From: Conor Dooley conor.dooley@microchip.com
The kernel uses the standard rustc targets for non-x86 targets, and out of those only 64-bit arm's target has kcfi support enabled. For x86, the custom 64-bit target enables kcfi.
The HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC config option that allows CFI_CLANG to be used in combination with RUST does not check whether the rustc target supports kcfi. This breaks the build on riscv (and presumably 32-bit arm) when CFI_CLANG and RUST are enabled at the same time.
Ordinarily, a rustc-option check would be used to detect target support but unfortunately rustc-option filters out the target for reasons given in commit 46e24a545cdb4 ("rust: kasan/kbuild: fix missing flags on first build"). As a result, if the host supports kcfi but the target does not, e.g. when building for riscv on x86_64, the build would remain broken.
Instead, make HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC depend on the only two architectures where the target used supports it to fix the build.
CC: stable@vger.kernel.org Fixes: ca627e636551e ("rust: cfi: add support for CFI_CLANG with Rust") Signed-off-by: Conor Dooley conor.dooley@microchip.com --- CC: Paul Walmsley paul.walmsley@sifive.com CC: Palmer Dabbelt palmer@dabbelt.com CC: Alexandre Ghiti alex@ghiti.fr CC: Miguel Ojeda ojeda@kernel.org CC: Alex Gaynor alex.gaynor@gmail.com CC: Boqun Feng boqun.feng@gmail.com CC: Gary Guo gary@garyguo.net CC: "Björn Roy Baron" bjorn3_gh@protonmail.com CC: Benno Lossin lossin@kernel.org CC: Andreas Hindborg a.hindborg@kernel.org CC: Alice Ryhl aliceryhl@google.com CC: Trevor Gross tmgross@umich.edu CC: Danilo Krummrich dakr@kernel.org CC: Kees Cook kees@kernel.org CC: Sami Tolvanen samitolvanen@google.com CC: Matthew Maurer mmaurer@google.com CC: "Peter Zijlstra (Intel)" peterz@infradead.org CC: linux-kernel@vger.kernel.org CC: linux-riscv@lists.infradead.org CC: rust-for-linux@vger.kernel.org --- arch/Kconfig | 1 + 1 file changed, 1 insertion(+)
diff --git a/arch/Kconfig b/arch/Kconfig index d1b4ffd6e0856..880cddff5eda7 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -917,6 +917,7 @@ config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC def_bool y depends on HAVE_CFI_ICALL_NORMALIZE_INTEGERS_CLANG depends on RUSTC_VERSION >= 107900 + depends on ARM64 || X86_64 # With GCOV/KASAN we need this fix: https://github.com/rust-lang/rust/pull/129373 depends on (RUSTC_LLVM_VERSION >= 190103 && RUSTC_VERSION >= 108200) || \ (!GCOV_KERNEL && !KASAN_GENERIC && !KASAN_SW_TAGS)
On Mon, Sep 8, 2025 at 3:13 PM Conor Dooley conor@kernel.org wrote:
From: Conor Dooley conor.dooley@microchip.com
The kernel uses the standard rustc targets for non-x86 targets, and out of those only 64-bit arm's target has kcfi support enabled. For x86, the custom 64-bit target enables kcfi.
The HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC config option that allows CFI_CLANG to be used in combination with RUST does not check whether the rustc target supports kcfi. This breaks the build on riscv (and presumably 32-bit arm) when CFI_CLANG and RUST are enabled at the same time.
Ordinarily, a rustc-option check would be used to detect target support but unfortunately rustc-option filters out the target for reasons given in commit 46e24a545cdb4 ("rust: kasan/kbuild: fix missing flags on first build"). As a result, if the host supports kcfi but the target does not, e.g. when building for riscv on x86_64, the build would remain broken.
Instead, make HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC depend on the only two architectures where the target used supports it to fix the build.
