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- 11 Jul, 2023 1 commit
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Petr Pavlu authored
Sections .text..refcount were previously used to hold an error path code for fast refcount overflow protection on x86, see commit 7a46ec0e ("locking/refcounts, x86/asm: Implement fast refcount overflow protection") and commit 564c9cc8 ("locking/refcounts, x86/asm: Use unique .text section for refcount exceptions"). The code was replaced and removed in commit fb041bb7 ("locking/refcount: Consolidate implementations of refcount_t") and no sections .text..refcount are present since then. Remove then a relic referencing these sections from TEXT_TEXT to avoid confusing people, like me. This is a non-functional change. Signed-off-by: Petr Pavlu <petr.pavlu@suse.com> Link: https://lore.kernel.org/r/20230711125054.9000-1-petr.pavlu@suse.comSigned-off-by: Kees Cook <keescook@chromium.org>
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- 25 Jun, 2023 1 commit
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Jisheng Zhang authored
If building with -fdata-sections on riscv, LD_ORPHAN_WARN will warn similar as below: riscv64-linux-gnu-ld: warning: orphan section `.init.data.efi_loglevel' from `./drivers/firmware/efi/libstub/printk.stub.o' being placed in section `.init.data.efi_loglevel' I believe this is caused by a a typo: init.data.* should be .init.data.* Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> # build Link: https://lore.kernel.org/r/20230523165502.2592-4-jszhang@kernel.orgSigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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- 22 Jun, 2023 1 commit
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Masahiro Yamada authored
Commit 7b453719 ("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 22823ab4 ("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 8651ec01 ("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>
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- 16 Jun, 2023 1 commit
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Omar Sandoval authored
Commits ffb1b4a4 ("x86/unwind/orc: Add 'signal' field to ORC metadata") and fb799447 ("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: ffb1b4a4 ("x86/unwind/orc: Add 'signal' field to ORC metadata") Fixes: fb799447 ("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
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- 16 May, 2023 1 commit
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Josh Poimboeuf authored
When tooling reads ELF notes, it assumes each note entry is aligned to the value listed in the .note section header's sh_addralign field. The kernel-created ELF notes in the .note.Linux and .note.Xen sections are aligned to 4 bytes. This causes the toolchain to set those sections' sh_addralign values to 4. On the other hand, the GCC-created .note.gnu.property section has an sh_addralign value of 8 for some reason, despite being based on struct Elf32_Nhdr which only needs 4-byte alignment. When the mismatched input sections get linked together into the vmlinux .notes output section, the higher alignment "wins", resulting in an sh_addralign of 8, which confuses tooling. For example: $ readelf -n .tmp_vmlinux.btf ... readelf: .tmp_vmlinux.btf: Warning: note with invalid namesz and/or descsz found at offset 0x170 readelf: .tmp_vmlinux.btf: Warning: type: 0x4, namesize: 0x006e6558, descsize: 0x00008801, alignment: 8 In this case readelf thinks there's alignment padding where there is none, so it starts reading an ELF note in the middle. With newer toolchains (e.g., latest Fedora Rawhide), a similar mismatch triggers a build failure when combined with CONFIG_X86_KERNEL_IBT: btf_encoder__encode: btf__dedup failed! Failed to encode BTF libbpf: failed to find '.BTF' ELF section in vmlinux FAILED: load BTF from vmlinux: No data available make[1]: *** [scripts/Makefile.vmlinux:35: vmlinux] Error 255 This latter error was caused by pahole crashing when it encountered the corrupt .notes section. This crash has been fixed in dwarves version 1.25. As Tianyi Liu describes: "Pahole reads .notes to look for LINUX_ELFNOTE_BUILD_LTO. When LTO is enabled, pahole needs to call cus__merge_and_process_cu to merge compile units, at which point there should only be one unspecified type (used to represent some compilation information) in the global context. However, when the kernel is compiled without LTO, if pahole calls cus__merge_and_process_cu due to alignment issues with notes, multiple unspecified types may appear after merging the cus, and older versions of pahole only support up to one. This is why pahole 1.24 crashes, while newer versions support multiple. However, the latest version of pahole still does not solve the problem of incorrect LTO recognition, so compiling the kernel may be slower than normal." Even with the newer pahole, the note section misaligment issue still exists and pahole is misinterpreting the LTO note. Fix it by discarding the .note.gnu.property section. While GNU properties are important for user space (and VDSO), they don't seem to have any use for vmlinux. (In fact, they're already getting (inadvertently) stripped from vmlinux when CONFIG_DEBUG_INFO_BTF is enabled. The BTF data is extracted from vmlinux.o with "objcopy --only-section=.BTF" into .btf.vmlinux.bin.o. That file doesn't have .note.gnu.property, so when it gets modified and linked back into the main object, the linker automatically strips it (see "How GNU properties are merged" in the ld man page).) Reported-by: Daniel Xu <dxu@dxuuu.xyz> Link: https://lkml.kernel.org/bpf/57830c30-cd77-40cf-9cd1-3bb608aa602e@app.fastmail.comDebugged-by: Tianyi Liu <i.pear@outlook.com> Suggested-by: Joan Bruguera Micó <joanbrugueram@gmail.com> Link: https://lore.kernel.org/r/20230418214925.ay3jpf2zhw75kgmd@trebleSigned-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
