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, 387 insertions, 0 deletions

diff --git a/drivers/usb/dwc3/trace.h b/drivers/usb/dwc3/trace.h
new file mode 100644
index 000000000..5253da23d
--- /dev/null
+++ b/drivers/usb/dwc3/trace.h
@@ -0,0 +1,387 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * trace.h - DesignWare USB3 DRD Controller Trace Support
+ *
+ * Copyright (C) 2014 Texas Instruments Incorporated - https://www.ti.com
+ *
+ * Author: Felipe Balbi <balbi@ti.com>
+ */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM dwc3
+
+#if !defined(__DWC3_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define __DWC3_TRACE_H
+
+#include <linux/types.h>
+#include <linux/tracepoint.h>
+#include <asm/byteorder.h>
+#include "core.h"
+#include "debug.h"
+
+DECLARE_EVENT_CLASS(dwc3_log_set_prtcap,
+	TP_PROTO(struct dwc3 *dwc, u32 mode),
+	TP_ARGS(dwc, mode),
+	TP_STRUCT__entry(
+		__field(phys_addr_t, base_address)
+		__field(u32, mode)
+	),
+	TP_fast_assign(
+		__entry->base_address = dwc->xhci_resources[0].start;
+		__entry->mode = mode;
+	),
+	TP_printk("%pa: mode %s", &__entry->base_address, dwc3_mode_string(__entry->mode))
+);
+
+DEFINE_EVENT(dwc3_log_set_prtcap, dwc3_set_prtcap,
+	TP_PROTO(struct dwc3 *dwc, u32 mode),
+	TP_ARGS(dwc, mode)
+);
+
+DECLARE_EVENT_CLASS(dwc3_log_io,
+	TP_PROTO(struct dwc3 *dwc, void *base, u32 offset, u32 value),
+	TP_ARGS(dwc, base, offset, value),
+	TP_STRUCT__entry(
+		__field(phys_addr_t, base_address)
+		__field(void *, base)
+		__field(u32, offset)
+		__field(u32, value)
+	),
+	TP_fast_assign(
+		__entry->base_address = dwc->xhci_resources[0].start;
+		__entry->base = base;
+		__entry->offset = offset;
+		__entry->value = value;
+	),
+	TP_printk("%pa: addr %p offset %04x value %08x",
+		&__entry->base_address,
+		__entry->base + __entry->offset,
+		__entry->offset,
+		__entry->value)
+);
+
+DEFINE_EVENT(dwc3_log_io, dwc3_readl,
+	TP_PROTO(struct dwc3 *dwc, void __iomem *base, u32 offset, u32 value),
+	TP_ARGS(dwc, base, offset, value)
+);
+
+DEFINE_EVENT(dwc3_log_io, dwc3_writel,
+	TP_PROTO(struct dwc3 *dwc, void __iomem *base, u32 offset, u32 value),
+	TP_ARGS(dwc, base, offset, value)
+);
+
+DECLARE_EVENT_CLASS(dwc3_log_event,
+	TP_PROTO(u32 event, struct dwc3 *dwc),
+	TP_ARGS(event, dwc),
+	TP_STRUCT__entry(
+		__field(phys_addr_t, base_address)
+		__field(u32, event)
+		__field(u32, ep0state)
+	),
+	TP_fast_assign(
+		__entry->base_address = dwc->xhci_resources[0].start;
+		__entry->event = event;
+		__entry->ep0state = dwc->ep0state;
+	),
+	TP_printk("%pa: event (%08x): %s", &__entry->base_address, __entry->event,
+			dwc3_decode_event(__get_buf(DWC3_MSG_MAX), DWC3_MSG_MAX,
+					__entry->event, __entry->ep0state))
+);
+
+DEFINE_EVENT(dwc3_log_event, dwc3_event,
+	TP_PROTO(u32 event, struct dwc3 *dwc),
+	TP_ARGS(event, dwc)
+);
+
+DECLARE_EVENT_CLASS(dwc3_log_ctrl,
