- Jan 14, 2021
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Sami Tolvanen authored
Disable LTO for the vDSO by filtering out CC_FLAGS_LTO, as there's no point in using link-time optimization for the small amount of C code. Signed-off-by:
Sami Tolvanen <samitolvanen@google.com> Reviewed-by:
Kees Cook <keescook@chromium.org> Acked-by:
Will Deacon <will@kernel.org> Signed-off-by:
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Sami Tolvanen authored
With CONFIG_MODVERSIONS, version information is linked into each compilation unit that exports symbols. With LTO, we cannot use this method as all C code is compiled into LLVM bitcode instead. This change collects symbol versions into .symversions files and merges them in link-vmlinux.sh where they are all linked into vmlinux.o at the same time. Signed-off-by:
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Sami Tolvanen authored
This change adds build system support for Clang's Link Time Optimization (LTO). With -flto, instead of ELF object files, Clang produces LLVM bitcode, which is compiled into native code at link time, allowing the final binary to be optimized globally. For more details, see: https://llvm.org/docs/LinkTimeOptimization.html The Kconfig option CONFIG_LTO_CLANG is implemented as a choice, which defaults to LTO being disabled. To use LTO, the architecture must select ARCH_SUPPORTS_LTO_CLANG and support: - compiling with Clang, - compiling all assembly code with Clang's integrated assembler, - and linking with LLD. While using CONFIG_LTO_CLANG_FULL results in the best runtime performance, the compilation is not scalable in time or memory. CONFIG_LTO_CLANG_THIN enables ThinLTO, which allows parallel optimization and faster incremental builds. ThinLTO is used by default if the architecture also selects ARCH_SUPPORTS_LTO_CLANG_THIN: https://clang.llvm.org/docs/ThinLTO.html To enable LTO, LLVM tools must be used to handle bitcode files, by passing LLVM=1 and LLVM_IAS=1 options to make: $ make LLVM=1 LLVM_IAS=1 defconfig $ scripts/config -e LTO_CLANG_THIN $ make LLVM=1 LLVM_IAS=1 To prepare for LTO support with other compilers, common parts are gated behind the CONFIG_LTO option, and LTO can be disabled for specific files by filtering out CC_FLAGS_LTO. Signed-off-by:
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- Dec 30, 2020
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Heiko Carstens authored
...and add comments at the top and bottom. Signed-off-by:
Heiko Carstens <hca@linux.ibm.com> Signed-off-by:
Vasily Gorbik <gor@linux.ibm.com>
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Heiko Carstens authored
Signed-off-by:
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- Dec 29, 2020
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Randy Dunlap authored
Make <asm-generic/local64.h> mandatory in include/asm-generic/Kbuild and remove all arch/*/include/asm/local64.h arch-specific files since they only #include <asm-generic/local64.h>. This fixes build errors on arch/c6x/ and arch/nios2/ for block/blk-iocost.c. Build-tested on 21 of 25 arch-es. (tools problems on the others) Yes, we could even rename <asm-generic/local64.h> to <linux/local64.h> and change all #includes to use <linux/local64.h> instead. Link: https://lkml.kernel.org/r/20201227024446.17018-1-rdunlap@infradead.org Signed-off-by:
Randy Dunlap <rdunlap@infradead.org> Suggested-by:
Christoph Hellwig <hch@infradead.org> Reviewed-by:
Masahiro Yamada <masahiroy@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Ley Foon Tan <ley.foon.tan@intel.com> Cc: Mark Salter <msalter@redhat.com> Cc: Aurelien Jacquiot <jacquiot.aurelien@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Baoquan He authored
