summaryrefslogtreecommitdiffstats
path: root/arch/arm64/kernel/alternative.c
Commit message (Collapse)AuthorAgeFilesLines
* arm64: alternatives: mark patch_alternative() as `noinstr`Joey Gouly2022-04-061-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The alternatives code must be `noinstr` such that it does not patch itself, as the cache invalidation is only performed after all the alternatives have been applied. Mark patch_alternative() as `noinstr`. Mark branch_insn_requires_update() and get_alt_insn() with `__always_inline` since they are both only called through patch_alternative(). Booting a kernel in QEMU TCG with KCSAN=y and ARM64_USE_LSE_ATOMICS=y caused a boot hang: [ 0.241121] CPU: All CPU(s) started at EL2 The alternatives code was patching the atomics in __tsan_read4() from LL/SC atomics to LSE atomics. The following fragment is using LL/SC atomics in the .text section: | <__tsan_unaligned_read4+304>: ldxr x6, [x2] | <__tsan_unaligned_read4+308>: add x6, x6, x5 | <__tsan_unaligned_read4+312>: stxr w7, x6, [x2] | <__tsan_unaligned_read4+316>: cbnz w7, <__tsan_unaligned_read4+304> This LL/SC atomic sequence was to be replaced with LSE atomics. However since the alternatives code was instrumentable, __tsan_read4() was being called after only the first instruction was replaced, which led to the following code in memory: | <__tsan_unaligned_read4+304>: ldadd x5, x6, [x2] | <__tsan_unaligned_read4+308>: add x6, x6, x5 | <__tsan_unaligned_read4+312>: stxr w7, x6, [x2] | <__tsan_unaligned_read4+316>: cbnz w7, <__tsan_unaligned_read4+304> This caused an infinite loop as the `stxr` instruction never completed successfully, so `w7` was always 0. Signed-off-by: Joey Gouly <joey.gouly@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20220405104733.11476-1-joey.gouly@arm.com Signed-off-by: Will Deacon <will@kernel.org>
* arm64: Rename arm64-internal cache maintenance functionsFuad Tabba2021-05-251-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Although naming across the codebase isn't that consistent, it tends to follow certain patterns. Moreover, the term "flush" isn't defined in the Arm Architecture reference manual, and might be interpreted to mean clean, invalidate, or both for a cache. Rename arm64-internal functions to make the naming internally consistent, as well as making it consistent with the Arm ARM, by specifying whether it applies to the instruction, data, or both caches, whether the operation is a clean, invalidate, or both. Also specify which point the operation applies to, i.e., to the point of unification (PoU), coherency (PoC), or persistence (PoP). This commit applies the following sed transformation to all files under arch/arm64: "s/\b__flush_cache_range\b/caches_clean_inval_pou_macro/g;"\ "s/\b__flush_icache_range\b/caches_clean_inval_pou/g;"\ "s/\binvalidate_icache_range\b/icache_inval_pou/g;"\ "s/\b__flush_dcache_area\b/dcache_clean_inval_poc/g;"\ "s/\b__inval_dcache_area\b/dcache_inval_poc/g;"\ "s/__clean_dcache_area_poc\b/dcache_clean_poc/g;"\ "s/\b__clean_dcache_area_pop\b/dcache_clean_pop/g;"\ "s/\b__clean_dcache_area_pou\b/dcache_clean_pou/g;"\ "s/\b__flush_cache_user_range\b/caches_clean_inval_user_pou/g;"\ "s/\b__flush_icache_all\b/icache_inval_all_pou/g;" Note that __clean_dcache_area_poc is deliberately missing a word boundary check at the beginning in order to match the efistub symbols in image-vars.h. Also note that, despite its name, __flush_icache_range operates on both instruction and data caches. The name change here reflects that. No functional change intended. Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Fuad Tabba <tabba@google.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/20210524083001.2586635-19-tabba@google.com Signed-off-by: Will Deacon <will@kernel.org>
* Merge tag 'arm64-fixes' of ↵Linus Torvalds2021-05-071-3/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux Pull more arm64 updates from Catalin Marinas: "A mix of fixes and clean-ups that turned up too late for the first pull request: - Restore terminal stack frame records. Their previous removal caused traces which cross secondary_start_kernel to terminate one entry too late, with a spurious "0" entry. - Fix boot warning with pseudo-NMI due to the way we manipulate the PMR register. - ACPI fixes: avoid corruption of interrupt mappings on watchdog probe failure (GTDT), prevent unregistering of GIC SGIs. - Force SPARSEMEM_VMEMMAP as the only memory model, it saves with having to test all the other combinations. - Documentation fixes and updates: tagged address ABI exceptions on brk/mmap/mremap(), event stream frequency, update booting requirements on the