From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- drivers/android/binder/trace.rs | 105 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 105 insertions(+) create mode 100644 drivers/android/binder/trace.rs (limited to 'drivers/android/binder/trace.rs') diff --git a/drivers/android/binder/trace.rs b/drivers/android/binder/trace.rs new file mode 100644 index 000000000..5539672d7 --- /dev/null +++ b/drivers/android/binder/trace.rs @@ -0,0 +1,105 @@ +// SPDX-License-Identifier: GPL-2.0 + +// Copyright (C) 2025 Google LLC. + +use crate::transaction::Transaction; + +use kernel::bindings::{rust_binder_transaction, task_struct}; +use kernel::error::Result; +use kernel::ffi::{c_int, c_uint, c_ulong}; +use kernel::task::Task; +use kernel::tracepoint::declare_trace; + +declare_trace! { + unsafe fn binder_ioctl(cmd: c_uint, arg: c_ulong); + unsafe fn binder_ioctl_done(ret: c_int); + unsafe fn binder_read_done(ret: c_int); + unsafe fn binder_write_done(ret: c_int); + unsafe fn binder_wait_for_work(proc_work: bool, transaction_stack: bool, thread_todo: bool); + unsafe fn binder_transaction(reply: bool, t: rust_binder_transaction, thread: *mut task_struct); + unsafe fn binder_transaction_received(t: rust_binder_transaction); + unsafe fn binder_transaction_fd_send(t_debug_id: c_int, fd: c_int, offset: usize); + unsafe fn binder_transaction_fd_recv(t_debug_id: c_int, fd: c_int, offset: usize); + unsafe fn binder_command(cmd: u32); + unsafe fn binder_return(ret: u32); +} + +#[inline] +fn raw_transaction(t: &Transaction) -> rust_binder_transaction { + t as *const Transaction as rust_binder_transaction +} + +#[inline] +fn to_errno(ret: Result) -> i32 { + match ret { + Ok(()) => 0, + Err(err) => err.to_errno(), + } +} + +#[inline] +pub(crate) fn trace_ioctl(cmd: u32, arg: usize) { + // SAFETY: Always safe to call. + unsafe { binder_ioctl(cmd, arg as c_ulong) } +} + +#[inline] +pub(crate) fn trace_ioctl_done(ret: Result) { + // SAFETY: Always safe to call. + unsafe { binder_ioctl_done(to_errno(ret)) } +} +#[inline] +pub(crate) fn trace_read_done(ret: Result) { + // SAFETY: Always safe to call. + unsafe { binder_read_done(to_errno(ret)) } +} +#[inline] +pub(crate) fn trace_write_done(ret: Result) { + // SAFETY: Always safe to call. + unsafe { binder_write_done(to_errno(ret)) } +} + +#[inline] +pub(crate) fn trace_wait_for_work(proc_work: bool, transaction_stack: bool, thread_todo: bool) { + // SAFETY: Always safe to call. + unsafe { binder_wait_for_work(proc_work, transaction_stack, thread_todo) } +} + +#[inline] +pub(crate) fn trace_transaction(reply: bool, t: &Transaction, thread: Option<&Task>) { + let thread = match thread { + Some(thread) => thread.as_ptr(), + None => core::ptr::null_mut(), + }; + // SAFETY: The raw transaction is valid for the duration of this call. The thread pointer is + // valid or null. + unsafe { binder_transaction(reply, raw_transaction(t), thread) } +} + +#[inline] +pub(crate) fn trace_transaction_received(t: &Transaction) { + // SAFETY: The raw transaction is valid for the duration of this call. + unsafe { binder_transaction_received(raw_transaction(t)) } +} + +#[inline] +pub(crate) fn trace_transaction_fd_send(t_debug_id: usize, fd: u32, offset: usize) { + // SAFETY: This function is always safe to call. + unsafe { binder_transaction_fd_send(t_debug_id as c_int, fd as c_int, offset) } +} +#[inline] +pub(crate) fn trace_transaction_fd_recv(t_debug_id: usize, fd: u32, offset: usize) { + // SAFETY: This function is always safe to call. + unsafe { binder_transaction_fd_recv(t_debug_id as c_int, fd as c_int, offset) } +} + +#[inline] +pub(crate) fn trace_command(cmd: u32) { + // SAFETY: This function is always safe to call. + unsafe { binder_command(cmd) } +} +#[inline] +pub(crate) fn trace_return(ret: u32) { + // SAFETY: This function is always safe to call. + unsafe { binder_return(ret) } +} -- cgit v1.3.1