Merge tag 'rust-6.12' of https://github.com/Rust-for-Linux/linux

Pull Rust updates from Miguel Ojeda:
 "Toolchain and infrastructure:

   - Support 'MITIGATION_{RETHUNK,RETPOLINE,SLS}' (which cleans up
     objtool warnings), teach objtool about 'noreturn' Rust symbols and
     mimic '___ADDRESSABLE()' for 'module_{init,exit}'. With that, we
     should be objtool-warning-free, so enable it to run for all Rust
     object files.

   - KASAN (no 'SW_TAGS'), KCFI and shadow call sanitizer support.

   - Support 'RUSTC_VERSION', including re-config and re-build on
     change.

   - Split helpers file into several files in a folder, to avoid
     conflicts in it. Eventually those files will be moved to the right
     places with the new build system. In addition, remove the need to
     manually export the symbols defined there, reusing existing
     machinery for that.

   - Relax restriction on configurations with Rust + GCC plugins to just
     the RANDSTRUCT plugin.

  'kernel' crate:

   - New 'list' module: doubly-linked linked list for use with reference
     counted values, which is heavily used by the upcoming Rust Binder.

     This includes 'ListArc' (a wrapper around 'Arc' that is guaranteed
     unique for the given ID), 'AtomicTracker' (tracks whether a
     'ListArc' exists using an atomic), 'ListLinks' (the prev/next
     pointers for an item in a linked list), 'List' (the linked list
     itself), 'Iter' (an iterator over a 'List'), 'Cursor' (a cursor
     into a 'List' that allows to remove elements), 'ListArcField' (a
     field exclusively owned by a 'ListArc'), as well as support for
     heterogeneous lists.

   - New 'rbtree' module: red-black tree abstractions used by the
     upcoming Rust Binder.

     This includes 'RBTree' (the red-black tree itself), 'RBTreeNode' (a
     node), 'RBTreeNodeReservation' (a memory reservation for a node),
     'Iter' and 'IterMut' (immutable and mutable iterators), 'Cursor'
     (bidirectional cursor that allows to remove elements), as well as
     an entry API similar to the Rust standard library one.

   - 'init' module: add 'write_[pin_]init' methods and the
     'InPlaceWrite' trait. Add the 'assert_pinned!' macro.

   - 'sync' module: implement the 'InPlaceInit' trait for 'Arc' by
     introducing an associated type in the trait.

   - 'alloc' module: add 'drop_contents' method to 'BoxExt'.

   - 'types' module: implement the 'ForeignOwnable' trait for
     'Pin<Box<T>>' and improve the trait's documentation. In addition,
     add the 'into_raw' method to the 'ARef' type.

   - 'error' module: in preparation for the upcoming Rust support for
     32-bit architectures, like arm, locally allow Clippy lint for
     those.

  Documentation:

   - https://rust.docs.kernel.org has been announced, so link to it.

   - Enable rustdoc's "jump to definition" feature, making its output a
     bit closer to the experience in a cross-referencer.

   - Debian Testing now also provides recent Rust releases (outside of
     the freeze period), so add it to the list.

  MAINTAINERS:

   - Trevor is joining as reviewer of the "RUST" entry.

  And a few other small bits"

* tag 'rust-6.12' of https://github.com/Rust-for-Linux/linux: (54 commits)
  kasan: rust: Add KASAN smoke test via UAF
  kbuild: rust: Enable KASAN support
  rust: kasan: Rust does not support KHWASAN
  kbuild: rust: Define probing macros for rustc
  kasan: simplify and clarify Makefile
  rust: cfi: add support for CFI_CLANG with Rust
  cfi: add CONFIG_CFI_ICALL_NORMALIZE_INTEGERS
  rust: support for shadow call stack sanitizer
  docs: rust: include other expressions in conditional compilation section
  kbuild: rust: replace proc macros dependency on `core.o` with the version text
  kbuild: rust: rebuild if the version text changes
  kbuild: rust: re-run Kconfig if the version text changes
  kbuild: rust: add `CONFIG_RUSTC_VERSION`
  rust: avoid `box_uninit_write` feature
  MAINTAINERS: add Trevor Gross as Rust reviewer
  rust: rbtree: add `RBTree::entry`
  rust: rbtree: add cursor
  rust: rbtree: add mutable iterator
  rust: rbtree: add iterator
  rust: rbtree: add red-black tree implementation backed by the C version
  ...

