2017-06-23 04:42:01

by Nick Desaulniers

Subject: [PATCH] KVM: x86: remove ignored type attribute

The macro insn_fetch marks the 'type' argument as having a specified
alignment. Type attributes can only be applied to structs, unions, or
enums, but insn_fetch is only ever invoked with integral types, so Clang
produces 19 -Wignored-attributes warnings for this source file.

Signed-off-by: Nick Desaulniers <[email protected]>
---
arch/x86/kvm/emulate.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 7611c034bf95..409081977e59 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -900,7 +900,7 @@ static __always_inline int do_insn_fetch_bytes(struct x86_emulate_ctxt *ctxt,
if (rc != X86EMUL_CONTINUE) \
goto done; \
ctxt->_eip += sizeof(_type); \
- _x = *(_type __aligned(1) *) ctxt->fetch.ptr; \
+ _x = *(_type *) ctxt->fetch.ptr; \
ctxt->fetch.ptr += sizeof(_type); \
_x; \
})
--
2.11.0

2017-06-27 14:32:27

by Paolo Bonzini

Subject: Re: [PATCH] KVM: x86: remove ignored type attribute

On 23/06/2017 06:41, Nick Desaulniers wrote:
> The macro insn_fetch marks the 'type' argument as having a specified
> alignment. Type attributes can only be applied to structs, unions, or
> enums, but insn_fetch is only ever invoked with integral types, so Clang
> produces 19 -Wignored-attributes warnings for this source file.
>
> Signed-off-by: Nick Desaulniers <[email protected]>
> ---
> arch/x86/kvm/emulate.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index 7611c034bf95..409081977e59 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -900,7 +900,7 @@ static __always_inline int do_insn_fetch_bytes(struct x86_emulate_ctxt *ctxt,
> if (rc != X86EMUL_CONTINUE) \
> goto done; \
> ctxt->_eip += sizeof(_type); \
> - _x = *(_type __aligned(1) *) ctxt->fetch.ptr; \
> + _x = *(_type *) ctxt->fetch.ptr; \
> ctxt->fetch.ptr += sizeof(_type); \
> _x; \
> })
>

Can you make a patch that uses memcpy instead? Both GCC and clang will
compile it to a simple load.

Paolo

2017-06-28 02:37:40

by Nick Desaulniers

Subject: [PATCH v2] KVM: x86: remove ignored type attribute

The macro insn_fetch marks the 'type' argument as having a specified
alignment. Type attributes can only be applied to structs, unions, or
enums, but insn_fetch is only ever invoked with integral types, so Clang
produces 19 -Wignored-attributes warnings for this source file.

Signed-off-by: Nick Desaulniers <[email protected]>
---
Changes in v2:
* prefer memcpy
* fix up trailing tabs

arch/x86/kvm/emulate.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 7611c034bf95..f9c0359f3fdd 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -900,7 +900,7 @@ static __always_inline int do_insn_fetch_bytes(struct x86_emulate_ctxt *ctxt,
if (rc != X86EMUL_CONTINUE) \
goto done; \
ctxt->_eip += sizeof(_type); \
- _x = *(_type __aligned(1) *) ctxt->fetch.ptr; \
+ memcpy(&_x, ctxt->fetch.ptr, sizeof(_type)); \
ctxt->fetch.ptr += sizeof(_type); \
_x; \
})
--
2.11.0

2017-06-28 02:44:37

by Nick Desaulniers

Subject: Re: [PATCH v2] KVM: x86: remove ignored type attribute

gah, forgot to amend the trailing tab change in.

Do you mind just fixing it up when you merge or shall I send v3?

2017-06-30 10:46:55

by Paolo Bonzini

Subject: Re: [PATCH v2] KVM: x86: remove ignored type attribute

On 28/06/2017 04:37, Nick Desaulniers wrote:
> The macro insn_fetch marks the 'type' argument as having a specified
> alignment. Type attributes can only be applied to structs, unions, or
> enums, but insn_fetch is only ever invoked with integral types, so Clang
> produces 19 -Wignored-attributes warnings for this source file.
>
> Signed-off-by: Nick Desaulniers <[email protected]>
> ---
> Changes in v2:
> * prefer memcpy
> * fix up trailing tabs
>
> arch/x86/kvm/emulate.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index 7611c034bf95..f9c0359f3fdd 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -900,7 +900,7 @@ static __always_inline int do_insn_fetch_bytes(struct x86_emulate_ctxt *ctxt,
> if (rc != X86EMUL_CONTINUE) \
> goto done; \
> ctxt->_eip += sizeof(_type); \
> - _x = *(_type __aligned(1) *) ctxt->fetch.ptr; \
> + memcpy(&_x, ctxt->fetch.ptr, sizeof(_type)); \
> ctxt->fetch.ptr += sizeof(_type); \
> _x; \
> })
>

Fixed up the tab and pushed, thanks.

Paolo