* Re: [PATCH] x86/cpu/vmware: use the full form of inl in VMWARE_PORT
[not found] <20191007192129.104336-1-samitolvanen@google.com>
@ 2019-10-07 19:29 ` Thomas Hellstrom via Virtualization
2019-10-07 19:57 ` Nick Desaulniers via Virtualization
2019-10-08 0:44 ` Kees Cook
2 siblings, 0 replies; 3+ messages in thread
From: Thomas Hellstrom via Virtualization @ 2019-10-07 19:29 UTC (permalink / raw)
To: Sami Tolvanen, Pv-drivers, Thomas Gleixner, Ingo Molnar,
Borislav Petkov
Cc: Kees Cook, x86@kernel.org, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
clang-built-linux@googlegroups.com, hpa@zytor.com
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:
>
> <inline asm>: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 <samitolvanen@google.com>
Acked-by: Thomas Hellstrom <thellstrom@vmware.com>
> ---
> 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), \
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] x86/cpu/vmware: use the full form of inl in VMWARE_PORT
[not found] <20191007192129.104336-1-samitolvanen@google.com>
2019-10-07 19:29 ` [PATCH] x86/cpu/vmware: use the full form of inl in VMWARE_PORT Thomas Hellstrom via Virtualization
@ 2019-10-07 19:57 ` Nick Desaulniers via Virtualization
2019-10-08 0:44 ` Kees Cook
2 siblings, 0 replies; 3+ messages in thread
From: Nick Desaulniers via Virtualization @ 2019-10-07 19:57 UTC (permalink / raw)
To: Sami Tolvanen
Cc: Thomas Hellstrom, Kees Cook, pv-drivers,
maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT), LKML,
virtualization, clang-built-linux, Ingo Molnar, Borislav Petkov,
H. Peter Anvin, Thomas Gleixner
On Mon, Oct 7, 2019 at 12:21 PM 'Sami Tolvanen' via Clang Built Linux
<clang-built-linux@googlegroups.com> wrote:
>
> LLVM's assembler doesn't accept the short form inl (%%dx) instruction,
> but instead insists on the output register to be explicitly specified:
>
> <inline asm>: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 <samitolvanen@google.com>
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:
0000000000000000 <.text>:
0: ed in (%dx),%eax
1: ed in (%dx),%eax
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> ---
> 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
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] x86/cpu/vmware: use the full form of inl in VMWARE_PORT
[not found] <20191007192129.104336-1-samitolvanen@google.com>
2019-10-07 19:29 ` [PATCH] x86/cpu/vmware: use the full form of inl in VMWARE_PORT Thomas Hellstrom via Virtualization
2019-10-07 19:57 ` Nick Desaulniers via Virtualization
@ 2019-10-08 0:44 ` Kees Cook
2 siblings, 0 replies; 3+ messages in thread
From: Kees Cook @ 2019-10-08 0:44 UTC (permalink / raw)
To: Sami Tolvanen
Cc: Thomas Hellstrom, pv-drivers, x86, linux-kernel, virtualization,
clang-built-linux, Ingo Molnar, Borislav Petkov, hpa,
Thomas Gleixner
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:
>
> <inline asm>: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 <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
-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
^ permalink raw reply [flat|nested] 3+ messages in thread