mirror of https://github.com/torvalds/linux.git
objtool/klp: Add --checksum option to generate per-function checksums
In preparation for the objtool klp diff subcommand, add a command-line option to generate a unique checksum for each function. This will enable detection of functions which have changed between two versions of an object file. Acked-by: Petr Mladek <pmladek@suse.com> Tested-by: Joe Lawrence <joe.lawrence@redhat.com> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
This commit is contained in:
Josh Poimboeuf
parent
f6b740ef5f
commit
0d83da43b1
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@ -2,6 +2,27 @@
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include ../scripts/Makefile.include
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include ../scripts/Makefile.arch
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ifeq ($(SRCARCH),x86)
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BUILD_ORC := y
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ARCH_HAS_KLP := y
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endif
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ifeq ($(SRCARCH),loongarch)
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BUILD_ORC := y
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endif
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ifeq ($(ARCH_HAS_KLP),y)
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HAVE_XXHASH = $(shell echo "int main() {}" | \
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$(HOSTCC) -xc - -o /dev/null -lxxhash 2> /dev/null && echo y || echo n)
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ifeq ($(HAVE_XXHASH),y)
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LIBXXHASH_CFLAGS := $(shell $(HOSTPKG_CONFIG) libxxhash --cflags 2>/dev/null) \
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-DBUILD_KLP
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LIBXXHASH_LIBS := $(shell $(HOSTPKG_CONFIG) libxxhash --libs 2>/dev/null || echo -lxxhash)
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endif
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endif
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export BUILD_ORC
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ifeq ($(srctree),)
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srctree := $(patsubst %/,%,$(dir $(CURDIR)))
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srctree := $(patsubst %/,%,$(dir $(srctree)))
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@ -36,10 +57,10 @@ INCLUDES := -I$(srctree)/tools/include \
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-I$(srctree)/tools/objtool/arch/$(SRCARCH)/include \
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-I$(LIBSUBCMD_OUTPUT)/include
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OBJTOOL_CFLAGS := -std=gnu11 -fomit-frame-pointer -O2 -g \
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$(WARNINGS) $(INCLUDES) $(LIBELF_FLAGS) $(HOSTCFLAGS)
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OBJTOOL_CFLAGS := -std=gnu11 -fomit-frame-pointer -O2 -g $(WARNINGS) \
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$(INCLUDES) $(LIBELF_FLAGS) $(LIBXXHASH_CFLAGS) $(HOSTCFLAGS)
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OBJTOOL_LDFLAGS := $(LIBSUBCMD) $(LIBELF_LIBS) $(HOSTLDFLAGS)
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OBJTOOL_LDFLAGS := $(LIBSUBCMD) $(LIBELF_LIBS) $(LIBXXHASH_LIBS) $(HOSTLDFLAGS)
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# Allow old libelf to be used:
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elfshdr := $(shell echo '$(pound)include <libelf.h>' | $(HOSTCC) $(OBJTOOL_CFLAGS) -x c -E - 2>/dev/null | grep elf_getshdr)
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@ -51,17 +72,6 @@ HOST_OVERRIDES := CC="$(HOSTCC)" LD="$(HOSTLD)" AR="$(HOSTAR)"
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AWK = awk
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MKDIR = mkdir
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BUILD_ORC := n
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ifeq ($(SRCARCH),x86)
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BUILD_ORC := y
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endif
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ifeq ($(SRCARCH),loongarch)
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BUILD_ORC := y
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endif
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export BUILD_ORC
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export srctree OUTPUT CFLAGS SRCARCH AWK
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include $(srctree)/tools/build/Makefile.include
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@ -73,6 +73,7 @@ static int parse_hacks(const struct option *opt, const char *str, int unset)
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static const struct option check_options[] = {
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OPT_GROUP("Actions:"),
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OPT_BOOLEAN(0, "checksum", &opts.checksum, "generate per-function checksums"),
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OPT_BOOLEAN(0, "cfi", &opts.cfi, "annotate kernel control flow integrity (kCFI) function preambles"),
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OPT_CALLBACK_OPTARG('h', "hacks", NULL, NULL, "jump_label,noinstr,skylake", "patch toolchain bugs/limitations", parse_hacks),
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OPT_BOOLEAN('i', "ibt", &opts.ibt, "validate and annotate IBT"),
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@ -160,7 +161,15 @@ static bool opts_valid(void)
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return false;
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}
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if (opts.hack_jump_label ||
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#ifndef BUILD_KLP
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if (opts.checksum) {
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ERROR("--checksum not supported; install xxhash-devel and recompile");
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return false;
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}
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#endif
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if (opts.checksum ||
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opts.hack_jump_label ||
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opts.hack_noinstr ||
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opts.ibt ||
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opts.mcount ||
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@ -14,6 +14,7 @@
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#include <objtool/check.h>
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#include <objtool/special.h>
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#include <objtool/warn.h>
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#include <objtool/checksum.h>
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#include <linux/objtool_types.h>
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#include <linux/hashtable.h>
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@ -971,6 +972,59 @@ static int create_direct_call_sections(struct objtool_file *file)
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return 0;
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}
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#ifdef BUILD_KLP
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static int create_sym_checksum_section(struct objtool_file *file)
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{