configuration of traps" * tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: arm64: kernel: Update the stale comment arm64: Fix the documented event stream frequency arm64: entry: always set GIC_PRIO_PSR_I_SET during entry arm64: Explicitly document boot requirements for SVE arm64: Explicitly require that FPSIMD instructions do not trap arm64: Relax booting requirements for configuration of traps arm64: cpufeatures: use min and max arm64: stacktrace: restore terminal records arm64/vdso: Discard .note.gnu.property sections in vDSO arm64: doc: Add brk/mmap/mremap() to the Tagged Address ABI Exceptions psci: Remove unneeded semicolon ACPI: irq: Prevent unregistering of GIC SGIs ACPI: GTDT: Don't corrupt interrupt mappings on watchdow probe failure arm64: Show three registers per line arm64: remove HAVE_DEBUG_BUGVERBOSE arm64: alternative: simplify passing alt_region arm64: Force SPARSEMEM_VMEMMAP as the only memory management model arm64: vdso32: drop -no-integrated-as flag
| * arm64: alternative: simplify passing alt_regionMark Rutland2021-04-231-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | In __apply_alternatives() we take a pointer to void which we later assign to a pointer to struct alt_region. As all callers are passing a pointer to struct alt_region to begin with, it's simpler and more robust to take a pointer to struct alt region, so let's do so and avoid the need for a temporary variable. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will@kernel.org> Acked-by: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20210416163032.10857-1-mark.rutland@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* | arm64: add __nocfi to __apply_alternativesSami Tolvanen2021-04-081-2/+2
|/ | | | | | | | | | | | | | __apply_alternatives makes indirect calls to functions whose address is taken in assembly code using the alternative_cb macro. With non-canonical CFI, the compiler won't replace these function references with the jump table addresses, which trips CFI. Disable CFI checking in the function to work around the issue. 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/20210408182843.1754385-16-samitolvanen@google.com
* arm64: improve whitespaceZhiyuan Dai2021-02-041-1/+1
| | | | | | | | | | | | | In a few places we don't have whitespace between macro parameters, which makes them hard to read. This patch adds whitespace to clearly separate the parameters. In a few places we have unnecessary whitespace around unary operators, which is confusing, This patch removes the unnecessary whitespace. Signed-off-by: Zhiyuan Dai <daizhiyuan@phytium.com.cn> Link: https://lore.kernel.org/r/1612403029-5011-1-git-send-email-daizhiyuan@phytium.com.cn Signed-off-by: Will Deacon <will@kernel.org>
* arm64: alternatives: Remove READ_ONCE() usage during patch operationWill Deacon2020-11-091-3/+4
| | | | | | | | | | In preparation for patching the internals of READ_ONCE() itself, replace its usage on the alternatives patching patch with a volatile variable instead. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will@kernel.org>
* arm64/alternatives: don't patch up internal branchesArd Biesheuvel2020-07-091-14/+2
| | | | | | | | | | | | | | | | | | | | | | | Commit f7b93d42945c ("arm64/alternatives: use subsections for replacement sequences") moved the alternatives replacement sequences into subsections, in order to keep the as close as possible to the code that they replace. Unfortunately, this broke the logic in branch_insn_requires_update, which assumed that any branch into kernel executable code was a branch that required updating, which is no longer the case now that the code sequences that are patched in are in the same section as the patch site itself. So the only way to discriminate branches that require updating and ones that don't is to check whether the branch targets the replacement sequence itself, and so we can drop the call to kernel_text_address() entirely. Fixes: f7b93d42945c ("arm64/alternatives: use subsections for replacement sequences") Reported-by: Alexandru Elisei <alexandru.elisei@arm.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Tested-by: Alexandru Elisei <alexandru.elisei@arm.com> Link: https://lore.kernel.org/r/20200709125953.30918-1-ardb@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
* treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 234Thomas Gleixner2019-06-191-12/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not see http www gnu org licenses extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 503 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexios Zavras <alexios.zavras@intel.com> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Enrico Weigelt <info@metux.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190602204653.811534538@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* arm64: alternative: Apply alternatives early in boot processDaniel Thompson2019-02-061-5/+38