+	TP_PROTO(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl),
+	TP_ARGS(dwc, ctrl),
+	TP_STRUCT__entry(
+		__field(phys_addr_t, base_address)
+		__field(__u8, bRequestType)
+		__field(__u8, bRequest)
+		__field(__u16, wValue)
+		__field(__u16, wIndex)
+		__field(__u16, wLength)
+	),
+	TP_fast_assign(
+		__entry->base_address = dwc->xhci_resources[0].start;
+		__entry->bRequestType = ctrl->bRequestType;
+		__entry->bRequest = ctrl->bRequest;
+		__entry->wValue = le16_to_cpu(ctrl->wValue);
+		__entry->wIndex = le16_to_cpu(ctrl->wIndex);
+		__entry->wLength = le16_to_cpu(ctrl->wLength);
+	),
+	TP_printk("%pa: %s", &__entry->base_address, usb_decode_ctrl(__get_buf(DWC3_MSG_MAX),
+					DWC3_MSG_MAX,
+					__entry->bRequestType,
+					__entry->bRequest, __entry->wValue,
+					__entry->wIndex, __entry->wLength)
+	)
+);
+
+DEFINE_EVENT(dwc3_log_ctrl, dwc3_ctrl_req,
+	TP_PROTO(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl),
+	TP_ARGS(dwc, ctrl)
+);
+
+DECLARE_EVENT_CLASS(dwc3_log_request,
+	TP_PROTO(struct dwc3_request *req),
+	TP_ARGS(req),
+	TP_STRUCT__entry(
+		__field(phys_addr_t, base_address)
+		__string(name, req->dep->name)
+		__field(struct dwc3_request *, req)
+		__field(unsigned int, actual)
+		__field(unsigned int, length)
+		__field(int, status)
+		__field(int, zero)
+		__field(int, short_not_ok)
+		__field(int, no_interrupt)
+	),
+	TP_fast_assign(
+		__entry->base_address = req->dep->dwc->xhci_resources[0].start;
+		__entry->req = req;
+		__entry->actual = req->request.actual;
+		__entry->length = req->request.length;
+		__entry->status = req->request.status;
+		__entry->zero = req->request.zero;
+		__entry->short_not_ok = req->request.short_not_ok;
+		__entry->no_interrupt = req->request.no_interrupt;
+	),
+	TP_printk("%pa: %s: req %p length %u/%u %s%s%s ==> %d",
+		&__entry->base_address,
+		__get_str(name), __entry->req,
+		__entry->actual, __entry->length,
+		__entry->zero ? "Z" : "z",
+		__entry->short_not_ok ? "S" : "s",
+		__entry->no_interrupt ? "i" : "I",
+		__entry->status
+	)
+);
+
+DEFINE_EVENT(dwc3_log_request, dwc3_alloc_request,
+	TP_PROTO(struct dwc3_request *req),
+	TP_ARGS(req)
+);
+
+DEFINE_EVENT(dwc3_log_request, dwc3_free_request,
+	TP_PROTO(struct dwc3_request *req),
+	TP_ARGS(req)
+);
+
+DEFINE_EVENT(dwc3_log_request, dwc3_ep_queue,
+	TP_PROTO(struct dwc3_request *req),
+	TP_ARGS(req)
+);
+
+DEFINE_EVENT(dwc3_log_request, dwc3_ep_dequeue,
+	TP_PROTO(struct dwc3_request *req),
+	TP_ARGS(req)
+);
+
+DEFINE_EVENT(dwc3_log_request, dwc3_gadget_giveback,
+	TP_PROTO(struct dwc3_request *req),
+	TP_ARGS(req)
+);
+
+DECLARE_EVENT_CLASS(dwc3_log_generic_cmd,
+	TP_PROTO(struct dwc3 *dwc, unsigned int cmd, u32 param, int status),
+	TP_ARGS(dwc, cmd, param, status),
+	TP_STRUCT__entry(
+		__field(phys_addr_t, base_address)
+		__field(unsigned int, cmd)
+		__field(u32, param)
+		__field(int, status)