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- 13 Jan, 2023 1 commit
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Peter Zijlstra authored
Idle code is very like entry code in that RCU isn't available. As such, add a little validation. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Tony Lindgren <tony@atomide.com> Tested-by: Ulf Hansson <ulf.hansson@linaro.org> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lore.kernel.org/r/20230112195540.373461409@infradead.org
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- 30 Dec, 2022 1 commit
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Masahiro Yamada authored
Dennis Gilmore reports that the BuildID is missing in the arm64 vmlinux since commit 994b7ac1 ("arm64: remove special treatment for the link order of head.o"). The issue is that the type of .notes section, which contains the BuildID, changed from NOTES to PROGBITS. Ard Biesheuvel figured out that whichever object gets linked first gets to decide the type of a section. The PROGBITS type is the result of the compiler emitting .note.GNU-stack as PROGBITS rather than NOTE. While Ard provided a fix for arm64, I want to fix this globally because the same issue is happening on riscv since commit 2348e6bf ("riscv: remove special treatment for the link order of head.o"). This problem will happen in general for other architectures if they start to drop unneeded entries from scripts/head-object-list.txt. Discard .note.GNU-stack in include/asm-generic/vmlinux.lds.h. Link: https://lore.kernel.org/lkml/CAABkxwuQoz1CTbyb57n0ZX65eSYiTonFCU8-LCQc=74D=xE=rA@mail.gmail.com/ Fixes: 994b7ac1 ("arm64: remove special treatment for the link order of head.o") Fixes: 2348e6bf ("riscv: remove special treatment for the link order of head.o") Reported-by: Dennis Gilmore <dennis@ausil.us> Suggested-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
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- 17 Nov, 2022 2 commits
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Jim Cromie authored
These macros elaborate on BOUNDED_SECTION_(PRE|POST)_LABEL macros, prepending an optional KEEP(.gnu.linkonce##_sec_) reservation, and a linker-symbol to address it. This allows a developer to define a header struct (which must fit with the section's base struct-type), and could contain: 1- fields whose value is common to the entire set of data-records. This allows the header & data structs to specialize, complement each other, and shrink. 2- an uplink pointer to an organizing struct which refs other related/sub data-tables header record is addressable via the extern'd header linker-symbol Once the linker-symbols created by the macro are ref'd extern in code, that code can compute a record's index (ptr - start) in the "primary" table, then use it to index into the related/sub tables. Adding a primary.map_* field foreach sub-table would then allow deduplication and remapping of that sub-table. This is aimed at dyndbg's struct _ddebug __dyndbg[] section, whose 3 columns: function, file, module are 50%, 90%, 100% redundant. The module column is fully recoverable after dynamic_debug_init() saves it to each ddebug_table.module as the builtin __dyndbg[] table is parsed. Given that those 3 columns use 24/56 of a _ddebug record, a dyndbg=y kernel with ~5k callsites could reduce kernel memory substantially. Returning that memory to the kernel buddy-allocator? is then possible. Signed-off-by: Jim Cromie <jim.cromie@gmail.com> Link: https://lore.kernel.org/r/20221117171633.923628-3-jim.cromie@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Jim Cromie authored
Commit 2f465b92 ("vmlinux.lds.h: place optional header space in BOUNDED_SECTION") added BOUNDED_SECTION_(PRE|POST)_LABEL macros, encapsulating the basic boilerplate to KEEP/pack records into a section, and to mark the begin and end of the section with linker-symbols. But it tried to do extra, adding KEEP(*(.gnu.linkonce.##_sec_)) to optionally reserve a header record in front of the data. It wrongly placed the KEEP after the linker-symbol starting the section, so if a header was added, it would wind up in the data. Moving the KEEP to the "correct" place proved brittle, and too clever by half. The obvious safe fix is to remove the KEEP and restore the plain old boilerplate. The header can be added later, with separate macros. Also, the macro var-names: _s_, _e_ are nearly invisible, change them to more obvious names: _BEGIN_, _END_ Fixes: 2f465b92 ("vmlinux.lds.h: place optional header space in BOUNDED_SECTION") Signed-off-by: Jim Cromie <jim.cromie@gmail.com> Link: https://lore.kernel.org/r/20221117171633.923628-2-jim.cromie@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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- 10 Nov, 2022 2 commits
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Jim Cromie authored
Extend recently added BOUNDED_SECTION(_name) macro by adding a KEEP(*(.gnu.linkonce.##_name)) before the KEEP(*(_name)). This does nothing by itself, vmlinux is the same before and after this patch. But if a developer adds a .gnu.linkonce.foo record, that record is placed in the front of the section, where it can be used as a header for the table. The intent is to create an up-link to another organizing struct, from where related tables can be referenced. And since every item in a table has a known offset from its header, that same offset can be used to fetch records from the related tables. By itself, this doesnt gain much, unless maybe the pattern of access is to scan 1 or 2 fields in each fat record, but with 2 16 bit .map* fields added, we could de-duplicate 2 related tables. The use case here is struct _ddebug, which has 3 pointers (function, file, module) with substantial repetition; respectively 53%, 90%, and the module column is fully recoverable after dynamic_debug_init() splits the table into a linked list of "module" chunks. On a DYNAMIC_DEBUG=y kernel with 5k pr_debugs, the memory savings should be ~100 KiB. Signed-off-by: Jim Cromie <jim.cromie@gmail.com> Link: https://lore.kernel.org/r/20221022225637.1406715-3-jim.cromie@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Jim Cromie authored