| | | | | | | | | | | | | | | | | | | | | Currently alternatives are applied very late in the boot process (and a long time after we enable scheduling). Some alternative sequences, such as those that alter the way CPU context is stored, must be applied much earlier in the boot sequence. Introduce apply_boot_alternatives() to allow some alternatives to be applied immediately after we detect the CPU features of the boot CPU. Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> [julien.thierry@arm.com: rename to fit new cpufeature framework better, apply BOOT_SCOPE feature early in boot] Signed-off-by: Julien Thierry <julien.thierry@arm.com> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Reviewed-by: Marc Zyngier <marc.zyngier@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Christoffer Dall <christoffer.dall@arm.com> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* arm64: alternative: Allow alternative status checking per cpufeatureJulien Thierry2019-02-061-4/+17
| | | | | | | | | | | | | | | | | | In preparation for the application of alternatives at different points during the boot process, provide the possibility to check whether alternatives for a feature of interest was already applied instead of having a global boolean for all alternatives. Make VHE enablement code check for the VHE feature instead of considering all alternatives. Signed-off-by: Julien Thierry <julien.thierry@arm.com> Acked-by: Marc Zyngier <marc.zyngier@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Marc Zyngier <Marc.Zyngier@arm.com> Cc: Christoffer Dall <Christoffer.Dall@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* arm64: alternative: Use true and false for boolean valuesGustavo A. R. Silva2018-08-081-2/+2
| | | | | | | | | Return statements in functions returning bool should use true or false instead of an integer value. This code was detected with the help of Coccinelle. Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
* arm64: Avoid flush_icache_range() in alternatives patching codeWill Deacon2018-06-271-7/+44
| | | | | | | | | | | | | | | | | | The implementation of flush_icache_range() includes instruction sequences which are themselves patched at runtime, so it is not safe to call from the patching framework. This patch reworks the alternatives cache-flushing code so that it rolls its own internal D-cache maintenance using DC CIVAC before invalidating the entire I-cache after all alternatives have been applied at boot. Modules don't cause any issues, since flush_icache_range() is safe to call by the time they are loaded. Acked-by: Mark Rutland <mark.rutland@arm.com> Reported-by: Rohit Khanna <rokhanna@nvidia.com> Cc: Alexander Van Brunt <avanbrunt@nvidia.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* arm64: alternatives: Add dynamic patching featureMarc Zyngier2018-03-191-11/+32
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We've so far relied on a patching infrastructure that only gave us a single alternative, without any way to provide a range of potential replacement instructions. For a single feature, this is an all or nothing thing. It would be interesting to have a more flexible grained way of patching the kernel though, where we could dynamically tune the code that gets injected. In order to achive this, let's introduce a new form of dynamic patching, assiciating a callback to a patching site. This callback gets source and target locations of the patching request, as well as the number of instructions to be patched. Dynamic patching is declared with the new ALTERNATIVE_CB and alternative_cb directives: asm volatile(ALTERNATIVE_CB("mov %0, #0\n", callback) : "r" (v)); or alternative_cb callback mov x0, #0 alternative_cb_end where callback is the C function computing the alternative. Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
* arm64: alternatives: use tpidr_el2 on VHE hostsJames Morse2018-01-131-4/+5
| | | | | | | | | | | | Now that KVM uses tpidr_el2 in the same way as Linux's cpu_offset in tpidr_el1, merge the two. This saves KVM from save/restoring tpidr_el1 on VHE hosts, and allows future code to blindly access per-cpu variables without triggering world-switch. Signed-off-by: James Morse <james.morse@arm.com> Reviewed-by: Christoffer Dall <cdall@linaro.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* arm64: fix endianness annotation for __apply_alternatives()/get_alt_insn()Luc Van Oostenryck2017-06-291-4/+4
