This patch series adds __rust_helper to every single rust helper. The patches do not depend on each other, so maintainers please go ahead and pick up any patches relevant to your subsystem! Or provide your Acked-by so that Miguel can pick them up.
These changes were generated by adding __rust_helper and running ClangFormat. Unrelated formatting changes were removed manually.
Why is __rust_helper needed? ============================
Currently, C helpers cannot be inlined into Rust even when using LTO because LLVM detects slightly different options on the codegen units.
* LLVM doesn't want to inline functions compiled with `-fno-delete-null-pointer-checks` with code compiled without. The C CGUs all have this enabled and Rust CGUs don't. Inlining is okay since this is one of the hardening features that does not change the ABI, and we shouldn't have null pointer dereferences in these helpers.
* LLVM doesn't want to inline functions with different list of builtins. C side has `-fno-builtin-wcslen`; `wcslen` is not a Rust builtin, so they should be compatible, but LLVM does not perform inlining due to attributes mismatch.
* clang and Rust doesn't have the exact target string. Clang generates `+cmov,+cx8,+fxsr` but Rust doesn't enable them (in fact, Rust will complain if `-Ctarget-feature=+cmov,+cx8,+fxsr` is used). x86-64 always enable these features, so they are in fact the same target string, but LLVM doesn't understand this and so inlining is inhibited. This can be bypassed with `--ignore-tti-inline-compatible`, but this is a hidden option.
(This analysis was written by Gary Guo.)
How is this fixed? ==================
To fix this we need to add __always_inline to all helpers when compiling with LTO. However, it should not be added when running bindgen as bindgen will ignore functions marked inline. To achieve this, we are using a #define called __rust_helper that is defined differently depending on whether bindgen is running or not.
Note that __rust_helper is currently always #defined to nothing. Changing it to __always_inline will happen separately in another patch series.
Signed-off-by: Alice Ryhl aliceryhl@google.com --- Alice Ryhl (46): rust: auxiliary: add __rust_helper to helpers rust: barrier: add __rust_helper to helpers rust: binder: add __rust_helper to helpers rust: bitmap: add __rust_helper to helpers rust: bitops: add __rust_helper to helpers rust: blk: add __rust_helper to helpers rust: bug: add __rust_helper to helpers rust: clk: add __rust_helper to helpers rust: completion: add __rust_helper to helpers rust: cpu: add __rust_helper to helpers rust: cpufreq: add __rust_helper to helpers rust: cpumask: add __rust_helper to helpers rust: cred: add __rust_helper to helpers rust: device: add __rust_helper to helpers rust: dma: add __rust_helper to helpers rust: drm: add __rust_helper to helpers rust: err: add __rust_helper to helpers rust: fs: add __rust_helper to helpers rust: io: add __rust_helper to helpers rust: irq: add __rust_helper to helpers rust: jump_label: add __rust_helper to helpers rust: kunit: add __rust_helper to helpers rust: maple_tree: add __rust_helper to helpers rust: mm: add __rust_helper to helpers rust: of: add __rust_helper to helpers rust: pci: add __rust_helper to helpers rust: pid_namespace: add __rust_helper to helpers rust: platform: add __rust_helper to helpers rust: poll: add __rust_helper to helpers rust: processor: add __rust_helper to helpers rust: property: add __rust_helper to helpers rust: rbtree: add __rust_helper to helpers rust: rcu: add __rust_helper to helpers rust: refcount: add __rust_helper to helpers rust: regulator: add __rust_helper to helpers rust: scatterlist: add __rust_helper to helpers rust: security: add __rust_helper to helpers rust: slab: add __rust_helper to helpers rust: sync: add __rust_helper to helpers rust: task: add __rust_helper to helpers rust: time: add __rust_helper to helpers rust: uaccess: add __rust_helper to helpers rust: usb: add __rust_helper to helpers rust: wait: add __rust_helper to helpers rust: workqueue: add __rust_helper to helpers rust: xarray: add __rust_helper to helpers
