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x86/retbleed: Add fine grained Kconfig knobs

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Do fine-grained Kconfig for all the various retbleed parts.

NOTE: if your compiler doesn't support return thunks this will
silently 'upgrade' your mitigation to IBPB, you might not like this.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
This commit is contained in:
Peter Zijlstra
2022-06-27 22:21:17 +00:00
committed by Borislav Petkov
parent 26aae8ccbc
commit f43b9876e8
19 changed files with 178 additions and 69 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
tools/objtool/builtin-check.c
View File

@ -68,6 +68,7 @@ const struct option check_options[] = {
OPT_BOOLEAN('n', "noinstr", &opts.noinstr, "validate noinstr rules"),
OPT_BOOLEAN('o', "orc", &opts.orc, "generate ORC metadata"),
OPT_BOOLEAN('r', "retpoline", &opts.retpoline, "validate and annotate retpoline usage"),
OPT_BOOLEAN(0, "rethunk", &opts.rethunk, "validate and annotate rethunk usage"),
OPT_BOOLEAN(0, "unret", &opts.unret, "validate entry unret placement"),
OPT_BOOLEAN('l', "sls", &opts.sls, "validate straight-line-speculation mitigations"),
OPT_BOOLEAN('s', "stackval", &opts.stackval, "validate frame pointer rules"),
@ -124,6 +125,7 @@ static bool opts_valid(void)
opts.noinstr ||
opts.orc ||
opts.retpoline ||
opts.rethunk ||
opts.sls ||
opts.stackval ||
opts.static_call ||
@ -136,6 +138,11 @@ static bool opts_valid(void)
return true;
}
if (opts.unret && !opts.rethunk) {
ERROR("--unret requires --rethunk");
return false;
}
if (opts.dump_orc)
return true;

9
tools/objtool/check.c
View File

@ -3732,8 +3732,11 @@ static int validate_retpoline(struct objtool_file *file)
continue;
if (insn->type == INSN_RETURN) {
WARN_FUNC("'naked' return found in RETPOLINE build",
insn->sec, insn->offset);
if (opts.rethunk) {
WARN_FUNC("'naked' return found in RETHUNK build",
insn->sec, insn->offset);
} else
continue;
} else {
WARN_FUNC("indirect %s found in RETPOLINE build",
insn->sec, insn->offset,
@ -4264,7 +4267,9 @@ int check(struct objtool_file *file)
if (ret < 0)
goto out;
warnings += ret;
}
if (opts.rethunk) {
ret = create_return_sites_sections(file);
if (ret < 0)
goto out;

1
tools/objtool/include/objtool/builtin.h
View File

@ -19,6 +19,7 @@ struct opts {
bool noinstr;
bool orc;
bool retpoline;
bool rethunk;
bool unret;
bool sls;
bool stackval;