VMware observed a performance regression during memmap init on their platform, and bisected to commit 73a6e474 ("mm: memmap_init: iterate over memblock regions rather that check each PFN") causing it. Before the commit: [0.033176] Normal zone: 1445888 pages used for memmap [0.033176] Normal zone: 89391104 pages, LIFO batch:63 [0.035851] ACPI: PM-Timer IO Port: 0x448 With commit [0.026874] Normal zone: 1445888 pages used for memmap [0.026875] Normal zone: 89391104 pages, LIFO batch:63 [2.028450] ACPI: PM-Timer IO Port: 0x448 The root cause is the current memmap defer init doesn't work as expected. Before, memmap_init_zone() was used to do memmap init of one whole zone, to initialize all low zones of one numa node, but defer memmap init of the last zone in that numa node. However, since commit 73a6e474, function memmap_init() is adapted to iterater over memblock regions inside one zone, then call memmap_init_zone() to do memmap init for each region. E.g, on VMware's system, the memory layout is as below, there are two memory regions in node 2. The current code will mistakenly initialize the whole 1st region [mem 0xab00000000-0xfcffffffff], then do memmap defer to iniatialize only one memmory section on the 2nd region [mem 0x10000000000-0x1033fffffff]. In fact, we only expect to see that there's only one memory section's memmap initialized. That's why more time is costed at the time. [ 0.008842] ACPI: SRAT: Node 0 PXM 0 [mem 0x00000000-0x0009ffff] [ 0.008842] ACPI: SRAT: Node 0 PXM 0 [mem 0x00100000-0xbfffffff] [ 0.008843] ACPI: SRAT: Node 0 PXM 0 [mem 0x100000000-0x55ffffffff] [ 0.008844] ACPI: SRAT: Node 1 PXM 1 [mem 0x5600000000-0xaaffffffff] [ 0.008844] ACPI: SRAT: Node 2 PXM 2 [mem 0xab00000000-0xfcffffffff] [ 0.008845] ACPI: SRAT: Node 2 PXM 2 [mem 0x10000000000-0x1033fffffff] Now, let's add a parameter 'zone_end_pfn' to memmap_init_zone() to pass down the real zone end pfn so that defer_init() can use it to judge whether defer need be taken in zone wide. Link: https://lkml.kernel.org/r/20201223080811.16211-1-bhe@redhat.com Link: https://lkml.kernel.org/r/20201223080811.16211-2-bhe@redhat.com Fixes: commit 73a6e474 ("mm: memmap_init: iterate over memblock regions rather that check each PFN") Signed-off-by:
Baoquan He <bhe@redhat.com> Reported-by:
Rahul Gopakumar <gopakumarr@vmware.com> Reviewed-by:
Mike Rapoport <rppt@linux.ibm.com> Cc: David Hildenbrand <david@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by:
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- Dec 22, 2020
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Andi Kleen authored
When a split lock is detected always make sure to disable interrupts before returning from the trap handler. The kernel exit code assumes that all exits run with interrupts disabled, otherwise the SWAPGS sequence can race against interrupts and cause recursing page faults and later panics. The problem will only happen on CPUs with split lock disable functionality, so Icelake Server, Tiger Lake, Snow Ridge, Jacobsville. Fixes: ca4c6a98 ("x86/traps: Make interrupt enable/disable symmetric in C code") Fixes: bce9b042 ("x86/traps: Disable interrupts in exc_aligment_check()") # v5.8+ Signed-off-by:
Andi Kleen <ak@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Tony Luck <tony.luck@intel.com> Reviewed-by:
Thomas Gleixner <tglx@linutronix.de> Signed-off-by:
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Andrey Konovalov authored
Even though hardware tag-based mode currently doesn't support checking vmalloc allocations, it doesn't use shadow memory and works with VMAP_STACK as is. Change VMAP_STACK definition accordingly. Link: https://lkml.kernel.org/r/ecdb2a1658ebd88eb276dee2493518ac0e82de41.1606162397.git.andreyknvl@google.com Link: https://linux-review.googlesource.com/id/I3552cbc12321dec82cd7372676e9372a2eb452ac Signed-off-by:
Andrey Konovalov <andreyknvl@google.com> Reviewed-by:
Marco Elver <elver@google.com> Acked-by:
Catalin Marinas <catalin.marinas@arm.com> Reviewed-by:
Dmitry Vyukov <dvyukov@google.com> Tested-by:
Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Branislav Rankov <Branislav.Rankov@arm.com> Cc: Evgenii Stepanov <eugenis@google.com> Cc: Kevin Brodsky <kevin.brodsky@arm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by:
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Andrey Konovalov authored