| | | | | | | | | | | | | | | get_alt_insn() is used to read and create ARM instructions, which are always stored in memory in little-endian order. These values are thus correctly converted to/from native order when processed but the pointers used to hold the address of these instructions are declared as for native order values. Fix this by declaring the pointers as __le32* instead of u32* and make the few appropriate needed changes like removing the unneeded cast '(u32*)' in front of __ALT_PTR()'s definition. Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
* arm64: alternatives: apply boot time fixups via the linear mappingArd Biesheuvel2017-03-231-5/+6
| | | | | | | | | | | | | | | | | | | | One important rule of thumb when desiging a secure software system is that memory should never be writable and executable at the same time. We mostly adhere to this rule in the kernel, except at boot time, when regions may be mapped RWX until after we are done applying alternatives or making other one-off changes. For the alternative patching, we can improve the situation by applying the fixups via the linear mapping, which is never mapped with executable permissions. So map the linear alias of .text with RW- permissions initially, and remove the write permissions as soon as alternative patching has completed. Reviewed-by: Laura Abbott <labbott@redhat.com> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Tested-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* arm64: alternative: Add support for patching adrp instructionsSuzuki K Poulose2016-09-091-0/+15
| | | | | | | | | | | | | | | adrp uses PC-relative address offset to a page (of 4K size) of a symbol. If it appears in an alternative code patched in, we should adjust the offset to reflect the address where it will be run from. This patch adds support for fixing the offset for adrp instructions. Cc: Will Deacon <will.deacon@arm.com> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Andre Przywara <andre.przywara@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
* arm64: alternative: Disallow patching instructions using literalsSuzuki K Poulose2016-09-091-0/+6
| | | | | | | | | | | | | | | The alternative code patching doesn't check if the replaced instruction uses a pc relative literal. This could cause silent corruption in the instruction stream as the instruction will be executed from a different address than what it was compiled for. Catch all such cases. Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Andre Przywara <andre.przywara@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Suggested-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
* arm64: Create sections.hJames Morse2016-08-251-4/+3
| | | | | | | | | | | | | | | Each time new section markers are added, kernel/vmlinux.ld.S is updated, and new extern char __start_foo[] definitions are scattered through the tree. Create asm/include/sections.h to collect these definitions (and include the existing asm-generic version). Signed-off-by: James Morse <james.morse@arm.com> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Tested-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
* arm64: mm: fold alternatives into .initMark Rutland2015-12-101-6/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | Currently we treat the alternatives separately from other data that's only used during initialisation, using separate .altinstructions and .altinstr_replacement linker sections. These are freed for general allocation separately from .init*. This is problematic as: * We do not remove execute permissions, as we do for .init, leaving the memory executable. * We pad between them, making the kernel Image bianry up to PAGE_SIZE bytes larger than necessary. This patch moves the two sections into the contiguous region used for .init*. This saves some memory, ensures that we remove execute permissions, and allows us to remove some code made redundant by this reorganisation. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Andre Przywara <andre.przywara@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Jeremy Linton <jeremy.linton@arm.com> Cc: Laura Abbott <labbott@fedoraproject.org> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
* arm64: alternatives: ensure secondary CPUs execute ISB after patchingWill Deacon2015-08-041-0/+1
| | | | | | | | | | | | | | | | In order to guarantee that the patched instruction stream is visible to a CPU, that CPU must execute an isb instruction after any related cache maintenance has completed. The instruction patching routines in kernel/insn.c get this right for things like jump labels and ftrace, but the alternatives patching omits it entirely leaving secondary cores in a potential limbo between the old and the new code. This patch adds an isb following the secondary polling loop in the altenatives patching. Signed-off-by: Will Deacon <will.deacon@arm.com>
