation of exception_table_entry sizeMasahiro Yamada2023-05-221-57/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | find_extable_entry_size() is completely broken. It has awesome comments about how to calculate sizeof(struct exception_table_entry). It was based on these assumptions: - struct exception_table_entry has two fields - both of the fields have the same size Then, we came up with this equation: (offset of the second field) * 2 == (size of struct) It was true for all architectures when commit 52dc0595d540 ("modpost: handle relocations mismatch in __ex_table.") was applied. Our mathematics broke when commit 548acf19234d ("x86/mm: Expand the exception table logic to allow new handling options") introduced the third field. Now, the definition of exception_table_entry is highly arch-dependent. For x86, sizeof(struct exception_table_entry) is apparently 12, but find_extable_entry_size() sets extable_entry_size to 8. I could fix it, but I do not see much value in this code. extable_entry_size is used just for selecting a slightly different error message. If the first field ("insn") references to a non-executable section, The relocation at %s+0x%lx references section "%s" which is not executable, IOW it is not possible for the kernel to fault at that address. Something is seriously wrong and should be fixed. If the second field ("fixup") references to a non-executable section, The relocation at %s+0x%lx references section "%s" which is not executable, IOW the kernel will fault if it ever tries to jump to it. Something is seriously wrong and should be fixed. Merge the two error messages rather than adding even more complexity. Change fatal() to error() to make it continue running and catch more possible errors. Fixes: 548acf19234d ("x86/mm: Expand the exception table logic to allow new handling options") Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
| * modpost: error out if addend_*_rel() is not implemented for REL archMasahiro Yamada2023-05-221-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | The section mismatch check relies on the relocation entries. For REL, the addend value is implicit, so we need some code to compute it. Currently, EM_386, EM_ARM, and EM_MIPS are supported. This commit makes sure we covered all the cases. I believe the other architectures use RELA, where the explicit r_addend field exists. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
* | Merge tag 'vfio-v6.5-rc1' of https://github.com/awilliam/linux-vfioLinus Torvalds2023-06-302-1/+17
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull VFIO updates from Alex Williamson: - Adjust log levels for common messages (Oleksandr Natalenko, Alex Williamson) - Support for dynamic MSI-X allocation (Reinette Chatre) - Enable and report PCIe AtomicOp Completer capabilities (Alex Williamson) - Cleanup Kconfigs for vfio bus drivers (Alex Williamson) - Add support for CDX bus based devices (Nipun Gupta) - Fix race with concurrent mdev initialization (Eric Farman) * tag 'vfio-v6.5-rc1' of https://github.com/awilliam/linux-vfio: vfio/mdev: Move the compat_class initialization to module init vfio/cdx: add support for CDX bus vfio/fsl: Create Kconfig sub-menu vfio/platform: Cleanup Kconfig vfio/pci: Cleanup Kconfig vfio/pci-core: Add capability for AtomicOp completer support vfio/pci: Also demote hiding standard cap messages vfio/pci: Clear VFIO_IRQ_INFO_NORESIZE for MSI-X vfio/pci: Support dynamic MSI-X vfio/pci: Probe and store ability to support dynamic MSI-X vfio/pci: Use bitfield for struct vfio_pci_core_device flags vfio/pci: Update stale comment vfio/pci: Remove interrupt context counter vfio/pci: Use xarray for interrupt context storage vfio/pci: Move to single error path vfio/pci: Prepare for dynamic interrupt context storage vfio/pci: Remove negative check on unsigned vector vfio/pci: Consolidate irq cleanup on MSI/MSI-X disable vfio/pci: demote hiding ecap messages to debug level
| * | vfio/cdx: add support for CDX busNipun Gupta2023-06-162-1/+17
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | vfio-cdx driver enables IOCTLs for user space to query MMIO regions for CDX devices and mmap them. This change also adds support for reset of CDX devices. With VFIO enabled on CDX devices, user-space applications can also exercise DMA securely via IOMMU on these devices. This change adds the VFIO CDX driver and enables the following ioctls for CDX devices: - VFIO_DEVICE_GET_INFO: - VFIO_DEVICE_GET_REGION_INFO - VFIO_DEVICE_RESET Signed-off-by: Nipun Gupta <nipun.gupta@amd.com> Reviewed-by: Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@amd.com> Tested-by: Nikhil Agarwal <nikhil.agarwal@amd.com> Link: https://lore.kernel.org/r/20230531124557.11009-1-nipun.gupta@amd.com Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
* / x86/unwind/orc: Add ELF section with ORC version identifierOmar Sandoval2023-06-161-0/+5