vmlinux.lds.h has ~45 occurrences of this general pattern: __start_foo = .; KEEP(*(foo)) __stop_foo = .; Reduce this pattern to a (group of 4) macros, and use them to reduce linecount. This was inspired by the codetag patchset. no functional change. CC: Suren Baghdasaryan <surenb@google.com> CC: Kent Overstreet <kent.overstreet@linux.dev> Signed-off-by: Jim Cromie <jim.cromie@gmail.com> Link: https://lore.kernel.org/r/20221022225637.1406715-2-jim.cromie@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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- 09 Nov, 2022 1 commit
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Ard Biesheuvel authored
Enable asynchronous unwind table generation for both the core kernel as well as modules, and emit the resulting .eh_frame sections as init code so we can use the unwind directives for code patching at boot or module load time. This will be used by dynamic shadow call stack support, which will rely on code patching rather than compiler codegen to emit the shadow call stack push and pop instructions. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Sami Tolvanen <samitolvanen@google.com> Tested-by: Sami Tolvanen <samitolvanen@google.com> Link: https://lore.kernel.org/r/20221027155908.1940624-2-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>
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- 08 Nov, 2022 1 commit
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Nathan Chancellor authored
Commit d4c63999 ("vmlinux.lds.h: Avoid orphan section with !SMP") fixed an orphan section warning by adding the '.data..decrypted' section to the linker script under the PERCPU_DECRYPTED_SECTION define but that placement introduced a panic with !SMP, as the percpu sections are not instantiated with that configuration so attempting to access variables defined with DEFINE_PER_CPU_DECRYPTED() will result in a page fault. Move the '.data..decrypted' section to the DATA_MAIN define so that the variables in it are properly instantiated at boot time with CONFIG_SMP=n. Cc: stable@vger.kernel.org Fixes: d4c63999 ("vmlinux.lds.h: Avoid orphan section with !SMP") Link: https://lore.kernel.org/cbbd3548-880c-d2ca-1b67-5bb93b291d5f@huawei.com/Debugged-by: Ard Biesheuvel <ardb@kernel.org> Reported-by: Zhao Wenhui <zhaowenhui8@huawei.com> Tested-by: xiafukun <xiafukun@huawei.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20221108174934.3384275-1-nathan@kernel.org
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- 20 Oct, 2022 1 commit
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Peter Zijlstra authored
Different function signatures means they needs to be different functions; otherwise CFI gets upset. As triggered by the ftrace boot tests: [] CFI failure at ftrace_return_to_handler+0xac/0x16c (target: ftrace_stub+0x0/0x14; expected type: 0x0a5d5347) Fixes: 3c516f89 ("x86: Add support for CONFIG_CFI_CLANG") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Tested-by: Mark Rutland <mark.rutland@arm.com> Link: https://lkml.kernel.org/r/Y06dg4e1xF6JTdQq@hirez.programming.kicks-ass.net
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- 17 Oct, 2022 1 commit
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Peter Zijlstra authored
Generic function-alignment infrastructure. Architectures can select FUNCTION_ALIGNMENT_xxB symbols; the FUNCTION_ALIGNMENT symbol is then set to the largest such selected size, 0 otherwise. From this the -falign-functions compiler argument and __ALIGN macro are set. This incorporates the DEBUG_FORCE_FUNCTION_ALIGN_64B knob and future alignment requirements for x86_64 (later in this series) into a single place. NOTE: also removes the 0x90 filler byte from the generic __ALIGN primitive, that value makes no sense outside of x86. NOTE: .balign 0 reverts to a no-op. Requested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20220915111143.719248727@infradead.org
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- 26 Sep, 2022 1 commit
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Sami Tolvanen authored
Switch from Clang's original forward-edge control-flow integrity implementation to -fsanitize=kcfi, which is better suited for the kernel, as it doesn't require LTO, doesn't use a jump table that requires altering function references, and won't break cross-module function address equality. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Tested-by: Kees Cook <keescook@chromium.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20220908215504.3686827-6-samitolvanen@google.com
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- 23 Sep, 2022 1 commit
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Will Deacon authored
