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| author | Miguel Ojeda <ojeda@kernel.org> | 2026-08-16 15:32:33 +0200 |
|---|---|---|
| committer | Miguel Ojeda <ojeda@kernel.org> | 2026-08-23 21:27:17 +0200 |
| commit | 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 (patch) | |
| tree | 93a1ed1d337bc53adf1e572c2586d347703b286e /samples/vfio-mdev/mdpy-defs.h | |
| download | linux-stable-5febf432df1cfa5b25d99b54c32103fafbdd0eb9.tar.gz linux-stable-5febf432df1cfa5b25d99b54c32103fafbdd0eb9.zip | |
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>
Diffstat (limited to 'samples/vfio-mdev/mdpy-defs.h')
| -rw-r--r-- | samples/vfio-mdev/mdpy-defs.h | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/samples/vfio-mdev/mdpy-defs.h b/samples/vfio-mdev/mdpy-defs.h new file mode 100644 index 000000000..961c55ec3 --- /dev/null +++ b/samples/vfio-mdev/mdpy-defs.h @@ -0,0 +1,22 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Simple pci display device. + * + * Framebuffer memory is pci bar 0. + * Configuration (read-only) is in pci config space. + * Format field uses drm fourcc codes. + * ATM only DRM_FORMAT_XRGB8888 is supported. + */ + +/* pci ids */ +#define MDPY_PCI_VENDOR_ID PCI_VENDOR_ID_REDHAT +#define MDPY_PCI_DEVICE_ID 0x000f +#define MDPY_PCI_SUBVENDOR_ID PCI_SUBVENDOR_ID_REDHAT_QUMRANET +#define MDPY_PCI_SUBDEVICE_ID PCI_SUBDEVICE_ID_QEMU + +/* pci cfg space offsets for fb config (dword) */ +#define MDPY_VENDORCAP_OFFSET 0x40 +#define MDPY_VENDORCAP_SIZE 0x10 +#define MDPY_FORMAT_OFFSET (MDPY_VENDORCAP_OFFSET + 0x04) +#define MDPY_WIDTH_OFFSET (MDPY_VENDORCAP_OFFSET + 0x08) +#define MDPY_HEIGHT_OFFSET (MDPY_VENDORCAP_OFFSET + 0x0c) |