rust/helpers/auxiliary.c | 6 +++-- rust/helpers/barrier.c | 6 ++--- rust/helpers/binder.c | 13 ++++----- rust/helpers/bitmap.c | 6 +++-- rust/helpers/bitops.c | 11 +++++--- rust/helpers/blk.c | 4 +-- rust/helpers/bug.c | 4 +-- rust/helpers/build_bug.c | 2 +- rust/helpers/clk.c | 24 +++++++++-------- rust/helpers/completion.c | 2 +- rust/helpers/cpu.c | 2 +- rust/helpers/cpufreq.c | 3 ++- rust/helpers/cpumask.c | 32 +++++++++++++--------- rust/helpers/cred.c | 4 +-- rust/helpers/device.c | 16 +++++------ rust/helpers/dma.c | 15 ++++++----- rust/helpers/drm.c | 7 ++--- rust/helpers/err.c | 6 ++--- rust/helpers/fs.c | 2 +- rust/helpers/io.c | 64 +++++++++++++++++++++++--------------------- rust/helpers/irq.c | 6 +++-- rust/helpers/jump_label.c | 2 +- rust/helpers/kunit.c | 2 +- rust/helpers/maple_tree.c | 3 ++- rust/helpers/mm.c | 20 +++++++------- rust/helpers/mutex.c | 13 ++++----- rust/helpers/of.c | 2 +- rust/helpers/page.c | 9 ++++--- rust/helpers/pci.c | 13 +++++---- rust/helpers/pid_namespace.c | 8 +++--- rust/helpers/platform.c | 2 +- rust/helpers/poll.c | 5 ++-- rust/helpers/processor.c | 2 +- rust/helpers/property.c | 2 +- rust/helpers/rbtree.c | 5 ++-- rust/helpers/rcu.c | 4 +-- rust/helpers/refcount.c | 10 +++---- rust/helpers/regulator.c | 24 ++++++++++------- rust/helpers/scatterlist.c | 12 +++++---- rust/helpers/security.c | 26 ++++++++++-------- rust/helpers/signal.c | 2 +- rust/helpers/slab.c | 14 +++++----- rust/helpers/spinlock.c | 13 ++++----- rust/helpers/sync.c | 4 +-- rust/helpers/task.c | 24 ++++++++--------- rust/helpers/time.c | 12 ++++----- rust/helpers/uaccess.c | 8 +++--- rust/helpers/usb.c | 3 ++- rust/helpers/vmalloc.c | 7 ++--- rust/helpers/wait.c | 2 +- rust/helpers/workqueue.c | 8 +++--- rust/helpers/xarray.c | 10 +++---- 52 files changed, 280 insertions(+), 226 deletions(-) --- base-commit: 54e3eae855629702c566bd2e130d9f40e7f35bde change-id: 20251202-define-rust-helper-f7b531813007
Best regards,
This is needed to inline these helpers into Rust code.
Signed-off-by: Alice Ryhl aliceryhl@google.com --- Cc: Brendan Higgins brendan.higgins@linux.dev Cc: David Gow davidgow@google.com Cc: Rae Moar rmoar@google.com Cc: linux-kselftest@vger.kernel.org --- rust/helpers/kunit.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/rust/helpers/kunit.c b/rust/helpers/kunit.c index b85a4d394c118906d35ffef85221cf1a8b3c6fe3..cafb94b6776c07fe505e1749de71f91125006131 100644 --- a/rust/helpers/kunit.c +++ b/rust/helpers/kunit.c @@ -2,7 +2,7 @@
#include <kunit/test-bug.h>
-struct kunit *rust_helper_kunit_get_current_test(void) +__rust_helper struct kunit *rust_helper_kunit_get_current_test(void) { return kunit_get_current_test(); }
On Tue, Dec 02, 2025 at 07:37:24PM +0000, Alice Ryhl wrote:
This patch series adds __rust_helper to every single rust helper. The patches do not depend on each other, so maintainers please go ahead and pick up any patches relevant to your subsystem! Or provide your Acked-by so that Miguel can pick them up.
These changes were generated by adding __rust_helper and running ClangFormat. Unrelated formatting changes were removed manually.
Why is __rust_helper needed?