Due to undocumented, hysterical raisins on x86, the CFI jump-table sections in .text are needlessly aligned to PMD_SIZE in the vmlinux linker script. When compiling a CFI-enabled arm64 kernel with a 64KiB page-size, a PMD maps 512MiB of virtual memory and so the .text section increases to a whopping 940MiB and blows the final Image up to 960MiB. Others report a link failure. Since the CFI jump-table requires only instruction alignment, reduce the alignment directives to function alignment for parity with other parts of the .text section. This reduces the size of the .text section for the aforementioned 64KiB page size arm64 kernel to 19MiB for a much more reasonable total Image size of 39MiB. Cc: Sami Tolvanen <samitolvanen@google.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: "Mohan Rao .vanimina" <mailtoc.mohanrao@gmail.com> Cc: Kees Cook <keescook@chromium.org> Cc: Nathan Chancellor <nathan@kernel.org> Cc: <stable@vger.kernel.org> Link: https://lore.kernel.org/all/CAL_GTzigiNOMYkOPX1KDnagPhJtFNqSK=1USNbS0wUL4PW6-Uw@mail.gmail.com/ Fixes: cf68fffb ("add support for Clang CFI") Reviewed-by: Mark Rutland <mark.rutland@arm.com> Tested-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20220922215715.13345-1-will@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>
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- 16 Sep, 2022 1 commit
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Peter Zijlstra (Intel) authored
x86 will shortly start using -fpatchable-function-entry for purposes other than ftrace, make sure the __patchable_function_entry section isn't merged in the mcount_loc section. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20220903131154.420467-2-jolsa@kernel.org
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- 07 Sep, 2022 1 commit
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Jim Cromie authored
Add __dyndbg_classes section, using __dyndbg as a model. Use it: vmlinux.lds.h: KEEP the new section, which also silences orphan section warning on loadable modules. Add (__start_/__stop_)__dyndbg_classes linker symbols for the c externs (below). kernel/module/main.c: - fill new fields in find_module_sections(), using section_objs() - extend callchain prototypes to pass classes, length load_module(): pass new info to dynamic_debug_setup() dynamic_debug_setup(): new params, pass through to ddebug_add_module() dynamic_debug.c: - add externs to the linker symbols. ddebug_add_module(): - It currently builds a debug_table, and *will* find and attach classes. dynamic_debug_init(): - add class fields to the _ddebug_info cursor var: di. Signed-off-by: Jim Cromie <jim.cromie@gmail.com> Link: https://lore.kernel.org/r/20220904214134.408619-16-jim.cromie@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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- 19 May, 2022 1 commit
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Peter Zijlstra authored
Because GCC-12 is fully stupid about array bounds and it's just really hard to get a solid array definition from a linker script, flip the array order to avoid needing negative offsets :-/ This makes the whole relational pointer magic a little less obvious, but alas. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lkml.kernel.org/r/YoOLLmLG7HRTXeEm@hirez.programming.kicks-ass.net
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- 15 Mar, 2022 1 commit
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Peter Zijlstra authored
Without CONFIG_HAVE_STATIC_CALL_INLINE there's no point in creating the .static_call_sites section and it's related symbols. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20220308154317.223798256@infradead.org
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- 04 Feb, 2022 1 commit
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Daniel Lezcano authored
The init table section is freed after the system booted. However the next changes will make per module the DTPM description, so the table won't be accessible when the module is loaded. In order to fix that, we should move the table to the data section where there are very few entries and that makes strange to add it there. The main goal of the table was to keep self-encapsulated code and we can keep it almost as it by using an array instead. Suggested-by: Ulf Hansson <ulf.hansson@linaro.org> Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Link: https://lore.kernel.org/r/20220128163537.212248-2-daniel.lezcano@linaro.org
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- 27 Oct, 2021 1 commit
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Kristen Carlson Accardi authored
When using -ffunction-sections to place each function in its own text section (so it can be randomized at load time in the future FGKASLR series), the linker will place most of the functions into separate .text.* sections. SIZEOF(.text) won't work here for calculating the ORC lookup table size, so the total text size must be calculated to include .text AND all .text.* sections. Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com> [ alobakin: move it to vmlinux.lds.h and make arch-indep ] Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Tony Luck <tony.luck@intel.com> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Tested-by: Tony Luck <tony.luck@intel.com> Link: https://lore.kernel.org/r/20211013175742.1197608-5-keescook@chromium.org
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- 22 Oct, 2021 1 commit
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Luis Chamberlain authored
The firmware loader built-in firmware is only available when FW_LOADER is built-in, so tuck away the sections for built-in firmware under it. This ensures no oddball user tries to uses these sections without first enabling FW_LOADER=y. Reviewed-by: Borislav Petkov <bp@suse.de> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Link: https://lore.kernel.org/r/20211021155843.1969401-6-mcgrof@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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- 20 Oct, 2021 1 commit
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Steven Rostedt (VMware) authored