5 files changed, 50 insertions, 3 deletions

diff --git a/arch/Kconfig b/arch/Kconfig
index 405c85ab86f2..98157b38f5cf 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -835,6 +835,22 @@ config CFI_CLANG
 
 	    https://clang.llvm.org/docs/ControlFlowIntegrity.html
 
+config CFI_ICALL_NORMALIZE_INTEGERS
+	bool "Normalize CFI tags for integers"
+	depends on CFI_CLANG
+	depends on $(cc-option,-fsanitize=kcfi -fsanitize-cfi-icall-experimental-normalize-integers)
+	help
+	  This option normalizes the CFI tags for integer types so that all
+	  integer types of the same size and signedness receive the same CFI
+	  tag.
+
+	  The option is separate from CONFIG_RUST because it affects the ABI.
+	  When working with build systems that care about the ABI, it is
+	  convenient to be able to turn on this flag first, before Rust is
+	  turned on.
+
+	  This option is necessary for using CFI with Rust. If unsure, say N.
+
 config CFI_PERMISSIVE
 	bool "Use CFI in permissive mode"
 	depends on CFI_CLANG
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 49f054dcd4de..3e29b44d2d7b 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -235,7 +235,7 @@ config ARM64
 	select HAVE_FUNCTION_ARG_ACCESS_API
 	select MMU_GATHER_RCU_TABLE_FREE
 	select HAVE_RSEQ
-	select HAVE_RUST if CPU_LITTLE_ENDIAN
+	select HAVE_RUST if RUSTC_SUPPORTS_ARM64
 	select HAVE_STACKPROTECTOR
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_KPROBES
@@ -270,6 +270,18 @@ config ARM64
 	help
 	  ARM 64-bit (AArch64) Linux support.
 
+config RUSTC_SUPPORTS_ARM64
+	def_bool y
+	depends on CPU_LITTLE_ENDIAN
+	# Shadow call stack is only supported on certain rustc versions.
+	#
+	# When using the UNWIND_PATCH_PAC_INTO_SCS option, rustc version 1.80+ is
+	# required due to use of the -Zfixed-x18 flag.
+	#
+	# Otherwise, rustc version 1.82+ is required due to use of the
+	# -Zsanitizer=shadow-call-stack flag.
+	depends on !SHADOW_CALL_STACK || RUSTC_VERSION >= 108200 || RUSTC_VERSION >= 108000 && UNWIND_PATCH_PAC_INTO_SCS
+
 config CLANG_SUPPORTS_DYNAMIC_FTRACE_WITH_ARGS
 	def_bool CC_IS_CLANG
 	# https://github.com/ClangBuiltLinux/linux/issues/1507
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index f6bc3da1ef11..b058c4803efb 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -57,9 +57,11 @@ KBUILD_AFLAGS	+= $(call cc-option,-mabi=lp64)
 ifneq ($(CONFIG_UNWIND_TABLES),y)
 KBUILD_CFLAGS	+= -fno-asynchronous-unwind-tables -fno-unwind-tables
 KBUILD_AFLAGS	+= -fno-asynchronous-unwind-tables -fno-unwind-tables
+KBUILD_RUSTFLAGS += -Cforce-unwind-tables=n
 else
 KBUILD_CFLAGS	+= -fasynchronous-unwind-tables
 KBUILD_AFLAGS	+= -fasynchronous-unwind-tables
+KBUILD_RUSTFLAGS += -Cforce-unwind-tables=y -Zuse-sync-unwind=n
 endif
 