CC: stable@vger.kernel.org Fixes: ca627e636551e ("rust: cfi: add support for CFI_CLANG with Rust") Signed-off-by: Conor Dooley conor.dooley@microchip.com
Reviewed-by: Alice Ryhl aliceryhl@google.com
On Mon, Sep 8, 2025 at 3:13 PM Conor Dooley conor@kernel.org wrote:
From: Conor Dooley conor.dooley@microchip.com
The kernel uses the standard rustc targets for non-x86 targets, and out of those only 64-bit arm's target has kcfi support enabled. For x86, the custom 64-bit target enables kcfi.
The HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC config option that allows CFI_CLANG to be used in combination with RUST does not check whether the rustc target supports kcfi. This breaks the build on riscv (and presumably 32-bit arm) when CFI_CLANG and RUST are enabled at the same time.
Ordinarily, a rustc-option check would be used to detect target support but unfortunately rustc-option filters out the target for reasons given in commit 46e24a545cdb4 ("rust: kasan/kbuild: fix missing flags on first build"). As a result, if the host supports kcfi but the target does not, e.g. when building for riscv on x86_64, the build would remain broken.
Instead, make HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC depend on the only two architectures where the target used supports it to fix the build.
CC: stable@vger.kernel.org Fixes: ca627e636551e ("rust: cfi: add support for CFI_CLANG with Rust") Signed-off-by: Conor Dooley conor.dooley@microchip.com
If you are taking this through RISC-V:
Acked-by: Miguel Ojeda ojeda@kernel.org
Cheers, Miguel
On Mon, Sep 08, 2025 at 02:12:35PM +0100, Conor Dooley wrote:
From: Conor Dooley conor.dooley@microchip.com
The kernel uses the standard rustc targets for non-x86 targets, and out of those only 64-bit arm's target has kcfi support enabled. For x86, the custom 64-bit target enables kcfi.
The HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC config option that allows CFI_CLANG to be used in combination with RUST does not check whether the rustc target supports kcfi. This breaks the build on riscv (and presumably 32-bit arm) when CFI_CLANG and RUST are enabled at the same time.
Ordinarily, a rustc-option check would be used to detect target support but unfortunately rustc-option filters out the target for reasons given in commit 46e24a545cdb4 ("rust: kasan/kbuild: fix missing flags on first build"). As a result, if the host supports kcfi but the target does not, e.g. when building for riscv on x86_64, the build would remain broken.
Instead, make HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC depend on the only two architectures where the target used supports it to fix the build.
I'm generally fine with this, but normally we do arch-specific stuff only in arch/$arch/Kconfig, and expose some kind of ARCH_HAS_CFI_ICALL_NORMALIZE_INTEGERS that would get tested here. Should we do that here too?
-Kees
CC: stable@vger.kernel.org Fixes: ca627e636551e ("rust: cfi: add support for CFI_CLANG with Rust") Signed-off-by: Conor Dooley conor.dooley@microchip.com
CC: Paul Walmsley paul.walmsley@sifive.com CC: Palmer Dabbelt palmer@dabbelt.com CC: Alexandre Ghiti alex@ghiti.fr CC: Miguel Ojeda ojeda@kernel.org CC: Alex Gaynor alex.gaynor@gmail.com CC: Boqun Feng boqun.feng@gmail.com CC: Gary Guo gary@garyguo.net CC: "Björn Roy Baron" bjorn3_gh@protonmail.com CC: Benno Lossin lossin@kernel.org CC: Andreas Hindborg a.hindborg@kernel.org CC: Alice Ryhl aliceryhl@google.com CC: Trevor Gross tmgross@umich.edu CC: Danilo Krummrich dakr@kernel.org CC: Kees Cook kees@kernel.org CC: Sami Tolvanen samitolvanen@google.com CC: Matthew Maurer mmaurer@google.com CC: "Peter Zijlstra (Intel)" peterz@infradead.org CC: linux-kernel@vger.kernel.org CC: linux-riscv@lists.infradead.org CC: rust-for-linux@vger.kernel.org
arch/Kconfig | 1 + 1 file changed, 1 insertion(+)
diff --git a/arch/Kconfig b/arch/Kconfig index d1b4ffd6e0856..880cddff5eda7 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -917,6 +917,7 @@ config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC def_bool y depends on HAVE_CFI_ICALL_NORMALIZE_INTEGERS_CLANG depends on RUSTC_VERSION >= 107900
- depends on ARM64 || X86_64 # With GCOV/KASAN we need this fix: https://github.com/rust-lang/rust/pull/129373 depends on (RUSTC_LLVM_VERSION >= 190103 && RUSTC_VERSION >= 108200) || \ (!GCOV_KERNEL && !KASAN_GENERIC && !KASAN_SW_TAGS)
-- 2.47.2
On Mon, Sep 08, 2025 at 08:11:48PM -0700, Kees Cook wrote:
On Mon, Sep 08, 2025 at 02:12:35PM +0100, Conor Dooley wrote:
From: Conor Dooley conor.dooley@microchip.com
The kernel uses the standard rustc targets for non-x86 targets, and out of those only 64-bit arm's target has kcfi support enabled. For x86, the custom 64-bit target enables kcfi.
The HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC config option that allows CFI_CLANG to be used in combination with RUST does not check whether the rustc target supports kcfi. This breaks the build on riscv (and presumably 32-bit arm) when CFI_CLANG and RUST are enabled at the same time.
Ordinarily, a rustc-option check would be used to detect target support but unfortunately rustc-option filters out the target for reasons given in commit 46e24a545cdb4 ("rust: kasan/kbuild: fix missing flags on first build"). As a result, if the host supports kcfi but the target does not, e.g. when building for riscv on x86_64, the build would remain broken.
Instead, make HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC depend on the only two architectures where the target used supports it to fix the build.
I'm generally fine with this, but normally we do arch-specific stuff only in arch/$arch/Kconfig, and expose some kind of ARCH_HAS_CFI_ICALL_NORMALIZE_INTEGERS that would get tested here. Should we do that here too?
I'm thinking in this case it makes sense to keep this patch simple as it's a fix. Once rustc supports cfi on riscv (which should really just be changing the target to list it as supported), we can reorganize it to match what you're describing at that point.
CC: stable@vger.kernel.org Fixes: ca627e636551e ("rust: cfi: add support for CFI_CLANG with Rust") Signed-off-by: Conor Dooley conor.dooley@microchip.com
CC: Paul Walmsley paul.walmsley@sifive.com CC: Palmer Dabbelt palmer@dabbelt.com CC: Alexandre Ghiti alex@ghiti.fr CC: Miguel Ojeda ojeda@kernel.org CC: Alex Gaynor alex.gaynor@gmail.com CC: Boqun Feng boqun.feng@gmail.com CC: Gary Guo gary@garyguo.net CC: "Björn Roy Baron" bjorn3_gh@protonmail.com CC: Benno Lossin lossin@kernel.org CC: Andreas Hindborg a.hindborg@kernel.org CC: Alice Ryhl aliceryhl@google.com CC: Trevor Gross tmgross@umich.edu CC: Danilo Krummrich dakr@kernel.org CC: Kees Cook kees@kernel.org CC: Sami Tolvanen samitolvanen@google.com CC: Matthew Maurer mmaurer@google.com CC: "Peter Zijlstra (Intel)" peterz@infradead.org CC: linux-kernel@vger.kernel.org CC: linux-riscv@lists.infradead.org CC: rust-for-linux@vger.kernel.org
arch/Kconfig | 1 + 1 file changed, 1 insertion(+)
diff --git a/arch/Kconfig b/arch/Kconfig index d1b4ffd6e0856..880cddff5eda7 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -917,6 +917,7 @@ config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC def_bool y depends on HAVE_CFI_ICALL_NORMALIZE_INTEGERS_CLANG depends on RUSTC_VERSION >= 107900
- depends on ARM64 || X86_64 # With GCOV/KASAN we need this fix: https://github.com/rust-lang/rust/pull/129373 depends on (RUSTC_LLVM_VERSION >= 190103 && RUSTC_VERSION >= 108200) || \ (!GCOV_KERNEL && !KASAN_GENERIC && !KASAN_SW_TAGS)
-- 2.47.2
-- Kees Cook
linux-stable-mirror@lists.linaro.org
-
Alice Ryhl -
Conor Dooley -
Kees Cook -
Miguel Ojeda