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 --- lib/fw_table.c | 232 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 232 insertions(+) create mode 100644 lib/fw_table.c (limited to 'lib/fw_table.c') diff --git a/lib/fw_table.c b/lib/fw_table.c new file mode 100644 index 000000000..162918144 --- /dev/null +++ b/lib/fw_table.c @@ -0,0 +1,232 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * fw_tables.c - Parsing support for ACPI and ACPI-like tables provided by + * platform or device firmware + * + * Copyright (C) 2001 Paul Diefenbaugh + * Copyright (C) 2023 Intel Corp. + */ +#include +#include +#include +#include +#include +#include +#include + +enum acpi_subtable_type { + ACPI_SUBTABLE_COMMON, + ACPI_SUBTABLE_HMAT, + ACPI_SUBTABLE_PRMT, + ACPI_SUBTABLE_CEDT, + CDAT_SUBTABLE, +}; + +struct acpi_subtable_entry { + union acpi_subtable_headers *hdr; + enum acpi_subtable_type type; +}; + +static unsigned long __init_or_fwtbl_lib +acpi_get_entry_type(struct acpi_subtable_entry *entry) +{ + switch (entry->type) { + case ACPI_SUBTABLE_COMMON: + return entry->hdr->common.type; + case ACPI_SUBTABLE_HMAT: + return entry->hdr->hmat.type; + case ACPI_SUBTABLE_PRMT: + return 0; + case ACPI_SUBTABLE_CEDT: + return entry->hdr->cedt.type; + case CDAT_SUBTABLE: + return entry->hdr->cdat.type; + } + return 0; +} + +static unsigned long __init_or_fwtbl_lib +acpi_get_entry_length(struct acpi_subtable_entry *entry) +{ + switch (entry->type) { + case ACPI_SUBTABLE_COMMON: + return entry->hdr->common.length; + case ACPI_SUBTABLE_HMAT: + return entry->hdr->hmat.length; + case ACPI_SUBTABLE_PRMT: + return entry->hdr->prmt.length; + case ACPI_SUBTABLE_CEDT: + return entry->hdr->cedt.length; + case CDAT_SUBTABLE: { + __le16 length = (__force __le16)entry->hdr->cdat.length; + + return le16_to_cpu(length); + } + } + return 0; +} + +static unsigned long __init_or_fwtbl_lib +acpi_get_subtable_header_length(struct acpi_subtable_entry *entry) +{ + switch (entry->type) { + case ACPI_SUBTABLE_COMMON: + return sizeof(entry->hdr->common); + case ACPI_SUBTABLE_HMAT: + return sizeof(entry->hdr->hmat); + case ACPI_SUBTABLE_PRMT: + return sizeof(entry->hdr->prmt); + case ACPI_SUBTABLE_CEDT: + return sizeof(entry->hdr->cedt); + case CDAT_SUBTABLE: + return sizeof(entry->hdr->cdat); + } + return 0; +} + +static enum acpi_subtable_type __init_or_fwtbl_lib +acpi_get_subtable_type(char *id) +{ + if (strncmp(id, ACPI_SIG_HMAT, 4) == 0) + return ACPI_SUBTABLE_HMAT; + if (strncmp(id, ACPI_SIG_PRMT, 4) == 0) + return ACPI_SUBTABLE_PRMT; + if (strncmp(id, ACPI_SIG_CEDT, 4) == 0) + return ACPI_SUBTABLE_CEDT; + if (strncmp(id, ACPI_SIG_CDAT, 4) == 0) + return CDAT_SUBTABLE; + return ACPI_SUBTABLE_COMMON; +} + +static unsigned long __init_or_fwtbl_lib +acpi_table_get_length(enum acpi_subtable_type type, + union fw_table_header *header) +{ + if (type == CDAT_SUBTABLE) { + __le32 length = (__force __le32)header->cdat.length; + + return le32_to_cpu(length); + } + + return header->acpi.length; +} + +static __init_or_fwtbl_lib int call_handler(struct acpi_subtable_proc *proc, + union acpi_subtable_headers *hdr, + unsigned long end) +{ + if (proc->handler) + return proc->handler(hdr, end); + if (proc->handler_arg) + return proc->handler_arg(hdr, proc->arg, end); + return -EINVAL; +} + +/** + * acpi_parse_entries_array - for each proc_num find a suitable subtable + * + * @id: table id (for debugging purposes) + * @table_size: size of the root table + * @max_length: maximum size of the table (ignore if 0) + * @table_header: where does the table start? + * @proc: array of acpi_subtable_proc struct containing entry id + * and associated handler with it + * @proc_num: how big proc is? + * @max_entries: how many entries can we process? + * + * For each proc_num find a subtable with proc->id and run proc->handler + * on it. Assumption is that there's only single handler for particular + * entry id. + * + * The table_size is not the size of the complete ACPI table (the length + * field in the header struct), but only the size of the root table; i.e., + * the offset from the very first byte of the complete ACPI table, to the + * first byte of the very first subtable. + * + * On success returns sum of all matching entries for all proc handlers. + * Otherwise, -ENODEV or -EINVAL is returned. + */ +int __init_or_fwtbl_lib +acpi_parse_entries_array(char *id, unsigned long table_size, + union fw_table_header *table_header, + unsigned long max_length, + struct acpi_subtable_proc *proc, + int proc_num, unsigned int max_entries) +{ + unsigned long table_len, table_end, subtable_len, entry_len; + struct acpi_subtable_entry entry; + enum acpi_subtable_type type; + int count = 0; + int i; + + type = acpi_get_subtable_type(id); + table_len = acpi_table_get_length(type, table_header); + if (max_length && max_length < table_len) + table_len = max_length; + table_end = (unsigned long)table_header + table_len; + + /* Parse all entries looking for a match. */ + + entry.type = type; + entry.hdr = (union acpi_subtable_headers *) + ((unsigned long)table_header + table_size); + subtable_len = acpi_get_subtable_header_length(&entry); + + while (((unsigned long)entry.hdr) + subtable_len < table_end) { + for (i = 0; i < proc_num; i++) { + if (acpi_get_entry_type(&entry) != proc[i].id) + continue; + + if (!max_entries || count < max_entries) + if (call_handler(&proc[i], entry.hdr, table_end)) + return -EINVAL; + + proc[i].count++; + count++; + break; + } + + /* + * If entry->length is 0, break from this loop to avoid + * infinite loop. + */ + entry_len = acpi_get_entry_length(&entry); + if (entry_len == 0) { + pr_err("[%4.4s:0x%02x] Invalid zero length\n", id, proc->id); + return -EINVAL; + } + + entry.hdr = (union acpi_subtable_headers *) + ((unsigned long)entry.hdr + entry_len); + } + + if (max_entries && count > max_entries) { + pr_warn("[%4.4s:0x%02x] ignored %i entries of %i found\n", + id, proc->id, count - max_entries, count); + } + + return count; +} + +int __init_or_fwtbl_lib +cdat_table_parse(enum acpi_cdat_type type, + acpi_tbl_entry_handler_arg handler_arg, + void *arg, + struct acpi_table_cdat *table_header, + unsigned long length) +{ + struct acpi_subtable_proc proc = { + .id = type, + .handler_arg = handler_arg, + .arg = arg, + }; + + if (!table_header) + return -EINVAL; + + return acpi_parse_entries_array(ACPI_SIG_CDAT, + sizeof(struct acpi_table_cdat), + (union fw_table_header *)table_header, + length, &proc, 1, 0); +} +EXPORT_SYMBOL_FWTBL_LIB(cdat_table_parse); -- cgit v1.3.1