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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120// SPDX-License-Identifier: GPL-2.0-or-later/* * Emit the .klp.symid table which allows "objtool klp diff" to reliably * disambiguate duplicate-named local symbols in vmlinux. * * Livepatch identifies a duplicate-named symbol by its position (sympos) * among the same-named kallsyms entries, counted in ascending address order * in the final linked vmlinux. That order can't be derived from vmlinux.o * alone: the final link reorders sub-sections (.text.unlikely*, .data..*, * etc). * * Bridge the gap with a table which survives the final link: a single * non-alloc section containing an array of { id, addr } entries, where * 'id' is a unique counter identifier and 'addr' has a relocation to the * symbol. The linker copies 'id' verbatim and resolves 'addr' to the symbol's * final address. * * The table is only emitted for vmlinux.o, and only when klp-build asks for it * with KLP_SYMIDS=1, which adds --klp-symids to the vmlinux.o objtool run. * * It can't survive --gc-sections, which sweeps the whole section; klp-build * rejects CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. */#include <linux/string.h>
#include <objtool/objtool.h>#include <objtool/warn.h>#include <objtool/endianness.h>#include <objtool/klp.h>
static const char * const discarded_secs[] = { ".discard", ".exitcall.exit", ".modinfo", ".no_trim_symbol", "__tracepoint_check",};
static bool discarded_sec(struct section *sec){ if (!(sec->sh.sh_flags & SHF_ALLOC)) return true;
for (int i = 0; i < ARRAY_SIZE(discarded_secs); i++) if (strstarts(sec->name, discarded_secs[i])) return true;
return false;}
static bool symid_needed(struct elf *elf, struct symbol *sym){ struct symbol *s;
if (!is_local_sym(sym) || is_undef_sym(sym)) return false;
if (!is_func_sym(sym) && !is_object_sym(sym)) return false;
if (is_prefix_func(sym)) return false;
if (discarded_sec(sym->sec)) return false;
for_each_sym_by_name(elf, sym->name, s) { if (s == sym || is_sec_sym(s) || is_file_sym(s) || is_undef_sym(s)) continue; return true; }
return false;}
int klp_create_symid_sections(struct objtool_file *file){ struct elf *elf = file->elf; struct klp_symid *symids; struct section *sec; struct symbol *sym; u64 nr = 0, i = 0;
if (!str_ends_with(objname, "vmlinux.o")) return 0;
for_each_sym(elf, sym) if (symid_needed(elf, sym)) nr++;
if (!nr) return 0;
sec = elf_create_section(elf, KLP_SYMID_SEC, 0, sizeof(struct klp_symid), SHT_PROGBITS, 8, 0); if (!sec) return -1;
symids = elf_add_data(elf, sec, NULL, nr * sizeof(struct klp_symid)); if (!symids) return -1;
for_each_sym(elf, sym) { if (!symid_needed(elf, sym)) continue;
symids[i].id = bswap_if_needed(elf, i);
if (!elf_create_reloc(elf, sec, i * sizeof(struct klp_symid) + offsetof(struct klp_symid, addr), sym, 0, R_ABS64)) return -1;
i++; }
return 0;}