linux-kernel - [PATCH] x86/asm: Fix UNWIND_HINT

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Date:   Mon,  7 Aug 2017 09:38:05 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     x86@...nel.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>, linux-kernel@...r.kernel.org
Subject: [PATCH] x86/asm: Fix UNWIND_HINT_REGS macro for older binutils

Apparently the binutils 2.20 assembler can't handle the '&&' operator in
the UNWIND_HINT_REGS macro.  Rearrange the macro to do without it.

This fixes the following error:

  arch/x86/entry/entry_64.S: Assembler messages:
  arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement
  arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement
  arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement
  arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement
  arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement
  arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement
  arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement
  arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement
  arch/x86/entry/entry_64.S:521: Error: non-constant expression in ".if" statement

Reported-by: Andrew Morton <akpm@...ux-foundation.org>
Fixes: 39358a033b2e ("objtool, x86: Add facility for asm code to provide unwind hints")
Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
---
 arch/x86/include/asm/unwind_hints.h | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/unwind_hints.h b/arch/x86/include/asm/unwind_hints.h
index 5e02b11c9b86..bae46fc6b9de 100644
--- a/arch/x86/include/asm/unwind_hints.h
+++ b/arch/x86/include/asm/unwind_hints.h
@@ -44,10 +44,12 @@
 .endm
 
 .macro UNWIND_HINT_REGS base=%rsp offset=0 indirect=0 extra=1 iret=0
-	.if \base == %rsp && \indirect
-		.set sp_reg, ORC_REG_SP_INDIRECT
-	.elseif \base == %rsp
-		.set sp_reg, ORC_REG_SP
+	.if \base == %rsp
+		.if \indirect
+			.set sp_reg, ORC_REG_SP_INDIRECT
+		.else
+			.set sp_reg, ORC_REG_SP
+		.endif
 	.elseif \base == %rbp
 		.set sp_reg, ORC_REG_BP
 	.elseif \base == %rdi
-- 
2.13.3