 ifeq ($(CONFIG_STACKPROTECTOR_PER_TASK),y)
@@ -114,6 +116,7 @@ endif
 
 ifeq ($(CONFIG_SHADOW_CALL_STACK), y)
 KBUILD_CFLAGS	+= -ffixed-x18
+KBUILD_RUSTFLAGS += -Zfixed-x18
 endif
 
 ifeq ($(CONFIG_CPU_BIG_ENDIAN), y)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index b6d515db869b..22dc5ea4196c 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -177,7 +177,7 @@ config RISCV
 	select HAVE_REGS_AND_STACK_ACCESS_API
 	select HAVE_RETHOOK if !XIP_KERNEL
 	select HAVE_RSEQ
-	select HAVE_RUST if 64BIT
+	select HAVE_RUST if RUSTC_SUPPORTS_RISCV
 	select HAVE_SAMPLE_FTRACE_DIRECT
 	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI
 	select HAVE_STACKPROTECTOR
@@ -209,6 +209,13 @@ config RISCV
 	select USER_STACKTRACE_SUPPORT
 	select ZONE_DMA32 if 64BIT
 
+config RUSTC_SUPPORTS_RISCV
+	def_bool y
+	depends on 64BIT
+	# Shadow call stack requires rustc version 1.82+ due to use of the
+	# -Zsanitizer=shadow-call-stack flag.
+	depends on !SHADOW_CALL_STACK || RUSTC_VERSION >= 108200
+
 config CLANG_SUPPORTS_DYNAMIC_FTRACE
 	def_bool CC_IS_CLANG
 	# https://github.com/ClangBuiltLinux/linux/issues/1817
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 801fd85c3ef6..cd75e78a06c1 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -24,11 +24,15 @@ RETPOLINE_CFLAGS	+= $(call cc-option,-mindirect-branch-cs-prefix)
 
 ifdef CONFIG_MITIGATION_RETHUNK
 RETHUNK_CFLAGS		:= -mfunction-return=thunk-extern
+RETHUNK_RUSTFLAGS	:= -Zfunction-return=thunk-extern
 RETPOLINE_CFLAGS	+= $(RETHUNK_CFLAGS)
+RETPOLINE_RUSTFLAGS	+= $(RETHUNK_RUSTFLAGS)
 endif
 
 export RETHUNK_CFLAGS
+export RETHUNK_RUSTFLAGS
 export RETPOLINE_CFLAGS
+export RETPOLINE_RUSTFLAGS
 export RETPOLINE_VDSO_CFLAGS
 
 # For gcc stack alignment is specified with -mpreferred-stack-boundary,
@@ -218,9 +222,10 @@ KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
 # Avoid indirect branches in kernel to deal with Spectre
 ifdef CONFIG_MITIGATION_RETPOLINE
   KBUILD_CFLAGS += $(RETPOLINE_CFLAGS)
+  KBUILD_RUSTFLAGS += $(RETPOLINE_RUSTFLAGS)
   # Additionally, avoid generating expensive indirect jumps which
   # are subject to retpolines for small number of switch cases.
-  # clang turns off jump table generation by default when under
+  # LLVM turns off jump table generation by default when under
   # retpoline builds, however, gcc does not for x86. This has
   # only been fixed starting from gcc stable version 8.4.0 and
   # onwards, but not for older ones. See gcc bug #86952.
@@ -237,6 +242,10 @@ ifdef CONFIG_CALL_PADDING
 PADDING_CFLAGS := -fpatchable-function-entry=$(CONFIG_FUNCTION_PADDING_BYTES),$(CONFIG_FUNCTION_PADDING_BYTES)
 KBUILD_CFLAGS += $(PADDING_CFLAGS)
 export PADDING_CFLAGS
+
+PADDING_RUSTFLAGS := -Zpatchable-function-entry=$(CONFIG_FUNCTION_PADDING_BYTES),$(CONFIG_FUNCTION_PADDING_BYTES)
+KBUILD_RUSTFLAGS += $(PADDING_RUSTFLAGS)
+export PADDING_RUSTFLAGS
 endif
 
 KBUILD_LDFLAGS += -m elf_$(UTS_MACHINE)