In an effort to enable -Wcast-function-type in the top-level Makefile to support Control Flow Integrity builds, all function casts need to be removed. This means that ftrace_ops_list_func() can no longer be defined as ftrace_ops_no_ops(). The reason for ftrace_ops_no_ops() is to use that when an architecture calls ftrace_ops_list_func() with only two parameters (called from assembly). And to make sure there's no C side-effects, those archs call ftrace_ops_no_ops() which only has two parameters, as ftrace_ops_list_func() has four parameters. Instead of a typecast, use vmlinux.lds.h to define ftrace_ops_list_func() to arch_ftrace_ops_list_func() that will define the proper set of parameters. Link: https://lore.kernel.org/r/20200614070154.6039-1-oscar.carter@gmx.com Link: https://lkml.kernel.org/r/20200617165616.52241bde@oasis.local.home Link: https://lore.kernel.org/all/20211005053922.GA702049@embeddedor/Requested-by: Oscar Carter <oscar.carter@gmx.com> Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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- 13 Sep, 2021 1 commit
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Nick Desaulniers authored
Now that GCC 5.1 is the minimally supported version of GCC, we can effectively revert commit 85c2ce91 ("sched, vmlinux.lds: Increase STRUCT_ALIGNMENT to 64 bytes for GCC-4.9") Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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- 11 Aug, 2021 1 commit
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Nathan Chancellor authored
A recent change in LLVM causes module_{c,d}tor sections to appear when CONFIG_K{A,C}SAN are enabled, which results in orphan section warnings because these are not handled anywhere: ld.lld: warning: arch/x86/pci/built-in.a(legacy.o):(.text.asan.module_ctor) is being placed in '.text.asan.module_ctor' ld.lld: warning: arch/x86/pci/built-in.a(legacy.o):(.text.asan.module_dtor) is being placed in '.text.asan.module_dtor' ld.lld: warning: arch/x86/pci/built-in.a(legacy.o):(.text.tsan.module_ctor) is being placed in '.text.tsan.module_ctor' Fangrui explains: "the function asan.module_ctor has the SHF_GNU_RETAIN flag, so it is in a separate section even with -fno-function-sections (default)". Place them in the TEXT_TEXT section so that these technologies continue to work with the newer compiler versions. All of the KASAN and KCSAN KUnit tests continue to pass after this change. Cc: stable@vger.kernel.org Link: https://github.com/ClangBuiltLinux/linux/issues/1432 Link: https://github.com/llvm/llvm-project/commit/7b789562244ee941b7bf2cefeb3fc08a59a01865Signed-off-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Fangrui Song <maskray@google.com> Acked-by: Marco Elver <elver@google.com> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20210731023107.1932981-1-nathan@kernel.org
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- 19 Jul, 2021 1 commit
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Chris Down authored
We have a number of systems industry-wide that have a subset of their functionality that works as follows: 1. Receive a message from local kmsg, serial console, or netconsole; 2. Apply a set of rules to classify the message; 3. Do something based on this classification (like scheduling a remediation for the machine), rinse, and repeat. As a couple of examples of places we have this implemented just inside Facebook, although this isn't a Facebook-specific problem, we have this inside our netconsole processing (for alarm classification), and as part of our machine health checking. We use these messages to determine fairly important metrics around production health, and it's important that we get them right. While for some kinds of issues we have counters, tracepoints, or metrics with a stable interface which can reliably indicate the issue, in order to react to production issues quickly we need to work with the interface which most kernel developers naturally use when developing: printk. Most production issues come from unexpected phenomena, and as such usually the code in question doesn't have easily usable tracepoints or other counters available for the specific problem being mitigated. We have a number of lines of monitoring defence against problems in production (host metrics, process metrics, service metrics, etc), and where it's not feasible to reliably monitor at another level, this kind of pragmatic netconsole monitoring is essential. As one would expect, monitoring using printk is rather brittle for a number of reasons -- most notably that the message might disappear entirely in a new version of the kernel, or that the message may change in some way that the regex or other classification methods start to silently fail. One factor that makes this even harder is that, under normal operation, many of these messages are never expected to be hit. For example, there may be a rare hardware bug which one wants to detect if it was to ever happen again, but its recurrence is not likely or anticipated. This precludes using something like checking whether the printk in question was printed somewhere fleetwide recently to determine whether the message in question is still present or not, since we don't anticipate that it should be printed anywhere, but still need to monitor for its future presence in the long-term. This class of issue has happened on a number of occasions, causing unhealthy machines with hardware issues to remain in production for longer than ideal. As a recent example, some monitoring around blk_update_request fell out of date and caused semi-broken machines to remain in production for longer than would be desirable. Searching through the codebase to find the message is also extremely fragile, because many of the messages are further constructed beyond their callsite (eg. btrfs_printk and other module-specific wrappers, each with their own functionality). Even if they aren't, guessing the format and formulation of the underlying message based on the aesthetics of the message emitted is not a recipe for success at scale, and our previous issues with fleetwide machine health checking demonstrate as much. This provides a solution to the issue of silently changed or deleted printks: we record pointers to all printk format strings known at compile time into a new .printk_index section, both in vmlinux and modules. At runtime, this can then be iterated by looking at <debugfs>/printk/index/<module>, which emits the following format, both readable by humans and able to be parsed by machines: $ head -1 vmlinux; shuf -n 5 vmlinux # <level[,flags]> filename:line function "format" <5> block/blk-settings.c:661 disk_stack_limits "%s: Warning: Device %s is misaligned\n" <4> kernel/trace/trace.c:8296 trace_create_file "Could not create tracefs '%s' entry\n" <6> arch/x86/kernel/hpet.c:144 _hpet_print_config "hpet: %s(%d):\n" <6> init/do_mounts.c:605 prepare_namespace "Waiting for root device %s...