* [PATCH] x86/kvm: Move kvm_fastop_exception to .fixup section
@ 2017-10-04 14:43 Josh Poimboeuf
2017-10-04 15:16 ` Guenter Roeck
0 siblings, 1 reply; 5+ messages in thread
From: Josh Poimboeuf @ 2017-10-04 14:43 UTC (permalink / raw)
To: x86; +Cc: linux-kernel, Guenter Roeck
When compiling the kernel with the '-frecord-gcc-switches' flag, objtool
complains:
arch/x86/kvm/emulate.o: warning: objtool: .GCC.command.line+0x0: special: can't find new instruction
And also the kernel fails to link.
The problem is that the 'kvm_fastop_exception' code gets placed into the
throwaway '.GCC.command.line' section instead of '.text'.
Exception fixup code is conventionally placed in the '.fixup' section,
so put it there where it belongs.
Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
arch/x86/kvm/emulate.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index a36254cbf776..d90cdc77e077 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -425,8 +425,10 @@ static int fastop(struct x86_emulate_ctxt *ctxt, void (*fop)(struct fastop *));
#op " %al \n\t" \
FOP_RET
-asm(".global kvm_fastop_exception \n"
- "kvm_fastop_exception: xor %esi, %esi; ret");
+asm(".pushsection .fixup, \"ax\"\n"
+ ".global kvm_fastop_exception \n"
+ "kvm_fastop_exception: xor %esi, %esi; ret\n"
+ ".popsection");
FOP_START(setcc)
FOP_SETCC(seto)
--
2.13.6
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] x86/kvm: Move kvm_fastop_exception to .fixup section
2017-10-04 14:43 [PATCH] x86/kvm: Move kvm_fastop_exception to .fixup section Josh Poimboeuf
@ 2017-10-04 15:16 ` Guenter Roeck
2017-10-04 15:36 ` Josh Poimboeuf
0 siblings, 1 reply; 5+ messages in thread
From: Guenter Roeck @ 2017-10-04 15:16 UTC (permalink / raw)
To: Josh Poimboeuf; +Cc: x86, linux-kernel
On Wed, Oct 04, 2017 at 09:43:06AM -0500, Josh Poimboeuf wrote:
> When compiling the kernel with the '-frecord-gcc-switches' flag, objtool
> complains:
>
> arch/x86/kvm/emulate.o: warning: objtool: .GCC.command.line+0x0: special: can't find new instruction
>
> And also the kernel fails to link.
>
> The problem is that the 'kvm_fastop_exception' code gets placed into the
> throwaway '.GCC.command.line' section instead of '.text'.
>
> Exception fixup code is conventionally placed in the '.fixup' section,
> so put it there where it belongs.
>
> Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net>
> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Thanks!
Guenter
> ---
> arch/x86/kvm/emulate.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index a36254cbf776..d90cdc77e077 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -425,8 +425,10 @@ static int fastop(struct x86_emulate_ctxt *ctxt, void (*fop)(struct fastop *));
> #op " %al \n\t" \
> FOP_RET
>
> -asm(".global kvm_fastop_exception \n"
> - "kvm_fastop_exception: xor %esi, %esi; ret");
> +asm(".pushsection .fixup, \"ax\"\n"
> + ".global kvm_fastop_exception \n"
> + "kvm_fastop_exception: xor %esi, %esi; ret\n"
> + ".popsection");
>
> FOP_START(setcc)
> FOP_SETCC(seto)
> --
> 2.13.6
>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] x86/kvm: Move kvm_fastop_exception to .fixup section
2017-10-04 15:16 ` Guenter Roeck
@ 2017-10-04 15:36 ` Josh Poimboeuf
0 siblings, 0 replies; 5+ messages in thread
From: Josh Poimboeuf @ 2017-10-04 15:36 UTC (permalink / raw)
To: Guenter Roeck; +Cc: x86, linux-kernel
On Wed, Oct 04, 2017 at 08:16:36AM -0700, Guenter Roeck wrote:
> On Wed, Oct 04, 2017 at 09:43:06AM -0500, Josh Poimboeuf wrote:
> > When compiling the kernel with the '-frecord-gcc-switches' flag, objtool
> > complains:
> >
> > arch/x86/kvm/emulate.o: warning: objtool: .GCC.command.line+0x0: special: can't find new instruction
> >
> > And also the kernel fails to link.
