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| author | Miguel Ojeda <ojeda@kernel.org> | 2024-07-25 20:33:20 +0200 |
|---|---|---|
| committer | Miguel Ojeda <ojeda@kernel.org> | 2024-08-18 23:34:37 +0200 |
| commit | d7868550d5731e05148c881f035423f009a2b4d5 (patch) | |
| tree | 23e3b75ac1875f1c1dfe8fd897be0f9445920319 | |
| parent | x86/rust: support MITIGATION_RETPOLINE (diff) | |
| download | linux-d7868550d5731e05148c881f035423f009a2b4d5.tar.xz linux-d7868550d5731e05148c881f035423f009a2b4d5.zip | |
x86/rust: support MITIGATION_RETHUNK
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 <gary@garyguo.net>
Tested-by: Alice Ryhl <aliceryhl@google.com>
Tested-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
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 <ojeda@kernel.org>
| -rw-r--r-- | arch/x86/Makefile | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/x86/Makefile b/arch/x86/Makefile index e8214bff1aeb..a1883a30a5d8 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, @@ -218,6 +222,7 @@ 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. # LLVM turns off jump table generation by default when under |