[PATCH] x86/xen: Fix a -Wmissing prototypes warning for xen_start_kernel()

[PATCH] x86/xen: Fix a -Wmissing prototypes warning for xen_start_kernel()

[Benjamin Thiel]

Fix:

  arch/x86/xen/enlighten_pv.c:1212:34:
  warning: no previous prototype for ‘xen_start_kernel’ [-Wmissing-prototypes]
  asmlinkage __visible void __init xen_start_kernel(void)

Add a prototype for xen_start_kernel() in a separate xen-specific header.

Signed-off-by: Benjamin Thiel <b.thiel@posteo.de>
---
 arch/x86/include/asm/xen/setup.h | 7 +++++++
 arch/x86/xen/enlighten_pv.c      | 1 +
 2 files changed, 8 insertions(+)
 create mode 100644 arch/x86/include/asm/xen/setup.h

diff --git a/arch/x86/include/asm/xen/setup.h b/arch/x86/include/asm/xen/setup.h
new file mode 100644
index 000000000000..b7bd97f4b837
--- /dev/null
+++ b/arch/x86/include/asm/xen/setup.h
@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_XEN_SETUP_H
+#define _ASM_X86_XEN_SETUP_H
+
+asmlinkage __visible void __init xen_start_kernel(void);
+
+#endif /*_ASM_X86_XEN_SETUP_H */
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 35321f4d49f1..dc0850f09c70 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -55,6 +55,7 @@
 #include <asm/xen/hypercall.h>
 #include <asm/xen/hypervisor.h>
 #include <asm/xen/cpuid.h>
+#include <asm/xen/setup.h>
 #include <asm/fixmap.h>
 #include <asm/processor.h>
 #include <asm/proto.h>
-- 
2.20.1

Re: [PATCH] x86/xen: Fix a -Wmissing prototypes warning for xen_start_kernel()

[Boris Ostrovsky]

On 6/6/20 10:27 AM, Benjamin Thiel wrote:
> Fix:
>
>   arch/x86/xen/enlighten_pv.c:1212:34:
>   warning: no previous prototype for ‘xen_start_kernel’ [-Wmissing-prototypes]
>   asmlinkage __visible void __init xen_start_kernel(void)
>
> Add a prototype for xen_start_kernel() in a separate xen-specific header.


TBH I am not sure it's worth a new header file for a routine that is
only called from assembly (and never returns). I'd just add the
prototype right above function definition, with a comment describing
why. I see a few examples of this in the tree. Or maybe we even have an
attribute for this case?


(I also suspect the same may be needed for xen_prepare_pvh() BTW).


-boris

Re: [PATCH] x86/xen: Fix a -Wmissing prototypes warning for xen_start_kernel()

[Borislav Petkov]

On Mon, Jun 08, 2020 at 03:30:13PM -0400, Boris Ostrovsky wrote:
> TBH I am not sure it's worth a new header file for a routine that is
> only called from assembly (and never returns). I'd just add the
> prototype right above function definition, with a comment describing
> why. 

Right, that works too.

> I see a few examples of this in the tree. Or maybe we even have an
> attribute for this case?

Not that I'm aware of.

> (I also suspect the same may be needed for xen_prepare_pvh() BTW).

Yeah, Benni is working through the rest of them. Btw, the final goal of
this whole work is to enable -Wmissing-prototypes by default on x86.

Thx.

-- 
Regards/Gruss,
    Boris.

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