+	),
+	TP_fast_assign(
+		__entry->base_address = dwc->xhci_resources[0].start;
+		__entry->cmd = cmd;
+		__entry->param = param;
+		__entry->status = status;
+	),
+	TP_printk("%pa: cmd '%s' [%x] param %08x --> status: %s",
+		&__entry->base_address, dwc3_gadget_generic_cmd_string(__entry->cmd),
+		__entry->cmd, __entry->param,
+		dwc3_gadget_generic_cmd_status_string(__entry->status)
+	)
+);
+
+DEFINE_EVENT(dwc3_log_generic_cmd, dwc3_gadget_generic_cmd,
+	TP_PROTO(struct dwc3 *dwc, unsigned int cmd, u32 param, int status),
+	TP_ARGS(dwc, cmd, param, status)
+);
+
+DECLARE_EVENT_CLASS(dwc3_log_gadget_ep_cmd,
+	TP_PROTO(struct dwc3_ep *dep, unsigned int cmd,
+		struct dwc3_gadget_ep_cmd_params *params, int cmd_status),
+	TP_ARGS(dep, cmd, params, cmd_status),
+	TP_STRUCT__entry(
+		__field(phys_addr_t, base_address)
+		__string(name, dep->name)
+		__field(unsigned int, cmd)
+		__field(u32, param0)
+		__field(u32, param1)
+		__field(u32, param2)
+		__field(int, cmd_status)
+	),
+	TP_fast_assign(
+		__entry->base_address = dep->dwc->xhci_resources[0].start;
+		__assign_str(name);
+		__entry->cmd = cmd;
+		__entry->param0 = params->param0;
+		__entry->param1 = params->param1;
+		__entry->param2 = params->param2;
+		__entry->cmd_status = cmd_status;
+	),
+	TP_printk("%pa: %s: cmd '%s' [%x] params %08x %08x %08x --> status: %s",
+		&__entry->base_address, __get_str(name),
+		dwc3_gadget_ep_cmd_string(__entry->cmd),
+		__entry->cmd, __entry->param0,
+		__entry->param1, __entry->param2,
+		dwc3_ep_cmd_status_string(__entry->cmd_status)
+	)
+);
+
+DEFINE_EVENT(dwc3_log_gadget_ep_cmd, dwc3_gadget_ep_cmd,
+	TP_PROTO(struct dwc3_ep *dep, unsigned int cmd,
+		struct dwc3_gadget_ep_cmd_params *params, int cmd_status),
+	TP_ARGS(dep, cmd, params, cmd_status)
+);
+
+DECLARE_EVENT_CLASS(dwc3_log_trb,
+	TP_PROTO(struct dwc3_ep *dep, struct dwc3_trb *trb),
+	TP_ARGS(dep, trb),
+	TP_STRUCT__entry(
+		__field(phys_addr_t, base_address)
+		__string(name, dep->name)
+		__field(struct dwc3_trb *, trb)
+		__field(u32, bpl)
+		__field(u32, bph)
+		__field(u32, size)
+		__field(u32, ctrl)
+		__field(u32, type)
+		__field(u32, enqueue)
+		__field(u32, dequeue)
+	),
+	TP_fast_assign(
+		__entry->base_address = dep->dwc->xhci_resources[0].start;
+		__assign_str(name);
+		__entry->trb = trb;
+		__entry->bpl = trb->bpl;
+		__entry->bph = trb->bph;
+		__entry->size = trb->size;
+		__entry->ctrl = trb->ctrl;
+		__entry->type = usb_endpoint_type(dep->endpoint.desc);
+		__entry->enqueue = dep->trb_enqueue;
+		__entry->dequeue = dep->trb_dequeue;
+	),
+	TP_printk("%pa: %s: trb %p (E%d:D%d) buf %08x%08x size %s%d ctrl %08x sofn %08x (%c%c%c%c:%c%c:%s)",
+		&__entry->base_address, __get_str(name), __entry->trb, __entry->enqueue,
+		__entry->dequeue, __entry->bph, __entry->bpl,
+		({char *s;
+		int pcm = ((__entry->size >> 24) & 3) + 1;
+
+		switch (__entry->type) {