Currently, C helpers cannot be inlined into Rust even when using LTO because LLVM detects slightly different options on the codegen units.
LLVM doesn't want to inline functions compiled with `-fno-delete-null-pointer-checks` with code compiled without. The C CGUs all have this enabled and Rust CGUs don't. Inlining is okay since this is one of the hardening features that does not change the ABI, and we shouldn't have null pointer dereferences in these helpers.
LLVM doesn't want to inline functions with different list of builtins. C side has `-fno-builtin-wcslen`; `wcslen` is not a Rust builtin, so they should be compatible, but LLVM does not perform inlining due to attributes mismatch.
clang and Rust doesn't have the exact target string. Clang generates `+cmov,+cx8,+fxsr` but Rust doesn't enable them (in fact, Rust will complain if `-Ctarget-feature=+cmov,+cx8,+fxsr` is used). x86-64 always enable these features, so they are in fact the same target string, but LLVM doesn't understand this and so inlining is inhibited. This can be bypassed with `--ignore-tti-inline-compatible`, but this is a hidden option.
(This analysis was written by Gary Guo.)
How is this fixed?
To fix this we need to add __always_inline to all helpers when compiling with LTO. However, it should not be added when running bindgen as bindgen will ignore functions marked inline. To achieve this, we are using a #define called __rust_helper that is defined differently depending on whether bindgen is running or not.
Note that __rust_helper is currently always #defined to nothing. Changing it to __always_inline will happen separately in another patch series.
Signed-off-by: Alice Ryhl aliceryhl@google.com
For the whole series:
Reviewed-by: Boqun Feng boqun.feng@gmail.com
Regards, Boqun
[...]
On Tue, 02 Dec 2025 19:37:24 +0000 Alice Ryhl aliceryhl@google.com wrote:
This patch series adds __rust_helper to every single rust helper. The patches do not depend on each other, so maintainers please go ahead and pick up any patches relevant to your subsystem! Or provide your Acked-by so that Miguel can pick them up.
These changes were generated by adding __rust_helper and running ClangFormat. Unrelated formatting changes were removed manually.
Why is __rust_helper needed?
Currently, C helpers cannot be inlined into Rust even when using LTO because LLVM detects slightly different options on the codegen units.
LLVM doesn't want to inline functions compiled with `-fno-delete-null-pointer-checks` with code compiled without. The C CGUs all have this enabled and Rust CGUs don't. Inlining is okay since this is one of the hardening features that does not change the ABI, and we shouldn't have null pointer dereferences in these helpers.
LLVM doesn't want to inline functions with different list of builtins. C side has `-fno-builtin-wcslen`; `wcslen` is not a Rust builtin, so they should be compatible, but LLVM does not perform inlining due to attributes mismatch.
clang and Rust doesn't have the exact target string. Clang generates `+cmov,+cx8,+fxsr` but Rust doesn't enable them (in fact, Rust will complain if `-Ctarget-feature=+cmov,+cx8,+fxsr` is used). x86-64 always enable these features, so they are in fact the same target string, but LLVM doesn't understand this and so inlining is inhibited. This can be bypassed with `--ignore-tti-inline-compatible`, but this is a hidden option.
(This analysis was written by Gary Guo.)
How is this fixed?
To fix this we need to add __always_inline to all helpers when compiling with LTO. However, it should not be added when running bindgen as bindgen will ignore functions marked inline. To achieve this, we are using a #define called __rust_helper that is defined differently depending on whether bindgen is running or not.
Note that __rust_helper is currently always #defined to nothing. Changing it to __always_inline will happen separately in another patch series.
