Messages in this thread Patch in this message | | | From | Thomas Gleixner <> | Subject | [patch 09/38] objtool: Add .sym_sites section | Date | Sun, 17 Jul 2022 01:17:24 +0200 (CEST) |
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From: Peter Zijlstra <peterz@infradead.org>
In preparation for call depth tracking provide a section which collects all all !init symbols to generate thunks for.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- arch/x86/kernel/vmlinux.lds.S | 7 +++++ tools/objtool/check.c | 55 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 62 insertions(+)
--- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -297,6 +297,13 @@ SECTIONS *(.call_sites) __call_sites_end = .; } + + . = ALIGN(8); + .sym_sites : AT(ADDR(.sym_sites) - LOAD_OFFSET) { + __sym_sites = .; + *(.sym_sites) + __sym_sites_end = .; + } #endif #ifdef CONFIG_X86_KERNEL_IBT --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -941,6 +941,56 @@ static int create_direct_call_sections(s return 0; } +static int create_sym_thunk_sections(struct objtool_file *file) +{ + struct section *sec, *s; + struct symbol *sym; + unsigned int *loc; + int idx; + + sec = find_section_by_name(file->elf, ".sym_sites"); + if (sec) { + INIT_LIST_HEAD(&file->call_list); + WARN("file already has .sym_sites section, skipping"); + return 0; + } + + idx = 0; + for_each_sec(file, s) { + if (!s->text || s->init) + continue; + + list_for_each_entry(sym, &s->symbol_list, list) + idx++; + } + + sec = elf_create_section(file->elf, ".sym_sites", 0, sizeof(unsigned int), idx); + if (!sec) + return -1; + + idx = 0; + for_each_sec(file, s) { + if (!s->text || s->init) + continue; + + list_for_each_entry(sym, &s->symbol_list, list) { + + loc = (unsigned int *)sec->data->d_buf + idx; + memset(loc, 0, sizeof(unsigned int)); + + if (elf_add_reloc_to_insn(file->elf, sec, + idx * sizeof(unsigned int), + R_X86_64_PC32, + s, sym->offset)) + return -1; + + idx++; + } + } + + return 0; +} + /* * Warnings shouldn't be reported for ignored functions. */ @@ -4326,6 +4376,11 @@ int check(struct objtool_file *file) if (ret < 0) goto out; warnings += ret; + + ret = create_sym_thunk_sections(file); + if (ret < 0) + goto out; + warnings += ret; } if (opts.mcount) {
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