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Message-ID: <20220303112825.251775688@infradead.org>
User-Agent: quilt/0.66
Date:   Thu, 03 Mar 2022 12:23:26 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     x86@kernel.org, joao@overdrivepizza.com, hjl.tools@gmail.com,
        jpoimboe@redhat.com, andrew.cooper3@citrix.com
Cc:     linux-kernel@vger.kernel.org, peterz@infradead.org,
        ndesaulniers@google.com, keescook@chromium.org,
        samitolvanen@google.com, mark.rutland@arm.com,
        alyssa.milburn@intel.com, mbenes@suse.cz, rostedt@goodmis.org,
        mhiramat@kernel.org, alexei.starovoitov@gmail.com
Subject: [PATCH v3 05/39] x86/ibt: Add ANNOTATE_NOENDBR
References: <20220303112321.422525803@infradead.org>
MIME-Version: 1.0
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Precedence: bulk

In order to have objtool warn about code references to !ENDBR
instruction, we need an annotation to allow this for non-control-flow
instances -- consider text range checks, text patching, or return
trampolines etc.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
 include/linux/objtool.h |   16 ++++++++++++++++
 1 file changed, 16 insertions(+)

--- a/include/linux/objtool.h
+++ b/include/linux/objtool.h
@@ -77,6 +77,12 @@ struct unwind_hint {
 #define STACK_FRAME_NON_STANDARD_FP(func)
 #endif
 
+#define ANNOTATE_NOENDBR					\
+	"986: \n\t"						\
+	".pushsection .discard.noendbr\n\t"			\
+	_ASM_PTR " 986b\n\t"					\
+	".popsection\n\t"
+
 #else /* __ASSEMBLY__ */
 
 /*
@@ -129,6 +135,13 @@ struct unwind_hint {
 	.popsection
 .endm
 
+.macro ANNOTATE_NOENDBR
+.Lhere_\@:
+	.pushsection .discard.noendbr
+	.quad	.Lhere_\@
+	.popsection
+.endm
+
 #endif /* __ASSEMBLY__ */
 
 #else /* !CONFIG_STACK_VALIDATION */
@@ -139,12 +152,15 @@ struct unwind_hint {
 	"\n\t"
 #define STACK_FRAME_NON_STANDARD(func)
 #define STACK_FRAME_NON_STANDARD_FP(func)
+#define ANNOTATE_NOENDBR
 #else
 #define ANNOTATE_INTRA_FUNCTION_CALL
 .macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0
 .endm
 .macro STACK_FRAME_NON_STANDARD func:req
 .endm
+.macro ANNOTATE_NOENDBR
+.endm
 #endif
 
 #endif /* CONFIG_STACK_VALIDATION */