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commits ffb1b4a41016 ("x86/unwind/orc: Add 'signal' field to ORC metadata") and fb799447ae29 ("x86,objtool: Split UNWIND_HINT_EMPTY in two") changed the ORC format. Although ORC is internal to the kernel, it's the only way for external tools to get reliable kernel stack traces on x86-64. In particular, the drgn debugger [1] uses ORC for stack unwinding, and these format changes broke it [2]. As the drgn maintainer, I don't care how often or how much the kernel changes the ORC format as long as I have a way to detect the change. It suffices to store a version identifier in the vmlinux and kernel module ELF files (to use when parsing ORC sections from ELF), and in kernel memory (to use when parsing ORC from a core dump+symbol table). Rather than hard-coding a version number that needs to be manually bumped, Peterz suggested hashing the definitions from orc_types.h. If there is a format change that isn't caught by this, the hashing script can be updated. This patch adds an .orc_header allocated ELF section containing the 20-byte hash to vmlinux and kernel modules, along with the corresponding __start_orc_header and __stop_orc_header symbols in vmlinux. 1: https://github.com/osandov/drgn 2: https://github.com/osandov/drgn/issues/303 Fixes: ffb1b4a41016 ("x86/unwind/orc: Add 'signal' field to ORC metadata") Fixes: fb799447ae29 ("x86,objtool: Split UNWIND_HINT_EMPTY in two") Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Link: https://lkml.kernel.org/r/aef9c8dc43915b886a8c48509a12ec1b006ca1ca.1686690801.git.osandov@osandov.com
* Merge tag 'modules-6.4-rc1' of ↵Linus Torvalds2023-04-271-9/+3
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux Pull module updates from Luis Chamberlain: "The summary of the changes for this pull requests is: - Song Liu's new struct module_memory replacement - Nick Alcock's MODULE_LICENSE() removal for non-modules - My cleanups and enhancements to reduce the areas where we vmalloc module memory for duplicates, and the respective debug code which proves the remaining vmalloc pressure comes from userspace. Most of the changes have been in linux-next for quite some time except the minor fixes I made to check if a module was already loaded prior to allocating the final module memory with vmalloc and the respective debug code it introduces to help clarify the issue. Although the functional change is small it is rather safe as it can only *help* reduce vmalloc space for duplicates and is confirmed to fix a bootup issue with over 400 CPUs with KASAN enabled. I don't expect stable kernels to pick up that fix as the cleanups would have also had to have been picked up. Folks on larger CPU systems with modules will want to just upgrade if vmalloc space has been an issue on bootup. Given the size of this request, here's some more elaborate details: The functional change change in this pull request is the very first patch from Song Liu which replaces the 'struct module_layout' with a new 'struct module_memory'. The old data structure tried to put together all types of supported module memory types in one data structure, the new one abstracts the differences in memory types in a module to allow each one to provide their own set of details. This paves the way in the future so we can deal with them in a cleaner way. If you look at changes they also provide a nice cleanup of how we handle these different memory areas in a module. This change has been in linux-next since before the merge window opened for v6.3 so to provide more than a full kernel cycle of testing. It's a good thing as quite a bit of fixes have been found for it. Jason Baron then made dynamic debug a first class citizen module user by using module notifier callbacks to allocate / remove module specific dynamic debug information. Nick Alcock has done quite a bit of work cross-tree to remove module license tags from things which cannot possibly be module at my request so to: a) help him with his longer term tooling goals which require a deterministic evaluation if a piece a symbol code could ever be part of a module or not. But quite recently it is has been made clear that tooling is not the only one that would benefit. Disambiguating symbols also helps efforts such as live patching, kprobes and BPF, but for other reasons and R&D on this area is active with no clear solution in sight. b) help us inch closer to the now generally accepted long term goal of automating all the MODULE_LICENSE() tags from SPDX license tags In so far as a) is concerned, although module license tags are a no-op for non-modules, tools which would want create a mapping of possible modules can only rely on the module license tag after the commit 8b41fc4454e ("kbuild: create modules.builtin without Makefile.modbuiltin or tristate.conf"). Nick has been working on this *for years* and AFAICT I was the only one to suggest two alternatives to this approach for tooling. The complexity in one of my suggested approaches lies in that we'd need a possible-obj-m and a could-be-module which would check if the object being built is part of any kconfig build