\n" <6> drivers/acpi/osl.c:1410 acpi_no_auto_serialize_setup "ACPI: auto-serialization disabled\n" This mitigates the majority of cases where we have a highly-specific printk which we want to match on, as we can now enumerate and check whether the format changed or the printk callsite disappeared entirely in userspace. This allows us to catch changes to printks we monitor earlier and decide what to do about it before it becomes problematic. There is no additional runtime cost for printk callers or printk itself, and the assembly generated is exactly the same. Signed-off-by: Chris Down <chris@chrisdown.name> Cc: Petr Mladek <pmladek@suse.com> Cc: Jessica Yu <jeyu@kernel.org> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: John Ogness <john.ogness@linutronix.de> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kees Cook <keescook@chromium.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Tested-by: Petr Mladek <pmladek@suse.com> Reported-by: kernel test robot <lkp@intel.com> Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com> Acked-by: Jessica Yu <jeyu@kernel.org> # for module.{c,h} Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/e42070983637ac5e384f17fbdbe86d19c7b212a5.1623775748.git.chris@chrisdown.name
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- 02 Jun, 2021 1 commit
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Nathan Chancellor authored
With x86_64_defconfig and the following configs, there is an orphan section warning: CONFIG_SMP=n CONFIG_AMD_MEM_ENCRYPT=y CONFIG_HYPERVISOR_GUEST=y CONFIG_KVM=y CONFIG_PARAVIRT=y ld: warning: orphan section `.data..decrypted' from `arch/x86/kernel/cpu/vmware.o' being placed in section `.data..decrypted' ld: warning: orphan section `.data..decrypted' from `arch/x86/kernel/kvm.o' being placed in section `.data..decrypted' These sections are created with DEFINE_PER_CPU_DECRYPTED, which ultimately turns into __PCPU_ATTRS, which in turn has a section attribute with a value of PER_CPU_BASE_SECTION + the section name. When CONFIG_SMP is not set, the base section is .data and that is not currently handled in any linker script. Add .data..decrypted to PERCPU_DECRYPTED_SECTION, which is included in PERCPU_INPUT -> PERCPU_SECTION, which is include in the x86 linker script when either CONFIG_X86_64 or CONFIG_SMP is unset, taking care of the warning. Fixes: ac26963a ("percpu: Introduce DEFINE_PER_CPU_DECRYPTED") Link: https://github.com/ClangBuiltLinux/linux/issues/1360Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Nick Desaulniers <ndesaulniers@google.com> # build Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20210506001410.1026691-1-nathan@kernel.org
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- 08 Apr, 2021 1 commit
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Sami Tolvanen authored
This change adds support for Clang’s forward-edge Control Flow Integrity (CFI) checking. With CONFIG_CFI_CLANG, the compiler injects a runtime check before each indirect function call to ensure the target is a valid function with the correct static type. This restricts possible call targets and makes it more difficult for an attacker to exploit bugs that allow the modification of stored function pointers. For more details, see: https://clang.llvm.org/docs/ControlFlowIntegrity.html Clang requires CONFIG_LTO_CLANG to be enabled with CFI to gain visibility to possible call targets. Kernel modules are supported with Clang’s cross-DSO CFI mode, which allows checking between independently compiled components. With CFI enabled, the compiler injects a __cfi_check() function into the kernel and each module for validating local call targets. For cross-module calls that cannot be validated locally, the compiler calls the global __cfi_slowpath_diag() function, which determines the target module and calls the correct __cfi_check() function. This patch includes a slowpath implementation that uses __module_address() to resolve call targets, and with CONFIG_CFI_CLANG_SHADOW enabled, a shadow map that speeds up module look-ups by ~3x. Clang implements indirect call checking using jump tables and offers two methods of generating them. With canonical jump tables, the compiler renames each address-taken function to <function>.cfi and points the original symbol to a jump table entry, which passes __cfi_check() validation. This isn’t compatible with stand-alone assembly code, which the compiler doesn’t instrument, and would result in indirect calls to assembly code to fail. Therefore, we default to using non-canonical jump tables instead, where the compiler generates a local jump table entry <function>.cfi_jt for each address-taken function, and replaces all references to the function with the address of the jump table entry. Note that because non-canonical jump table addresses are local to each component, they break cross-module function address equality. Specifically, the address of a global function will be different in each module, as it's replaced with the address of a local jump table entry. If this address is passed to a different module, it won’t match the address of the same function taken there. This may break code that relies on comparing addresses passed from other components. CFI checking can be disabled in a function with the __nocfi attribute. Additionally, CFI can be disabled for an entire compilation unit by filtering out CC_FLAGS_CFI. By default, CFI failures result in a kernel panic to stop a potential exploit. CONFIG_CFI_PERMISSIVE enables a permissive mode, where the kernel prints out a rate-limited warning instead, and allows execution to continue. This option is helpful for locating type mismatches, but should only be enabled during development. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20210408182843.1754385-2-samitolvanen@google.com
