pm24.git/arch, branch rust-6.12

rust: cfi: add support for CFI_CLANG with Rust

2024-09-16T15:29:58Z

Make it possible to use the Control Flow Integrity (CFI) sanitizer when Rust is enabled. Enabling CFI with Rust requires that CFI is configured to normalize integer types so that all integer types of the same size and signedness are compatible under CFI. Rust and C use the same LLVM backend for code generation, so Rust KCFI is compatible with the KCFI used in the kernel for C. In the case of FineIBT, CFI also depends on -Zpatchable-function-entry for rewriting the function prologue, so we set that flag for Rust as well. The flag for FineIBT requires rustc 1.80.0 or later, so include a Kconfig requirement for that. Enabling Rust will select CFI_ICALL_NORMALIZE_INTEGERS because the flag is required to use Rust with CFI. Using select rather than `depends on` avoids the case where Rust is not visible in menuconfig due to CFI_ICALL_NORMALIZE_INTEGERS not being enabled. One disadvantage of select is that RUST must `depends on` all of the things that CFI_ICALL_NORMALIZE_INTEGERS depends on to avoid invalid configurations. Alice has been using KCFI on her phone for several months, so it is reasonably well tested on arm64. Signed-off-by: Matthew Maurer Co-developed-by: Alice Ryhl Signed-off-by: Alice Ryhl Reviewed-by: Sami Tolvanen Tested-by: Gatlin Newhouse Acked-by: Kees Cook Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20240801-kcfi-v2-2-c93caed3d121@google.com [ Replaced `!FINEIBT` requirement with `!CALL_PADDING` to prevent a build error on older Rust compilers. Fixed typo. - Miguel ] Signed-off-by: Miguel Ojeda

cfi: add CONFIG_CFI_ICALL_NORMALIZE_INTEGERS

2024-09-12T22:43:55Z

Introduce a Kconfig option for enabling the experimental option to normalize integer types. This ensures that integer types of the same size and signedness are considered compatible by the Control Flow Integrity sanitizer. The security impact of this flag is minimal. When Sami Tolvanen looked into it, he found that integer normalization reduced the number of unique type hashes in the kernel by ~1%, which is acceptable. This option exists for compatibility with Rust, as C and Rust do not have the same set of integer types. There are cases where C has two different integer types of the same size and signedness, but Rust only has one integer type of that size and signedness. When Rust calls into C functions using such types in their signature, this results in CFI failures. One example is 'unsigned long long' and 'unsigned long' which are both 64-bit on LP64 targets, so on those targets this flag will give both types the same CFI tag. This flag changes the ABI heavily. It is not applied automatically when CONFIG_RUST is turned on to make sure that the CONFIG_RUST option does not change the ABI of C code. For example, some build may need to make other changes atomically with toggling this flag. Having it be a separate option makes it possible to first turn on normalized integer tags, and then later turn on CONFIG_RUST. Similarly, when turning on CONFIG_RUST in a build, you may need a few attempts where the RUST=y commit gets reverted a few times. It is inconvenient if reverting RUST=y also requires reverting the changes you made to support normalized integer tags. To avoid having this flag impact builds that don't care about this, the next patch in this series will make CONFIG_RUST turn on this option using `select` rather than `depends on`. Signed-off-by: Alice Ryhl Reviewed-by: Sami Tolvanen Tested-by: Gatlin Newhouse Acked-by: Kees Cook Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20240801-kcfi-v2-1-c93caed3d121@google.com Signed-off-by: Miguel Ojeda

