kernel.git/arch/arm64/kernel/traps.c, branch linux-5.16.y

arm64/bpf: Remove 128MB limit for BPF JIT programs

2022-01-29T09:59:24Z

commit b89ddf4cca43f1269093942cf5c4e457fd45c335 upstream. Commit 91fc957c9b1d ("arm64/bpf: don't allocate BPF JIT programs in module memory") restricts BPF JIT program allocation to a 128MB region to ensure BPF programs are still in branching range of each other. However this restriction should not apply to the aarch64 JIT, since BPF_JMP | BPF_CALL are implemented as a 64-bit move into a register and then a BLR instruction - which has the effect of being able to call anything without proximity limitation. The practical reason to relax this restriction on JIT memory is that 128MB of JIT memory can be quickly exhausted, especially where PAGE_SIZE is 64KB - one page is needed per program. In cases where seccomp filters are applied to multiple VMs on VM launch - such filters are classic BPF but converted to BPF - this can severely limit the number of VMs that can be launched. In a world where we support BPF JIT always on, turning off the JIT isn't always an option either. Fixes: 91fc957c9b1d ("arm64/bpf: don't allocate BPF JIT programs in module memory") Suggested-by: Ard Biesheuvel Signed-off-by: Russell King Signed-off-by: Daniel Borkmann Tested-by: Alan Maguire Link: https://lore.kernel.org/bpf/1636131046-5982-2-git-send-email-alan.maguire@oracle.com Signed-off-by: Greg Kroah-Hartman

Merge branch 'for-next/misc' into for-next/core

2021-10-29T11:24:59Z

* for-next/misc: arm64: Select POSIX_CPU_TIMERS_TASK_WORK arm64: Document boot requirements for FEAT_SME_FA64 arm64: ftrace: use function_nocfi for _mcount as well arm64: asm: setup.h: export common variables arm64/traps: Avoid unnecessary kernel/user pointer conversion

Merge branch 'for-next/extable' into for-next/core

2021-10-29T11:24:37Z

* for-next/extable: arm64: vmlinux.lds.S: remove `.fixup` section arm64: extable: add load_unaligned_zeropad() handler arm64: extable: add a dedicated uaccess handler arm64: extable: add `type` and `data` fields arm64: extable: use `ex` for `exception_table_entry` arm64: extable: make fixup_exception() return bool arm64: extable: consolidate definitions arm64: gpr-num: support W registers arm64: factor out GPR numbering helpers arm64: kvm: use kvm_exception_table_entry arm64: lib: __arch_copy_to_user(): fold fixups into body arm64: lib: __arch_copy_from_user(): fold fixups into body arm64: lib: __arch_clear_user(): fold fixups into body

arm64: extable: add a dedicated uaccess handler

2021-10-21T09:45:22Z

For inline assembly, we place exception fixups out-of-line in the `.fixup` section such that these are out of the way of the fast path. This has a few drawbacks: * Since the fixup code is anonymous, backtraces will symbolize fixups as offsets from the nearest prior symbol, currently `__entry_tramp_text_end`. This is confusing, and painful to debug without access to the relevant vmlinux. * Since the exception handler adjusts the PC to execute the fixup, and the fixup uses a direct branch back into the function it fixes, backtraces of fixups miss the original function. This is confusing, and violates requirements for RELIABLE_STACKTRACE (and therefore LIVEPATCH). * Inline assembly and associated fixups are generated from templates, and we have many copies of logically identical fixups which only differ in which specific registers are written to and which address is branched to at the end of the fixup. This is potentially wasteful of I-cache resources, and makes it hard to add additional logic to fixups without significant bloat. This patch address all three concerns for inline uaccess fixups by adding a dedicated exception handler which updates registers in exception context and subsequent returns back into the function which faulted, removing the need for fixups specialized to each faulting instruction. Other than backtracing, there should be no functional change as a result of this patch. Signed-off-by: Mark Rutland Reviewed-by: Ard Biesheuvel Cc: Catalin Marinas Cc: James Morse Cc: Robin Murphy Cc: Will Deacon Link: https://lore.kernel.org/r/20211019160219.5202-12-mark.rutland@arm.com Signed-off-by: Will Deacon

arm64: Add handling of CNTVCTSS traps

2021-10-19T09:56:20Z

Since CNTVCTSS obey the same control bits as CNTVCT, add the necessary decoding to the hook table. Note that there is no known user of this at the moment. Acked-by: Will Deacon Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20211017124225.3018098-17-maz@kernel.org Signed-off-by: Will Deacon

arm64/traps: Avoid unnecessary kernel/user pointer conversion

2021-09-29T15:44:20Z

Annotating a pointer from kernel to __user and then back again requires an extra __force annotation to silent sparse warning. In call_undef_hook() this unnecessary complexity can be avoided by modifying the intermediate user pointer to unsigned long. This way there is no inter-changeable use of user and kernel pointers and the code is consistent. Note: This patch adds no functional changes to code. Cc: Catalin Marinas Cc: Will Deacon Signed-off-by: Amit Daniel Kachhap Acked-by: Mark Rutland Link: https://lore.kernel.org/r/20210917055811.22341-1-amit.kachhap@arm.com Signed-off-by: Will Deacon

Merge branch 'for-next/insn' into for-next/core

2021-06-24T13:03:24Z

Refactoring of our instruction decoding routines and addition of some missing encodings. * for-next/insn: arm64: insn: avoid circular include dependency arm64: insn: move AARCH64_INSN_SIZE into arm64: insn: decouple patching from insn code arm64: insn: Add load/store decoding helpers arm64: insn: Add some opcodes to instruction decoder arm64: insn: Add barrier encodings arm64: insn: Add SVE instruction class arm64: Move instruction encoder/decoder under lib/ arm64: Move aarch32 condition check functions arm64: Move patching utilities out of instruction encoding/decoding

arm64: insn: move AARCH64_INSN_SIZE into

2021-06-11T10:19:27Z

For histroical reasons, we define AARCH64_INSN_SIZE in , but it would make more sense to do so in . Let's move it into , and add the necessary include directives for this. Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: Will Deacon Link: https://lore.kernel.org/r/20210609102301.17332-3-mark.rutland@arm.com Signed-off-by: Will Deacon

arm64: insn: decouple patching from insn code

2021-06-11T10:19:27Z

Currently, includes . We intend that will be usable from userspace, so it doesn't make sense to include headers for kernel-only features such as the patching routines, and we'd intended to restrict to instruction encoding details. Let's decouple the patching code from , and explicitly include where it is needed. Since isn't included from assembly, we can drop the __ASSEMBLY__ guards. At the same time, sort the kprobes includes so that it's easier to see what is and isn't incldued. Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: Will Deacon Link: https://lore.kernel.org/r/20210609102301.17332-2-mark.rutland@arm.com Signed-off-by: Will Deacon

arm64: entry: split bad stack entry

2021-06-07T10:35:56Z

We'd like to keep all the entry sequencing in entry-common.c, as this will allow us to ensure this is consistent, and free from any unsound instrumentation. Currently handle_bad_stack() performs the NMI entry sequence in traps.c. Let's split the low-level entry sequence from the reporting, moving the former to entry-common.c and keeping the latter in traps.c. To make it clear that reporting function never returns, it is renamed to panic_bad_stack(). Signed-off-by: Mark Rutland Acked-by: Catalin Marinas Acked-by: Marc Zyngier Reviewed-by: Joey Gouly Cc: James Morse Cc: Will Deacon Link: https://lore.kernel.org/r/20210607094624.34689-17-mark.rutland@arm.com Signed-off-by: Will Deacon