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, 205 insertions, 0 deletions

diff --git a/drivers/bluetooth/btqca.h b/drivers/bluetooth/btqca.h
new file mode 100644
index 000000000..8f3c1b1c7
--- /dev/null
+++ b/drivers/bluetooth/btqca.h
@@ -0,0 +1,205 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ *  Bluetooth supports for Qualcomm Atheros ROME chips
+ *
+ *  Copyright (c) 2015 The Linux Foundation. All rights reserved.
+ */
+
+#define EDL_PATCH_CMD_OPCODE		0xFC00
+#define EDL_NVM_ACCESS_OPCODE		0xFC0B
+#define EDL_WRITE_BD_ADDR_OPCODE	0xFC14
+#define EDL_PATCH_CMD_LEN		1
+#define EDL_PATCH_VER_REQ_CMD		0x19
+#define EDL_PATCH_TLV_REQ_CMD		0x1E
+#define EDL_GET_BUILD_INFO_CMD		0x20
+#define EDL_GET_BID_REQ_CMD		0x23
+#define EDL_NVM_ACCESS_SET_REQ_CMD	0x01
+#define EDL_PATCH_CONFIG_CMD		0x28
+#define MAX_SIZE_PER_TLV_SEGMENT	243
+#define QCA_PRE_SHUTDOWN_CMD		0xFC08
+#define QCA_DISABLE_LOGGING		0xFC17
+
+#define EDL_CMD_REQ_RES_EVT		0x00
+#define EDL_PATCH_VER_RES_EVT		0x19
+#define EDL_APP_VER_RES_EVT		0x02
+#define EDL_TVL_DNLD_RES_EVT		0x04
+#define EDL_CMD_EXE_STATUS_EVT		0x00
+#define EDL_SET_BAUDRATE_RSP_EVT	0x92
+#define EDL_NVM_ACCESS_CODE_EVT		0x0B
+#define EDL_PATCH_CONFIG_RES_EVT	0x00
+#define QCA_DISABLE_LOGGING_SUB_OP	0x14
+
+#define EDL_TAG_ID_BD_ADDR		2
+#define EDL_TAG_ID_HCI			17
+#define EDL_TAG_ID_DEEP_SLEEP		27
+
+#define QCA_WCN3990_POWERON_PULSE	0xFC
+#define QCA_WCN3990_POWEROFF_PULSE	0xC0
+
+#define QCA_HCI_CC_OPCODE		0xFC00
+#define QCA_HCI_CC_SUCCESS		0x00
+
+#define QCA_WCN3991_SOC_ID		0x40014320
+
+#define QCA_WCN3950_SOC_ID_T		0x40074130
+#define QCA_WCN3950_SOC_ID_S		0x40075130
+
+/* QCA chipset version can be decided by patch and SoC
+ * version, combination with upper 2 bytes from SoC
+ * and lower 2 bytes from patch will be used.