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struct section *sec;
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struct symbol *sym;
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unsigned int idx = 0;
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struct sym_checksum *checksum;
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size_t entsize = sizeof(struct sym_checksum);
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sec = find_section_by_name(file->elf, ".discard.sym_checksum");
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if (sec) {
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if (!opts.dryrun)
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WARN("file already has .discard.sym_checksum section, skipping");
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return 0;
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}
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for_each_sym(file->elf, sym)
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if (sym->csum.checksum)
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idx++;
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if (!idx)
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return 0;
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sec = elf_create_section_pair(file->elf, ".discard.sym_checksum", entsize,
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idx, idx);
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if (!sec)
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return -1;
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idx = 0;
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for_each_sym(file->elf, sym) {
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if (!sym->csum.checksum)
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continue;
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if (!elf_init_reloc(file->elf, sec->rsec, idx, idx * entsize,
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sym, 0, R_TEXT64))
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return -1;
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checksum = (struct sym_checksum *)sec->data->d_buf + idx;
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checksum->addr = 0; /* reloc */
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checksum->checksum = sym->csum.checksum;
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mark_sec_changed(file->elf, sec, true);
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idx++;
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}
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return 0;
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}
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#else
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static int create_sym_checksum_section(struct objtool_file *file) { return -EINVAL; }
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#endif
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/*
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* Warnings shouldn't be reported for ignored functions.
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*/
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@ -1748,6 +1802,7 @@ static int handle_group_alt(struct objtool_file *file,
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nop->type = INSN_NOP;
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nop->sym = orig_insn->sym;
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nop->alt_group = new_alt_group;
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nop->fake = 1;
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}
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if (!special_alt->new_len) {
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@ -2517,6 +2572,14 @@ static void mark_holes(struct objtool_file *file)
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}
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}
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static bool validate_branch_enabled(void)
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{
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return opts.stackval ||
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opts.orc ||
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opts.uaccess ||
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opts.checksum;
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}
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static int decode_sections(struct objtool_file *file)
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{
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mark_rodata(file);
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@ -2545,8 +2608,7 @@ static int decode_sections(struct objtool_file *file)
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* Must be before add_jump_destinations(), which depends on 'func'
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* being set for alternatives, to enable proper sibling call detection.
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*/
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if (opts.stackval || opts.orc || opts.uaccess || opts.noinstr ||
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opts.hack_jump_label) {
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if (validate_branch_enabled() || opts.noinstr || opts.hack_jump_label) {
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if (add_special_section_alts(file))
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return -1;
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}
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@ -3518,6 +3580,50 @@ static bool skip_alt_group(struct instruction *insn)
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return alt_insn->type == INSN_CLAC || alt_insn->type == INSN_STAC;
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}
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static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
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struct instruction *insn)
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{
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struct reloc *reloc = insn_reloc(file, insn);
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unsigned long offset;
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struct symbol *sym;
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if (insn->fake)
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return;
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checksum_update(func, insn, insn->sec->data->d_buf + insn->offset, insn->len);
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if (!reloc) {
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struct symbol *call_dest = insn_call_dest(insn);
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if (call_dest)
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checksum_update(func, insn, call_dest->demangled_name,
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strlen(call_dest->demangled_name));
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return;
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}
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sym = reloc->sym;
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offset = arch_insn_adjusted_addend(insn, reloc);
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if (is_string_sec(sym->sec)) {
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char *str;
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str = sym->sec->data->d_buf + sym->offset + offset;
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checksum_update(func, insn, str, strlen(str));
