[PATCH] kbuild: rust: add `CONFIG_RUSTC_LLVM_VERSION`

Gary Guo
2024-10-11T11:41:02Z

Each version of Rust supports a range of LLVM versions. There are cases where
we want to gate a config on the LLVM version instead of the Rust version.
Normalized cfi integer tags are one example [1].

The invocation of rustc-version is being moved from init/Kconfig to
scripts/Kconfig.include for consistency with cc-version.

Link: https://lore.kernel.org/all/20240925-cfi-norm-kasan-fix-v1-1-0328985cdf33@google.com/ [1]
Signed-off-by: Gary Guo <gary@garyguo.net>
---
init/Kconfig | 6 +++++-
scripts/Kconfig.include | 3 +++
scripts/rustc-llvm-version.sh | 22 ++++++++++++++++++++++
3 files changed, 30 insertions(+), 1 deletion(-)
create mode 100755 scripts/rustc-llvm-version.sh

diff --git a/init/Kconfig b/init/Kconfig
index fbd0cb06a50a..304e2bd32bfd 100644
--- a/init/Kconfig
+++ b/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
diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
index 785a491e5996..33193ca6e803 100644
--- a/scripts/Kconfig.include
+++ b/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
diff --git a/scripts/rustc-llvm-version.sh b/scripts/rustc-llvm-version.sh
new file mode 100755
index 000000000000..b8ffa24afea8
--- /dev/null
+++ b/scripts/rustc-llvm-version.sh
@@ -0,0 +1,22 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+#
+# Usage: $ ./rustc-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

base-commit: f5e50614e39e74401b492a2fa125f2e2b6458bab
--
2.44.1