[Qemu-devel] [PATCH] ppc: Fix xsmaddmdp and friends

[Qemu-devel] [PATCH] ppc: Fix xsmaddmdp and friends

[Paul A. Clarke]

From: "Paul A. Clarke" <pc@us.ibm.com>

A class of instructions of the form:
  op Target,A,B
which operate like:
  Target = Target * A + B
have a bit set which distinguishes them from instructions that operate as:
  Target = Target * B + A

This bit is not being checked properly (using PPC_BIT macro), so all
instructions in this class are operating incorrectly as the second form
above.  The bit was being checked as if it were part of a 64-bit
instruction opcode, rather than a proper 32-bit opcode.  Fix by using the
macro (PPC_BIT32) which treats the opcode as a 32-bit quantity.

Signed-off-by: Paul A. Clarke <pc@us.ibm.com>
---
 target/ppc/translate/vsx-impl.inc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target/ppc/translate/vsx-impl.inc.c b/target/ppc/translate/vsx-impl.inc.c
index 3922686..8287e27 100644
--- a/target/ppc/translate/vsx-impl.inc.c
+++ b/target/ppc/translate/vsx-impl.inc.c
@@ -1308,7 +1308,7 @@ static void gen_##name(DisasContext *ctx)                                     \
     }                                                                         \
     xt = gen_vsr_ptr(xT(ctx->opcode));                                        \
     xa = gen_vsr_ptr(xA(ctx->opcode));                                        \
-    if (ctx->opcode & PPC_BIT(25)) {                                          \
+    if (ctx->opcode & PPC_BIT32(25)) {                                        \
         /*                                                                    \
          * AxT + B                                                            \
          */                                                                   \
-- 
1.8.3.1

Re: [Qemu-devel] [PATCH] ppc: Fix xsmaddmdp and friends

[David Gibson]

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On Wed, Aug 21, 2019 at 10:28:41AM -0500, Paul A. Clarke wrote:
> From: "Paul A. Clarke" <pc@us.ibm.com>
> 
> A class of instructions of the form:
>   op Target,A,B
> which operate like:
>   Target = Target * A + B
> have a bit set which distinguishes them from instructions that operate as:
>   Target = Target * B + A
> 
> This bit is not being checked properly (using PPC_BIT macro), so all
> instructions in this class are operating incorrectly as the second form
> above.  The bit was being checked as if it were part of a 64-bit
> instruction opcode, rather than a proper 32-bit opcode.  Fix by using the
> macro (PPC_BIT32) which treats the opcode as a 32-bit quantity.
> 
> Signed-off-by: Paul A. Clarke <pc@us.ibm.com>

Applied to ppc-for-4.2, thanks.

> ---
>  target/ppc/translate/vsx-impl.inc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/target/ppc/translate/vsx-impl.inc.c b/target/ppc/translate/vsx-impl.inc.c
> index 3922686..8287e27 100644
> --- a/target/ppc/translate/vsx-impl.inc.c
> +++ b/target/ppc/translate/vsx-impl.inc.c
> @@ -1308,7 +1308,7 @@ static void gen_##name(DisasContext *ctx)                                     \
>      }                                                                         \
>      xt = gen_vsr_ptr(xT(ctx->opcode));                                        \
>      xa = gen_vsr_ptr(xA(ctx->opcode));                                        \
> -    if (ctx->opcode & PPC_BIT(25)) {                                          \
> +    if (ctx->opcode & PPC_BIT32(25)) {                                        \
>          /*                                                                    \
>           * AxT + B                                                            \
>           */                                                                   \

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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Re: [Qemu-devel] [Qemu-ppc] [PATCH] ppc: Fix xsmaddmdp and friends

[Laurent Vivier]

On 22/08/2019 00:56, David Gibson wrote:
> On Wed, Aug 21, 2019 at 10:28:41AM -0500, Paul A. Clarke wrote:
>> From: "Paul A. Clarke" <pc@us.ibm.com>
>>
>> A class of instructions of the form:
>>   op Target,A,B
>> which operate like:
>>   Target = Target * A + B
>> have a bit set which distinguishes them from instructions that operate as:
>>   Target = Target * B + A
>>
>> This bit is not being checked properly (using PPC_BIT macro), so all
>> instructions in this class are operating incorrectly as the second form
>> above.  The bit was being checked as if it were part of a 64-bit
>> instruction opcode, rather than a proper 32-bit opcode.  Fix by using the
>> macro (PPC_BIT32) which treats the opcode as a 32-bit quantity.
>>
>> Signed-off-by: Paul A. Clarke <pc@us.ibm.com>
> 
> Applied to ppc-for-4.2, thanks.

David,

could you add:

Fixes: c9f4e4d8b632 ("target/ppc: improve VSX_FMADD with new GEN_VSX_HELPER_VSX_MADD macro")

Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Tested-by: Laurent Vivier <lvivier@redhat.com>

Thanks,
Laurent

Re: [Qemu-devel] [Qemu-ppc] [PATCH] ppc: Fix xsmaddmdp and friends

[David Gibson]

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On Wed, Aug 28, 2019 at 07:32:38PM +0200, Laurent Vivier wrote:
> On 22/08/2019 00:56, David Gibson wrote:
> > On Wed, Aug 21, 2019 at 10:28:41AM -0500, Paul A. Clarke wrote:
> >> From: "Paul A. Clarke" <pc@us.ibm.com>
> >>
> >> A class of instructions of the form:
> >>   op Target,A,B
> >> which operate like:
> >>   Target = Target * A + B
> >> have a bit set which distinguishes them from instructions that operate as:
> >>   Target = Target * B + A
> >>
> >> This bit is not being checked properly (using PPC_BIT macro), so all
> >> instructions in this class are operating incorrectly as the second form
> >> above.  The bit was being checked as if it were part of a 64-bit
> >> instruction opcode, rather than a proper 32-bit opcode.  Fix by using the
> >> macro (PPC_BIT32) which treats the opcode as a 32-bit quantity.
> >>
> >> Signed-off-by: Paul A. Clarke <pc@us.ibm.com>
> > 
> > Applied to ppc-for-4.2, thanks.
> 
> David,
> 
> could you add:
> 
> Fixes: c9f4e4d8b632 ("target/ppc: improve VSX_FMADD with new GEN_VSX_HELPER_VSX_MADD macro")
> 
> Reviewed-by: Laurent Vivier <lvivier@redhat.com>
> Tested-by: Laurent Vivier <lvivier@redhat.com>

Done, thanks.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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