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- 25 Feb, 2021 1 commit
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Nathan Chancellor authored
clang produces .eh_frame sections when CONFIG_GCOV_KERNEL is enabled, even when -fno-asynchronous-unwind-tables is in KBUILD_CFLAGS: $ make CC=clang vmlinux ... ld: warning: orphan section `.eh_frame' from `init/main.o' being placed in section `.eh_frame' ld: warning: orphan section `.eh_frame' from `init/version.o' being placed in section `.eh_frame' ld: warning: orphan section `.eh_frame' from `init/do_mounts.o' being placed in section `.eh_frame' ld: warning: orphan section `.eh_frame' from `init/do_mounts_initrd.o' being placed in section `.eh_frame' ld: warning: orphan section `.eh_frame' from `init/initramfs.o' being placed in section `.eh_frame' ld: warning: orphan section `.eh_frame' from `init/calibrate.o' being placed in section `.eh_frame' ld: warning: orphan section `.eh_frame' from `init/init_task.o' being placed in section `.eh_frame' ... $ rg "GCOV_KERNEL|GCOV_PROFILE_ALL" .config CONFIG_GCOV_KERNEL=y CONFIG_ARCH_HAS_GCOV_PROFILE_ALL=y CONFIG_GCOV_PROFILE_ALL=y This was already handled for a couple of other options in commit d812db78 ("vmlinux.lds.h: Avoid KASAN and KCSAN's unwanted sections") and there is an open LLVM bug for this issue. Take advantage of that section for this config as well so that there are no more orphan warnings. Link: https://bugs.llvm.org/show_bug.cgi?id=46478 Link: https://github.com/ClangBuiltLinux/linux/issues/1069Reported-by: kernel test robot <lkp@intel.com> Reviewed-by: Fangrui Song <maskray@google.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Fixes: d812db78 ("vmlinux.lds.h: Avoid KASAN and KCSAN's unwanted sections") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20210130004650.2682422-1-nathan@kernel.org
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- 23 Feb, 2021 1 commit
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Alexander Lobakin authored
LKP caught another bunch of orphaned instrumentation symbols [0]: mipsel-linux-ld: warning: orphan section `.data.$LPBX1' from `init/main.o' being placed in section `.data.$LPBX1' mipsel-linux-ld: warning: orphan section `.data.$LPBX0' from `init/main.o' being placed in section `.data.$LPBX0' mipsel-linux-ld: warning: orphan section `.data.$LPBX1' from `init/do_mounts.o' being placed in section `.data.$LPBX1' mipsel-linux-ld: warning: orphan section `.data.$LPBX0' from `init/do_mounts.o' being placed in section `.data.$LPBX0' mipsel-linux-ld: warning: orphan section `.data.$LPBX1' from `init/do_mounts_initrd.o' being placed in section `.data.$LPBX1' mipsel-linux-ld: warning: orphan section `.data.$LPBX0' from `init/do_mounts_initrd.o' being placed in section `.data.$LPBX0' mipsel-linux-ld: warning: orphan section `.data.$LPBX1' from `init/initramfs.o' being placed in section `.data.$LPBX1' mipsel-linux-ld: warning: orphan section `.data.$LPBX0' from `init/initramfs.o' being placed in section `.data.$LPBX0' mipsel-linux-ld: warning: orphan section `.data.$LPBX1' from `init/calibrate.o' being placed in section `.data.$LPBX1' mipsel-linux-ld: warning: orphan section `.data.$LPBX0' from `init/calibrate.o' being placed in section `.data.$LPBX0' [...] Soften the wildcard to .data.$L* to grab these ones into .data too. [0] https://lore.kernel.org/lkml/202102231519.lWPLPveV-lkp@intel.comReported-by: kernel test robot <lkp@intel.com> Signed-off-by: Alexander Lobakin <alobakin@pm.me> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
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- 17 Feb, 2021 1 commit
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Josh Poimboeuf authored
When exporting static_call_key; with EXPORT_STATIC_CALL*(), the module can use static_call_update() to change the function called. This is not desirable in general. Not exporting static_call_key however also disallows usage of static_call(), since objtool needs the key to construct the static_call_site. Solve this by allowing objtool to create the static_call_site using the trampoline address when it builds a module and cannot find the static_call_key symbol. The module loader will then try and map the trampole back to a key before it constructs the normal sites list. Doing this requires a trampoline -> key associsation, so add another magic section that keeps those. Originally-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20210127231837.ifddpn7rhwdaepiu@treble
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- 16 Feb, 2021 2 commits
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Alexander Lobakin authored
