1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
|
From 44f6a7c0755d8dd453c70557e11687bb080a6f21 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Mon, 14 Dec 2020 16:04:20 -0600
Subject: [PATCH] objtool: Fix seg fault with Clang non-section symbols
The Clang assembler likes to strip section symbols, which means objtool
can't reference some text code by its section. This confuses objtool
greatly, causing it to seg fault.
The fix is similar to what was done before, for ORC reloc generation:
e81e07244325 ("objtool: Support Clang non-section symbols in ORC generation")
Factor out that code into a common helper and use it for static call
reloc generation as well.
Reported-by: Arnd Bergmann <arnd@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://github.com/ClangBuiltLinux/linux/issues/1207
Link: https://lkml.kernel.org/r/ba6b6c0f0dd5acbba66e403955a967d9fdd1726a.1607983452.git.jpoimboe@redhat.com
Upstream-Status: Backport
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
---
tools/objtool/check.c | 11 +++++++++--
tools/objtool/elf.c | 26 ++++++++++++++++++++++++++
tools/objtool/elf.h | 2 ++
tools/objtool/orc_gen.c | 29 +++++------------------------
4 files changed, 42 insertions(+), 26 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index c6ab44543c92a..5f8d3eed78a18 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -467,13 +467,20 @@ static int create_static_call_sections(struct objtool_file *file)
/* populate reloc for 'addr' */
reloc = malloc(sizeof(*reloc));
+
if (!reloc) {
perror("malloc");
return -1;
}
memset(reloc, 0, sizeof(*reloc));
- reloc->sym = insn->sec->sym;
- reloc->addend = insn->offset;
+
+ insn_to_reloc_sym_addend(insn->sec, insn->offset, reloc);
+ if (!reloc->sym) {
+ WARN_FUNC("static call tramp: missing containing symbol",
+ insn->sec, insn->offset);
+ return -1;
+ }
+
reloc->type = R_X86_64_PC32;
reloc->offset = idx * sizeof(struct static_call_site);
reloc->sec = reloc_sec;
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 4e1d7460574b4..be89c741ba9a0 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -262,6 +262,32 @@ struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, uns
return find_reloc_by_dest_range(elf, sec, offset, 1);
}
+void insn_to_reloc_sym_addend(struct section *sec, unsigned long offset,
+ struct reloc *reloc)
+{
+ if (sec->sym) {
+ reloc->sym = sec->sym;
+ reloc->addend = offset;
+ return;
+ }
+
+ /*
+ * The Clang assembler strips section symbols, so we have to reference
+ * the function symbol instead:
+ */
+ reloc->sym = find_symbol_containing(sec, offset);
+ if (!reloc->sym) {
+ /*
+ * Hack alert. This happens when we need to reference the NOP
+ * pad insn immediately after the function.
+ */
+ reloc->sym = find_symbol_containing(sec, offset - 1);
+ }
+
+ if (reloc->sym)
+ reloc->addend = offset - reloc->sym->offset;
+}
+
static int read_sections(struct elf *elf)
{
Elf_Scn *s = NULL;
diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h
index 807f8c6700974..e6890cc70a25b 100644
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -140,6 +140,8 @@ struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, uns
struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec,
unsigned long offset, unsigned int len);
struct symbol *find_func_containing(struct section *sec, unsigned long offset);
+void insn_to_reloc_sym_addend(struct section *sec, unsigned long offset,
+ struct reloc *reloc);
int elf_rebuild_reloc_section(struct elf *elf, struct section *sec);
#define for_each_sec(file, sec) \
diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c
index 235663b96adc7..9ce68b385a1b8 100644
--- a/tools/objtool/orc_gen.c
+++ b/tools/objtool/orc_gen.c
@@ -105,30 +105,11 @@ static int create_orc_entry(struct elf *elf, struct section *u_sec, struct secti
}
memset(reloc, 0, sizeof(*reloc));
- if (insn_sec->sym) {
- reloc->sym = insn_sec->sym;
- reloc->addend = insn_off;
- } else {
- /*
- * The Clang assembler doesn't produce section symbols, so we
- * have to reference the function symbol instead:
- */
- reloc->sym = find_symbol_containing(insn_sec, insn_off);
- if (!reloc->sym) {
- /*
- * Hack alert. This happens when we need to reference
- * the NOP pad insn immediately after the function.
- */
- reloc->sym = find_symbol_containing(insn_sec,
- insn_off - 1);
- }
- if (!reloc->sym) {
- WARN("missing symbol for insn at offset 0x%lx\n",
- insn_off);
- return -1;
- }
-
- reloc->addend = insn_off - reloc->sym->offset;
+ insn_to_reloc_sym_addend(insn_sec, insn_off, reloc);
+ if (!reloc->sym) {
+ WARN("missing symbol for insn at offset 0x%lx",
+ insn_off);
+ return -1;
}
reloc->type = R_X86_64_PC32;
|
