Rust fixes for v6.12 (2nd)

Toolchain and infrastructure:
 
  - Fix several issues with the 'rustc-option' macro. It includes a
    refactor from Masahiro of three '{cc,rust}-*' macros, which is not
    a fix but avoids repeating the same commands (which would be several
    lines in the case of 'rustc-option').
 
  - Fix conditions for 'CONFIG_HAVE_CFI_ICALL_NORMALIZE_INTEGERS'. It
    includes the addition of 'CONFIG_RUSTC_LLVM_VERSION', which is not a
    fix but is needed for the actual fix.
 
 And a trivial grammar fix.
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Merge tag 'rust-fixes-6.12-2' of https://github.com/Rust-for-Linux/linux

Pull rust fixes from Miguel Ojeda:
 "Toolchain and infrastructure:

   - Fix several issues with the 'rustc-option' macro. It includes a
     refactor from Masahiro of three '{cc,rust}-*' macros, which is not
     a fix but avoids repeating the same commands (which would be
     several lines in the case of 'rustc-option').

   - Fix conditions for 'CONFIG_HAVE_CFI_ICALL_NORMALIZE_INTEGERS'. It
     includes the addition of 'CONFIG_RUSTC_LLVM_VERSION', which is not
     a fix but is needed for the actual fix.

  And a trivial grammar fix"

* tag 'rust-fixes-6.12-2' of https://github.com/Rust-for-Linux/linux:
  cfi: fix conditions for HAVE_CFI_ICALL_NORMALIZE_INTEGERS
  kbuild: rust: add `CONFIG_RUSTC_LLVM_VERSION`
  kbuild: fix issues with rustc-option
  kbuild: refactor cc-option-yn, cc-disable-warning, rust-option-yn macros
  lib/Kconfig.debug: fix grammar in RUST_BUILD_ASSERT_ALLOW

arch/Kconfig

@@ -838,7 +838,7 @@ config CFI_CLANG
 config CFI_ICALL_NORMALIZE_INTEGERS
 	bool "Normalize CFI tags for integers"
 	depends on CFI_CLANG
-	depends on HAVE_CFI_ICALL_NORMALIZE_INTEGERS
+	depends on HAVE_CFI_ICALL_NORMALIZE_INTEGERS_CLANG
 	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
@@ -851,21 +851,19 @@ config CFI_ICALL_NORMALIZE_INTEGERS
 
 	  This option is necessary for using CFI with Rust. If unsure, say N.
 
-config HAVE_CFI_ICALL_NORMALIZE_INTEGERS
+config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_CLANG
-	def_bool !GCOV_KERNEL && !KASAN
+	def_bool y
-	depends on CFI_CLANG
 	depends on $(cc-option,-fsanitize=kcfi -fsanitize-cfi-icall-experimental-normalize-integers)
-	help
+	# With GCOV/KASAN we need this fix: https://github.com/llvm/llvm-project/pull/104826
-	  Is CFI_ICALL_NORMALIZE_INTEGERS supported with the set of compilers
+	depends on CLANG_VERSION >= 190000 || (!GCOV_KERNEL && !KASAN_GENERIC && !KASAN_SW_TAGS)
-	  currently in use?
 
-	  This option defaults to false if GCOV or KASAN is enabled, as there is
+config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC
-	  an LLVM bug that makes normalized integers tags incompatible with
+	def_bool y
-	  KASAN and GCOV. Kconfig currently does not have the infrastructure to
+	depends on HAVE_CFI_ICALL_NORMALIZE_INTEGERS_CLANG
-	  detect whether your rustc compiler contains the fix for this bug, so
+	depends on RUSTC_VERSION >= 107900
-	  it is assumed that it doesn't. If your compiler has the fix, you can
+	# With GCOV/KASAN we need this fix: https://github.com/rust-lang/rust/pull/129373
-	  explicitly enable this option in your config file. The Kconfig logic
+	depends on (RUSTC_LLVM_VERSION >= 190000 && RUSTC_VERSION >= 108200) || \
-	  needed to detect this will be added in a future kernel release.
+		(!GCOV_KERNEL && !KASAN_GENERIC && !KASAN_SW_TAGS)
 
 config CFI_PERMISSIVE
 	bool "Use CFI in permissive mode"

init/Kconfig

@@ -62,7 +62,7 @@ config LLD_VERSION
 
 config RUSTC_VERSION
 	int
-	default $(shell,$(srctree)/scripts/rustc-version.sh $(RUSTC))
+	default $(rustc-version)
 	help
 	  It does not depend on `RUST` since that one may need to use the version
 	  in a `depends on`.
@@ -78,6 +78,10 @@ config RUST_IS_AVAILABLE
 	  In particular, the Makefile target 'rustavailable' is useful to check
 	  why the Rust toolchain is not being detected.
 