There's a config option CONFIG_KASAN_STACK that has to be enabled for KASAN to use stack instrumentation and perform validity checks for stack variables. There's no need to unpoison stack when CONFIG_KASAN_STACK is not enabled. Only call kasan_unpoison_task_stack[_below]() when CONFIG_KASAN_STACK is enabled. Note, that CONFIG_KASAN_STACK is an option that is currently always defined when CONFIG_KASAN is enabled, and therefore has to be tested with #if instead of #ifdef. Link: https://lkml.kernel.org/r/d09dd3f8abb388da397fd11598c5edeaa83fe559.1606162397.git.andreyknvl@google.com Link: https://linux-review.googlesource.com/id/If8a891e9fe01ea543e00b576852685afec0887e3 Signed-off-by:
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Andrey Konovalov authored
Hardware tag-based KASAN is now ready, enable the configuration option. Link: https://lkml.kernel.org/r/a6fa50d3bb6b318e05c6389a44095be96442b8b0.1606161801.git.andreyknvl@google.com Signed-off-by:
Alexander Potapenko <glider@google.com> Tested-by:
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Andrey Konovalov authored
Add error reporting for hardware tag-based KASAN. When CONFIG_KASAN_HW_TAGS is enabled, print KASAN report from the arm64 tag fault handler. SAS bits aren't set in ESR for all faults reported in EL1, so it's impossible to find out the size of the access the caused the fault. Adapt KASAN reporting code to handle this case. Link: https://lkml.kernel.org/r/b559c82b6a969afedf53b4694b475f0234067a1a.1606161801.git.andreyknvl@google.com Signed-off-by:
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Andrey Konovalov authored
Provide implementation of KASAN functions required for the hardware tag-based mode. Those include core functions for memory and pointer tagging (tags_hw.c) and bug reporting (report_tags_hw.c). Also adapt common KASAN code to support the new mode. Link: https://lkml.kernel.org/r/cfd0fbede579a6b66755c98c88c108e54f9c56bf.1606161801.git.andreyknvl@google.com Signed-off-by:
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Andrey Konovalov authored
Some #ifdef CONFIG_KASAN checks are only relevant for software KASAN modes (either related to shadow memory or compiler instrumentation). Expand those into CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS. Link: https://lkml.kernel.org/r/e6971e432dbd72bb897ff14134ebb7e169bdcf0c.1606161801.git.andreyknvl@google.com Signed-off-by:
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Andrey Konovalov authored
With the intoduction of hardware tag-based KASAN some kernel checks of this kind: ifdef CONFIG_KASAN will be updated to: if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) x86 and s390 use a trick to #undef CONFIG_KASAN for some of the code that isn't linked with KASAN runtime and shouldn't have any KASAN annotations. Also #undef CONFIG_KASAN_GENERIC with CONFIG_KASAN. Link: https://lkml.kernel.org/r/9d84bfaaf8fabe0fc89f913c9e420a30bd31a260.1606161801.git.andreyknvl@google.com Signed-off-by:
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Andrey Konovalov authored
This patch add a set of arch_*() memory tagging helpers currently only defined for arm64 when hardware tag-based KASAN is enabled. These helpers will be used by KASAN runtime to implement the hardware tag-based mode. The arch-level indirection level is introduced to simplify adding hardware tag-based KASAN support for other architectures in the future by defining the appropriate arch_*() macros. Link: https://lkml.kernel.org/r/fc9e5bb71201c03131a2fc00a74125723568dda9.1606161801.git.andreyknvl@google.com Signed-off-by:
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Andrey Konovalov authored
Hardware tag-based KASAN uses the memory tagging approach, which requires all allocations to be aligned to the memory granule size. Align the allocations to MTE_GRANULE_SIZE via ARCH_SLAB_MINALIGN when CONFIG_KASAN_HW_TAGS is enabled. Link: https://lkml.kernel.org/r/fe64131606b1c2aabfd34ae99554c0d9df18eb19.1606161801.git.andreyknvl@google.com Signed-off-by:
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Vincenzo Frascino authored