* arm64: alternative: put secondary CPUs into polling loop during patchWill Deacon2015-07-301-5/+24
| | | | | | | | | | | | | When patching the kernel text with alternatives, we may end up patching parts of the stop_machine state machine (e.g. atomic_dec_and_test in ack_state) and consequently corrupt the instruction stream of any secondary CPUs. This patch passes the cpu_online_mask to stop_machine, forcing all of the CPUs into our own callback which can place the secondary cores into a dumb (but safe!) polling loop whilst the patching is carried out. Signed-off-by: Will Deacon <will.deacon@arm.com>
* arm64: alternative: Allow immediate branch as alternative instructionMarc Zyngier2015-06-051-5/+66
| | | | | | | | | | | | | | | | Since all branches are PC-relative on AArch64, these instructions cannot be used as an alternative with the simplistic approach we currently have (the immediate has been computed from the .altinstr_replacement section, and end-up being completely off if the target is outside of the replacement sequence). This patch handles the branch instructions in a different way, using the insn framework to recompute the immediate, and generate the right displacement in the above case. Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* Revert "arm64: alternative: Allow immediate branch as alternative instruction"Will Deacon2015-05-051-52/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | This reverts most of commit fef7f2b2010381c795ae43743ad31931cc58f5ad. It turns out that there are a couple of problems with the way we're fixing up branch instructions used as part of alternative instruction sequences: (1) If the branch target is also in the alternative sequence, we'll generate a branch into the .altinstructions section which actually gets freed. (2) The calls to aarch64_insn_{read,write} bring an awful lot more code into the patching path (e.g. taking locks, poking the fixmap, invalidating the TLB) which isn't actually needed for the early patching run under stop_machine, but makes the use of alternative sequences extremely fragile (as we can't patch code that could be used by the patching code). Given that no code actually requires alternative patching of immediate branches, let's remove this support for now and revisit it when we've got a user. We leave the updated size check, since we really do require the sequences to be the same length. Acked-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
* arm64: alternative: Allow immediate branch as alternative instructionMarc Zyngier2015-03-301-2/+53
| | | | | | | | | | | | | | | | | Since all immediate branches are PC-relative on Aarch64, these instructions cannot be used as an alternative with the simplistic approach we currently have (the immediate has been computed from the .altinstr_replacement section, and end-up being completely off if we insert it directly). This patch handles the b and bl instructions in a different way, using the insn framework to recompute the immediate, and generate the right displacement. Reviewed-by: Andre Przywara <andre.przywara@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
* arm64: add module support for alternatives fixupsAndre Przywara2014-12-041-4/+25
| | | | | | | | | | | | | | | | | Currently the kernel patches all necessary instructions once at boot time, so modules are not covered by this. Change the apply_alternatives() function to take a beginning and an end pointer and introduce a new variant (apply_alternatives_all()) to cover the existing use case for the static kernel image section. Add a module_finalize() function to arm64 to check for an alternatives section in a module and patch only the instructions from that specific area. Since that module code is not touched before the module initialization has ended, we don't need to halt the machine before doing the patching in the module's code. Signed-off-by: Andre Przywara <andre.przywara@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
* arm64: add alternative runtime patchingAndre Przywara2014-11-251-0/+64
With a blatant copy of some x86 bits we introduce the alternative runtime patching "framework" to arm64. This is quite basic for now and we only provide the functions we need at this time. This is connected to the newly introduced feature bits. Signed-off-by: Andre Przywara <andre.przywara@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>