> >
> > The problem is that the 'kvm_fastop_exception' code gets placed into the
> > throwaway '.GCC.command.line' section instead of '.text'.
> >
> > Exception fixup code is conventionally placed in the '.fixup' section,
> > so put it there where it belongs.
> >
> > Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net>
> > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
>
> Thanks!
I forgot to add the kvm maintainers to CC. Will resend.
--
Josh
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH] x86/kvm: Move kvm_fastop_exception to .fixup section
@ 2017-10-04 15:39 Josh Poimboeuf
2017-10-05 6:54 ` Paolo Bonzini
0 siblings, 1 reply; 5+ messages in thread
From: Josh Poimboeuf @ 2017-10-04 15:39 UTC (permalink / raw)
To: Paolo Bonzini, Radim Krčmář
Cc: x86, linux-kernel, kvm, Guenter Roeck
When compiling the kernel with the '-frecord-gcc-switches' flag, objtool
complains:
arch/x86/kvm/emulate.o: warning: objtool: .GCC.command.line+0x0: special: can't find new instruction
And also the kernel fails to link.
The problem is that the 'kvm_fastop_exception' code gets placed into the
throwaway '.GCC.command.line' section instead of '.text'.
Exception fixup code is conventionally placed in the '.fixup' section,
so put it there where it belongs.
Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
arch/x86/kvm/emulate.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index a36254cbf776..d90cdc77e077 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -425,8 +425,10 @@ static int fastop(struct x86_emulate_ctxt *ctxt, void (*fop)(struct fastop *));
#op " %al \n\t" \
FOP_RET
-asm(".global kvm_fastop_exception \n"
- "kvm_fastop_exception: xor %esi, %esi; ret");
+asm(".pushsection .fixup, \"ax\"\n"
+ ".global kvm_fastop_exception \n"
+ "kvm_fastop_exception: xor %esi, %esi; ret\n"
+ ".popsection");
FOP_START(setcc)
FOP_SETCC(seto)
--
2.13.6
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] x86/kvm: Move kvm_fastop_exception to .fixup section
2017-10-04 15:39 Josh Poimboeuf
@ 2017-10-05 6:54 ` Paolo Bonzini
0 siblings, 0 replies; 5+ messages in thread
From: Paolo Bonzini @ 2017-10-05 6:54 UTC (permalink / raw)
To: Josh Poimboeuf, Radim Krčmář
Cc: x86, linux-kernel, kvm, Guenter Roeck
On 04/10/2017 17:39, Josh Poimboeuf wrote:
> When compiling the kernel with the '-frecord-gcc-switches' flag, objtool
> complains:
>
> arch/x86/kvm/emulate.o: warning: objtool: .GCC.command.line+0x0: special: can't find new instruction
>
> And also the kernel fails to link.
>
> The problem is that the 'kvm_fastop_exception' code gets placed into the
> throwaway '.GCC.command.line' section instead of '.text'.
>
> Exception fixup code is conventionally placed in the '.fixup' section,
> so put it there where it belongs.
>
> Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net>
> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> ---
> arch/x86/kvm/emulate.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index a36254cbf776..d90cdc77e077 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -425,8 +425,10 @@ static int fastop(struct x86_emulate_ctxt *ctxt, void (*fop)(struct fastop *));
> #op " %al \n\t" \
> FOP_RET
>
> -asm(".global kvm_fastop_exception \n"
> - "kvm_fastop_exception: xor %esi, %esi; ret");
> +asm(".pushsection .fixup, \"ax\"\n"
> + ".global kvm_fastop_exception \n"
> + "kvm_fastop_exception: xor %esi, %esi; ret\n"
> + ".popsection");
>
> FOP_START(setcc)
> FOP_SETCC(seto)
>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
^ permalink raw reply [flat|nested] 5+ messages in thread
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