Re: [PATCH] x86/cpu/vmware: use the full form of inl in VMWARE_PORT

2019-10-07 Thread Kees Cook 
On Mon, Oct 07, 2019 at 12:21:29PM -0700, Sami Tolvanen wrote:
> LLVM's assembler doesn't accept the short form inl (%%dx) instruction,
> but instead insists on the output register to be explicitly specified:
> 
>   :1:7: error: invalid operand for instruction
>   inl (%dx)
>  ^
>   LLVM ERROR: Error parsing inline asm
> 
> Use the full form of the instruction to fix the build.
> 
> Signed-off-by: Sami Tolvanen 

Reviewed-by: Kees Cook 

-Kees

> ---
>  arch/x86/kernel/cpu/vmware.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
> index 9735139cfdf8..46d732696c1c 100644
> --- a/arch/x86/kernel/cpu/vmware.c
> +++ b/arch/x86/kernel/cpu/vmware.c
> @@ -49,7 +49,7 @@
>  #define VMWARE_CMD_VCPU_RESERVED 31
>  
>  #define VMWARE_PORT(cmd, eax, ebx, ecx, edx) \
> - __asm__("inl (%%dx)" :  \
> + __asm__("inl (%%dx), %%eax" :   \
>   "=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :\
>   "a"(VMWARE_HYPERVISOR_MAGIC),   \
>   "c"(VMWARE_CMD_##cmd),  \
> -- 
> 2.23.0.581.g78d2f28ef7-goog
> 

-- 
Kees Cook

Re: [PATCH] x86/cpu/vmware: use the full form of inl in VMWARE_PORT

2019-10-07 Thread Nick Desaulniers 
On Mon, Oct 7, 2019 at 12:21 PM 'Sami Tolvanen' via Clang Built Linux
 wrote:
>
> LLVM's assembler doesn't accept the short form inl (%%dx) instruction,
> but instead insists on the output register to be explicitly specified:
>
>   :1:7: error: invalid operand for instruction
>   inl (%dx)
>  ^
>   LLVM ERROR: Error parsing inline asm
>
> Use the full form of the instruction to fix the build.
>
> Signed-off-by: Sami Tolvanen 

Thanks Sami, this looks like it addresses:
Link: https://github.com/ClangBuiltLinux/linux/issues/734
Looks like GAS' testsuite has some cases where the second operand is
indeed implicitly %eax if unspecified. (This should still be fixed in
Clang).
Just to triple check that they're equivalent:
$ cat inl.s
  inl (%dx)
  inl (%dx), %eax
$ as inl.s
$ objdump -d a.out

a.out: file format elf64-x86-64


Disassembly of section .text:

 <.text>:
   0: edin (%dx),%eax
   1: edin (%dx),%eax

Reviewed-by: Nick Desaulniers 

> ---
>  arch/x86/kernel/cpu/vmware.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
> index 9735139cfdf8..46d732696c1c 100644
> --- a/arch/x86/kernel/cpu/vmware.c
> +++ b/arch/x86/kernel/cpu/vmware.c
> @@ -49,7 +49,7 @@
>  #define VMWARE_CMD_VCPU_RESERVED 31
>
>  #define VMWARE_PORT(cmd, eax, ebx, ecx, edx)   \
> -   __asm__("inl (%%dx)" :  \
> +   __asm__("inl (%%dx), %%eax" :   \
> "=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :\
> "a"(VMWARE_HYPERVISOR_MAGIC),   \
> "c"(VMWARE_CMD_##cmd),  \

-- 
Thanks,
~Nick Desaulniers

Re: [PATCH] x86/cpu/vmware: use the full form of inl in VMWARE_PORT

2019-10-07 Thread Thomas Hellstrom 
On 10/7/19 9:21 PM, Sami Tolvanen wrote:
> LLVM's assembler doesn't accept the short form inl (%%dx) instruction,
> but instead insists on the output register to be explicitly specified:
>
>   :1:7: error: invalid operand for instruction
>   inl (%dx)
>  ^
>   LLVM ERROR: Error parsing inline asm
>
> Use the full form of the instruction to fix the build.
>
> Signed-off-by: Sami Tolvanen 

Acked-by: Thomas Hellstrom 

> ---
>  arch/x86/kernel/cpu/vmware.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
> index 9735139cfdf8..46d732696c1c 100644
> --- a/arch/x86/kernel/cpu/vmware.c
> +++ b/arch/x86/kernel/cpu/vmware.c
> @@ -49,7 +49,7 @@
>  #define VMWARE_CMD_VCPU_RESERVED 31
>  
>  #define VMWARE_PORT(cmd, eax, ebx, ecx, edx) \
> - __asm__("inl (%%dx)" :  \
> + __asm__("inl (%%dx), %%eax" :   \
>   "=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :\
>   "a"(VMWARE_HYPERVISOR_MAGIC),   \
>   "c"(VMWARE_CMD_##cmd),  \

[PATCH] x86/cpu/vmware: use the full form of inl in VMWARE_PORT

2019-10-07 Thread Sami Tolvanen 
LLVM's assembler doesn't accept the short form inl (%%dx) instruction,
but instead insists on the output register to be explicitly specified:

  :1:7: error: invalid operand for instruction
  inl (%dx)
 ^
  LLVM ERROR: Error parsing inline asm

Use the full form of the instruction to fix the build.

Signed-off-by: Sami Tolvanen 
---
 arch/x86/kernel/cpu/vmware.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
index 9735139cfdf8..46d732696c1c 100644
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -49,7 +49,7 @@
 #define VMWARE_CMD_VCPU_RESERVED 31
 
 #define VMWARE_PORT(cmd, eax, ebx, ecx, edx)   \
-   __asm__("inl (%%dx)" :  \
+   __asm__("inl (%%dx), %%eax" :   \
"=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :\
"a"(VMWARE_HYPERVISOR_MAGIC),   \
"c"(VMWARE_CMD_##cmd),  \
-- 
2.23.0.581.g78d2f28ef7-goog