From: Peter Zijlstra peterz@infradead.org
[ Upstream commit 1cc1e4c8aab4213bd4e6353dec2620476a233d6d ]
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 Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- tools/objtool/arch/x86/decode.c | 13 +++++++++---- tools/objtool/builtin-check.c | 3 ++- tools/objtool/check.c | 14 ++++++++++++++ tools/objtool/include/objtool/arch.h | 1 + tools/objtool/include/objtool/builtin.h | 2 +- 5 files changed, 27 insertions(+), 6 deletions(-)
--- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -529,6 +529,11 @@ int arch_decode_instruction(const struct } break;
+ case 0xcc: + /* int3 */ + *type = INSN_TRAP; + break; + case 0xe3: /* jecxz/jrcxz */ *type = INSN_JUMP_CONDITIONAL; @@ -665,10 +670,10 @@ 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) { --- 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(), };
--- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -2776,6 +2776,12 @@ static int validate_branch(struct objtoo 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: @@ -2819,6 +2825,14 @@ static int validate_branch(struct objtoo 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(insn, &state); --- 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, };
--- 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[]);