"Peter Zijlstra" <[email protected]> writes: > 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?
CONFIG_MODULES=y, yes I built without the patch first, then applied the series, enabled the option via menuconfig and ran the build. I thought maybe some dependency check is messed up so I retried the build from a clean state. Same result. Best regards, Andreas Hindborg