which could ever lead to it being part of a module, and if so define a new define -DPOSSIBLE_MODULE [0]. A more obvious yet theoretical approach I've suggested would be to have a tristate in kconfig imply the same new -DPOSSIBLE_MODULE as well but that means getting kconfig symbol names mapping to modules always, and I don't think that's the case today. I am not aware of Nick or anyone exploring either of these options. Quite recently Josh Poimboeuf has pointed out that live patching, kprobes and BPF would benefit from resolving some part of the disambiguation as well but for other reasons. The function granularity KASLR (fgkaslr) patches were mentioned but Joe Lawrence has clarified this effort has been dropped with no clear solution in sight [1]. In the meantime removing module license tags from code which could never be modules is welcomed for both objectives mentioned above. Some developers have also welcomed these changes as it has helped clarify when a module was never possible and they forgot to clean this up, and so you'll see quite a bit of Nick's patches in other pull requests for this merge window. I just picked up the stragglers after rc3. LWN has good coverage on the motivation behind this work [2] and the typical cross-tree issues he ran into along the way. The only concrete blocker issue he ran into was that we should not remove the MODULE_LICENSE() tags from files which have no SPDX tags yet, even if they can never be modules. Nick ended up giving up on his efforts due to having to do this vetting and backlash he ran into from folks who really did *not understand* the core of the issue nor were providing any alternative / guidance. I've gone through his changes and dropped the patches which dropped the module license tags where an SPDX license tag was missing, it only consisted of 11 drivers. To see if a pull request deals with a file which lacks SPDX tags you can just use: ./scripts/spdxcheck.py -f \ $(git diff --name-only commid-id | xargs echo) You'll see a core module file in this pull request for the above, but that's not related to his changes. WE just need to add the SPDX license tag for the kernel/module/kmod.c file in the future but it demonstrates the effectiveness of the script. Most of Nick's changes were spread out through different trees, and I just picked up the slack after rc3 for the last kernel was out. Those changes have been in linux-next for over two weeks. The cleanups, debug code I added and final fix I added for modules were motivated by David Hildenbrand's report of boot failing on a systems with over 400 CPUs when KASAN was enabled due to running out of virtual memory space. Although the functional change only consists of 3 lines in the patch "module: avoid allocation if module is already present and ready", proving that this was the best we can do on the modules side took quite a bit of effort and new debug code. The initial cleanups I did on the modules side of things has been in linux-next since around rc3 of the last kernel, the actual final fix for and debug code however have only been in linux-next for about a week or so but I think it is worth getting that code in for this merge window as it does help fix / prove / evaluate the issues reported with larger number of CPUs. Userspace is not yet fixed as it is taking a bit of time for folks to understand the crux of the issue and find a proper resolution. Worst come to worst, I have a kludge-of-concept [3] of how to make kernel_read*() calls for modules unique / converge them, but I'm currently inclined to just see if userspace can fix this instead" Link: https://lore.kernel.org/all/Y/kXDqW+7d71C4wz@bombadil.infradead.org/ [0] Link: https://lkml.kernel.org/r/025f2151-ce7c-5630-9b90-98742c97ac65@redhat.com [1] Link: https://lwn.net/Articles/927569/ [2] Link: https://lkml.kernel.org/r/20230414052840.1994456-3-mcgrof@kernel.org [3] * tag 'modules-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux: (121 commits) module: add debugging auto-load duplicate module support module: stats: fix invalid_mod_bytes typo module: remove use of uninitialized variable len module: fix building stats for 32-bit targets module: stats: include uapi/linux/module.h module: avoid allocation if module is already present and ready module: add debug stats to help identify memory pressure module: extract patient module check into helper modules/kmod: replace implementation with a semaphore Change DEFINE_SEMAPHORE() to take a number argument module: fix kmemleak annotations for non init ELF sections module: Ignore L0 and rename is_arm_mapping_symbol() module: Move is_arm_mapping_symbol() to module_symbol.h module: Sync code of is_arm_mapping_symbol() scripts/gdb: use mem instead of core_layout to get the module address interconnect: remove module-related code interconnect: remove MODULE_LICENSE in non-modules zswap: remove MODULE_LICENSE in non-modules zpool: remove MODULE_LICENSE in non-modules x86/mm/dump_pagetables: remove MODULE_LICENSE in non-modules ...
