kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted

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 <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 131 insertions, 0 deletions

diff --git a/include/dt-bindings/clock/omap5.h b/include/dt-bindings/clock/omap5.h
new file mode 100644
index 000000000..90e0d4b00
--- /dev/null
+++ b/include/dt-bindings/clock/omap5.h
@@ -0,0 +1,131 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2017 Texas Instruments, Inc.
+ */
+#ifndef __DT_BINDINGS_CLK_OMAP5_H
+#define __DT_BINDINGS_CLK_OMAP5_H
+
+#define OMAP5_CLKCTRL_OFFSET	0x20
+#define OMAP5_CLKCTRL_INDEX(offset)	((offset) - OMAP5_CLKCTRL_OFFSET)
+
+/* mpu clocks */
+#define OMAP5_MPU_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x20)
+
+/* dsp clocks */
+#define OMAP5_MMU_DSP_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x20)
+
+/* abe clocks */
+#define OMAP5_L4_ABE_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x20)
+#define OMAP5_AESS_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x28)
+#define OMAP5_MCPDM_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x30)
+#define OMAP5_DMIC_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x38)
+#define OMAP5_MCBSP1_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x48)
+#define OMAP5_MCBSP2_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x50)
+#define OMAP5_MCBSP3_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x58)
+#define OMAP5_TIMER5_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x68)
+#define OMAP5_TIMER6_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x70)
+#define OMAP5_TIMER7_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x78)
+#define OMAP5_TIMER8_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x80)
+
+/* l3main1 clocks */
+#define OMAP5_L3_MAIN_1_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x20)
+
+/* l3main2 clocks */
+#define OMAP5_L3_MAIN_2_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x20)
+#define OMAP5_L3_MAIN_2_GPMC_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x28)
+#define OMAP5_L3_MAIN_2_OCMC_RAM_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x30)
+
+/* ipu clocks */
+#define OMAP5_MMU_IPU_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x20)
+
+/* dma clocks */
+#define OMAP5_DMA_SYSTEM_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x20)
+
+/* emif clocks */
+#define OMAP5_DMM_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x20)
+#define OMAP5_EMIF1_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x30)
+#define OMAP5_EMIF2_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x38)
+
+/* l4cfg clocks */
+#define OMAP5_L4_CFG_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x20)
+#define OMAP5_SPINLOCK_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x28)
+#define OMAP5_MAILBOX_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x30)
+
+/* l3instr clocks */
+#define OMAP5_L3_MAIN_3_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x20)
+#define OMAP5_L3_INSTR_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x28)
+
+/* l4per clocks */
+#define OMAP5_TIMER10_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x28)
+#define OMAP5_TIMER11_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x30)
+#define OMAP5_TIMER2_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x38)
+#define OMAP5_TIMER3_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x40)
+#define OMAP5_TIMER4_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x48)
+#define OMAP5_TIMER9_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x50)
+#define OMAP5_GPIO2_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x60)
+#define OMAP5_GPIO3_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x68)
+#define OMAP5_GPIO4_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x70)
+#define OMAP5_GPIO5_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x78)
+#define OMAP5_GPIO6_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x80)
+#define OMAP5_I2C1_CLKCTRL	OMAP5_CLKCTRL_INDEX(0xa0)
+#define OMAP5_I2C2_CLKCTRL	OMAP5_CLKCTRL_INDEX(0xa8)
+#define OMAP5_I2C3_CLKCTRL	OMAP5_CLKCTRL_INDEX(0xb0)
+#define OMAP5_I2C4_CLKCTRL	OMAP5_CLKCTRL_INDEX(0xb8)
+#define OMAP5_L4_PER_CLKCTRL	OMAP5_CLKCTRL_INDEX(0xc0)
+#define OMAP5_MCSPI1_CLKCTRL	OMAP5_CLKCTRL_INDEX(0xf0)
+#define OMAP5_MCSPI2_CLKCTRL	OMAP5_CLKCTRL_INDEX(0xf8)
+#define OMAP5_MCSPI3_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x100)
+#define OMAP5_MCSPI4_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x108)
+#define OMAP5_GPIO7_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x110)
+#define OMAP5_GPIO8_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x118)
+#define OMAP5_MMC3_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x120)
+#define OMAP5_MMC4_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x128)
+#define OMAP5_UART1_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x140)
+#define OMAP5_UART2_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x148)
+#define OMAP5_UART3_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x150)
+#define OMAP5_UART4_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x158)
+#define OMAP5_MMC5_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x160)
+#define OMAP5_I2C5_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x168)
+#define OMAP5_UART5_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x170)
+#define OMAP5_UART6_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x178)
+
+/* l4_secure clocks */
+#define OMAP5_L4_SECURE_CLKCTRL_OFFSET	0x1a0
+#define OMAP5_L4_SECURE_CLKCTRL_INDEX(offset)	((offset) - OMAP5_L4_SECURE_CLKCTRL_OFFSET)
+#define OMAP5_AES1_CLKCTRL	OMAP5_L4_SECURE_CLKCTRL_INDEX(0x1a0)
+#define OMAP5_AES2_CLKCTRL	OMAP5_L4_SECURE_CLKCTRL_INDEX(0x1a8)
+#define OMAP5_DES3DES_CLKCTRL	OMAP5_L4_SECURE_CLKCTRL_INDEX(0x1b0)
+#define OMAP5_FPKA_CLKCTRL	OMAP5_L4_SECURE_CLKCTRL_INDEX(0x1b8)
+#define OMAP5_RNG_CLKCTRL	OMAP5_L4_SECURE_CLKCTRL_INDEX(0x1c0)
+#define OMAP5_SHA2MD5_CLKCTRL	OMAP5_L4_SECURE_CLKCTRL_INDEX(0x1c8)
+#define OMAP5_DMA_CRYPTO_CLKCTRL	OMAP5_L4_SECURE_CLKCTRL_INDEX(0x1d8)
+
+/* iva clocks */
+#define OMAP5_IVA_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x20)
+#define OMAP5_SL2IF_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x28)
+
+/* dss clocks */
+#define OMAP5_DSS_CORE_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x20)
+
+/* gpu clocks */
+#define OMAP5_GPU_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x20)
+
+/* l3init clocks */
+#define OMAP5_MMC1_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x28)
+#define OMAP5_MMC2_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x30)
+#define OMAP5_USB_HOST_HS_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x58)
+#define OMAP5_USB_TLL_HS_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x68)
+#define OMAP5_SATA_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x88)
+#define OMAP5_OCP2SCP1_CLKCTRL	OMAP5_CLKCTRL_INDEX(0xe0)
+#define OMAP5_OCP2SCP3_CLKCTRL	OMAP5_CLKCTRL_INDEX(0xe8)
+#define OMAP5_USB_OTG_SS_CLKCTRL	OMAP5_CLKCTRL_INDEX(0xf0)
+
+/* wkupaon clocks */
+#define OMAP5_L4_WKUP_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x20)
+#define OMAP5_WD_TIMER2_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x30)
+#define OMAP5_GPIO1_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x38)
+#define OMAP5_TIMER1_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x40)
+#define OMAP5_COUNTER_32K_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x50)
+#define OMAP5_KBD_CLKCTRL	OMAP5_CLKCTRL_INDEX(0x78)
+
+#endif