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 --- include/video/display_timing.h | 105 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 105 insertions(+) create mode 100644 include/video/display_timing.h (limited to 'include/video/display_timing.h') diff --git a/include/video/display_timing.h b/include/video/display_timing.h new file mode 100644 index 000000000..37a017607 --- /dev/null +++ b/include/video/display_timing.h @@ -0,0 +1,105 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright 2012 Steffen Trumtrar + * + * description of display timings + */ + +#ifndef __LINUX_DISPLAY_TIMING_H +#define __LINUX_DISPLAY_TIMING_H + +#include +#include + +enum display_flags { + DISPLAY_FLAGS_HSYNC_LOW = BIT(0), + DISPLAY_FLAGS_HSYNC_HIGH = BIT(1), + DISPLAY_FLAGS_VSYNC_LOW = BIT(2), + DISPLAY_FLAGS_VSYNC_HIGH = BIT(3), + + /* data enable flag */ + DISPLAY_FLAGS_DE_LOW = BIT(4), + DISPLAY_FLAGS_DE_HIGH = BIT(5), + /* drive data on pos. edge */ + DISPLAY_FLAGS_PIXDATA_POSEDGE = BIT(6), + /* drive data on neg. edge */ + DISPLAY_FLAGS_PIXDATA_NEGEDGE = BIT(7), + DISPLAY_FLAGS_INTERLACED = BIT(8), + DISPLAY_FLAGS_DOUBLESCAN = BIT(9), + DISPLAY_FLAGS_DOUBLECLK = BIT(10), + /* drive sync on pos. edge */ + DISPLAY_FLAGS_SYNC_POSEDGE = BIT(11), + /* drive sync on neg. edge */ + DISPLAY_FLAGS_SYNC_NEGEDGE = BIT(12), +}; + +/* + * A single signal can be specified via a range of minimal and maximal values + * with a typical value, that lies somewhere inbetween. + */ +struct timing_entry { + u32 min; + u32 typ; + u32 max; +}; + +/* + * Single "mode" entry. This describes one set of signal timings a display can + * have in one setting. This struct can later be converted to struct videomode + * (see include/video/videomode.h). As each timing_entry can be defined as a + * range, one struct display_timing may become multiple struct videomodes. + * + * Example: hsync active high, vsync active low + * + * Active Video + * Video ______________________XXXXXXXXXXXXXXXXXXXXXX_____________________ + * |<- sync ->|<- back ->|<----- active ----->|<- front ->|<- sync.. + * | | porch | | porch | + * + * HSync _|¯¯¯¯¯¯¯¯¯¯|___________________________________________|¯¯¯¯¯¯¯¯¯ + * + * VSync ¯|__________|¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯|_________ + */ +struct display_timing { + struct timing_entry pixelclock; + + struct timing_entry hactive; /* hor. active video */ + struct timing_entry hfront_porch; /* hor. front porch */ + struct timing_entry hback_porch; /* hor. back porch */ + struct timing_entry hsync_len; /* hor. sync len */ + + struct timing_entry vactive; /* ver. active video */ + struct timing_entry vfront_porch; /* ver. front porch */ + struct timing_entry vback_porch; /* ver. back porch */ + struct timing_entry vsync_len; /* ver. sync len */ + + enum display_flags flags; /* display flags */ +}; + +/* + * This describes all timing settings a display provides. + * The native_mode is the default setting for this display. + * Drivers that can handle multiple videomodes should work with this struct and + * convert each entry to the desired end result. + */ +struct display_timings { + unsigned int num_timings; + unsigned int native_mode; + + struct display_timing **timings; +}; + +/* get one entry from struct display_timings */ +static inline struct display_timing *display_timings_get(const struct + display_timings *disp, + unsigned int index) +{ + if (disp->num_timings > index) + return disp->timings[index]; + else + return NULL; +} + +void display_timings_release(struct display_timings *disp); + +#endif -- cgit v1.3.1