Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
objtool: Add base objtool support for livepatch modules
In preparation for klp-build, enable "classic" objtool to work on
livepatch modules:
- Avoid duplicate symbol/section warnings for prefix symbols and the
.static_call_sites and __mcount_loc sections which may have already
been extracted by klp diff.
- Add __klp_funcs to the IBT function pointer section whitelist.
- Prevent KLP symbols from getting incorrectly classified as cold
subfunctions.
Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
+53
-7
+47
-5
tools/objtool/check.c
+47
-5
tools/objtool/check.c
···
3
3
* Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
4
4
*/
5
5
6
+
#define _GNU_SOURCE /* memmem() */
6
7
#include <string.h>
7
8
#include <stdlib.h>
8
9
#include <inttypes.h>
···
612
611
return 0;
613
612
}
614
613
614
+
static bool is_livepatch_module(struct objtool_file *file)
615
+
{
616
+
struct section *sec;
617
+
618
+
if (!opts.module)
619
+
return false;
620
+
621
+
sec = find_section_by_name(file->elf, ".modinfo");
622
+
if (!sec)
623
+
return false;
624
+
625
+
return memmem(sec->data->d_buf, sec_size(sec), "\0livepatch=Y", 12);
626
+
}
627
+
615
628
static int create_static_call_sections(struct objtool_file *file)
616
629
{
617
630
struct static_call_site *site;
···
637
622
638
623
sec = find_section_by_name(file->elf, ".static_call_sites");
639
624
if (sec) {
640
-
WARN("file already has .static_call_sites section, skipping");
625
+
/*
626
+
* Livepatch modules may have already extracted the static call
627
+
* site entries to take advantage of vmlinux static call
628
+
* privileges.
629
+
*/
630
+
if (!file->klp)
631
+
WARN("file already has .static_call_sites section, skipping");
632
+
641
633
return 0;
642
634
}
643
635
···
688
666
689
667
key_sym = find_symbol_by_name(file->elf, tmp);
690
668
if (!key_sym) {
691
-
if (!opts.module) {
669
+
if (!opts.module || file->klp) {
692
670
ERROR("static_call: can't find static_call_key symbol: %s", tmp);
693
671
return -1;
694
672
}
···
907
885
908
886
sec = find_section_by_name(file->elf, "__mcount_loc");
909
887
if (sec) {
910
-
WARN("file already has __mcount_loc section, skipping");
888
+
/*
889
+
* Livepatch modules have already extracted their __mcount_loc
890
+
* entries to cover the !CONFIG_FTRACE_MCOUNT_USE_OBJTOOL case.
891
+
*/
892
+
if (!file->klp)
893
+
WARN("file already has __mcount_loc section, skipping");
894
+
911
895
return 0;
912
896
}
913
897
···
2597
2569
2598
2570
static int decode_sections(struct objtool_file *file)
2599
2571
{
2572
+
file->klp = is_livepatch_module(file);
2573
+
2600
2574
mark_rodata(file);
2601
2575
2602
2576
if (init_pv_ops(file))
···
4274
4244
* - compiler cloned functions (*.cold, *.part0, etc)
4275
4245
* - asm functions created with inline asm or without SYM_FUNC_START()
4276
4246
*
4247
+
* Also, the function may already have a prefix from a previous objtool run
4248
+
* (livepatch extracted functions, or manually running objtool multiple times).
4249
+
*
4277
4250
* So return 0 if the NOPs are missing or the function already has a prefix
4278
4251
* symbol.
4279
4252
*/
···
4298
4265
4299
4266
if (snprintf_check(name, SYM_NAME_LEN, "__pfx_%s", func->name))
4300
4267
return -1;
4268
+
4269
+
if (file->klp) {
4270
+
struct symbol *pfx;
4271
+
4272
+
pfx = find_symbol_by_offset(func->sec, func->offset - opts.prefix);
4273
+
if (pfx && is_prefix_func(pfx) && !strcmp(pfx->name, name))
4274
+
return 0;
4275
+
}
4301
4276
4302
4277
insn = find_insn(file, func->sec, func->offset);
4303
4278
if (!insn) {
···
4659
4618
!strncmp(sec->name, ".debug", 6) ||
4660
4619
!strcmp(sec->name, ".altinstructions") ||
4661
4620
!strcmp(sec->name, ".ibt_endbr_seal") ||
4621
+
!strcmp(sec->name, ".kcfi_traps") ||
4662
4622
!strcmp(sec->name, ".orc_unwind_ip") ||
4663
4623
!strcmp(sec->name, ".retpoline_sites") ||
4664
4624
!strcmp(sec->name, ".smp_locks") ||
···
4669
4627
!strcmp(sec->name, "__bug_table") ||
4670
4628
!strcmp(sec->name, "__ex_table") ||
4671
4629
!strcmp(sec->name, "__jump_table") ||
4630
+
!strcmp(sec->name, "__klp_funcs") ||
4672
4631
!strcmp(sec->name, "__mcount_loc") ||
4673
-
!strcmp(sec->name, ".kcfi_traps") ||
4674
4632
!strcmp(sec->name, ".llvm.call-graph-profile") ||
4675
4633
!strcmp(sec->name, ".llvm_bb_addr_map") ||
4676
4634
!strcmp(sec->name, "__tracepoints") ||
4677
-
strstr(sec->name, "__patchable_function_entries"))
4635
+
!strcmp(sec->name, "__patchable_function_entries"))
4678
4636
continue;
4679
4637
4680
4638
for_each_reloc(sec->rsec, reloc)
+4
-1
tools/objtool/elf.c
+4
-1
tools/objtool/elf.c
···
499
499
strstarts(sym->name, "__pi___cfi_")))
500
500
sym->prefix = 1;
501
501
502
-
if (is_func_sym(sym) && strstr(sym->name, ".cold"))
502
+
if (strstarts(sym->name, ".klp.sym"))
503
+
sym->klp = 1;
504
+
505
+
if (!sym->klp && is_func_sym(sym) && strstr(sym->name, ".cold"))
503
506
sym->cold = 1;
504
507
sym->pfunc = sym->cfunc = sym;
505
508
+1
tools/objtool/include/objtool/elf.h
+1
tools/objtool/include/objtool/elf.h
+1
-1
tools/objtool/include/objtool/objtool.h
+1
-1
tools/objtool/include/objtool/objtool.h