- 03 Sep, 2020 5 commits
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Kees Cook authored
We don't want to depend on the linker's orphan section placement heuristics as these can vary between linkers, and may change between versions. All sections need to be explicitly handled in the linker script. Now that all sections are explicitly handled, enable orphan section warnings. Signed-off-by:
Kees Cook <keescook@chromium.org> Signed-off-by:
Ingo Molnar <mingo@kernel.org> Reviewed-by:
Nick Desaulniers <ndesaulniers@google.com> Link: https://lore.kernel.org/r/20200902025347.2504702-6-keescook@chromium.org
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Kees Cook authored
We don't want to depend on the linker's orphan section placement heuristics as these can vary between linkers, and may change between versions. All sections need to be explicitly handled in the linker script. Now that all sections are explicitly handled, enable orphan section warnings. Signed-off-by:
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Kees Cook authored
We don't want to depend on the linker's orphan section placement heuristics as these can vary between linkers, and may change between versions. All sections need to be explicitly handled in the linker script. With all sections now handled, enable orphan section warning. Signed-off-by:
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Kees Cook authored
We don't want to depend on the linker's orphan section placement heuristics as these can vary between linkers, and may change between versions. All sections need to be explicitly handled in the linker script. Specifically, this would have made a recently fixed bug very obvious: ld: warning: orphan section `.fixup' from `arch/arm/lib/copy_from_user.o' being placed in section `.fixup' With all sections handled, enable orphan section warning. Signed-off-by:
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Kees Cook authored
We don't want to depend on the linker's orphan section placement heuristics as these can vary between linkers, and may change between versions. All sections need to be explicitly handled in the linker script. With all sections now handled, enable orphan section warnings. Signed-off-by:
Will Deacon <will@kernel.org> Reviewed-by:
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- 01 Sep, 2020 24 commits
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Kees Cook authored
Include the missing DWARF and STABS sections in the compressed image, when they are present. Signed-off-by:
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Kees Cook authored
In preparation for warning on orphan sections, stop the linker from generating the .eh_frame* sections, discard unwanted non-zero-sized generated sections, and enforce other expected-to-be-zero-sized sections (since discarding them might hide problems with them suddenly gaining unexpected entries). Signed-off-by:
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Kees Cook authored
For readability, move the zero-sized sections to the end after DISCARDS. Signed-off-by:
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Kees Cook authored
In preparation for warning on orphan sections, enforce other expected-to-be-zero-sized sections (since discarding them might hide problems with them suddenly gaining unexpected entries). Signed-off-by:
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Kees Cook authored
The .got.plt section should always be zero (or filled only with the linker-generated lazy dispatch entry). Enforce this with an assert and mark the section as INFO. This is more sensitive than just blindly discarding the section. Signed-off-by:
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Kees Cook authored
When !CONFIG_KPROBES, do not generate kprobe sections. This makes sure there are no unexpected sections encountered by the linker scripts. Signed-off-by:
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Kees Cook authored
In preparation for warning on orphan sections, use common macros for debug sections, discards, and text stubs. Add discards for unwanted .note, and .rel sections. Signed-off-by:
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Kees Cook authored
In preparation for warning on orphan sections, enforce expected-to-be-zero-sized sections (since discarding them might hide problems with them suddenly gaining unexpected entries). Signed-off-by:
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Kees Cook authored
Add missing text stub sections .vfp11_veneer and .v4_bx, as well as missing DWARF sections, when present in the build. Signed-off-by:
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Kees Cook authored
