Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'objtool_urgent_for_5.8_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull objtool fixes from Borislav Petkov:
"Three fixes from Peter Zijlstra suppressing KCOV instrumentation in
noinstr sections.
Peter Zijlstra says:
"Address KCOV vs noinstr. There is no function attribute to
selectively suppress KCOV instrumentation, instead teach objtool
to NOP out the calls in noinstr functions"
This cures a bunch of KCOV crashes (as used by syzcaller)"
* tag 'objtool_urgent_for_5.8_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool: Fix noinstr vs KCOV
objtool: Provide elf_write_{insn,reloc}()
objtool: Clean up elf_write() condition
+109
-9
+1
-1
arch/x86/Kconfig
+1
-1
arch/x86/Kconfig
···
67
67
select ARCH_HAS_FILTER_PGPROT
68
68
select ARCH_HAS_FORTIFY_SOURCE
69
69
select ARCH_HAS_GCOV_PROFILE_ALL
70
-
select ARCH_HAS_KCOV if X86_64
70
+
select ARCH_HAS_KCOV if X86_64 && STACK_VALIDATION
71
71
select ARCH_HAS_MEM_ENCRYPT
72
72
select ARCH_HAS_MEMBARRIER_SYNC_CORE
73
73
select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
+2
tools/objtool/arch.h
+2
tools/objtool/arch.h
+18
tools/objtool/arch/x86/decode.c
+18
tools/objtool/arch/x86/decode.c
···
565
565
state->regs[16].base = CFI_CFA;
566
566
state->regs[16].offset = -8;
567
567
}
568
+
569
+
const char *arch_nop_insn(int len)
570
+
{
571
+
static const char nops[5][5] = {
572
+
/* 1 */ { 0x90 },
573
+
/* 2 */ { 0x66, 0x90 },
574
+
/* 3 */ { 0x0f, 0x1f, 0x00 },
575
+
/* 4 */ { 0x0f, 0x1f, 0x40, 0x00 },
576
+
/* 5 */ { 0x0f, 0x1f, 0x44, 0x00, 0x00 },
577
+
};
578
+
579
+
if (len < 1 || len > 5) {
580
+
WARN("invalid NOP size: %d\n", len);
581
+
return NULL;
582
+
}
583
+
584
+
return nops[len-1];
585
+
}
+6
tools/objtool/arch/x86/include/arch_elf.h
+6
tools/objtool/arch/x86/include/arch_elf.h
+22
-1
tools/objtool/check.c
+22
-1
tools/objtool/check.c
···
12
12
#include "check.h"
13
13
#include "special.h"
14
14
#include "warn.h"
15
+
#include "arch_elf.h"
15
16
16
17
#include <linux/hashtable.h>
17
18
#include <linux/kernel.h>
···
765
764
}
766
765
} else
767
766
insn->call_dest = rela->sym;
767
+
768
+
/*
769
+
* Many compilers cannot disable KCOV with a function attribute
770
+
* so they need a little help, NOP out any KCOV calls from noinstr
771
+
* text.
772
+
*/
773
+
if (insn->sec->noinstr &&
774
+
!strncmp(insn->call_dest->name, "__sanitizer_cov_", 16)) {
775
+
if (rela) {
776
+
rela->type = R_NONE;
777
+
elf_write_rela(file->elf, rela);
778
+
}
779
+
780
+
elf_write_insn(file->elf, insn->sec,
781
+
insn->offset, insn->len,
782
+
arch_nop_insn(insn->len));
783
+
insn->type = INSN_NOP;
784
+
}
768
785
769
786
/*
770
787
* Whatever stack impact regular CALLs have, should be undone
···
2785
2766
2786
2767
objname = _objname;
2787
2768
2788
-
file.elf = elf_open_read(objname, orc ? O_RDWR : O_RDONLY);
2769
+
file.elf = elf_open_read(objname, O_RDWR);
2789
2770
if (!file.elf)
2790
2771
return 1;
2791
2772
···
2846
2827
ret = create_orc_sections(&file);
2847
2828
if (ret < 0)
2848
2829
goto out;
2830
+
}
2849
2831
2832
+
if (file.elf->changed) {
2850
2833
ret = elf_write(file.elf);
2851
2834
if (ret < 0)
2852
2835
goto out;
+50
-3
tools/objtool/elf.c
+50
-3
tools/objtool/elf.c
···
529
529
rela->addend = rela->rela.r_addend;
530
530
rela->offset = rela->rela.r_offset;
531
531
symndx = GELF_R_SYM(rela->rela.r_info);
532
-
rela->sym = find_symbol_by_index(elf, symndx);
533
532
rela->sec = sec;
533
+
rela->idx = i;
534
+
rela->sym = find_symbol_by_index(elf, symndx);
534
535
if (!rela->sym) {
535
536
WARN("can't find rela entry symbol %d for %s",
536
537
symndx, sec->name);
···
714
713