rust: support for shadow call stack sanitizer

2024-09-12T22:03:14Z

Add all of the flags that are needed to support the shadow call stack (SCS) sanitizer with Rust, and updates Kconfig to allow only configurations that work. The -Zfixed-x18 flag is required to use SCS on arm64, and requires rustc version 1.80.0 or greater. This restriction is reflected in Kconfig. When CONFIG_DYNAMIC_SCS is enabled, the build will be configured to include unwind tables in the build artifacts. Dynamic SCS uses the unwind tables at boot to find all places that need to be patched. The -Cforce-unwind-tables=y flag ensures that unwind tables are available for Rust code. In non-dynamic mode, the -Zsanitizer=shadow-call-stack flag is what enables the SCS sanitizer. Using this flag requires rustc version 1.82.0 or greater on the targets used by Rust in the kernel. This restriction is reflected in Kconfig. It is possible to avoid the requirement of rustc 1.80.0 by using -Ctarget-feature=+reserve-x18 instead of -Zfixed-x18. However, this flag emits a warning during the build, so this patch does not add support for using it and instead requires 1.80.0 or greater. The dependency is placed on `select HAVE_RUST` to avoid a situation where enabling Rust silently turns off the sanitizer. Instead, turning on the sanitizer results in Rust being disabled. We generally do not want changes to CONFIG_RUST to result in any mitigations being changed or turned off. At the time of writing, rustc 1.82.0 only exists via the nightly release channel. There is a chance that the -Zsanitizer=shadow-call-stack flag will end up needing 1.83.0 instead, but I think it is small. Reviewed-by: Sami Tolvanen Reviewed-by: Ard Biesheuvel Reviewed-by: Kees Cook Acked-by: Will Deacon Signed-off-by: Alice Ryhl Link: https://lore.kernel.org/r/20240829-shadow-call-stack-v7-1-2f62a4432abf@google.com [ Fixed indentation using spaces. - Miguel ] Signed-off-by: Miguel Ojeda

x86/rust: support MITIGATION_RETHUNK

2024-08-18T21:34:37Z

The Rust compiler added support for `-Zfunction-return=thunk-extern` [1] in 1.76.0 [2], i.e. the equivalent of `-mfunction-return=thunk-extern`. Thus add support for `MITIGATION_RETHUNK`. Without this, `objtool` would warn if enabled for Rust and already warns under IBT builds, e.g.: samples/rust/rust_print.o: warning: objtool: _R...init+0xa5c: 'naked' return found in RETHUNK build Link: https://github.com/rust-lang/rust/issues/116853 [1] Link: https://github.com/rust-lang/rust/pull/116892 [2] Reviewed-by: Gary Guo Tested-by: Alice Ryhl Tested-by: Benno Lossin Reviewed-by: Thomas Gleixner Link: https://github.com/Rust-for-Linux/linux/issues/945 Link: https://lore.kernel.org/r/20240725183325.122827-4-ojeda@kernel.org Signed-off-by: Miguel Ojeda

x86/rust: support MITIGATION_RETPOLINE

2024-08-18T21:34:37Z

Support `MITIGATION_RETPOLINE` by enabling the target features that Clang does. The existing target feature being enabled was a leftover from our old `rust` branch, and it is not enough: the target feature `retpoline-external-thunk` only implies `retpoline-indirect-calls`, but not `retpoline-indirect-branches` (see LLVM's `X86.td`), unlike Clang's flag of the same name `-mretpoline-external-thunk` which does imply both (see Clang's `lib/Driver/ToolChains/Arch/X86.cpp`). Without this, `objtool` would complain if enabled for Rust, e.g.: rust/core.o: warning: objtool: _R...escape_default+0x13: indirect jump found in RETPOLINE build In addition, change the comment to note that LLVM is the one disabling jump tables when retpoline is enabled, thus we do not need to use `-Zno-jump-tables` for Rust here -- see commit c58f2166ab39 ("Introduce the "retpoline" x86 mitigation technique ...") [1]: The goal is simple: avoid generating code which contains an indirect branch that could have its prediction poisoned by an attacker. In many cases, the compiler can simply use directed conditional branches and a small search tree. LLVM already has support for lowering switches in this way and the first step of this patch is to disable jump-table lowering of switches and introduce a pass to rewrite explicit indirectbr sequences into a switch over integers. As well as a live example at [2]. These should be eventually enabled via `-Ctarget-feature` when `rustc` starts recognizing them (or via a new dedicated flag) [3]. Cc: Daniel Borkmann Link: https://github.com/llvm/llvm-project/commit/c58f2166ab3987f37cb0d7815b561bff5a20a69a [1] Link: https://godbolt.org/z/G4YPr58qG [2] Link: https://github.com/rust-lang/rust/issues/116852 [3] Reviewed-by: Gary Guo Tested-by: Alice Ryhl Tested-by: Benno Lossin Link: https://github.com/Rust-for-Linux/linux/issues/945 Link: https://lore.kernel.org/r/20240725183325.122827-3-ojeda@kernel.org Signed-off-by: Miguel Ojeda

