On Wed, Jan 07, 2026 at 01:23:38PM +0100, Andreas Hindborg wrote: > Hi Alice, > > Alice Ryhl <[email protected]> writes: > > > Currently the only way for Rust code to call a static inline function is > > to go through a helper in rust/helpers/. This introduces performance > > costs due to additional function calls and also clutters backtraces and > > flame graphs with helper symbols. > > > > To get rid of these helper symbols, provide functionality to inline > > helpers into Rust using llvm-link. This option complements full LTO, by > > being much cheaper and avoiding incompatibility with BTF. > > > > I ran a microbenchmark showing the benefit of this. All the benchmark > > does is call refcount_inc() in a loop. This was chosen since refcounting > > is quite hot in Binder. The results are that Rust spends 6.35 ns per > > call vs 5.73 ns per call in C. When enabling this option, the two > > languages become equally fast, and disassembly confirms the exact same > > machine code is used (in particular there is no call to > > rust_helper_refcount_inc). Benchmarking Binder also results in an > > improvement from this change. > > > > This patch is complementary to: > > https://lore.kernel.org/all/[email protected]/ > > > > Signed-off-by: Alice Ryhl <[email protected]> > > I get the following modpost errors when building with this applied on top > of v6.19-rc4: > > ERROR: modpost: "__SCK__WARN_trap" [drivers/gpu/drm/nova/nova.ko] undefined! > ERROR: modpost: "__SCK__WARN_trap" [drivers/gpu/nova-core/nova_core.ko] > undefined! > ERROR: modpost: "__SCK__WARN_trap" [drivers/block/rnull/rnull_mod.ko] > undefined! > ERROR: modpost: "__SCK__WARN_trap" [samples/rust/rust_minimal.ko] undefined! > ERROR: modpost: "__SCK__WARN_trap" [samples/rust/rust_misc_device.ko] > undefined! > ERROR: modpost: "__SCK__WARN_trap" [samples/rust/rust_print.ko] undefined! > ERROR: modpost: "__SCK__WARN_trap" [samples/rust/rust_dma.ko] undefined! > ERROR: modpost: "__SCK__WARN_trap" [samples/rust/rust_driver_pci.ko] > undefined! > ERROR: modpost: "__SCK__WARN_trap" [samples/rust/rust_driver_platform.ko] > undefined! > ERROR: modpost: "__SCK__WARN_trap" [samples/rust/rust_driver_faux.ko] > undefined!
Looks like it used the wrong static_call_mod() version, was MODULE defined?
