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>

6 files changed, 122 insertions, 0 deletions

diff --git a/include/soc/rockchip/pm_domains.h b/include/soc/rockchip/pm_domains.h
new file mode 100644
index 000000000..7dbd941fc
--- /dev/null
+++ b/include/soc/rockchip/pm_domains.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright 2022, The Chromium OS Authors. All rights reserved.
+ */
+
+#ifndef __SOC_ROCKCHIP_PM_DOMAINS_H__
+#define __SOC_ROCKCHIP_PM_DOMAINS_H__
+
+#ifdef CONFIG_ROCKCHIP_PM_DOMAINS
+
+int rockchip_pmu_block(void);
+void rockchip_pmu_unblock(void);
+
+#else /* CONFIG_ROCKCHIP_PM_DOMAINS */
+
+static inline int rockchip_pmu_block(void)
+{
+	return 0;
+}
+
+static inline void rockchip_pmu_unblock(void) { }
+
+#endif /* CONFIG_ROCKCHIP_PM_DOMAINS */
+
+#endif /* __SOC_ROCKCHIP_PM_DOMAINS_H__ */
diff --git a/include/soc/rockchip/rk3399_grf.h b/include/soc/rockchip/rk3399_grf.h
new file mode 100644
index 000000000..39cd44cec
--- /dev/null
+++ b/include/soc/rockchip/rk3399_grf.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Rockchip General Register Files definitions
+ *
+ * Copyright (c) 2018, Collabora Ltd.
+ * Author: Enric Balletbo i Serra <enric.balletbo@collabora.com>
+ */
+
+#ifndef __SOC_RK3399_GRF_H
+#define __SOC_RK3399_GRF_H
+
+/* PMU GRF Registers */
+#define RK3399_PMUGRF_OS_REG2		0x308
+#define RK3399_PMUGRF_OS_REG2_DDRTYPE		GENMASK(15, 13)
+#define RK3399_PMUGRF_OS_REG2_BW_CH0		GENMASK(3, 2)
+#define RK3399_PMUGRF_OS_REG2_BW_CH1		GENMASK(19, 18)
+
+#endif
diff --git a/include/soc/rockchip/rk3568_grf.h b/include/soc/rockchip/rk3568_grf.h
new file mode 100644
index 000000000..52853efd6
--- /dev/null
+++ b/include/soc/rockchip/rk3568_grf.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+#ifndef __SOC_RK3568_GRF_H
+#define __SOC_RK3568_GRF_H
+
+#define RK3568_PMUGRF_OS_REG2		0x208
+#define RK3568_PMUGRF_OS_REG2_DRAMTYPE_INFO		GENMASK(15, 13)
+#define RK3568_PMUGRF_OS_REG2_BW_CH0			GENMASK(3, 2)
+
+#define RK3568_PMUGRF_OS_REG3		0x20c
+#define RK3568_PMUGRF_OS_REG3_DRAMTYPE_INFO_V3		GENMASK(13, 12)
+#define RK3568_PMUGRF_OS_REG3_SYSREG_VERSION		GENMASK(31, 28)
+
+#endif /* __SOC_RK3568_GRF_H */
diff --git a/include/soc/rockchip/rk3588_grf.h b/include/soc/rockchip/rk3588_grf.h
new file mode 100644
index 000000000..db0092fc6
--- /dev/null
+++ b/include/soc/rockchip/rk3588_grf.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+#ifndef __SOC_RK3588_GRF_H
+#define __SOC_RK3588_GRF_H
+
+#define RK3588_PMUGRF_OS_REG2		0x208
+#define RK3588_PMUGRF_OS_REG2_DRAMTYPE_INFO		GENMASK(15, 13)
+#define RK3588_PMUGRF_OS_REG2_BW_CH0			GENMASK(3, 2)
+#define RK3588_PMUGRF_OS_REG2_BW_CH1                    GENMASK(19, 18)
+#define RK3588_PMUGRF_OS_REG2_CH_INFO                   GENMASK(29, 28)
+
+#define RK3588_PMUGRF_OS_REG3		0x20c
+#define RK3588_PMUGRF_OS_REG3_DRAMTYPE_INFO_V3		GENMASK(13, 12)
+#define RK3588_PMUGRF_OS_REG3_SYSREG_VERSION		GENMASK(31, 28)
+
+#define RK3588_PMUGRF_OS_REG4				0x210
+#define RK3588_PMUGRF_OS_REG5				0x214
+#define RK3588_PMUGRF_OS_REG6				0x218
+#define RK3588_PMUGRF_OS_REG6_LP5_BANK_MODE		GENMASK(2, 1)
+/* Whether the LPDDR5 is in 2:1 (= 0) or 4:1 (= 1) CKR a.k.a. DQS mode */
+#define RK3588_PMUGRF_OS_REG6_LP5_CKR			BIT(0)
+
+#define RK3588_SYSGRF_SOC_CON6			0x0318
+
+#endif /* __SOC_RK3588_GRF_H */
diff --git a/include/soc/rockchip/rockchip_grf.h b/include/soc/rockchip/rockchip_grf.h
new file mode 100644
index 000000000..41c7bb26f
--- /dev/null
+++ b/include/soc/rockchip/rockchip_grf.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Rockchip General Register Files definitions
+ */
+
+#ifndef __SOC_ROCKCHIP_GRF_H
+#define __SOC_ROCKCHIP_GRF_H
+
+/* Rockchip DDRTYPE defines */
+enum {
+	ROCKCHIP_DDRTYPE_DDR3	= 3,
+	ROCKCHIP_DDRTYPE_LPDDR2	= 5,
+	ROCKCHIP_DDRTYPE_LPDDR3	= 6,
+	ROCKCHIP_DDRTYPE_LPDDR4	= 7,
+	ROCKCHIP_DDRTYPE_LPDDR4X = 8,
+	ROCKCHIP_DDRTYPE_LPDDR5	= 9,
+};
+
+#endif /* __SOC_ROCKCHIP_GRF_H */
diff --git a/include/soc/rockchip/rockchip_sip.h b/include/soc/rockchip/rockchip_sip.h
new file mode 100644
index 000000000..501ad1fed
--- /dev/null
+++ b/include/soc/rockchip/rockchip_sip.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2016, Fuzhou Rockchip Electronics Co., Ltd
+ * Author: Lin Huang <hl@rock-chips.com>
+ */
+#ifndef __SOC_ROCKCHIP_SIP_H
+#define __SOC_ROCKCHIP_SIP_H
+
+#define ROCKCHIP_SIP_SUSPEND_MODE		0x82000003
+#define ROCKCHIP_SLEEP_PD_CONFIG		0xff
+
+#define ROCKCHIP_SIP_DRAM_FREQ			0x82000008
+#define ROCKCHIP_SIP_CONFIG_DRAM_INIT		0x00
+#define ROCKCHIP_SIP_CONFIG_DRAM_SET_RATE	0x01
+#define ROCKCHIP_SIP_CONFIG_DRAM_ROUND_RATE	0x02
+#define ROCKCHIP_SIP_CONFIG_DRAM_SET_AT_SR	0x03
+#define ROCKCHIP_SIP_CONFIG_DRAM_GET_BW		0x04
+#define ROCKCHIP_SIP_CONFIG_DRAM_GET_RATE	0x05
+#define ROCKCHIP_SIP_CONFIG_DRAM_CLR_IRQ	0x06
+#define ROCKCHIP_SIP_CONFIG_DRAM_SET_PARAM	0x07
+#define ROCKCHIP_SIP_CONFIG_DRAM_SET_ODT_PD	0x08
+
+#endif