elf_hash_add(elf->section_hash, &sec->hash, sec->idx);
715
714
elf_hash_add(elf->section_name_hash, &sec->name_hash, str_hash(sec->name));
716
715
716
+
elf->changed = true;
717
+
717
718
return sec;
718
719
}
719
720
···
749
746
return sec;
750
747
}
751
748
752
-
int elf_rebuild_rela_section(struct section *sec)
749
+
int elf_rebuild_rela_section(struct elf *elf, struct section *sec)
753
750
{
754
751
struct rela *rela;
755
752
int nr, idx = 0, size;
···
765
762
perror("malloc");
766
763
return -1;
767
764
}
765
+
766
+
sec->changed = true;
767
+
elf->changed = true;
768
768
769
769
sec->data->d_buf = relas;
770
770
sec->data->d_size = size;
···
785
779
return 0;
786
780
}
787
781
788
-
int elf_write(const struct elf *elf)
782
+
int elf_write_insn(struct elf *elf, struct section *sec,
783
+
unsigned long offset, unsigned int len,
784
+
const char *insn)
785
+
{
786
+
Elf_Data *data = sec->data;
787
+
788
+
if (data->d_type != ELF_T_BYTE || data->d_off) {
789
+
WARN("write to unexpected data for section: %s", sec->name);
790
+
return -1;
791
+
}
792
+
793
+
memcpy(data->d_buf + offset, insn, len);
794
+
elf_flagdata(data, ELF_C_SET, ELF_F_DIRTY);
795
+
796
+
elf->changed = true;
797
+
798
+
return 0;
799
+
}
800
+
801
+
int elf_write_rela(struct elf *elf, struct rela *rela)
802
+
{
803
+
struct section *sec = rela->sec;
804
+
805
+
rela->rela.r_info = GELF_R_INFO(rela->sym->idx, rela->type);
806
+
rela->rela.r_addend = rela->addend;
807
+
rela->rela.r_offset = rela->offset;
808
+
809
+
if (!gelf_update_rela(sec->data, rela->idx, &rela->rela)) {
810
+
WARN_ELF("gelf_update_rela");
811
+
return -1;
812
+
}
813
+
814
+
elf->changed = true;
815
+
816
+
return 0;
817
+
}
818
+
819
+
int elf_write(struct elf *elf)
789
820
{
790
821
struct section *sec;
791
822
Elf_Scn *s;
···
839
796
WARN_ELF("gelf_update_shdr");
840
797
return -1;
841
798
}
799
+
800
+
sec->changed = false;
842
801
}
843
802
}
844
803
···
852
807
WARN_ELF("elf_update");
853
808
return -1;
854
809
}
810
+
811
+
elf->changed = false;
855
812
856
813
return 0;
857
814
}
+9
-3
tools/objtool/elf.h
+9
-3
tools/objtool/elf.h
···
64
64
GElf_Rela rela;
65
65
struct section *sec;
66
66
struct symbol *sym;
67
-
unsigned int type;
68
67
unsigned long offset;
68
+
unsigned int type;
69
69
int addend;
70
+
int idx;
70
71
bool jump_table_start;
71
72
};
72
73
···
77
76
Elf *elf;
78
77
GElf_Ehdr ehdr;
79
78
int fd;
79
+
bool changed;
80
80
char *name;
81
81
struct list_head sections;
82
82
DECLARE_HASHTABLE(symbol_hash, ELF_HASH_BITS);
···
120
118
struct section *elf_create_section(struct elf *elf, const char *name, size_t entsize, int nr);
121
119
struct section *elf_create_rela_section(struct elf *elf, struct section *base);
122
120
void elf_add_rela(struct elf *elf, struct rela *rela);
123
-
int elf_write(const struct elf *elf);
121
+
int elf_write_insn(struct elf *elf, struct section *sec,
122
+
unsigned long offset, unsigned int len,
123
+
const char *insn);
124
+
int elf_write_rela(struct elf *elf, struct rela *rela);
125
+
int elf_write(struct elf *elf);
124
126
void elf_close(struct elf *elf);
125
127
126
128
struct section *find_section_by_name(const struct elf *elf, const char *name);
···
136
130
struct rela *find_rela_by_dest_range(const struct elf *elf, struct section *sec,
137
131
unsigned long offset, unsigned int len);
138
132
struct symbol *find_func_containing(struct section *sec, unsigned long offset);
139
-
int elf_rebuild_rela_section(struct section *sec);
133
+
int elf_rebuild_rela_section(struct elf *elf, struct section *sec);
140
134
141
135
#define for_each_sec(file, sec) \
142
136
list_for_each_entry(sec, &file->elf->sections, list)