Signed-off-by: Alice Ryhl aliceryhl@google.com
Alice Ryhl (46): rust: auxiliary: add __rust_helper to helpers rust: barrier: add __rust_helper to helpers rust: binder: add __rust_helper to helpers rust: bitmap: add __rust_helper to helpers rust: bitops: add __rust_helper to helpers rust: blk: add __rust_helper to helpers rust: bug: add __rust_helper to helpers rust: clk: add __rust_helper to helpers rust: completion: add __rust_helper to helpers rust: cpu: add __rust_helper to helpers rust: cpufreq: add __rust_helper to helpers rust: cpumask: add __rust_helper to helpers rust: cred: add __rust_helper to helpers rust: device: add __rust_helper to helpers rust: dma: add __rust_helper to helpers rust: drm: add __rust_helper to helpers rust: err: add __rust_helper to helpers rust: fs: add __rust_helper to helpers rust: io: add __rust_helper to helpers rust: irq: add __rust_helper to helpers rust: jump_label: add __rust_helper to helpers rust: kunit: add __rust_helper to helpers rust: maple_tree: add __rust_helper to helpers rust: mm: add __rust_helper to helpers rust: of: add __rust_helper to helpers rust: pci: add __rust_helper to helpers rust: pid_namespace: add __rust_helper to helpers rust: platform: add __rust_helper to helpers rust: poll: add __rust_helper to helpers rust: processor: add __rust_helper to helpers rust: property: add __rust_helper to helpers rust: rbtree: add __rust_helper to helpers rust: rcu: add __rust_helper to helpers rust: refcount: add __rust_helper to helpers rust: regulator: add __rust_helper to helpers rust: scatterlist: add __rust_helper to helpers rust: security: add __rust_helper to helpers rust: slab: add __rust_helper to helpers rust: sync: add __rust_helper to helpers rust: task: add __rust_helper to helpers rust: time: add __rust_helper to helpers rust: uaccess: add __rust_helper to helpers rust: usb: add __rust_helper to helpers rust: wait: add __rust_helper to helpers rust: workqueue: add __rust_helper to helpers rust: xarray: add __rust_helper to helpers
Thansk for sending this Alice! With this series in first, my series for inlining helpers should be much easier to apply.
For the whole series:
Reviewed-by: Gary Guo gary@garyguo.net
Best, Gary
rust/helpers/auxiliary.c | 6 +++-- rust/helpers/barrier.c | 6 ++--- rust/helpers/binder.c | 13 ++++----- rust/helpers/bitmap.c | 6 +++-- rust/helpers/bitops.c | 11 +++++--- rust/helpers/blk.c | 4 +-- rust/helpers/bug.c | 4 +-- rust/helpers/build_bug.c | 2 +- rust/helpers/clk.c | 24 +++++++++-------- rust/helpers/completion.c | 2 +- rust/helpers/cpu.c | 2 +- rust/helpers/cpufreq.c | 3 ++- rust/helpers/cpumask.c | 32 +++++++++++++--------- rust/helpers/cred.c | 4 +-- rust/helpers/device.c | 16 +++++------ rust/helpers/dma.c | 15 ++++++----- rust/helpers/drm.c | 7 ++--- rust/helpers/err.c | 6 ++--- rust/helpers/fs.c | 2 +- rust/helpers/io.c | 64 +++++++++++++++++++++++--------------------- rust/helpers/irq.c | 6 +++-- rust/helpers/jump_label.c | 2 +- rust/helpers/kunit.c | 2 +- rust/helpers/maple_tree.c | 3 ++- rust/helpers/mm.c | 20 +++++++------- rust/helpers/mutex.c | 13 ++++----- rust/helpers/of.c | 2 +- rust/helpers/page.c | 9 ++++--- rust/helpers/pci.c | 13 +++++---- rust/helpers/pid_namespace.c | 8 +++--- rust/helpers/platform.c | 2 +- rust/helpers/poll.c | 5 ++-- rust/helpers/processor.c | 2 +- rust/helpers/property.c | 2 +- rust/helpers/rbtree.c | 5 ++-- rust/helpers/rcu.c | 4 +-- rust/helpers/refcount.c | 10 +++---- rust/helpers/regulator.c | 24 ++++++++++------- rust/helpers/scatterlist.c | 12 +++++---- rust/helpers/security.c | 26 ++++++++++-------- rust/helpers/signal.c | 2 +- rust/helpers/slab.c | 14 +++++----- rust/helpers/spinlock.c | 13 ++++----- rust/helpers/sync.c | 4 +-- rust/helpers/task.c | 24 ++++++++--------- rust/helpers/time.c | 12 ++++----- rust/helpers/uaccess.c | 8 +++--- rust/helpers/usb.c | 3 ++- rust/helpers/vmalloc.c | 7 ++--- rust/helpers/wait.c | 2 +- rust/helpers/workqueue.c | 8 +++--- rust/helpers/xarray.c | 10 +++---- 52 files changed, 280 insertions(+), 226 deletions(-)
base-commit: 54e3eae855629702c566bd2e130d9f40e7f35bde change-id: 20251202-define-rust-helper-f7b531813007
Best regards,
On Tue, 02 Dec 2025 19:37:24 +0000, Alice Ryhl wrote:
This patch series adds __rust_helper to every single rust helper. The patches do not depend on each other, so maintainers please go ahead and pick up any patches relevant to your subsystem! Or provide your Acked-by so that Miguel can pick them up.
