arm64: alternatives: Move length validation in alternative_{insn, endif}

stable inclusion
from linux-4.19.189
commit 5b834b40a584d8d10dc3f8459ced30d5dac26ce0

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

commit 22315a22 upstream.

After commit 2decad92 ("arm64: mte: Ensure TIF_MTE_ASYNC_FAULT is
set atomically"), LLVM's integrated assembler fails to build entry.S:

<instantiation>:5:7: error: expected assembly-time absolute expression
 .org . - (664b-663b) + (662b-661b)
      ^
<instantiation>:6:7: error: expected assembly-time absolute expression
 .org . - (662b-661b) + (664b-663b)
      ^

The root cause is LLVM's assembler has a one-pass design, meaning it
cannot figure out these instruction lengths when the .org directive is
outside of the subsection that they are in, which was changed by the
.arch_extension directive added in the above commit.

Apply the same fix from commit 966a0acc ("arm64/alternatives: move
length validation inside the subsection") to the alternative_endif
macro, shuffling the .org directives so that the length validation
happen will always happen in the same subsections. alternative_insn has
not shown any issue yet but it appears that it could have the same issue
in the future so just preemptively change it.

Fixes: f7b93d42 ("arm64/alternatives: use subsections for replacement sequences")
Cc: <stable@vger.kernel.org> # 5.8.x
Link: https://github.com/ClangBuiltLinux/linux/issues/1347Signed-off-by: NNathan Chancellor <nathan@kernel.org>
Reviewed-by: NSami Tolvanen <samitolvanen@google.com>
Tested-by: NSami Tolvanen <samitolvanen@google.com>
Reviewed-by: NNick Desaulniers <ndesaulniers@google.com>
Tested-by: NNick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20210414000803.662534-1-nathan@kernel.orgSigned-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

arch/arm64/include/asm/alternative.h

@@ -119,9 +119,9 @@ static inline void apply_alternatives_module(void *start, size_t length) { }
 	.popsection
 	.subsection 1
 663:	\insn2
-664:	.previous
-	.org	. - (664b-663b) + (662b-661b)
+664:	.org	. - (664b-663b) + (662b-661b)
 	.org	. - (662b-661b) + (664b-663b)
+	.previous
 	.endif
 .endm
 
@@ -191,11 +191,11 @@ static inline void apply_alternatives_module(void *start, size_t length) { }
  */
 .macro alternative_endif
 664:
+	.org	. - (664b-663b) + (662b-661b)
+	.org	. - (662b-661b) + (664b-663b)
 	.if .Lasm_alt_mode==0
 	.previous
 	.endif
-	.org	. - (664b-663b) + (662b-661b)
-	.org	. - (662b-661b) + (664b-663b)
 .endm
 
 /*