+ */
+#define get_soc_ver(soc_id, rom_ver)	\
+	((le32_to_cpu(soc_id) << 16) | (le16_to_cpu(rom_ver)))
+
+#define QCA_HSP_GF_SOC_ID		0x1200
+#define QCA_HSP_GF_SOC_MASK		0x0000ff00
+
+enum qca_baudrate {
+	QCA_BAUDRATE_115200	= 0,
+	QCA_BAUDRATE_57600,
+	QCA_BAUDRATE_38400,
+	QCA_BAUDRATE_19200,
+	QCA_BAUDRATE_9600,
+	QCA_BAUDRATE_230400,
+	QCA_BAUDRATE_250000,
+	QCA_BAUDRATE_460800,
+	QCA_BAUDRATE_500000,
+	QCA_BAUDRATE_720000,
+	QCA_BAUDRATE_921600,
+	QCA_BAUDRATE_1000000,
+	QCA_BAUDRATE_1250000,
+	QCA_BAUDRATE_2000000,
+	QCA_BAUDRATE_3000000,
+	QCA_BAUDRATE_4000000,
+	QCA_BAUDRATE_1600000,
+	QCA_BAUDRATE_3200000,
+	QCA_BAUDRATE_3500000,
+	QCA_BAUDRATE_AUTO	= 0xFE,
+	QCA_BAUDRATE_RESERVED
+};
+
+enum qca_tlv_dnld_mode {
+	QCA_SKIP_EVT_NONE,
+	QCA_SKIP_EVT_VSE,
+	QCA_SKIP_EVT_CC,
+	QCA_SKIP_EVT_VSE_CC
+};
+
+enum qca_tlv_type {
+	TLV_TYPE_PATCH = 1,
+	TLV_TYPE_NVM,
+	ELF_TYPE_PATCH,
+};
+
+struct qca_fw_config {
+	u8 type;
+	char fwname[64];
+	uint8_t user_baud_rate;
+	enum qca_tlv_dnld_mode dnld_mode;
+	enum qca_tlv_dnld_mode dnld_type;
+	bdaddr_t bdaddr;
+};
+
+struct edl_event_hdr {
+	__u8 cresp;
+	__u8 rtype;
+	__u8 data[];
+} __packed;
+
+struct qca_btsoc_version {
+	__le32 product_id;
+	__le16 patch_ver;
+	__le16 rom_ver;
+	__le32 soc_id;
+} __packed;
+
+struct tlv_seg_resp {
+	__u8 result;
+} __packed;
+
+struct tlv_type_patch {
+	__le32 total_size;
+	__le32 data_length;
+	__u8   format_version;
+	__u8   signature;
+	__u8   download_mode;
+	__u8   reserved1;
+	__le16 product_id;
+	__le16 rom_build;
+	__le16 patch_version;
+	__le16 reserved2;
+	__le32 entry;
+} __packed;
+
+struct tlv_type_nvm {
+	__le16 tag_id;
+	__le16 tag_len;
+	__le32 reserve1;
+	__le32 reserve2;
+	__u8   data[];
+} __packed;
+
+struct tlv_type_hdr {
+	__le32 type_len;
+	__u8   data[];
+} __packed;
+
+enum qca_btsoc_type {
+	QCA_INVALID = -1,
+	QCA_AR3002,
+	QCA_ROME,
+	QCA_WCN3950,
+	QCA_WCN3988,
+	QCA_WCN3990,
+	QCA_WCN3998,
+	QCA_WCN3991,
+	QCA_QCA2066,
+	QCA_QCA6390,
+	QCA_WCN6750,
+	QCA_WCN6855,
+	QCA_WCN7850,
+};
+
+#if IS_ENABLED(CONFIG_BT_QCA)
+
+int qca_set_bdaddr_rome(struct hci_dev *hdev, const bdaddr_t *bdaddr);
+int qca_uart_setup(struct hci_dev *hdev, uint8_t baudrate,
+		   enum qca_btsoc_type soc_type, struct qca_btsoc_version ver,
+		   const char *firmware_name, const char *rampatch_name);
+int qca_read_soc_version(struct hci_dev *hdev, struct qca_btsoc_version *ver,
+			 enum qca_btsoc_type);
+int qca_set_bdaddr(struct hci_dev *hdev, const bdaddr_t *bdaddr);
+int qca_send_pre_shutdown_cmd(struct hci_dev *hdev);
+#else
+
+static inline int qca_set_bdaddr_rome(struct hci_dev *hdev, const bdaddr_t *bdaddr)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int qca_uart_setup(struct hci_dev *hdev, uint8_t baudrate,
+				 enum qca_btsoc_type soc_type,
+				 struct qca_btsoc_version ver,
+				 const char *firmware_name,
+				 const char *rampatch_name)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int qca_read_soc_version(struct hci_dev *hdev,
+				       struct qca_btsoc_version *ver,
+				       enum qca_btsoc_type)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int qca_set_bdaddr(struct hci_dev *hdev, const bdaddr_t *bdaddr)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int qca_send_pre_shutdown_cmd(struct hci_dev *hdev)
+{
+	return -EOPNOTSUPP;
+}
+#endif