linux-kernel - Re: [PATCH v2] powerpc/32: sstep: Move variable `rc` within CONFIG

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Message-ID: <CA+7wUswLP5cffrYZuEZ9bJeq1-FNNq6LFurMrOM1bmnDDN7E-g@mail.gmail.com>
Date:   Tue, 28 May 2019 17:52:52 +0200
From:   Mathieu Malaterre <malat@...ian.org>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     Christophe Leroy <christophe.leroy@....fr>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] powerpc/32: sstep: Move variable `rc` within
 CONFIG_PPC64 sentinels

On Tue, May 28, 2019 at 1:40 PM Michael Ellerman <mpe@...erman.id.au> wrote:
>
> Mathieu Malaterre <malat@...ian.org> writes:
>
> > Fix warnings treated as errors with W=1:
> >
> >   arch/powerpc/lib/sstep.c:1172:31: error: variable 'rc' set but not used [-Werror=unused-but-set-variable]
> >
> > Suggested-by: Christophe Leroy <christophe.leroy@....fr>
> > Signed-off-by: Mathieu Malaterre <malat@...ian.org>
> > ---
> > v2: as suggested prefer CONFIG_PPC64 sentinel instead of unused keyword
>
> I'd rather avoid adding more ifdefs if we can.
>
> I think this works?

It does ! ;)

Reviewed-by: Mathieu Malaterre <malat@...ian.org>

> cheers
>
> diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
> index 3d33fb509ef4..600b036ddfda 100644
> --- a/arch/powerpc/lib/sstep.c
> +++ b/arch/powerpc/lib/sstep.c
> @@ -1169,7 +1169,7 @@ static nokprobe_inline int trap_compare(long v1, long v2)
>  int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
>                   unsigned int instr)
>  {
> -       unsigned int opcode, ra, rb, rc, rd, spr, u;
> +       unsigned int opcode, ra, rb, rd, spr, u;
>         unsigned long int imm;
>         unsigned long int val, val2;
>         unsigned int mb, me, sh;
> @@ -1292,7 +1292,6 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
>         rd = (instr >> 21) & 0x1f;
>         ra = (instr >> 16) & 0x1f;
>         rb = (instr >> 11) & 0x1f;
> -       rc = (instr >> 6) & 0x1f;
>
>         switch (opcode) {
>  #ifdef __powerpc64__
> @@ -1307,10 +1306,14 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
>                 return 1;
>
>  #ifdef __powerpc64__
> -       case 4:
> +       case 4: {
> +               unsigned int rc;
> +
>                 if (!cpu_has_feature(CPU_FTR_ARCH_300))
>                         return -1;
>
> +               rc = (instr >> 6) & 0x1f;
> +
>                 switch (instr & 0x3f) {
>                 case 48:        /* maddhd */
>                         asm volatile(PPC_MADDHD(%0, %1, %2, %3) :
> @@ -1336,6 +1339,7 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
>                  * primary opcode which do not have emulation support yet.
>                  */
>                 return -1;
> +       }
>  #endif
>
>         case 7:         /* mulli */