linux-kernel - Re: [PATCH 02/22] x86/kvm: Fix fastop function ELF metadata

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Message-ID: <a78c29e4-5377-88c1-28a9-b04569fdb0c9@redhat.com>
Date:   Mon, 15 Jul 2019 11:05:00 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>, x86@...nel.org
Cc:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Arnd Bergmann <arnd@...db.de>, Jann Horn <jannh@...gle.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Radim Krčmář <rkrcmar@...hat.com>
Subject: Re: [PATCH 02/22] x86/kvm: Fix fastop function ELF metadata

On 15/07/19 02:36, Josh Poimboeuf wrote:
> Some of the fastop functions, e.g. em_setcc(), are actually just used as
> global labels which point to blocks of functions.  The global labels are
> incorrectly annotated as functions.  Also the functions themselves don't
> have size annotations.
> 
> Fixes a bunch of warnings like the following:
> 
>   arch/x86/kvm/emulate.o: warning: objtool: seto() is missing an ELF size annotation
>   arch/x86/kvm/emulate.o: warning: objtool: em_setcc() is missing an ELF size annotation
>   arch/x86/kvm/emulate.o: warning: objtool: setno() is missing an ELF size annotation
>   arch/x86/kvm/emulate.o: warning: objtool: setc() is missing an ELF size annotation
> 
> Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
> ---
> Cc: Paolo Bonzini <pbonzini@...hat.com>
> Cc: Radim Krčmář <rkrcmar@...hat.com>
> ---
>  arch/x86/kvm/emulate.c | 44 +++++++++++++++++++++++++++++-------------
>  1 file changed, 31 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index 8e409ad448f9..718f7d9afedc 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -312,29 +312,42 @@ static void invalidate_registers(struct x86_emulate_ctxt *ctxt)
>  
>  static int fastop(struct x86_emulate_ctxt *ctxt, void (*fop)(struct fastop *));
>  
> -#define FOP_FUNC(name) \
> +#define __FOP_FUNC(name) \
>  	".align " __stringify(FASTOP_SIZE) " \n\t" \
>  	".type " name ", @function \n\t" \
>  	name ":\n\t"
>  
> -#define FOP_RET   "ret \n\t"
> +#define FOP_FUNC(name) \
> +	__FOP_FUNC(#name)
> +
> +#define __FOP_RET(name) \
> +	"ret \n\t" \
> +	".size " name ", .-" name "\n\t"
> +
> +#define FOP_RET(name) \
> +	__FOP_RET(#name)
>  
>  #define FOP_START(op) \
>  	extern void em_##op(struct fastop *fake); \
>  	asm(".pushsection .text, \"ax\" \n\t" \
>  	    ".global em_" #op " \n\t" \
> -	    FOP_FUNC("em_" #op)
> +	    ".align " __stringify(FASTOP_SIZE) " \n\t" \
> +	    "em_" #op ":\n\t"
>  
>  #define FOP_END \
>  	    ".popsection")
>  
> +#define __FOPNOP(name) \
> +	__FOP_FUNC(name) \
> +	__FOP_RET(name)
> +
>  #define FOPNOP() \
> -	FOP_FUNC(__stringify(__UNIQUE_ID(nop))) \
> -	FOP_RET
> +	__FOPNOP(__stringify(__UNIQUE_ID(nop)))
>  
>  #define FOP1E(op,  dst) \
> -	FOP_FUNC(#op "_" #dst) \
> -	"10: " #op " %" #dst " \n\t" FOP_RET
> +	__FOP_FUNC(#op "_" #dst) \
> +	"10: " #op " %" #dst " \n\t" \
> +	__FOP_RET(#op "_" #dst)
>  
>  #define FOP1EEX(op,  dst) \
>  	FOP1E(op, dst) _ASM_EXTABLE(10b, kvm_fastop_exception)
> @@ -366,8 +379,9 @@ static int fastop(struct x86_emulate_ctxt *ctxt, void (*fop)(struct fastop *));
>  	FOP_END
>  
>  #define FOP2E(op,  dst, src)	   \
> -	FOP_FUNC(#op "_" #dst "_" #src) \
> -	#op " %" #src ", %" #dst " \n\t" FOP_RET
> +	__FOP_FUNC(#op "_" #dst "_" #src) \
> +	#op " %" #src ", %" #dst " \n\t" \
> +	__FOP_RET(#op "_" #dst "_" #src)
>  
>  #define FASTOP2(op) \
>  	FOP_START(op) \
> @@ -405,8 +419,9 @@ static int fastop(struct x86_emulate_ctxt *ctxt, void (*fop)(struct fastop *));
>  	FOP_END
>  
>  #define FOP3E(op,  dst, src, src2) \
> -	FOP_FUNC(#op "_" #dst "_" #src "_" #src2) \
> -	#op " %" #src2 ", %" #src ", %" #dst " \n\t" FOP_RET
> +	__FOP_FUNC(#op "_" #dst "_" #src "_" #src2) \
> +	#op " %" #src2 ", %" #src ", %" #dst " \n\t"\
> +	__FOP_RET(#op "_" #dst "_" #src "_" #src2)
>  
>  /* 3-operand, word-only, src2=cl */
>  #define FASTOP3WCL(op) \
> @@ -423,7 +438,7 @@ static int fastop(struct x86_emulate_ctxt *ctxt, void (*fop)(struct fastop *));
>  	".type " #op ", @function \n\t" \
>  	#op ": \n\t" \
>  	#op " %al \n\t" \
> -	FOP_RET
> +	__FOP_RET(#op)
>  
>  asm(".pushsection .fixup, \"ax\"\n"
>      ".global kvm_fastop_exception \n"
> @@ -449,7 +464,10 @@ FOP_SETCC(setle)
>  FOP_SETCC(setnle)
>  FOP_END;
>  
> -FOP_START(salc) "pushf; sbb %al, %al; popf \n\t" FOP_RET
> +FOP_START(salc)
> +FOP_FUNC(salc)
> +"pushf; sbb %al, %al; popf \n\t"
> +FOP_RET(salc)
>  FOP_END;
>  
>  /*
> 

Acked-by: Paolo Bonzini <pbonzini@...hat.com>