+config RUSTC_LLVM_VERSION
+	int
+	default $(rustc-llvm-version)
+
 config CC_CAN_LINK
 	bool
 	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(USERCFLAGS) $(USERLDFLAGS) $(m64-flag)) if 64BIT
@@ -1946,7 +1950,7 @@ config RUST
 	depends on !GCC_PLUGIN_RANDSTRUCT
 	depends on !RANDSTRUCT
 	depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
-	depends on !CFI_CLANG || RUSTC_VERSION >= 107900 && HAVE_CFI_ICALL_NORMALIZE_INTEGERS
+	depends on !CFI_CLANG || HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC
 	select CFI_ICALL_NORMALIZE_INTEGERS if CFI_CLANG
 	depends on !CALL_PADDING || RUSTC_VERSION >= 108100
 	depends on !KASAN_SW_TAGS

lib/Kconfig.debug

@@ -3060,7 +3060,7 @@ config RUST_BUILD_ASSERT_ALLOW
 	bool "Allow unoptimized build-time assertions"
 	depends on RUST
 	help
-	  Controls how are `build_error!` and `build_assert!` handled during build.
+	  Controls how `build_error!` and `build_assert!` are handled during the build.
 
 	  If calls to them exist in the binary, it may indicate a violated invariant
 	  or that the optimizer failed to verify the invariant during compilation.

scripts/Kconfig.include

@@ -65,6 +65,9 @@ cc-option-bit = $(if-success,$(CC) -Werror $(1) -E -x c /dev/null -o /dev/null,$
 m32-flag := $(cc-option-bit,-m32)
 m64-flag := $(cc-option-bit,-m64)
 
+rustc-version := $(shell,$(srctree)/scripts/rustc-version.sh $(RUSTC))
+rustc-llvm-version := $(shell,$(srctree)/scripts/rustc-llvm-version.sh $(RUSTC))
+
 # $(rustc-option,<flag>)
 # Return y if the Rust compiler supports <flag>, n otherwise
 # Calls to this should be guarded so that they are not evaluated if

scripts/Makefile.compiler

@@ -53,13 +53,11 @@ cc-option = $(call __cc-option, $(CC),\
 
 # cc-option-yn
 # Usage: flag := $(call cc-option-yn,-march=winchip-c6)
-cc-option-yn = $(call try-run,\
+cc-option-yn = $(if $(call cc-option,$1),y,n)
-	$(CC) -Werror $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",y,n)
 
 # cc-disable-warning
 # Usage: cflags-y += $(call cc-disable-warning,unused-but-set-variable)
-cc-disable-warning = $(call try-run,\
+cc-disable-warning = $(if $(call cc-option,-W$(strip $1)),-Wno-$(strip $1))
-	$(CC) -Werror $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
 
 # gcc-min-version
 # Usage: cflags-$(call gcc-min-version, 70100) += -foo
@@ -75,8 +73,11 @@ ld-option = $(call try-run, $(LD) $(KBUILD_LDFLAGS) $(1) -v,$(1),$(2),$(3))
 
 # __rustc-option
 # Usage: MY_RUSTFLAGS += $(call __rustc-option,$(RUSTC),$(MY_RUSTFLAGS),-Cinstrument-coverage,-Zinstrument-coverage)
+# TODO: remove RUSTC_BOOTSTRAP=1 when we raise the minimum GNU Make version to 4.4
 __rustc-option = $(call try-run,\
-	$(1) $(2) $(3) --crate-type=rlib /dev/null --out-dir=$$TMPOUT -o "$$TMP",$(3),$(4))
+	echo '#![allow(missing_docs)]#![feature(no_core)]#![no_core]' | RUSTC_BOOTSTRAP=1\
+	$(1) --sysroot=/dev/null $(filter-out --sysroot=/dev/null,$(2)) $(3)\
+	--crate-type=rlib --out-dir=$(TMPOUT) --emit=obj=- - >/dev/null,$(3),$(4))
 
 # rustc-option
 # Usage: rustflags-y += $(call rustc-option,-Cinstrument-coverage,-Zinstrument-coverage)
@@ -85,5 +86,4 @@ rustc-option = $(call __rustc-option, $(RUSTC),\
 
 # rustc-option-yn
 # Usage: flag := $(call rustc-option-yn,-Cinstrument-coverage)
-rustc-option-yn = $(call try-run,\
+rustc-option-yn = $(if $(call rustc-option,$1),y,n)
-	$(RUSTC) $(KBUILD_RUSTFLAGS) $(1) --crate-type=rlib /dev/null --out-dir=$$TMPOUT -o "$$TMP",y,n)

scripts/rustc-llvm-version.sh

@@ -0,0 +1,22 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+#
+# Usage: $ ./rustc-llvm-version.sh rustc
+#
+# Print the LLVM version that the Rust compiler uses in a 6 digit form.
+
+# Convert the version string x.y.z to a canonical up-to-6-digits form.
+get_canonical_version()
+{
+	IFS=.
+	set -- $1
+	echo $((10000 * $1 + 100 * $2 + $3))
+}
+
+if output=$("$@" --version --verbose 2>/dev/null | grep LLVM); then
+	set -- $output
+	get_canonical_version $3
+else
+	echo 0
+	exit 1
+fi