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 --- arch/powerpc/boot/libfdt-wrapper.c | 185 +++++++++++++++++++++++++++++++++++++ 1 file changed, 185 insertions(+) create mode 100644 arch/powerpc/boot/libfdt-wrapper.c (limited to 'arch/powerpc/boot/libfdt-wrapper.c') diff --git a/arch/powerpc/boot/libfdt-wrapper.c b/arch/powerpc/boot/libfdt-wrapper.c new file mode 100644 index 000000000..217d0d7a6 --- /dev/null +++ b/arch/powerpc/boot/libfdt-wrapper.c @@ -0,0 +1,185 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * This file does the necessary interface mapping between the bootwrapper + * device tree operations and the interface provided by shared source + * files flatdevicetree.[ch]. + * + * Copyright 2007 David Gibson, IBM Corporation. + */ + +#include +#include +#include +#include +#include "ops.h" + +#define DEBUG 0 +#define BAD_ERROR(err) (((err) < 0) \ + && ((err) != -FDT_ERR_NOTFOUND) \ + && ((err) != -FDT_ERR_EXISTS)) + +#define check_err(err) \ + ({ \ + if (BAD_ERROR(err) || ((err < 0) && DEBUG)) \ + printf("%s():%d %s\n\r", __func__, __LINE__, \ + fdt_strerror(err)); \ + if (BAD_ERROR(err)) \ + exit(); \ + (err < 0) ? -1 : 0; \ + }) + +#define offset_devp(off) \ + ({ \ + unsigned long _offset = (off); \ + check_err(_offset) ? NULL : (void *)(_offset+1); \ + }) + +#define devp_offset_find(devp) (((unsigned long)(devp))-1) +#define devp_offset(devp) (devp ? ((unsigned long)(devp))-1 : 0) + +static void *fdt; +static void *buf; /* = NULL */ + +#define EXPAND_GRANULARITY 1024 + +static void expand_buf(int minexpand) +{ + int size = fdt_totalsize(fdt); + int rc; + + size = _ALIGN(size + minexpand, EXPAND_GRANULARITY); + buf = platform_ops.realloc(buf, size); + if (!buf) + fatal("Couldn't find %d bytes to expand device tree\n\r", size); + rc = fdt_open_into(fdt, buf, size); + if (rc != 0) + fatal("Couldn't expand fdt into new buffer: %s\n\r", + fdt_strerror(rc)); + + fdt = buf; +} + +static void *fdt_wrapper_finddevice(const char *path) +{ + return offset_devp(fdt_path_offset(fdt, path)); +} + +static int fdt_wrapper_getprop(const void *devp, const char *name, + void *buf, const int buflen) +{ + const void *p; + int len; + + p = fdt_getprop(fdt, devp_offset(devp), name, &len); + if (!p) + return check_err(len); + memcpy(buf, p, min(len, buflen)); + return len; +} + +static int fdt_wrapper_setprop(const void *devp, const char *name, + const void *buf, const int len) +{ + int rc; + + rc = fdt_setprop(fdt, devp_offset(devp), name, buf, len); + if (rc == -FDT_ERR_NOSPACE) { + expand_buf(len + 16); + rc = fdt_setprop(fdt, devp_offset(devp), name, buf, len); + } + + return check_err(rc); +} + +static int fdt_wrapper_del_node(const void *devp) +{ + return fdt_del_node(fdt, devp_offset(devp)); +} + +static void *fdt_wrapper_get_parent(const void *devp) +{ + return offset_devp(fdt_parent_offset(fdt, devp_offset(devp))); +} + +static void *fdt_wrapper_create_node(const void *devp, const char *name) +{ + int offset; + + offset = fdt_add_subnode(fdt, devp_offset(devp), name); + if (offset == -FDT_ERR_NOSPACE) { + expand_buf(strlen(name) + 16); + offset = fdt_add_subnode(fdt, devp_offset(devp), name); + } + + return offset_devp(offset); +} + +static void *fdt_wrapper_find_node_by_prop_value(const void *prev, + const char *name, + const char *val, + int len) +{ + int offset = fdt_node_offset_by_prop_value(fdt, devp_offset_find(prev), + name, val, len); + return offset_devp(offset); +} + +static void *fdt_wrapper_find_node_by_compatible(const void *prev, + const char *val) +{ + int offset = fdt_node_offset_by_compatible(fdt, devp_offset_find(prev), + val); + return offset_devp(offset); +} + +static char *fdt_wrapper_get_path(const void *devp, char *buf, int len) +{ + int rc; + + rc = fdt_get_path(fdt, devp_offset(devp), buf, len); + if (check_err(rc)) + return NULL; + return buf; +} + +static unsigned long fdt_wrapper_finalize(void) +{ + int rc; + + rc = fdt_pack(fdt); + if (rc != 0) + fatal("Couldn't pack flat tree: %s\n\r", + fdt_strerror(rc)); + return (unsigned long)fdt; +} + +void fdt_init(void *blob) +{ + int err; + int bufsize; + + dt_ops.finddevice = fdt_wrapper_finddevice; + dt_ops.getprop = fdt_wrapper_getprop; + dt_ops.setprop = fdt_wrapper_setprop; + dt_ops.get_parent = fdt_wrapper_get_parent; + dt_ops.create_node = fdt_wrapper_create_node; + dt_ops.find_node_by_prop_value = fdt_wrapper_find_node_by_prop_value; + dt_ops.find_node_by_compatible = fdt_wrapper_find_node_by_compatible; + dt_ops.del_node = fdt_wrapper_del_node; + dt_ops.get_path = fdt_wrapper_get_path; + dt_ops.finalize = fdt_wrapper_finalize; + + /* Make sure the dt blob is the right version and so forth */ + fdt = blob; + bufsize = fdt_totalsize(fdt) + EXPAND_GRANULARITY; + buf = malloc(bufsize); + if(!buf) + fatal("malloc failed. can't relocate the device tree\n\r"); + + err = fdt_open_into(fdt, buf, bufsize); + + if (err != 0) + fatal("fdt_init(): %s\n\r", fdt_strerror(err)); + + fdt = buf; +} -- cgit v1.3.1