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authorPeter Zijlstra <peterz@infradead.org>2022-06-15 00:16:03 +0300
committerBorislav Petkov <bp@suse.de>2022-06-27 11:34:00 +0300
commita09a6e2399ba0595c3042b3164f3ca68a3cff33e (patch)
treebf16062820b967a0b9c59169adf156eec8ed55a4 /tools/objtool/builtin-check.c
parent0fe4aeea9c01baabecc8c3afc7889c809d939bc2 (diff)
downloadlinux-a09a6e2399ba0595c3042b3164f3ca68a3cff33e.tar.xz
objtool: Add entry UNRET validation
Since entry asm is tricky, add a validation pass that ensures the retbleed mitigation has been done before the first actual RET instruction. Entry points are those that either have UNWIND_HINT_ENTRY, which acts as UNWIND_HINT_EMPTY but marks the instruction as an entry point, or those that have UWIND_HINT_IRET_REGS at +0. This is basically a variant of validate_branch() that is intra-function and it will simply follow all branches from marked entry points and ensures that all paths lead to ANNOTATE_UNRET_END. If a path hits RET or an indirection the path is a fail and will be reported. There are 3 ANNOTATE_UNRET_END instances: - UNTRAIN_RET itself - exception from-kernel; this path doesn't need UNTRAIN_RET - all early exceptions; these also don't need UNTRAIN_RET Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de>
Diffstat (limited to 'tools/objtool/builtin-check.c')
-rw-r--r--tools/objtool/builtin-check.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index f4c3a5091737..c063e1ff96b2 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -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, "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"),
OPT_BOOLEAN('t', "static-call", &opts.static_call, "annotate static calls"),
@@ -163,6 +164,11 @@ static bool link_opts_valid(struct objtool_file *file)
return false;
}
+ if (opts.unret) {
+ ERROR("--unret requires --link");
+ return false;
+ }
+
return true;
}