Re: [Xen-devel] [PATCH] x86/Viridian: don't depend on undefined register state

[Paul Durrant]

> -Original Message-
> From: Jan Beulich [mailto:jbeul...@suse.com]
> Sent: 14 October 2016 05:38
> To: xen-devel 
> Cc: Paul Durrant 
> Subject: [PATCH] x86/Viridian: don't depend on undefined register state
> 
> The high halves of all GPRs are undefined in 32-bit and compat modes,
> and the dependency is being obfuscated by our structure field names not
> matching architectural register names (it was actually while putting
> together a patch to correct this when I noticed the issue here).
> 
> For consistency also use the architecturally correct names on the
> output side.
> 
> Signed-off-by: Jan Beulich 

Reviewed-by: Paul Durrant 

> 
> --- a/xen/arch/x86/hvm/viridian.c
> +++ b/xen/arch/x86/hvm/viridian.c
> @@ -667,9 +667,9 @@ int viridian_hypercall(struct cpu_user_r
>  output_params_gpa = regs->r8;
>  break;
>  case 4:
> -input.raw = ((uint64_t)regs->edx << 32) | regs->eax;
> -input_params_gpa = ((uint64_t)regs->ebx << 32) | regs->ecx;
> -output_params_gpa = ((uint64_t)regs->edi << 32) | regs->esi;
> +input.raw = (regs->rdx << 32) | regs->_eax;
> +input_params_gpa = (regs->rbx << 32) | regs->_ecx;
> +output_params_gpa = (regs->rdi << 32) | regs->_esi;
>  break;
>  default:
>  goto out;
> @@ -770,8 +770,8 @@ out:
>  regs->rax = output.raw;
>  break;
>  default:
> -regs->edx = output.raw >> 32;
> -regs->eax = output.raw;
> +regs->rdx = output.raw >> 32;
> +regs->rax = (uint32_t)output.raw;
>  break;
>  }
> 
> 
> 

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Re: [Xen-devel] [PATCH] x86/Viridian: don't depend on undefined register state

[Andrew Cooper]

On 14/10/16 10:37, Jan Beulich wrote:
> The high halves of all GPRs are undefined in 32-bit and compat modes,
> and the dependency is being obfuscated by our structure field names not
> matching architectural register names (it was actually while putting
> together a patch to correct this when I noticed the issue here).
>
> For consistency also use the architecturally correct names on the
> output side.
>
> Signed-off-by: Jan Beulich 

Reviewed-by: Andrew Cooper 

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[Xen-devel] [PATCH] x86/Viridian: don't depend on undefined register state

[Jan Beulich]

The high halves of all GPRs are undefined in 32-bit and compat modes,
and the dependency is being obfuscated by our structure field names not
matching architectural register names (it was actually while putting
together a patch to correct this when I noticed the issue here).

For consistency also use the architecturally correct names on the
output side.

Signed-off-by: Jan Beulich 

--- a/xen/arch/x86/hvm/viridian.c
+++ b/xen/arch/x86/hvm/viridian.c
@@ -667,9 +667,9 @@ int viridian_hypercall(struct cpu_user_r
 output_params_gpa = regs->r8;
 break;
 case 4:
-input.raw = ((uint64_t)regs->edx << 32) | regs->eax;
-input_params_gpa = ((uint64_t)regs->ebx << 32) | regs->ecx;
-output_params_gpa = ((uint64_t)regs->edi << 32) | regs->esi;
+input.raw = (regs->rdx << 32) | regs->_eax;
+input_params_gpa = (regs->rbx << 32) | regs->_ecx;
+output_params_gpa = (regs->rdi << 32) | regs->_esi;
 break;
 default:
 goto out;
@@ -770,8 +770,8 @@ out:
 regs->rax = output.raw;
 break;
 default:
-regs->edx = output.raw >> 32;
-regs->eax = output.raw;
+regs->rdx = output.raw >> 32;
+regs->rax = (uint32_t)output.raw;
 break;
 }
 


x86/Viridian: don't depend on undefined register state

The high halves of all GPRs are undefined in 32-bit and compat modes,
and the dependency is being obfuscated by our structure field names not
matching architectural register names (it was actually while putting
together a patch to correct this when I noticed the issue here).

For consistency also use the architecturally correct names on the
output side.

Signed-off-by: Jan Beulich 

--- a/xen/arch/x86/hvm/viridian.c
+++ b/xen/arch/x86/hvm/viridian.c
@@ -667,9 +667,9 @@ int viridian_hypercall(struct cpu_user_r
 output_params_gpa = regs->r8;
 break;
 case 4:
-input.raw = ((uint64_t)regs->edx << 32) | regs->eax;
-input_params_gpa = ((uint64_t)regs->ebx << 32) | regs->ecx;
-output_params_gpa = ((uint64_t)regs->edi << 32) | regs->esi;
+input.raw = (regs->rdx << 32) | regs->_eax;
+input_params_gpa = (regs->rbx << 32) | regs->_ecx;
+output_params_gpa = (regs->rdi << 32) | regs->_esi;
 break;
 default:
 goto out;
@@ -770,8 +770,8 @@ out:
 regs->rax = output.raw;
 break;
 default:
-regs->edx = output.raw >> 32;
-regs->eax = output.raw;
+regs->rdx = output.raw >> 32;
+regs->rax = (uint32_t)output.raw;
 break;
 }
 
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