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2023-09-01modpost: Skip .llvm.call-graph-profile section checkDenis Nikitin1-0/+1
.llvm.call-graph-profile section is added by clang when the kernel is built with profiles (e.g. -fprofile-sample-use= or -fprofile-use=). Note that .llvm.call-graph-profile intentionally uses REL relocations to decrease the object size, for more details see https://reviews.llvm.org/D104080. The section contains edge information derived from text sections, so .llvm.call-graph-profile itself doesn't need more analysis as the text sections have been analyzed. This change fixes the kernel build with clang and a sample profile which currently fails with: "FATAL: modpost: Please add code to calculate addend for this architecture" Signed-off-by: Denis Nikitin <denik@chromium.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Fangrui Song <maskray@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-07-31modpost: remove ElF_Rela variables from for-loop in section_rel(a)Masahiro Yamada1-14/+11
Remove the Elf_Rela variables used in the for-loop in section_rel(). This makes the code consistent; section_rel() only uses Elf_Rel, section_rela() only uses Elf_Rela. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-07-31modpost: clean up MIPS64 little endian relocation codeMasahiro Yamada2-55/+43
MIPS64 little endian target has an odd encoding of r_info. This commit makes the special handling less ugly. It is still ugly, but #if conditionals will go away, at least. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2023-07-31modpost: pass r_type to addend_*_rel()Masahiro Yamada1-13/+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>
2023-07-31modpost: change return type of addend_*_rel()Masahiro Yamada1-39/+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>
2023-07-24linux/export.h: make <linux/export.h> independent of CONFIG_MODULESMasahiro Yamada1-2/+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>
2023-07-01Merge tag 'kbuild-v6.5' of ↵Linus Torvalds2-418/+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() ...
2023-07-01Merge tag 'vfio-v6.5-rc1' of https://github.com/awilliam/linux-vfioLinus Torvalds2-1/+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
2023-06-28modpost: define more R_ARM_* for old distributionsMasahiro Yamada1-0/+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>
2023-06-25modpost: continue even with unknown relocation typeMasahiro Yamada1-10/+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>
2023-06-25modpost: factor out Elf_Sym pointer calculation to section_rel()Masahiro Yamada1-4/+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>
2023-06-25modpost: factor out inst location calculation to section_rel()Masahiro Yamada1-16/+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>
2023-06-24script: modpost: emit a warning when the description is missingVincenzo Palazzo1-0/+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>
2023-06-22modpost: show offset from symbol for section mismatch warningsMasahiro Yamada1-2/+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>
2023-06-22modpost: merge two similar section mismatch warningsMasahiro Yamada1-15/+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>
2023-06-22kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without recursionMasahiro Yamada1-5/+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>
2023-06-22modpost: use null string instead of NULL pointer for default namespaceMasahiro Yamada1-6/+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>
2023-06-22modpost: squash sym_update_namespace() into sym_add_exported()Masahiro Yamada1-23/+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>
2023-06-22modpost: check static EXPORT_SYMBOL* by modpost againMasahiro Yamada1-0/+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>
2023-06-22kbuild: generate KSYMTAB entries by modpostMasahiro Yamada2-33/+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>
2023-06-16vfio/cdx: add support for CDX busNipun Gupta2-1/+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>
2023-06-16x86/unwind/orc: Add ELF section with ORC version identifierOmar Sandoval1-0/+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
2023-06-15modpost: pass struct module pointer to check_section_mismatch()Masahiro Yamada1-11/+11
The next commit will use it. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2023-06-08modpost: fix off by one in is_executable_section()Dan Carpenter1-1/+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>
2023-06-07modpost: propagate W=1 build option to modpostMasahiro Yamada1-1/+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>
2023-06-03modpost: detect section mismatch for R_ARM_REL32Masahiro Yamada1-0/+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>
2023-06-03modpost: fix section_mismatch message for R_ARM_THM_{CALL,JUMP24,JUMP19}Masahiro Yamada1-6/+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>
2023-06-03modpost: detect section mismatch for R_ARM_THM_{MOVW_ABS_NC,MOVT_ABS}Masahiro Yamada1-5/+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>
2023-06-02modpost: refactor find_fromsym() and find_tosym()Masahiro Yamada1-56/+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>
2023-06-02modpost: detect section mismatch for R_ARM_{MOVW_ABS_NC,MOVT_ABS}Masahiro Yamada1-2/+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>
2023-06-02modpost: fix section mismatch message for R_ARM_{PC24,CALL,JUMP24}Masahiro Yamada1-0/+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>
2023-06-02modpost: fix section mismatch message for R_ARM_ABS32Masahiro Yamada1-3/+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>
2023-05-28modpost: remove *_sections[] arraysMasahiro Yamada1-27/+9
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 Yamada1-11/+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>
2023-05-28modpost: merge fromsec=DATA_SECTIONS entries in sectioncheck tableMasahiro Yamada1-6/+1
You can merge these entries. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2023-05-28modpost: remove is_shndx_special() check from section_rel(a)Masahiro Yamada2-17/+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>
2023-05-28modpost: replace r->r_offset, r->r_addend with faddr, taddrMasahiro Yamada1-15/+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>
2023-05-28modpost: unify 'sym' and 'to' in default_mismatch_handler()Masahiro Yamada1-5/+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>
2023-05-28modpost: remove unused argument from secref_whitelist()Masahiro Yamada1-3/+2
secref_whitelist() does not use the argument 'mismatch'. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2023-05-28Revert "modpost: skip ELF local symbols during section mismatch check"Masahiro Yamada1-12/+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>
2023-05-22modpost: rename find_elf_symbol() and find_elf_symbol2()Masahiro Yamada1-6/+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>
2023-05-22modpost: pass section index to find_elf_symbol2()Masahiro Yamada1-19/+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>
2023-05-22modpost: pass 'tosec' down to default_mismatch_handler()Masahiro Yamada1-4/+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>
2023-05-22modpost: squash extable_mismatch_handler() into default_mismatch_handler()Masahiro Yamada1-58/+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>
2023-05-22modpost: clean up is_executable_section()Masahiro Yamada1-8/+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>
2023-05-22modpost: squash report_sec_mismatch() into default_mismatch_handler()Masahiro Yamada1-35/+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>
2023-05-22modpost: squash report_extable_warnings() into extable_mismatch_handler()Masahiro Yamada1-26/+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>
2023-05-22modpost: remove get_prettyname()Masahiro Yamada1-25/+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>
2023-05-22modpost: remove fromsym info in __ex_table section mismatch warningMasahiro Yamada1-9/+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>
2023-05-22modpost: remove broken calculation of exception_table_entry sizeMasahiro Yamada1-57/+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>
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