+		case USB_ENDPOINT_XFER_INT:
+		case USB_ENDPOINT_XFER_ISOC:
+			switch (pcm) {
+			case 1:
+				s = "1x ";
+				break;
+			case 2:
+				s = "2x ";
+				break;
+			case 3:
+			default:
+				s = "3x ";
+				break;
+			}
+			break;
+		default:
+			s = "";
+		} s; }),
+		DWC3_TRB_SIZE_LENGTH(__entry->size), __entry->ctrl,
+		DWC3_TRB_CTRL_GET_SID_SOFN(__entry->ctrl),
+		__entry->ctrl & DWC3_TRB_CTRL_HWO ? 'H' : 'h',
+		__entry->ctrl & DWC3_TRB_CTRL_LST ? 'L' : 'l',
+		__entry->ctrl & DWC3_TRB_CTRL_CHN ? 'C' : 'c',
+		__entry->ctrl & DWC3_TRB_CTRL_CSP ? 'S' : 's',
+		__entry->ctrl & DWC3_TRB_CTRL_ISP_IMI ? 'S' : 's',
+		__entry->ctrl & DWC3_TRB_CTRL_IOC ? 'C' : 'c',
+		  dwc3_trb_type_string(DWC3_TRBCTL_TYPE(__entry->ctrl))
+	)
+);
+
+DEFINE_EVENT(dwc3_log_trb, dwc3_prepare_trb,
+	TP_PROTO(struct dwc3_ep *dep, struct dwc3_trb *trb),
+	TP_ARGS(dep, trb)
+);
+
+DEFINE_EVENT(dwc3_log_trb, dwc3_complete_trb,
+	TP_PROTO(struct dwc3_ep *dep, struct dwc3_trb *trb),
+	TP_ARGS(dep, trb)
+);
+
+DECLARE_EVENT_CLASS(dwc3_log_ep,
+	TP_PROTO(struct dwc3_ep *dep),
+	TP_ARGS(dep),
+	TP_STRUCT__entry(
+		__field(phys_addr_t, base_address)
+		__string(name, dep->name)
+		__field(unsigned int, maxpacket)
+		__field(unsigned int, maxpacket_limit)
+		__field(unsigned int, max_streams)
+		__field(unsigned int, maxburst)
+		__field(unsigned int, flags)
+		__field(unsigned int, direction)
+		__field(u8, trb_enqueue)
+		__field(u8, trb_dequeue)
+	),
+	TP_fast_assign(
+		__entry->base_address = dep->dwc->xhci_resources[0].start;
+		__assign_str(name);
+		__entry->maxpacket = dep->endpoint.maxpacket;
+		__entry->maxpacket_limit = dep->endpoint.maxpacket_limit;
+		__entry->max_streams = dep->endpoint.max_streams;
+		__entry->maxburst = dep->endpoint.maxburst;
+		__entry->flags = dep->flags;
+		__entry->direction = dep->direction;
+		__entry->trb_enqueue = dep->trb_enqueue;
+		__entry->trb_dequeue = dep->trb_dequeue;
+	),
+	TP_printk("%pa: %s: mps %d/%d streams %d burst %d ring %d/%d flags %c:%c%c%c%c:%c",
+		&__entry->base_address, __get_str(name), __entry->maxpacket,
+		__entry->maxpacket_limit, __entry->max_streams,
+		__entry->maxburst, __entry->trb_enqueue,
+		__entry->trb_dequeue,
+		__entry->flags & DWC3_EP_ENABLED ? 'E' : 'e',
+		__entry->flags & DWC3_EP_STALL ? 'S' : 's',
+		__entry->flags & DWC3_EP_WEDGE ? 'W' : 'w',
+		__entry->flags & DWC3_EP_TRANSFER_STARTED ? 'B' : 'b',
+		__entry->flags & DWC3_EP_PENDING_REQUEST ? 'P' : 'p',
+		__entry->direction ? '<' : '>'
+	)
+);
+
+DEFINE_EVENT(dwc3_log_ep, dwc3_gadget_ep_enable,
+	TP_PROTO(struct dwc3_ep *dep),
+	TP_ARGS(dep)
+);
+
+DEFINE_EVENT(dwc3_log_ep, dwc3_gadget_ep_disable,
+	TP_PROTO(struct dwc3_ep *dep),
+	TP_ARGS(dep)
+);
+
+#endif /* __DWC3_TRACE_H */
+
+/* this part has to be here */
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE trace
+
+#include <trace/define_trace.h>