In preparation for adding --orphan-handling=warn, explicitly keep the .ARM.attributes section (at address 0[1]) by expanding the existing ELF_DETAILS macro into ARM_DETAILS. [1] https://reviews.llvm.org/D85867Suggested-by:
Fangrui Song <maskray@google.com> Cc: Russell King <linux@armlinux.org.uk> Link: https://lore.kernel.org/lkml/CAKwvOdk-racgq5pxsoGS6Vtifbtrk5fmkmnoLxrQMaOvV0nPWw@mail.gmail.com/ Link: https://lore.kernel.org/r/20200821194310.3089815-17-keescook@chromium.org
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Kees Cook authored
In preparation for adding --orphan-handling=warn, refactor the linker script header includes, and extract common macros. Signed-off-by:
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Kees Cook authored
In preparation for warning on orphan sections, discard unwanted non-zero-sized generated sections, and enforce other expected-to-be-zero-sized sections (since discarding them might hide problems with them suddenly gaining unexpected entries). Suggested-by:
Ard Biesheuvel <ardb@kernel.org> Signed-off-by:
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Kees Cook authored
Explicitly include DWARF sections when they're present in the build. Signed-off-by:
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Kees Cook authored
Use the common DISCARDS rule for the linker script in an effort to regularize the linker script to prepare for warning on orphaned sections. Additionally clean up left-over no-op macros. Signed-off-by:
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Kees Cook authored
Avoid .eh_frame* section generation by making sure both CFLAGS and AFLAGS contain -fno-asychronous-unwind-tables and -fno-unwind-tables. With all sources of .eh_frame now removed from the build, drop this DISCARD so we can be alerted in the future if it returns unexpectedly once orphan section warnings have been enabled. Suggested-by:
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Kees Cook authored
Remove last instance of an .eh_frame section by removing the needless Call Frame Information annotations which were likely leftovers from 32-bit ARM. Suggested-by:
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Kees Cook authored
Fix a case of needless quotes in __section(), which Clang doesn't like. Signed-off-by:
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Kees Cook authored
In preparation for adding --orphan-handling=warn to more architectures, disable -mbranch-protection, as EFI does not yet support it[1]. This was noticed due to it producing unwanted .note.gnu.property sections (prefixed with .init due to the objcopy build step). However, we must also work around a bug in Clang where the section is still emitted for code-less object files[2], so also remove the section during the objcopy. [1] https://lore.kernel.org/lkml/CAMj1kXHck12juGi=E=P4hWP_8vQhQ+-x3vBMc3TGeRWdQ-XkxQ@mail.gmail.com [2] https://bugs.llvm.org/show_bug.cgi?id=46480Signed-off-by:
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Nick Desaulniers authored
Basically, consider .text.{hot|unlikely|unknown}.* part of .text, too. When compiling with profiling information (collected via PGO instrumentations or AutoFDO sampling), Clang will separate code into .text.hot, .text.unlikely, or .text.unknown sections based on profiling information. After D79600 (clang-11), these sections will have a trailing `.` suffix, ie. .text.hot., .text.unlikely., .text.unknown.. When using -ffunction-sections together with profiling infomation, either explicitly (FGKASLR) or implicitly (LTO), code may be placed in sections following the convention: .text.hot.<foo>, .text.unlikely.<bar>, .text.unknown.<baz> where <foo>, <bar>, and <baz> are functions. (This produces one section per function; we generally try to merge these all back via linker script so that we don't have 50k sections). For the above cases, we need to teach our linker scripts that such sections might exist and that we'd explicitly like them grouped together, otherwise we can wind up with code outside of the _stext/_etext boundaries that might not be mapped properly for some architectures, resulting in boot failures. If the linker script is not told about possible input sections, then where the section is placed as output is a heuristic-laiden mess that's non-portable between linkers (ie. BFD and LLD), and has resulted in many hard to debug bugs. Kees Cook is working on cleaning this up by adding --orphan-handling=warn linker flag used in ARCH=powerpc to additional architectures. In the case of linker scripts, borrowing from the Zen of Python: explicit is better than implicit. Also, ld.bfd's internal linker script considers .text.hot AND .text.hot.* to be part of .text, as well as .text.unlikely and .text.unlikely.*. I didn't see support for .text.unknown.*, and didn't see Clang producing such code in our kernel builds, but I see code in LLVM that can produce such section names if profiling information is missing. That may point to a larger issue with generating or collecting profiles, but I would much rather be safe and explicit than have to debug yet another issue related to orphan section placement. Reported-by:Jian Cai <jiancai@google.com> Suggested-by:
Luis Lozano <llozano@google.com> Tested-by:
Manoj Gupta <manojgupta@google.com> Acked-by:
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Kees Cook authored
When linking vmlinux with LLD, the synthetic sections .symtab, .strtab, and .shstrtab are listed as orphaned. Add them to the ELF_DETAILS section so there will be no warnings when --orphan-handling=warn is used more widely. (They are added above comment as it is the more common order[1].) ld.lld: warning: <internal>:(.symtab) is being placed in '.symtab' ld.lld: warning: <internal>:(.shstrtab) is being placed in '.shstrtab' ld.lld: warning: <internal>:(.strtab) is being placed in '.strtab' [1] https://lore.kernel.org/lkml/20200622224928.o2a7jkq33guxfci4@google.com/Reported-by:
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Kees Cook authored
The .comment section doesn't belong in STABS_DEBUG. Split it out into a new macro named ELF_DETAILS. This will gain other non-debug sections that need to be accounted for when linking with --orphan-handling=warn. Signed-off-by:
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Kees Cook authored
KASAN (-fsanitize=kernel-address) and KCSAN (-fsanitize=thread) produce unwanted[1] .eh_frame and .init_array.* sections. Add them to COMMON_DISCARDS, except with CONFIG_CONSTRUCTORS, which wants to keep .init_array.* sections. [1] https://bugs.llvm.org/show_bug.cgi?id=46478Signed-off-by:
Marco Elver <elver@google.com> Cc: linux-arch@vger.kernel.org Link: https://lore.kernel.org/r/20200821194310.3089815-4-keescook@chromium.org
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Kees Cook authored
For vmlinux linking, no architecture uses the .gnu.version* sections, so remove it via the COMMON_DISCARDS macro in preparation for adding --orphan-handling=warn more widely. This is a work-around for what appears to be a bug[1] in ld.bfd which warns for this synthetic section even when none is found in input objects, and even when no section is emitted for an output object[2]. [1] https://sourceware.org/bugzilla/show_bug.cgi?id=26153 [2] https://lore.kernel.org/lkml/202006221524.CEB86E036B@keescook/Signed-off-by:
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Kees Cook authored
Collect the common DISCARD sections for architectures that need more specialized discard control than what the standard DISCARDS section provides. Signed-off-by:
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- 14 Aug, 2020 7 commits
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Arvind Sankar authored
Add a linker script check that there are no run-time relocations, and remove the old one that tries to check via looking for specially-named sections in the object files. Drop the tests for -fPIE compiler option and -pie linker option, as they are available in all supported gcc and binutils versions (as well as clang and lld). Signed-off-by:
Arvind Sankar <nivedita@alum.mit.edu> Signed-off-by:
Sedat Dilek <sedat.dilek@gmail.com> Reviewed-by:
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Arvind Sankar authored
The BFD linker generates run-time relocations for z_input_len and z_output_len, even though they are absolute symbols. This is fixed for binutils-2.35 [1]. Work around this for earlier versions by defining two variables input_len and output_len in addition to the symbols, and use them via position-independent references. This eliminates the last two run-time relocations in the head code and allows us to drop the -z noreloc-overflow flag to the linker. Move the -pie and --no-dynamic-linker LDFLAGS to LDFLAGS_vmlinux instead of KBUILD_LDFLAGS. There shouldn't be anything else getting linked, but this is the more logical location for these flags, and modversions might call the linker if an EXPORT_SYMBOL is left over accidentally in one of the decompressors. [1] https://sourceware.org/bugzilla/show_bug.cgi?id=25754Signed-off-by:
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Arvind Sankar authored