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return;
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}
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if (is_sec_sym(sym)) {
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sym = find_symbol_containing(reloc->sym->sec, offset);
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if (!sym)
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return;
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offset -= sym->offset;
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}
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checksum_update(func, insn, sym->demangled_name, strlen(sym->demangled_name));
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checksum_update(func, insn, &offset, sizeof(offset));
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}
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/*
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* Follow the branch starting at the given instruction, and recursively follow
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* any other branches (jumps). Meanwhile, track the frame pointer state at
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@ -3538,6 +3644,9 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
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while (1) {
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next_insn = next_insn_to_validate(file, insn);
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if (opts.checksum && func && insn->sec)
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checksum_update_insn(file, func, insn);
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if (func && insn_func(insn) && func != insn_func(insn)->pfunc) {
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/* Ignore KCFI type preambles, which always fall through */
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if (is_prefix_func(func))
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@ -3787,7 +3896,13 @@ static int validate_unwind_hint(struct objtool_file *file,
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struct insn_state *state)
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{
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if (insn->hint && !insn->visited) {
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int ret = validate_branch(file, insn_func(insn), insn, *state);
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struct symbol *func = insn_func(insn);
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int ret;
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if (opts.checksum)
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checksum_init(func);
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ret = validate_branch(file, func, insn, *state);
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if (ret)
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BT_INSN(insn, "<=== (hint)");
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return ret;
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@ -4166,6 +4281,7 @@ static int validate_symbol(struct objtool_file *file, struct section *sec,
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struct symbol *sym, struct insn_state *state)
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{
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struct instruction *insn;
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struct symbol *func;
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int ret;
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if (!sym->len) {
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@ -4183,9 +4299,18 @@ static int validate_symbol(struct objtool_file *file, struct section *sec,
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if (opts.uaccess)
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state->uaccess = sym->uaccess_safe;
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ret = validate_branch(file, insn_func(insn), insn, *state);
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func = insn_func(insn);
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if (opts.checksum)
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checksum_init(func);
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ret = validate_branch(file, func, insn, *state);
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if (ret)
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BT_INSN(insn, "<=== (sym)");
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if (opts.checksum)
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checksum_finish(func);
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return ret;
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}
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@ -4703,7 +4828,7 @@ int check(struct objtool_file *file)
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if (opts.retpoline)
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warnings += validate_retpoline(file);
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if (opts.stackval || opts.orc || opts.uaccess) {
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if (validate_branch_enabled()) {
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int w = 0;
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w += validate_functions(file);
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@ -4782,6 +4907,12 @@ int check(struct objtool_file *file)
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if (opts.noabs)
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warnings += check_abs_references(file);
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if (opts.checksum) {
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ret = create_sym_checksum_section(file);
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if (ret)
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goto out;
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}
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if (opts.orc && nr_insns) {
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ret = orc_create(file);
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if (ret)
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@ -17,6 +17,7 @@
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#include <unistd.h>
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#include <errno.h>
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#include <libgen.h>
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#include <ctype.h>
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#include <linux/interval_tree_generic.h>
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#include <objtool/builtin.h>
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#include <objtool/elf.h>
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@ -412,7 +413,38 @@ static int read_sections(struct elf *elf)
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return 0;
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}
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static void elf_add_symbol(struct elf *elf, struct symbol *sym)
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static const char *demangle_name(struct symbol *sym)
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{
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char *str;
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if (!is_local_sym(sym))
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return sym->name;
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if (!is_func_sym(sym) && !is_object_sym(sym))
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return sym->name;
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if (!strstarts(sym->name, "__UNIQUE_ID_") && !strchr(sym->name, '.'))