These changes were generated by adding __rust_helper and running ClangFormat. Unrelated formatting changes were removed manually.
[...]
Applied to the vfs-6.20.rust branch of the vfs/vfs.git tree. Patches in the vfs-6.20.rust branch should appear in linux-next soon.
Please report any outstanding bugs that were missed during review in a new review to the original patch series allowing us to drop it.
It's encouraged to provide Acked-bys and Reviewed-bys even though the patch has now been applied. If possible patch trailers will be updated.
Note that commit hashes shown below are subject to change due to rebase, trailer updates or similar. If in doubt, please check the listed branch.
tree: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git branch: vfs-6.20.rust
[18/46] rust: fs: add __rust_helper to helpers https://git.kernel.org/vfs/vfs/c/02c444cc60e5 [27/46] rust: pid_namespace: add __rust_helper to helpers https://git.kernel.org/vfs/vfs/c/f28a178408e4 [29/46] rust: poll: add __rust_helper to helpers https://git.kernel.org/vfs/vfs/c/de98ed59d678
On Wed, 3 Dec 2025 at 03:38, Alice Ryhl aliceryhl@google.com wrote:
This is needed to inline these helpers into Rust code.
Signed-off-by: Alice Ryhl aliceryhl@google.com
Cc: Brendan Higgins brendan.higgins@linux.dev Cc: David Gow davidgow@google.com Cc: Rae Moar rmoar@google.com Cc: linux-kselftest@vger.kernel.org
I'm assuming you'd prefer all of these to go in via the rust tree? (But if you prefer, there's no problem with us taking this via the kselftest/kunit tree.)
Reviewed-by: David Gow davidgow@google.com
Cheers, -- David
rust/helpers/kunit.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/rust/helpers/kunit.c b/rust/helpers/kunit.c index b85a4d394c118906d35ffef85221cf1a8b3c6fe3..cafb94b6776c07fe505e1749de71f91125006131 100644 --- a/rust/helpers/kunit.c +++ b/rust/helpers/kunit.c @@ -2,7 +2,7 @@
#include <kunit/test-bug.h>
-struct kunit *rust_helper_kunit_get_current_test(void) +__rust_helper struct kunit *rust_helper_kunit_get_current_test(void) { return kunit_get_current_test(); }
-- 2.52.0.158.g65b55ccf14-goog
On Sat, Dec 13, 2025 at 11:12 AM David Gow davidgow@google.com wrote:
On Wed, 3 Dec 2025 at 03:38, Alice Ryhl aliceryhl@google.com wrote:
This is needed to inline these helpers into Rust code.
Signed-off-by: Alice Ryhl aliceryhl@google.com
Cc: Brendan Higgins brendan.higgins@linux.dev Cc: David Gow davidgow@google.com Cc: Rae Moar rmoar@google.com Cc: linux-kselftest@vger.kernel.org
I'm assuming you'd prefer all of these to go in via the rust tree? (But if you prefer, there's no problem with us taking this via the kselftest/kunit tree.)
Picking it up through the kselftest/kunit tree would be great!
Alice
linux-kselftest-mirror@lists.linaro.org
-
Alice Ryhl -
Boqun Feng -
Christian Brauner -
David Gow -
Gary Guo