When MTE is present, the GCR_EL1 register contains the tags mask that allows to exclude tags from the random generation via the IRG instruction. With the introduction of the new Tag-Based KASAN API that provides a mechanism to reserve tags for special reasons, the MTE implementation has to make sure that the GCR_EL1 setting for the kernel does not affect the userspace processes and viceversa. Save and restore the kernel/user mask in GCR_EL1 in kernel entry and exit. Link: https://lkml.kernel.org/r/578b03294708cc7258fad0dc9c2a2e809e5a8214.1606161801.git.andreyknvl@google.com Signed-off-by:
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Vincenzo Frascino authored
The gcr_user mask is a per thread mask that represents the tags that are excluded from random generation when the Memory Tagging Extension is present and an 'irg' instruction is invoked. gcr_user affects the behavior on EL0 only. Currently that mask is an include mask and it is controlled by the user via prctl() while GCR_EL1 accepts an exclude mask. Convert the include mask into an exclude one to make it easier the register setting. Note: This change will affect gcr_kernel (for EL1) introduced with a future patch. Link: https://lkml.kernel.org/r/946dd31be833b660334c4f93410acf6d6c4cf3c4.1606161801.git.andreyknvl@google.com Signed-off-by:
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Vincenzo Frascino authored
Hardware tag-based KASAN relies on Memory Tagging Extension (MTE) feature and requires it to be enabled. MTE supports This patch adds a new mte_enable_kernel() helper, that enables MTE in Synchronous mode in EL1 and is intended to be called from KASAN runtime during initialization. The Tag Checking operation causes a synchronous data abort as a consequence of a tag check fault when MTE is configured in synchronous mode. As part of this change enable match-all tag for EL1 to allow the kernel to access user pages without faulting. This is required because the kernel does not have knowledge of the tags set by the user in a page. Note: For MTE, the TCF bit field in SCTLR_EL1 affects only EL1 in a similar way as TCF0 affects EL0. MTE that is built on top of the Top Byte Ignore (TBI) feature hence we enable it as part of this patch as well. Link: https://lkml.kernel.org/r/7352b0a0899af65c2785416c8ca6bf3845b66fa1.1606161801.git.andreyknvl@google.com Signed-off-by:
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Vincenzo Frascino authored
Add the implementation of the in-kernel fault handler. When a tag fault happens on a kernel address: * MTE is disabled on the current CPU, * the execution continues. When a tag fault happens on a user address: * the kernel executes do_bad_area() and panics. The tag fault handler for kernel addresses is currently empty and will be filled in by a future commit. Link: https://lkml.kernel.org/r/20201203102628.GB2224@gaia Link: https://lkml.kernel.org/r/ad31529b073e22840b7a2246172c2b67747ed7c4.1606161801.git.andreyknvl@google.com Signed-off-by:
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Vincenzo Frascino authored
The hardware tag-based KASAN for compatibility with the other modes stores the tag associated to a page in page->flags. Due to this the kernel faults on access when it allocates a page with an initial tag and the user changes the tags. Reset the tag associated by the kernel to a page in all the meaningful places to prevent kernel faults on access. Note: An alternative to this approach could be to modify page_to_virt(). This though could end up being racy, in fact if a CPU checks the PG_mte_tagged bit and decides that the page is not tagged but another CPU maps the same with PROT_MTE and becomes tagged the subsequent kernel access would fail. Link: https://lkml.kernel.org/r/9073d4e973747a6f78d5bdd7ebe17f290d087096.1606161801.git.andreyknvl@google.com Signed-off-by:
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Vincenzo Frascino authored
