linux-kernel - Re: [PATCH 4/8] objtool: Add support for intra-function calls

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Date:   Fri, 24 Apr 2020 16:07:33 +0200 (CEST)
From:   Miroslav Benes <mbenes@...e.cz>
To:     Peter Zijlstra <peterz@...radead.org>
cc:     jpoimboe@...hat.com, alexandre.chartre@...cle.com,
        linux-kernel@...r.kernel.org, jthierry@...hat.com,
        tglx@...utronix.de, x86@...nel.org
Subject: Re: [PATCH 4/8] objtool: Add support for intra-function calls

> ---
> 
> diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
> index 6340ea0dd527..be6520155cfd 100644
> --- a/tools/objtool/arch/x86/decode.c
> +++ b/tools/objtool/arch/x86/decode.c
> @@ -100,6 +100,7 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
>  		      rex_x = 0, modrm = 0, modrm_mod = 0, modrm_rm = 0,
>  		      modrm_reg = 0, sib = 0;
>  	struct stack_op *op = NULL;
> +	struct symbol *sym;
>  
>  	x86_64 = is_x86_64(elf);
>  	if (x86_64 == -1)
> @@ -496,22 +497,24 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
>  		*type = INSN_RETURN;
>  		break;
>  
> -	case 0xcf: /* iret */
> -		*type = INSN_EXCEPTION_RETURN;
> -
> -		ADD_OP(op) {
> -			/* add $40, %rsp */
> -			op->src.type = OP_SRC_ADD;
> -			op->src.reg = CFI_SP;
> -			op->src.offset = 5*8;
> -			op->dest.type = OP_DEST_REG;
> -			op->dest.reg = CFI_SP;
> -		}
> -		break;
> -
>  	case 0xca: /* retf */
>  	case 0xcb: /* retf */
> +	case 0xcf: /* iret */
>  		*type = INSN_CONTEXT_SWITCH;
> +
> +		sym = find_symbol_by_offset(sec, offset);

sym = find_symbol_containing(sec, offset);

of course

> +		if (sym && sym->type == STT_FUNC) {
> +			*type = INSN_OTHER;
> +
> +			ADD_OP(op) {
> +				/* add $40, %rsp */
> +				op->src.type = OP_SRC_ADD;
> +				op->src.reg = CFI_SP;
> +				op->src.offset = 5*8;
> +				op->dest.type = OP_DEST_REG;
> +				op->dest.reg = CFI_SP;
> +			}
> +		}
>  		break;