Merge tag 'driver-core-6.11-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2024-08-18T17:19:49Z

Pull driver core fixes from Greg KH: "Here are two driver fixes for regressions from 6.11-rc1 due to the driver core change making a structure in a driver core callback const. These were missed by all testing EXCEPT for what Bart happened to be running, so I appreciate the fixes provided here for some odd/not-often-used driver subsystems that nothing else happened to catch. Both of these fixes have been in linux-next all week with no reported issues" * tag 'driver-core-6.11-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: mips: sgi-ip22: Fix the build ARM: riscpc: ecard: Fix the build

Merge tag 'powerpc-6.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

2024-08-18T02:23:02Z

Pull powerpc fixes from Michael Ellerman: - Fix crashes on 85xx with some configs since the recent hugepd rework. - Fix boot warning with hugepages and CONFIG_DEBUG_VIRTUAL on some platforms. - Don't enable offline cores when changing SMT modes, to match existing userspace behaviour. Thanks to Christophe Leroy, Dr. David Alan Gilbert, Guenter Roeck, Nysal Jan K.A, Shrikanth Hegde, Thomas Gleixner, and Tyrel Datwyler. * tag 'powerpc-6.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: powerpc/topology: Check if a core is online cpu/SMT: Enable SMT only if a core is online powerpc/mm: Fix boot warning with hugepages and CONFIG_DEBUG_VIRTUAL powerpc/mm: Fix size of allocated PGDIR soc: fsl: qbman: remove unused struct 'cgr_comp'

Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

2024-08-17T00:02:32Z

Pull arm64 fixes from Catalin Marinas: - Fix the arm64 __get_mem_asm() to use the _ASM_EXTABLE_##type##ACCESS() macro instead of the *_ERR() one in order to avoid writing -EFAULT to the value register in case of a fault - Initialise all elements of the acpi_early_node_map[] to NUMA_NO_NODE. Prior to this fix, only the first element was initialised - Move the KASAN random tag seed initialisation after the per-CPU areas have been initialised (prng_state is __percpu) * tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: arm64: Fix KASAN random tag seed initialization arm64: ACPI: NUMA: initialize all values of acpi_early_node_map to NUMA_NO_NODE arm64: uaccess: correct thinko in __get_mem_asm()

Merge tag 'riscv-for-linus-6.11-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

2024-08-16T18:18:09Z

Pull RISC-V fixes from Palmer Dabbelt: - reintroduce the text patching global icache flush - fix syscall entry code to correctly initialize a0, which manifested as a strace bug - XIP kernels now map the entire kernel, which fixes boot under at least DEBUG_VIRTUAL=y - initialize all nodes in the acpi_early_node_map initializer - fix OOB access in the Andes vendor extension probing code - A new key for scalar misaligned access performance in hwprobe, which correctly treat the values as an enum (as opposed to a bitmap) * tag 'riscv-for-linus-6.11-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: riscv: Fix out-of-bounds when accessing Andes per hart vendor extension array RISC-V: hwprobe: Add SCALAR to misaligned perf defines RISC-V: hwprobe: Add MISALIGNED_PERF key RISC-V: ACPI: NUMA: initialize all values of acpi_early_node_map to NUMA_NO_NODE riscv: change XIP's kernel_map.size to be size of the entire kernel riscv: entry: always initialize regs->a0 to -ENOSYS riscv: Re-introduce global icache flush in patch_text_XXX()

Merge patch series "RISC-V: hwprobe: Misaligned scalar perf fix and rename"

2024-08-15T20:12:21Z

Evan Green says: The CPUPERF0 hwprobe key was documented and identified in code as a bitmask value, but its contents were an enum. This produced incorrect behavior in conjunction with the WHICH_CPUS hwprobe flag. The first patch in this series fixes the bitmask/enum problem by creating a new hwprobe key that returns the same data, but is properly described as a value instead of a bitmask. The second patch renames the value definitions in preparation for adding vector misaligned access info. As of this version, the old defines are kept in place to maintain source compatibility with older userspace programs. * b4-shazam-merge: RISC-V: hwprobe: Add SCALAR to misaligned perf defines RISC-V: hwprobe: Add MISALIGNED_PERF key Link: https://lore.kernel.org/r/20240809214444.3257596-1-evan@rivosinc.com Signed-off-by: Palmer Dabbelt