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return sym->name;
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str = strdup(sym->name);
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if (!str) {
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ERROR_GLIBC("strdup");
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return NULL;
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}
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for (int i = strlen(str) - 1; i >= 0; i--) {
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char c = str[i];
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if (!isdigit(c) && c != '.') {
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str[i + 1] = '\0';
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break;
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}
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};
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return str;
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}
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static int elf_add_symbol(struct elf *elf, struct symbol *sym)
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{
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struct list_head *entry;
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struct rb_node *pnode;
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@ -456,6 +488,12 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
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if (is_func_sym(sym) && strstr(sym->name, ".cold"))
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sym->cold = 1;
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sym->pfunc = sym->cfunc = sym;
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sym->demangled_name = demangle_name(sym);
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if (!sym->demangled_name)
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return -1;
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return 0;
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}
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static int read_symbols(struct elf *elf)
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@ -529,7 +567,8 @@ static int read_symbols(struct elf *elf)
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} else
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sym->sec = find_section_by_index(elf, 0);
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elf_add_symbol(elf, sym);
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if (elf_add_symbol(elf, sym))
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return -1;
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}
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if (opts.stats) {
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@ -867,7 +906,8 @@ struct symbol *elf_create_symbol(struct elf *elf, const char *name,
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mark_sec_changed(elf, symtab_shndx, true);
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}
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elf_add_symbol(elf, sym);
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if (elf_add_symbol(elf, sym))
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return NULL;
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return sym;
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}
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@ -9,12 +9,15 @@
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struct opts {
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/* actions: */
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bool cfi;
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bool checksum;
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bool dump_orc;
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bool hack_jump_label;
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bool hack_noinstr;
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bool hack_skylake;
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bool ibt;
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bool mcount;
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bool noabs;
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bool noinstr;
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bool orc;
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bool retpoline;
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@ -25,8 +28,6 @@ struct opts {
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bool static_call;
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bool uaccess;
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int prefix;
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bool cfi;
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bool noabs;
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/* options: */
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bool backtrace;
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@ -65,8 +65,9 @@ struct instruction {
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unret : 1,
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visited : 4,
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no_reloc : 1,
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hole : 1;
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/* 10 bit hole */
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hole : 1,
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fake : 1;
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/* 9 bit hole */
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struct alt_group *alt_group;
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struct instruction *jump_dest;
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@ -0,0 +1,42 @@
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/* SPDX-License-Identifier: GPL-2.0-or-later */
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#ifndef _OBJTOOL_CHECKSUM_H
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#define _OBJTOOL_CHECKSUM_H
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#include <objtool/elf.h>
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#ifdef BUILD_KLP
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static inline void checksum_init(struct symbol *func)
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{
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if (func && !func->csum.state) {
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func->csum.state = XXH3_createState();
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XXH3_64bits_reset(func->csum.state);
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}
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}
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static inline void checksum_update(struct symbol *func,
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struct instruction *insn,
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const void *data, size_t size)
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{
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XXH3_64bits_update(func->csum.state, data, size);
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}
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static inline void checksum_finish(struct symbol *func)
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{
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if (func && func->csum.state) {
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func->csum.checksum = XXH3_64bits_digest(func->csum.state);
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func->csum.state = NULL;
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||||
}
|
||||
}
|
||||
|
||||
#else /* !BUILD_KLP */
|
||||
|
||||
static inline void checksum_init(struct symbol *func) {}
|
||||
static inline void checksum_update(struct symbol *func,
|
||||
struct instruction *insn,
|
||||
const void *data, size_t size) {}
|
||||
static inline void checksum_finish(struct symbol *func) {}
|
||||
|
||||
#endif /* !BUILD_KLP */
|
||||
|
||||
#endif /* _OBJTOOL_CHECKSUM_H */
|
||||
|
|
@ -0,0 +1,25 @@
|
|||
/* SPDX-License-Identifier: GPL-2.0 */
|
||||
#ifndef _OBJTOOL_CHECKSUM_TYPES_H
|
||||
#define _OBJTOOL_CHECKSUM_TYPES_H
|
||||
|
||||
struct sym_checksum {
|
||||
u64 addr;
|
||||
u64 checksum;
|
||||
};
|
||||
|
||||
#ifdef BUILD_KLP
|
||||
|
||||
#include <xxhash.h>
|
||||
|
||||
struct checksum {
|
||||
XXH3_state_t *state;
|
||||
XXH64_hash_t checksum;
|
||||
};
|
||||
|
||||
#else /* !BUILD_KLP */
|
||||
|
||||
struct checksum {};
|
||||
|
||||
#endif /* !BUILD_KLP */
|
||||
|
||||
#endif /* _OBJTOOL_CHECKSUM_TYPES_H */
|
||||
|
|
@ -15,6 +15,7 @@
|
|||
#include <linux/jhash.h>
|
||||
|
||||
#include <objtool/endianness.h>
|
||||
#include <objtool/checksum_types.h>
|
||||
#include <arch/elf.h>
|
||||
|
||||
#define SYM_NAME_LEN 512
|
||||
|
|
@ -61,7 +62,7 @@ struct symbol {
|
|||
struct elf_hash_node name_hash;
|
||||
GElf_Sym sym;
|
||||
struct section *sec;
|
||||
const char *name;
|
||||
const char *name, *demangled_name;
|
||||
unsigned int idx, len;
|
||||
unsigned long offset;
|
||||
unsigned long __subtree_last;
|
||||
|
|
@ -84,6 +85,7 @@ struct symbol {
|
|||
struct list_head pv_target;
|
||||
struct reloc *relocs;
|
||||
struct section *group_sec;
|
||||
struct checksum csum;
|
||||
};
|
||||
|
||||
struct reloc {
|
||||
|
|
|
|||
Loading…
Reference in New Issue