| * module: Ignore L0 and rename is_arm_mapping_symbol()Tiezhu Yang2023-04-131-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The L0 symbol is generated when build module on LoongArch, ignore it in modpost and when looking at module symbols, otherwise we can not see the expected call trace. Now is_arm_mapping_symbol() is not only for ARM, in order to reflect the reality, rename is_arm_mapping_symbol() to is_mapping_symbol(). This is related with commit c17a2538704f ("mksysmap: Fix the mismatch of 'L0' symbols in System.map"). (1) Simple test case [loongson@linux hello]$ cat hello.c #include <linux/init.h> #include <linux/module.h> #include <linux/printk.h> static void test_func(void) { pr_info("This is a test\n"); dump_stack(); } static int __init hello_init(void) { pr_warn("Hello, world\n"); test_func(); return 0; } static void __exit hello_exit(void) { pr_warn("Goodbye\n"); } module_init(hello_init); module_exit(hello_exit); MODULE_LICENSE("GPL"); [loongson@linux hello]$ cat Makefile obj-m:=hello.o ccflags-y += -g -Og all: make -C /lib/modules/$(shell uname -r)/build/ M=$(PWD) modules clean: make -C /lib/modules/$(shell uname -r)/build/ M=$(PWD) clean (2) Test environment system: LoongArch CLFS 5.5 https://github.com/sunhaiyong1978/CLFS-for-LoongArch/releases/tag/5.0 It needs to update grub to avoid booting error "invalid magic number". kernel: 6.3-rc1 with loongson3_defconfig + CONFIG_DYNAMIC_FTRACE=y (3) Test result Without this patch: [root@linux hello]# insmod hello.ko [root@linux hello]# dmesg ... Hello, world This is a test ... Call Trace: [<9000000000223728>] show_stack+0x68/0x18c [<90000000013374cc>] dump_stack_lvl+0x60/0x88 [<ffff800002050028>] L0\x01+0x20/0x2c [hello] [<ffff800002058028>] L0\x01+0x20/0x30 [hello] [<900000000022097c>] do_one_initcall+0x88/0x288 [<90000000002df890>] do_init_module+0x54/0x200 [<90000000002e1e18>] __do_sys_finit_module+0xc4/0x114 [<90000000013382e8>] do_syscall+0x7c/0x94 [<9000000000221e3c>] handle_syscall+0xbc/0x158 With this patch: [root@linux hello]# insmod hello.ko [root@linux hello]# dmesg ... Hello, world This is a test ... Call Trace: [<9000000000223728>] show_stack+0x68/0x18c [<90000000013374cc>] dump_stack_lvl+0x60/0x88 [<ffff800002050028>] test_func+0x28/0x34 [hello] [<ffff800002058028>] hello_init+0x28/0x38 [hello] [<900000000022097c>] do_one_initcall+0x88/0x288 [<90000000002df890>] do_init_module+0x54/0x200 [<90000000002e1e18>] __do_sys_finit_module+0xc4/0x114 [<90000000013382e8>] do_syscall+0x7c/0x94 [<9000000000221e3c>] handle_syscall+0xbc/0x158 Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Tested-by: Youling Tang <tangyouling@loongson.cn> # for LoongArch Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
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