The assembly code in head_{32,64}.S, while meant to be position-independent, generates run-time relocations because it uses instructions such as: leal gdt(%edx), %eax which make the assembler and linker think that the code is using %edx as an index into gdt, and hence gdt needs to be relocated to its run-time address. On 32-bit, with lld Dmitry Golovin reports that this results in a link-time error with default options (i.e. unless -z notext is explicitly passed): LD arch/x86/boot/compressed/vmlinux ld.lld: error: can't create dynamic relocation R_386_32 against local symbol in readonly segment; recompile object files with -fPIC or pass '-Wl,-z,notext' to allow text relocations in the output With the BFD linker, this generates a warning during the build, if --warn-shared-textrel is enabled, which at least Gentoo enables by default: LD arch/x86/boot/compressed/vmlinux ld: arch/x86/boot/compressed/head_32.o: warning: relocation in read-only section `.head.text' ld: warning: creating a DT_TEXTREL in object On 64-bit, it is not possible to link the kernel as -pie with lld, and it is only possible with a BFD linker that supports -z noreloc-overflow, i.e. versions >2.26. This is because these instructions cannot really be relocated: the displacement field is only 32-bits wide, and thus cannot be relocated for a 64-bit load address. The -z noreloc-overflow option simply overrides the linker error, and results in R_X86_64_RELATIVE relocations that apply a 64-bit relocation to a 32-bit field anyway. This happens to work because nothing will process these run-time relocations. Start fixing this by removing relocations from .head.text: - On 32-bit, use a base register that holds the address of the GOT and reference symbol addresses using @GOTOFF, i.e. leal gdt@GOTOFF(%edx), %eax - On 64-bit, most of the code can (and already does) use %rip-relative addressing, however the .code32 bits can't, and the 64-bit code also needs to reference symbol addresses as they will be after moving the compressed kernel to the end of the decompression buffer. For these cases, reference the symbols as an offset to startup_32 to avoid creating relocations, i.e.: leal (gdt-startup_32)(%bp), %eax This only works in .head.text as the subtraction cannot be represented as a PC-relative relocation unless startup_32 is in the same section as the code. Move efi32_pe_entry into .head.text so that it can use the same method to avoid relocations. Reported-by:Dmitry Golovin <dima@golovin.in> Signed-off-by:
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Arvind Sankar authored
GCC puts the main function into .text.startup when compiled with -Os (or -O2). This results in arch/x86/boot/main.c having a .text.startup section which is currently not included explicitly in the linker script setup.ld in the same directory. The BFD linker places this orphan section immediately after .text, so this still works. However, LLD git, since [1], is choosing to place it immediately after the .bstext section instead (this is the first code section). This plays havoc with the section layout that setup.elf requires to create the setup header, for eg on 64-bit: LD arch/x86/boot/setup.elf ld.lld: error: section .text.startup file range overlaps with .header >>> .text.startup range is [0x200040, 0x2001FE] >>> .header range is [0x2001EF, 0x20026B] ld.lld: error: section .header file range overlaps with .bsdata >>> .header range is [0x2001EF, 0x20026B] >>> .bsdata range is [0x2001FF, 0x200398] ld.lld: error: section .bsdata file range overlaps with .entrytext >>> .bsdata range is [0x2001FF, 0x200398] >>> .entrytext range is [0x20026C, 0x2002D3] ld.lld: error: section .text.startup virtual address range overlaps with .header >>> .text.startup range is [0x40, 0x1FE] >>> .header range is [0x1EF, 0x26B] ld.lld: error: section .header virtual address range overlaps with .bsdata >>> .header range is [0x1EF, 0x26B] >>> .bsdata range is [0x1FF, 0x398] ld.lld: error: section .bsdata virtual address range overlaps with .entrytext >>> .bsdata range is [0x1FF, 0x398] >>> .entrytext range is [0x26C, 0x2D3] ld.lld: error: section .text.startup load address range overlaps with .header >>> .text.startup range is [0x40, 0x1FE] >>> .header range is [0x1EF, 0x26B] ld.lld: error: section .header load address range overlaps with .bsdata >>> .header range is [0x1EF, 0x26B] >>> .bsdata range is [0x1FF, 0x398] ld.lld: error: section .bsdata load address range overlaps with .entrytext >>> .bsdata range is [0x1FF, 0x398] >>> .entrytext range is [0x26C, 0x2D3] Add .text.* to the .text output section to fix this, and also prevent any future surprises if the compiler decides to create other such sections. [1] https://reviews.llvm.org/D75225Signed-off-by: -
Ard Biesheuvel authored
In a previous patch, we have eliminated GOT entries from the decompressor binary and added an assertion that the .got section is empty. This means that the GOT fixup routines that exist in both the 32-bit and 64-bit startup routines have become dead code, and can be removed. While at it, drop the KEEP() from the linker script, as it has no effect on the contents of output sections that are created by the linker itself. Signed-off-by:
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Ard Biesheuvel authored
Eliminate all GOT entries in the decompressor binary, by forcing hidden visibility for all symbol references, which informs the compiler that such references will be resolved at link time without the need for allocating GOT entries. To ensure that no GOT entries will creep back in, add an assertion to the decompressor linker script that will fire if the .got section has a non-zero size. [Arvind: move hidden.h to include/linux instead of making a copy] Signed-off-by:
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Ard Biesheuvel authored
The .got.plt section contains the part of the GOT which is used by PLT entries, and which gets updated lazily by the dynamic loader when function calls are dispatched through those PLT entries. On fully linked binaries such as the kernel proper or the decompressor, this never happens, and so in practice, the .got.plt section consists only of the first 3 magic entries that are meant to point at the _DYNAMIC section and at the fixup routine in the loader. However, since we don't use a dynamic loader, those entries are never populated or used. This means that treating those entries like ordinary GOT entries, and updating their values based on the actual placement of the executable in memory is completely pointless, and we can just ignore the .got.plt section entirely, provided that it has no additional entries beyond the first 3 ones. So add an assertion in the linker script to ensure that this assumption holds, and move the contents out of the [_got, _egot) memory range that is modified by the GOT fixup routines. While at it, drop the KEEP(), since it has no effect on the contents of output sections that are created by the linker itself. Signed-off-by:
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- 13 Aug, 2020 1 commit
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git://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linuxLinus Torvalds authored
Pull RTC updates from Alexandre Belloni: "Not much this cycle - mostly non urgent driver fixes: - ds1374: use watchdog core - pcf2127: add alarm and pcf2129 support" * tag 'rtc-5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linux: rtc: pcf2127: fix alarm handling rtc: pcf2127: add alarm support rtc: pcf2127: add pca2129 device id rtc: max77686: Fix wake-ups for max77620 rtc: ds1307: provide an indication that the watchdog has fired rtc: ds1374: remove unused define rtc: ds1374: fix RTC_DRV_DS1374_WDT dependencies rtc: cleanup obsolete comment about struct rtc_class_ops rtc: pl031: fix set_alarm by adding back call to alarm_irq_enable rtc: ds1374: wdt: Use watchdog core for watchdog part rtc: Replace HTTP links with HTTPS ones rtc: goldfish: Enable interrupt in set_alarm() when necessary rtc: max77686: Do not allow interrupt to fire before system resume rtc: imxdi: fix trivial typos rtc: cpcap: fix range
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- 12 Aug, 2020 3 commits
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git://github.com/ceph/ceph-clientLinus Torvalds authored
Pull ceph updates from Ilya Dryomov: "Xiubo has completed his work on filesystem client metrics, they are sent to all available MDSes once per second now. Other than that, we have a lot of fixes and cleanups all around the filesystem, including a tweak to cut down on MDS request resends in multi-MDS setups from Yanhu and fixups for SELinux symlink labeling and MClientSession message decoding from Jeff" * tag 'ceph-for-5.9-rc1' of git://github.com/ceph/ceph-client: (22 commits) ceph: handle zero-length feature mask in session messages ceph: use frag's MDS in either mode ceph: move sb->wb_pagevec_pool to be a global mempool ceph: set sec_context xattr on symlink creation ceph: remove redundant initialization of variable mds ceph: fix use-after-free for fsc->mdsc ceph: remove unused variables in ceph_mdsmap_decode() ceph: delete repeated words in fs/ceph/ ceph: send client provided metric flags in client metadata ceph: periodically send perf metrics to MDSes ceph: check the sesion state and return false in case it is closed libceph: replace HTTP links with HTTPS ones ceph: remove unnecessary cast in kfree() libceph: just have osd_req_op_init() return a pointer ceph: do not access the kiocb after aio requests ceph: clean up and optimize ceph_check_delayed_caps() ceph: fix potential mdsc use-after-free crash ceph: switch to WARN_ON_ONCE in encode_supported_features() ceph: add global total_caps to count the mdsc's total caps number ceph: add check_session_state() helper and make it global ...