Provide helper functions to manipulate allocation and pointer tags for kernel addresses. Low-level helper functions (mte_assign_*, written in assembly) operate tag values from the [0x0, 0xF] range. High-level helper functions (mte_get/set_*) use the [0xF0, 0xFF] range to preserve compatibility with normal kernel pointers that have 0xFF in their top byte. MTE_GRANULE_SIZE and related definitions are moved to mte-def.h header that doesn't have any dependencies and is safe to include into any low-level header. Link: https://lkml.kernel.org/r/c31bf759b4411b2d98cdd801eb928e241584fd1f.1606161801.git.andreyknvl@google.com Signed-off-by:
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Vincenzo Frascino authored
Hardware tag-based KASAN relies on Memory Tagging Extension (MTE) which is an armv8.5-a architecture extension. Enable the correct asm option when the compiler supports it in order to allow the usage of ALTERNATIVE()s with MTE instructions. Link: https://lkml.kernel.org/r/d03d1157124ea3532eaeb77507988733f5734986.1606161801.git.andreyknvl@google.com Signed-off-by:
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Andrey Konovalov authored
Rename kasan_init_tags() to kasan_init_sw_tags() as the upcoming hardware tag-based KASAN mode will have its own initialization routine. Also similarly to kasan_init() mark kasan_init_tags() as __init. Link: https://lkml.kernel.org/r/71e52af72a09f4b50c8042f16101c60e50649fbb.1606161801.git.andreyknvl@google.com Signed-off-by:
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Andrey Konovalov authored
Software tag-based KASAN mode is fully initialized with kasan_init_tags(), while the generic mode only requires kasan_init(). Move the initialization message for tag-based mode into kasan_init_tags(). Also fix pr_fmt() usage for KASAN code: generic.c doesn't need it as it doesn't use any printing functions; tag-based mode should use "kasan:" instead of KBUILD_MODNAME (which stands for file name). Link: https://lkml.kernel.org/r/29a30ea4e1750450dd1f693d25b7b6cb05913ecf.1606161801.git.andreyknvl@google.com Signed-off-by:
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Andrey Konovalov authored
This is a preparatory commit for the upcoming addition of a new hardware tag-based (MTE-based) KASAN mode. Hardware tag-based KASAN won't use kasan_depth. Only define and use it when one of the software KASAN modes are enabled. No functional changes for software modes. Link: https://lkml.kernel.org/r/e16f15aeda90bc7fb4dfc2e243a14b74cc5c8219.1606161801.git.andreyknvl@google.com Signed-off-by:
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Andrey Konovalov authored
This is a preparatory commit for the upcoming addition of a new hardware tag-based (MTE-based) KASAN mode. Hardware tag-based KASAN won't be using shadow memory. Only initialize it when one of the software KASAN modes are enabled. No functional changes for software modes. Link: https://lkml.kernel.org/r/d1742eea2cd728d150d49b144e49b6433405c7ba.1606161801.git.andreyknvl@google.com Signed-off-by:
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Atish Patra authored
memblock_enforce_memory_limit accepts the maximum memory size not the maximum address that can be handled by kernel. Fix the function invocation accordingly. Fixes: 1bd14a66 ("RISC-V: Remove any memblock representing unusable memory area") Cc: stable@vger.kernel.org Reported-by:
Bin Meng <bin.meng@windriver.com> Tested-by:
Atish Patra <atish.patra@wdc.com> Signed-off-by:
Palmer Dabbelt <palmerdabbelt@google.com>
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- Dec 21, 2020
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Christophe Leroy authored
We need r1 to be properly set before activating MMU, otherwise any new exception taken while saving registers into the stack in syscall prologs will use the user stack, which is wrong and will even lockup or crash when KUAP is selected. Do that by switching the meaning of r11 and r1 until we have saved r1 to the stack: copy r1 into r11 and setup the new stack pointer in r1. To avoid complicating and impacting all generic and specific prolog code (and more), copy back r1 into r11 once r11 is save onto the stack. We could get rid of copying r1 back and forth at the cost of rewriting everything to use r1 instead of r11 all the way when CONFIG_VMAP_STACK is set, but the effort is probably not worth it for now. Fixes: da7bb43a ("powerpc/32: Fix vmap stack - Properly set r1 before activating MMU") Cc: stable@vger.kernel.org # v5.10+ Signed-off-by:
Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by:
Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/a3d819d5c348cee9783a311d5d3f3ba9b48fd219.1608531452.git.christophe.leroy@csgroup.eu
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Ard Biesheuvel authored
The early ATAGS/DT mapping code uses SECTION_SHIFT to mask low order bits of R2, and decides that no ATAGS/DTB were provided if the resulting value is 0x0. This means that on systems where DRAM starts at 0x0 (such as Raspberry Pi), no explicit mapping of the DT will be created if R2 points into the first 1 MB section of memory. This was not a problem before, because the decompressed kernel is loaded at the base of DRAM and mapped using sections as well, and so as long as the DT is referenced via a virtual address that uses the same translation (the linear map, in this case), things work fine. However, commit 7a1be318 ("9012/1: move device tree mapping out of linear region") changes this, and now the DT is referenced via a virtual address that is disjoint from the linear mapping of DRAM, and so we need the early code to create the DT mapping unconditionally. So let's create the early DT mapping for any value of R2 != 0x0. Reported-by:
"kernelci.org bot" <bot@kernelci.org> Reviewed-by:
Linus Walleij <linus.walleij@linaro.org> Signed-off-by:
Ard Biesheuvel <ardb@kernel.org> Signed-off-by:
Russell King <rmk+kernel@armlinux.org.uk>
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Nathan Chancellor authored
When linking a multi_v7_defconfig + CONFIG_KASAN=y kernel with LD=ld.lld, the following error occurs: $ make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- LLVM=1 zImage ld.lld: error: section: .exit.data is not contiguous with other relro sections LLD defaults to '-z relro', which is unneeded for the kernel because program headers are not used nor is there any position independent code generation or linking for ARM. Add '-z norelro' to LDFLAGS_vmlinux to avoid this error. Link: https://github.com/ClangBuiltLinux/linux/issues/1189 Reviewed-by:
Nick Desaulniers <ndesaulniers@google.com> Tested-by:
Nathan Chancellor <natechancellor@gmail.com> Signed-off-by:
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Geert Uytterhoeven authored
The DTB magic marker is stored as a 32-bit big-endian value, and thus depends on the CPU's endianness. Add a macro to define this value in native endianness, to reduce #ifdef clutter and (future) duplication. Signed-off-by:
Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by:
Nicolas Pitre <nico@fluxnic.net> Signed-off-by:
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Geert Uytterhoeven authored
The dbgadtb macro is passed the size of the appended DTB, not the end address. Fixes: c03e4147 ("ARM: 9010/1: uncompress: Print the location of appended DTB") Signed-off-by:
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Geert Uytterhoeven authored
DTB stores all values as 32-bit big-endian integers. Add a macro to convert such values to native CPU endianness, to reduce duplication. Signed-off-by:
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Anshuman Khandual authored
Mapping between IPI type index and its string is direct without requiring an additional offset. Hence the existing macro S(x, s) is now redundant and can just be dropped. This also makes the code clean and simple. Cc: Marc Zyngier <maz@kernel.org> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Signed-off-by:
Anshuman Khandual <anshuman.khandual@arm.com> Signed-off-by:
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Anshuman Khandual authored