LKP triggered lots of LD orphan warnings [0]: mipsel-linux-ld: warning: orphan section `.data.$Lubsan_data299' from `init/do_mounts_rd.o' being placed in section `.data.$Lubsan_data299' mipsel-linux-ld: warning: orphan section `.data.$Lubsan_data183' from `init/do_mounts_rd.o' being placed in section `.data.$Lubsan_data183' mipsel-linux-ld: warning: orphan section `.data.$Lubsan_type3' from `init/do_mounts_rd.o' being placed in section `.data.$Lubsan_type3' mipsel-linux-ld: warning: orphan section `.data.$Lubsan_type2' from `init/do_mounts_rd.o' being placed in section `.data.$Lubsan_type2' mipsel-linux-ld: warning: orphan section `.data.$Lubsan_type0' from `init/do_mounts_rd.o' being placed in section `.data.$Lubsan_type0' [...] Seems like "unnamed data" isn't the only type of symbols that UBSAN instrumentation can emit. Catch these into .data with the wildcard as well. [0] https://lore.kernel.org/linux-mm/202102160741.k57GCNSR-lkp@intel.com Fixes: f41b233d ("vmlinux.lds.h: catch UBSAN's "unnamed data" into data") Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Alexander Lobakin <alobakin@pm.me> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
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Nick Desaulniers authored
We expect toolchains to produce these new debug info sections as part of DWARF v5. Add explicit placements to prevent the linker warnings from --orphan-section=warn. Compilers may produce such sections with explicit -gdwarf-5, or based on the implicit default version of DWARF when -g is used via DEBUG_INFO. This implicit default changes over time, and has changed to DWARF v5 with GCC 11. .debug_sup was mentioned in review, but without compilers producing it today, let's wait to add it until it becomes necessary. Cc: stable@vger.kernel.org Link: https://bugzilla.redhat.com/show_bug.cgi?id=1922707Reported-by: Chris Murphy <lists@colorremedies.com> Suggested-by: Fangrui Song <maskray@google.com> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Mark Wielaard <mark@klomp.org> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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- 10 Feb, 2021 1 commit
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Fangrui Song authored
arm64 references the start address of .builtin_fw (__start_builtin_fw) with a pair of R_AARCH64_ADR_PREL_PG_HI21/R_AARCH64_LDST64_ABS_LO12_NC relocations. The compiler is allowed to emit the R_AARCH64_LDST64_ABS_LO12_NC relocation because struct builtin_fw in include/linux/firmware.h is 8-byte aligned. The R_AARCH64_LDST64_ABS_LO12_NC relocation requires the address to be a multiple of 8, which may not be the case if .builtin_fw is empty. Unconditionally align .builtin_fw to fix the linker error. 32-bit architectures could use ALIGN(4) but that would add unnecessary complexity, so just use ALIGN(8). Link: https://lkml.kernel.org/r/20201208054646.2913063-1-maskray@google.com Link: https://github.com/ClangBuiltLinux/linux/issues/1204 Fixes: 5658c769 ("firmware: allow firmware files to be built into kernel image") Signed-off-by: Fangrui Song <maskray@google.com> Reported-by: kernel test robot <lkp@intel.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Douglas Anderson <dianders@chromium.org> Acked-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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- 08 Feb, 2021 2 commits
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Christoph Hellwig authored
EXPORT_UNUSED_SYMBOL* is not actually used anywhere. Remove the unused functionality as we generally just remove unused code anyway. Reviewed-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jessica Yu <jeyu@kernel.org>
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Christoph Hellwig authored
As far as I can tell this has never been used at all, and certainly not any time recently. Reviewed-by: Miroslav Benes <mbenes@suse.cz> Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jessica Yu <jeyu@kernel.org>
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- 15 Jan, 2021 2 commits
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Alexander Lobakin authored
When building kernel with both LD_DEAD_CODE_DATA_ELIMINATION and UBSAN, LLVM stack generates lots of "unnamed data" sections: ld.lld: warning: net/built-in.a(netfilter/utils.o): (.data.$__unnamed_2) is being placed in '.data.$__unnamed_2' ld.lld: warning: net/built-in.a(netfilter/utils.o): (.data.$__unnamed_3) is being placed in '.data.$__unnamed_3' ld.lld: warning: net/built-in.a(netfilter/utils.o): (.data.$__unnamed_4) is being placed in '.data.$__unnamed_4' ld.lld: warning: net/built-in.a(netfilter/utils.o): (.data.$__unnamed_5) is being placed in '.data.$__unnamed_5' [...] Also handle this by adding the related sections to generic definitions. Signed-off-by: Alexander Lobakin <alobakin@pm.me> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
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Alexander Lobakin authored
When building kernel with LD_DEAD_CODE_DATA_ELIMINATION, LLVM stack generates separate sections for compound literals, just like in case with enabled LTO [0]: ld.lld: warning: drivers/built-in.a(mtd/nand/spi/gigadevice.o): (.data..compoundliteral.14) is being placed in '.data..compoundliteral.14' ld.lld: warning: drivers/built-in.a(mtd/nand/spi/gigadevice.o): (.data..compoundliteral.15) is being placed in '.data..compoundliteral.15' ld.lld: warning: drivers/built-in.a(mtd/nand/spi/gigadevice.o): (.data..compoundliteral.16) is being placed in '.data..compoundliteral.16' ld.lld: warning: drivers/built-in.a(mtd/nand/spi/gigadevice.o): (.data..compoundliteral.17) is being placed in '.data..compoundliteral.17' [...] Handle this by adding the related sections to generic definitions as suggested by Sami [0]. [0] https://lore.kernel.org/lkml/20201211184633.3213045-3-samitolvanen@google.comSuggested-by: Sami Tolvanen <samitolvanen@google.com> Suggested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Alexander Lobakin <alobakin@pm.me> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
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