Linux Virtualization - Nov 2015 - [RFC PATCH] x86/paravirt: Kill some unused patching functions

From: Borislav Petkov <bp at suse.de>

paravirt_patch_ignore() is completely unused and paravirt_patch_nop()
doesn't do a whole lot. Remove them both.

Signed-off-by: Borislav Petkov <bp at suse.de>
Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Andy Lutomirski <luto at kernel.org>
Cc: Chris Wright <chrisw at sous-sol.org>
Cc: "H. Peter Anvin" <hpa at zytor.com>
Cc: Ingo Molnar <mingo at redhat.com>
Cc: Jeremy Fitzhardinge <jeremy at goop.org>
Cc: Juergen Gross <jgross at suse.com>
Cc: "Peter Zijlstra (Intel)" <peterz at infradead.org>
Cc: Rusty Russell <rusty at rustcorp.com.au>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: virtualization at lists.linux-foundation.org
Cc: xen-devel at lists.xenproject.org
---
 arch/x86/include/asm/paravirt_types.h |  2 --
 arch/x86/kernel/paravirt.c            | 13 +------------
 2 files changed, 1 insertion(+), 14 deletions(-)

diff --git a/arch/x86/include/asm/paravirt_types.h
b/arch/x86/include/asm/paravirt_types.h
index 31247b5bff7c..e1f31dfc3b31 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -402,10 +402,8 @@ extern struct pv_lock_ops pv_lock_ops;
 	__visible extern const char start_##ops##_##name[], end_##ops##_##name[];	\
 	asm(NATIVE_LABEL("start_", ops, name) code
NATIVE_LABEL("end_", ops, name))
 
-unsigned paravirt_patch_nop(void);
 unsigned paravirt_patch_ident_32(void *insnbuf, unsigned len);
 unsigned paravirt_patch_ident_64(void *insnbuf, unsigned len);
-unsigned paravirt_patch_ignore(unsigned len);
 unsigned paravirt_patch_call(void *insnbuf,
 			     const void *target, u16 tgt_clobbers,
 			     unsigned long addr, u16 site_clobbers,
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index c2130aef3f9d..4f32a10979db 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -74,16 +74,6 @@ void __init default_banner(void)
 /* Undefined instruction for dealing with missing ops pointers. */
 static const unsigned char ud2a[] = { 0x0f, 0x0b };
 
-unsigned paravirt_patch_nop(void)
-{
-	return 0;
-}
-
-unsigned paravirt_patch_ignore(unsigned len)
-{
-	return len;
-}
-
 struct branch {
 	unsigned char opcode;
 	u32 delta;
@@ -152,8 +142,7 @@ unsigned paravirt_patch_default(u8 type, u16 clobbers, void
*insnbuf,
 		/* If there's no function, patch it with a ud2a (BUG) */
 		ret = paravirt_patch_insns(insnbuf, len, ud2a, ud2a+sizeof(ud2a));
 	else if (opfunc == _paravirt_nop)
-		/* If the operation is a nop, then nop the callsite */
-		ret = paravirt_patch_nop();
+		ret = 0;
 
 	/* identity functions just return their single argument */
 	else if (opfunc == _paravirt_ident_32)
-- 
2.3.5

On 11/03/2015 10:18 AM, Borislav Petkov wrote:
> From: Borislav Petkov <bp at suse.de>
>
> paravirt_patch_ignore() is completely unused and paravirt_patch_nop()
> doesn't do a whole lot. Remove them both.
>
> Signed-off-by: Borislav Petkov <bp at suse.de>
Reviewed-by: Juergen Gross <jgross at suse.com>
> Cc: Andrew Morton <akpm at linux-foundation.org>
> Cc: Andy Lutomirski <luto at kernel.org>
> Cc: Chris Wright <chrisw at sous-sol.org>
> Cc: "H. Peter Anvin" <hpa at zytor.com>
> Cc: Ingo Molnar <mingo at redhat.com>
> Cc: Jeremy Fitzhardinge <jeremy at goop.org>
> Cc: Juergen Gross <jgross at suse.com>
> Cc: "Peter Zijlstra (Intel)" <peterz at infradead.org>
> Cc: Rusty Russell <rusty at rustcorp.com.au>
> Cc: Thomas Gleixner <tglx at linutronix.de>
> Cc: virtualization at lists.linux-foundation.org
> Cc: xen-devel at lists.xenproject.org
> ---
>   arch/x86/include/asm/paravirt_types.h |  2 --
>   arch/x86/kernel/paravirt.c            | 13 +------------
>   2 files changed, 1 insertion(+), 14 deletions(-)
>
> diff --git a/arch/x86/include/asm/paravirt_types.h
b/arch/x86/include/asm/paravirt_types.h
> index 31247b5bff7c..e1f31dfc3b31 100644
> --- a/arch/x86/include/asm/paravirt_types.h
> +++ b/arch/x86/include/asm/paravirt_types.h
> @@ -402,10 +402,8 @@ extern struct pv_lock_ops pv_lock_ops;
>   	__visible extern const char start_##ops##_##name[],
end_##ops##_##name[];	\
>   	asm(NATIVE_LABEL("start_", ops, name) code
NATIVE_LABEL("end_", ops, name))
>
> -unsigned paravirt_patch_nop(void);
>   unsigned paravirt_patch_ident_32(void *insnbuf, unsigned len);
>   unsigned paravirt_patch_ident_64(void *insnbuf, unsigned len);
> -unsigned paravirt_patch_ignore(unsigned len);
>   unsigned paravirt_patch_call(void *insnbuf,
>   			     const void *target, u16 tgt_clobbers,
>   			     unsigned long addr, u16 site_clobbers,
> diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
> index c2130aef3f9d..4f32a10979db 100644
> --- a/arch/x86/kernel/paravirt.c
> +++ b/arch/x86/kernel/paravirt.c
> @@ -74,16 +74,6 @@ void __init default_banner(void)
>   /* Undefined instruction for dealing with missing ops pointers. */
>   static const unsigned char ud2a[] = { 0x0f, 0x0b };
>
> -unsigned paravirt_patch_nop(void)
> -{
> -	return 0;
> -}
> -
> -unsigned paravirt_patch_ignore(unsigned len)
> -{
> -	return len;
> -}
> -
>   struct branch {
>   	unsigned char opcode;
>   	u32 delta;
> @@ -152,8 +142,7 @@ unsigned paravirt_patch_default(u8 type, u16 clobbers,
void *insnbuf,
>   		/* If there's no function, patch it with a ud2a (BUG) */
>   		ret = paravirt_patch_insns(insnbuf, len, ud2a, ud2a+sizeof(ud2a));
>   	else if (opfunc == _paravirt_nop)
> -		/* If the operation is a nop, then nop the callsite */
> -		ret = paravirt_patch_nop();
> +		ret = 0;
>
>   	/* identity functions just return their single argument */
>   	else if (opfunc == _paravirt_ident_32)
>