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git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linuxLinus Torvalds authored
Pull more parisc updates from Helge Deller: - Oscar Carter contributed a patch which fixes parisc's usage of dereference_function_descriptor() and thus will allow using the -Wcast-function-type compiler option in the top-level Makefile - Sven Schnelle fixed a bug in the SBA code to prevent crashes during kexec - John David Anglin provided implementations for __smp_store_release() and __smp_load_acquire barriers() which avoids using the sync assembler instruction and thus speeds up barrier paths - Some whitespace cleanups in parisc's atomic.h header file * 'parisc-5.9-2' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux: parisc: Implement __smp_store_release and __smp_load_acquire barriers parisc: mask out enable and reserved bits from sba imask parisc: Whitespace cleanups in atomic.h parisc/kernel/ftrace: Remove function callback casts sections.h: dereference_function_descriptor() returns void pointer
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git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds authored
Pull more KVM updates from Paolo Bonzini: "PPC: - Improvements and bugfixes for secure VM support, giving reduced startup time and memory hotplug support. - Locking fixes in nested KVM code - Increase number of guests supported by HV KVM to 4094 - Preliminary POWER10 support ARM: - Split the VHE and nVHE hypervisor code bases, build the EL2 code separately, allowing for the VHE code to now be built with instrumentation - Level-based TLB invalidation support - Restructure of the vcpu register storage to accomodate the NV code - Pointer Authentication available for guests on nVHE hosts - Simplification of the system register table parsing - MMU cleanups and fixes - A number of post-32bit cleanups and other fixes MIPS: - compilation fixes x86: - bugfixes - support for the SERIALIZE instruction" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (70 commits) KVM: MIPS/VZ: Fix build error caused by 'kvm_run' cleanup x86/kvm/hyper-v: Synic default SCONTROL MSR needs to be enabled MIPS: KVM: Convert a fallthrough comment to fallthrough MIPS: VZ: Only include loongson_regs.h for CPU_LOONGSON64 x86: Expose SERIALIZE for supported cpuid KVM: x86: Don't attempt to load PDPTRs when 64-bit mode is enabled KVM: arm64: Move S1PTW S2 fault logic out of io_mem_abort() KVM: arm64: Don't skip cache maintenance for read-only memslots KVM: arm64: Handle data and instruction external aborts the same way KVM: arm64: Rename kvm_vcpu_dabt_isextabt() KVM: arm: Add trace name for ARM_NISV KVM: arm64: Ensure that all nVHE hyp code is in .hyp.text KVM: arm64: Substitute RANDOMIZE_BASE for HARDEN_EL2_VECTORS KVM: arm64: Make nVHE ASLR conditional on RANDOMIZE_BASE KVM: PPC: Book3S HV: Rework secure mem slot dropping KVM: PPC: Book3S HV: Move kvmppc_svm_page_out up KVM: PPC: Book3S HV: Migrate hot plugged memory KVM: PPC: Book3S HV: In H_SVM_INIT_DONE, migrate remaining normal-GFNs to secure-GFNs KVM: PPC: Book3S HV: Track the state GFNs associated with secure VMs KVM: PPC: Book3S HV: Disable page merging in H_SVM_INIT_START ...
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