linux-kernel - [tip: x86/core] x86/ibt: Add ANNOTATE

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Date:   Tue, 15 Mar 2022 10:44:12 -0000
From:   "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Kees Cook <keescook@...omium.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/core] x86/ibt: Add ANNOTATE_NOENDBR

The following commit has been merged into the x86/core branch of tip:

Commit-ID:     c8c301abeae58ec756b8fcb2178a632bd3c9e284
Gitweb:        https://git.kernel.org/tip/c8c301abeae58ec756b8fcb2178a632bd3c9e284
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Tue, 08 Mar 2022 16:30:18 +01:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Tue, 15 Mar 2022 10:32:33 +01:00

x86/ibt: Add ANNOTATE_NOENDBR

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@...radead.org>
Reviewed-by: Kees Cook <keescook@...omium.org>
Acked-by: Josh Poimboeuf <jpoimboe@...hat.com>
Link: https://lore.kernel.org/r/20220308154317.578968224@infradead.org
---
 include/linux/objtool.h       | 16 ++++++++++++++++
 tools/include/linux/objtool.h | 16 ++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/include/linux/objtool.h b/include/linux/objtool.h
index aca52db..f797368 100644
--- 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 */
diff --git a/tools/include/linux/objtool.h b/tools/include/linux/objtool.h
index aca52db..f797368 100644
--- a/tools/include/linux/objtool.h
+++ b/tools/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 */