Macros used as functions can be problematic from the compiler perspective. There was a build failure report caused primarily because of non reference of an argument variable. Hence convert PUD level pgtable helper macros into functions in order to avoid such problems in the future. In the process, it fixes the argument variables sequence in set_pud() which probably remained hidden for being a macro. https://lore.kernel.org/linux-mm/202011020749.5XQ3Hfzc-lkp@intel.com/ https://lore.kernel.org/linux-mm/5fa49698.Vu2O3r+dU20UoEJ+%25lkp@intel.com/ Cc: Andrew Morton <akpm@linux-foundation.org> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Reviewed-by:
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Ard Biesheuvel authored
Commit aaac3733 ("ARM: kvm: replace open coded VA->PA calculations with adr_l call") removed all uses of .L__boot_cpu_mode_offset, so there is no longer a need to define it. Signed-off-by:
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Ard Biesheuvel authored
Commit f77ac2e3 ("ARM: 9030/1: entry: omit FP emulation for UND exceptions taken in kernel mode") failed to take into account that there is in fact a case where we relied on this code path: during boot, the VFP detection code issues a read of FPSID, which will trigger an undef exception on cores that lack VFP support. So let's reinstate this logic using an undef hook which is registered only for the duration of the initcall to vpf_init(), and which sets VFP_arch to a non-zero value - as before - if no VFP support is present. Fixes: f77ac2e3 ("ARM: 9030/1: entry: omit FP emulation for UND ...") Reported-by:
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Michael Ellerman authored
Skirmisher reported on IRC that the 32-bit LE VDSO was hanging. This turned out to be due to a branch to self in eg. __kernel_gettimeofday. Looking at the disassembly with objdump -dR shows why: 00000528 <__kernel_gettimeofday>: 528: f0 ff 21 94 stwu r1,-16(r1) 52c: a6 02 08 7c mflr r0 530: f0 ff 21 94 stwu r1,-16(r1) 534: 14 00 01 90 stw r0,20(r1) 538: 05 00 9f 42 bcl 20,4*cr7+so,53c <__kernel_gettimeofday+0x14> 53c: a6 02 a8 7c mflr r5 540: ff ff a5 3c addis r5,r5,-1 544: c4 fa a5 38 addi r5,r5,-1340 548: f0 00 a5 38 addi r5,r5,240 54c: 01 00 00 48 bl 54c <__kernel_gettimeofday+0x24> 54c: R_PPC_REL24 .__c_kernel_gettimeofday Because we don't process relocations for the VDSO, this branch remains a branch from 0x54c to 0x54c. With the preceding patch to prohibit R_PPC_REL24 relocations, we instead get a build failure: 0000054c R_PPC_REL24 .__c_kernel_gettimeofday 00000598 R_PPC_REL24 .__c_kernel_clock_gettime 000005e4 R_PPC_REL24 .__c_kernel_clock_gettime64 00000630 R_PPC_REL24 .__c_kernel_clock_getres 0000067c R_PPC_REL24 .__c_kernel_time arch/powerpc/kernel/vdso32/vdso32.so.dbg: dynamic relocations are not supported The root cause is that we're branching to `.__c_kernel_gettimeofday`. But this is 32-bit LE code, which doesn't use function descriptors, so there are no dot symbols. The reason we're trying to branch to a dot symbol is because we're using the DOTSYM macro, but the ifdefs we use to define the DOTSYM macro do not currently work for 32-bit LE. So like previous commits we need to differentiate if the current compilation unit is 64-bit, rather than the kernel as a whole. ie. switch from CONFIG_PPC64 to __powerpc64__. With that fixed 32-bit LE code gets the empty version of DOTSYM, which just resolves to the original symbol name, leading to a direct branch and no relocations: 000003f8 <__kernel_gettimeofday>: 3f8: f0 ff 21 94 stwu r1,-16(r1) 3fc: a6 02 08 7c mflr r0 400: f0 ff 21 94 stwu r1,-16(r1) 404: 14 00 01 90 stw r0,20(r1) 408: 05 00 9f 42 bcl 20,4*cr7+so,40c <__kernel_gettimeofday+0x14> 40c: a6 02 a8 7c mflr r5 410: ff ff a5 3c addis r5,r5,-1 414: f4 fb a5 38 addi r5,r5,-1036 418: f0 00 a5 38 addi r5,r5,240 41c: 85 06 00 48 bl aa0 <__c_kernel_gettimeofday> Fixes: ab037dd8 ("powerpc/vdso: Switch VDSO to generic C implementation.") Reported-by:"Will Springer <skirmisher@protonmail.com>"> Signed-off-by:
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