objtool: Update Retpoline validation

stable inclusion
from stable-v5.10.133
commit 28aa3fa0b2c9d0cd7bdac42d9eb7fe3d5f6c79e8
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5PTAS
CVE: CVE-2022-29900,CVE-2022-23816,CVE-2022-29901

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=28aa3fa0b2c9d0cd7bdac42d9eb7fe3d5f6c79e8

--------------------------------

commit 9bb2ec60 upstream.

Update retpoline validation with the new CONFIG_RETPOLINE requirement of
not having bare naked RET instructions.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NJosh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: NBorislav Petkov <bp@suse.de>
[cascardo: conflict fixup at arch/x86/xen/xen-head.S]
Signed-off-by: NThadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: NBen Hutchings <ben@decadent.org.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NLin Yujun <linyujun809@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/x86/include/asm/nospec-branch.h

@@ -75,6 +75,12 @@
 	.popsection
 .endm
 
+/*
+ * (ab)use RETPOLINE_SAFE on RET to annotate away 'bare' RET instructions
+ * vs RETBleed validation.
+ */
+#define ANNOTATE_UNRET_SAFE ANNOTATE_RETPOLINE_SAFE
+
 /*
  * JMP_NOSPEC and CALL_NOSPEC macros can be used instead of a simple
  * indirect jmp/call which may be susceptible to the Spectre variant 2

arch/x86/mm/mem_encrypt_boot.S

@@ -66,6 +66,7 @@ SYM_FUNC_START(sme_encrypt_execute)
 	pop	%rbp
 
 	/* Offset to __x86_return_thunk would be wrong here */
+	ANNOTATE_UNRET_SAFE
 	ret
 	int3
 SYM_FUNC_END(sme_encrypt_execute)
@@ -154,6 +155,7 @@ SYM_FUNC_START(__enc_copy)
 	pop	%r15
 
 	/* Offset to __x86_return_thunk would be wrong here */
+	ANNOTATE_UNRET_SAFE
 	ret
 	int3
 .L__enc_copy_end:

arch/x86/xen/xen-head.S

@@ -70,6 +70,7 @@ SYM_CODE_START(hypercall_page)
 	.rept (PAGE_SIZE / 32)
 		UNWIND_HINT_FUNC
 		.skip 31, 0x90
+		ANNOTATE_UNRET_SAFE
 		RET
 	.endr
 

tools/objtool/check.c

@@ -1798,8 +1798,9 @@ static int read_retpoline_hints(struct objtool_file *file)
 		}
 
 		if (insn->type != INSN_JUMP_DYNAMIC &&
-		    insn->type != INSN_CALL_DYNAMIC) {
-			WARN_FUNC("retpoline_safe hint not an indirect jump/call",
+		    insn->type != INSN_CALL_DYNAMIC &&
+		    insn->type != INSN_RETURN) {
+			WARN_FUNC("retpoline_safe hint not an indirect jump/call/ret",
 				  insn->sec, insn->offset);
 			return -1;
 		}
@@ -3050,7 +3051,8 @@ static int validate_retpoline(struct objtool_file *file)
 
 	for_each_insn(file, insn) {
 		if (insn->type != INSN_JUMP_DYNAMIC &&
-		    insn->type != INSN_CALL_DYNAMIC)
+		    insn->type != INSN_CALL_DYNAMIC &&
+		    insn->type != INSN_RETURN)
 			continue;
 
 		if (insn->retpoline_safe)
@@ -3065,9 +3067,14 @@ static int validate_retpoline(struct objtool_file *file)
 		if (!strcmp(insn->sec->name, ".init.text") && !module)
 			continue;
 
-		WARN_FUNC("indirect %s found in RETPOLINE build",
-			  insn->sec, insn->offset,
-			  insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
+		if (insn->type == INSN_RETURN) {
+			WARN_FUNC("'naked' return found in RETPOLINE build",
+				  insn->sec, insn->offset);
+		} else {
+			WARN_FUNC("indirect %s found in RETPOLINE build",
+				  insn->sec, insn->offset,
+				  insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
+		}
 
 		warnings++;
 	}