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authorPeter Zijlstra <peterz@infradead.org>2021-12-04 14:43:42 +0100
committerBorislav Petkov <bp@suse.de>2021-12-08 19:26:50 +0100
commit1cc1e4c8aab4213bd4e6353dec2620476a233d6d (patch)
tree098107adb9d0272c25287606abad1b846b3595e3 /tools/objtool
parentb17c2baa305cccbd16bafa289fd743cc2db77966 (diff)
objtool: Add straight-line-speculation validation
Teach objtool to validate the straight-line-speculation constraints: - speculation trap after indirect calls - speculation trap after RET Notable: when an instruction is annotated RETPOLINE_SAFE, indicating speculation isn't a problem, also don't care about sls for that instruction. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20211204134908.023037659@infradead.org
Diffstat (limited to 'tools/objtool')
-rw-r--r--tools/objtool/arch/x86/decode.c13
-rw-r--r--tools/objtool/builtin-check.c3
-rw-r--r--tools/objtool/check.c14
-rw-r--r--tools/objtool/include/objtool/arch.h1
-rw-r--r--tools/objtool/include/objtool/builtin.h2
5 files changed, 27 insertions, 6 deletions
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 4d6d7fc13255..c10ef78df050 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -531,6 +531,11 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
}
break;
+ case 0xcc:
+ /* int3 */
+ *type = INSN_TRAP;
+ break;
+
case 0xe3:
/* jecxz/jrcxz */
*type = INSN_JUMP_CONDITIONAL;
@@ -697,10 +702,10 @@ const char *arch_ret_insn(int len)
{
static const char ret[5][5] = {
{ BYTE_RET },
- { BYTE_RET, BYTES_NOP1 },
- { BYTE_RET, BYTES_NOP2 },
- { BYTE_RET, BYTES_NOP3 },
- { BYTE_RET, BYTES_NOP4 },
+ { BYTE_RET, 0xcc },
+ { BYTE_RET, 0xcc, BYTES_NOP1 },
+ { BYTE_RET, 0xcc, BYTES_NOP2 },
+ { BYTE_RET, 0xcc, BYTES_NOP3 },
};
if (len < 1 || len > 5) {
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 8b38b5d6fec7..38070f26105b 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -20,7 +20,7 @@
#include <objtool/objtool.h>
bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats,
- validate_dup, vmlinux, mcount, noinstr, backup;
+ validate_dup, vmlinux, mcount, noinstr, backup, sls;
static const char * const check_usage[] = {
"objtool check [<options>] file.o",
@@ -45,6 +45,7 @@ const struct option check_options[] = {
OPT_BOOLEAN('l', "vmlinux", &vmlinux, "vmlinux.o validation"),
OPT_BOOLEAN('M', "mcount", &mcount, "generate __mcount_loc"),
OPT_BOOLEAN('B', "backup", &backup, "create .orig files before modification"),
+ OPT_BOOLEAN('S', "sls", &sls, "validate straight-line-speculation"),
OPT_END(),
};
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 21735829b860..e28172f6e792 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3084,6 +3084,12 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
switch (insn->type) {
case INSN_RETURN:
+ if (next_insn && next_insn->type == INSN_TRAP) {
+ next_insn->ignore = true;
+ } else if (sls && !insn->retpoline_safe) {
+ WARN_FUNC("missing int3 after ret",
+ insn->sec, insn->offset);
+ }
return validate_return(func, insn, &state);
case INSN_CALL:
@@ -3127,6 +3133,14 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
break;
case INSN_JUMP_DYNAMIC:
+ if (next_insn && next_insn->type == INSN_TRAP) {
+ next_insn->ignore = true;
+ } else if (sls && !insn->retpoline_safe) {
+ WARN_FUNC("missing int3 after indirect jump",
+ insn->sec, insn->offset);
+ }
+
+ /* fallthrough */
case INSN_JUMP_DYNAMIC_CONDITIONAL:
if (is_sibling_call(insn)) {
ret = validate_sibling_call(file, insn, &state);
diff --git a/tools/objtool/include/objtool/arch.h b/tools/objtool/include/objtool/arch.h
index 589ff58426ab..76bae3078286 100644
--- a/tools/objtool/include/objtool/arch.h
+++ b/tools/objtool/include/objtool/arch.h
@@ -26,6 +26,7 @@ enum insn_type {
INSN_CLAC,
INSN_STD,
INSN_CLD,
+ INSN_TRAP,
INSN_OTHER,
};
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index 15ac0b7d3d6a..89ba869ed08f 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -9,7 +9,7 @@
extern const struct option check_options[];
extern bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats,
- validate_dup, vmlinux, mcount, noinstr, backup;
+ validate_dup, vmlinux, mcount, noinstr, backup, sls;
extern int cmd_parse_options(int argc, const char **argv, const char * const usage[]);