linux-kernel - [PATCH 4.14 042/121] powerpc/xmon: Fix opcode being uninitialized in print_insn

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Date:   Thu,  4 Apr 2019 10:47:10 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Nathan Chancellor <natechancellor@...il.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.14 042/121] powerpc/xmon: Fix opcode being uninitialized in print_insn_powerpc

4.14-stable review patch.  If anyone has any objections, please let me know.

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

[ Upstream commit e7140639b1de65bba435a6bd772d134901141f86 ]

When building with -Wsometimes-uninitialized, Clang warns:

  arch/powerpc/xmon/ppc-dis.c:157:7: warning: variable 'opcode' is used
  uninitialized whenever 'if' condition is false
  [-Wsometimes-uninitialized]
    if (cpu_has_feature(CPU_FTRS_POWER9))
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  arch/powerpc/xmon/ppc-dis.c:167:7: note: uninitialized use occurs here
    if (opcode == NULL)
        ^~~~~~
  arch/powerpc/xmon/ppc-dis.c:157:3: note: remove the 'if' if its
  condition is always true
    if (cpu_has_feature(CPU_FTRS_POWER9))
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  arch/powerpc/xmon/ppc-dis.c:132:38: note: initialize the variable
  'opcode' to silence this warning
    const struct powerpc_opcode *opcode;
                                       ^
                                        = NULL
  1 warning generated.

This warning seems to make no sense on the surface because opcode is set
to NULL right below this statement. However, there is a comma instead of
semicolon to end the dialect assignment, meaning that the opcode
assignment only happens in the if statement. Properly terminate that
line so that Clang no longer warns.

Fixes: 5b102782c7f4 ("powerpc/xmon: Enable disassembly files (compilation changes)")
Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/powerpc/xmon/ppc-dis.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/xmon/ppc-dis.c b/arch/powerpc/xmon/ppc-dis.c
index 31db8c072acd..006c7f864f65 100644
--- a/arch/powerpc/xmon/ppc-dis.c
+++ b/arch/powerpc/xmon/ppc-dis.c
@@ -162,7 +162,7 @@ int print_insn_powerpc (unsigned long insn, unsigned long memaddr)
     dialect |= (PPC_OPCODE_POWER5 | PPC_OPCODE_POWER6 | PPC_OPCODE_POWER7
 		| PPC_OPCODE_POWER8 | PPC_OPCODE_POWER9 | PPC_OPCODE_HTM
 		| PPC_OPCODE_ALTIVEC | PPC_OPCODE_ALTIVEC2
-		| PPC_OPCODE_VSX | PPC_OPCODE_VSX3),
+		| PPC_OPCODE_VSX | PPC_OPCODE_VSX3);
 
   /* Get the major opcode of the insn.  */
   opcode = NULL;
-- 
2.19.1