From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-186.mta1.migadu.com (out-186.mta1.migadu.com [95.215.58.186]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1620A32F757 for ; Thu, 19 Mar 2026 17:32:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.186 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773941553; cv=none; b=AK8uOd22OjL2mF6b3FXbgG/UzL4FMTPXrENSC0gBFiIrHMP5EE3lSXv/KWLO5bGGKXpPd3QPxi3naniHD/9AQH3TT6rx/fkmV1jw7Fc9YNbi0CFBEXIz6zTNRABGrESrI4hPuH4zNkn024EV1FE1ULjThP3WAgYZ2MR07zyIpNg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773941553; c=relaxed/simple; bh=bpqvR8J6/QG/+CtU1wW/hVktCz6ZD7fFdAxHTYrBc2Y=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=GveQ5e1fWYkj5O2phlKqJKwx5dUJj1f/6OICBKzi6Q2o2Xh1boEO9PV4/nDBcSZXqtL1tIUU5uOveUddYpVTrg1whxrLMUdfb5ia7gWKfONFLOTEzhhXxmSympcfMG1d2azn4Fm7zz6dmE6ZNxQAGz6tw2p+nQAdrPuW96T8IxM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=GYOCa+MO; arc=none smtp.client-ip=95.215.58.186 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="GYOCa+MO" Message-ID: <4e6b366f-eaea-4cc1-b9c2-629c8089967e@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1773941527; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=YWDwFX7RDlzg//VzZrJ7A37vtyfA4VbBikusGF6Mh3g=; b=GYOCa+MOdBygqHs9YnzKQS3lZcPIU+5RffiahGa5mBZ575dVQ01BYVI9zf1/OUBFmmQOD6 YzNlIDo9XT8cc0g6guzmNkL+dDoJ95SnIHoJdRFL8yX90qB5iNkC3LxhGZ++LIBur5H56L UUBwGYqzv5slx3iyUEZyMSs/kXwXe6M= Date: Thu, 19 Mar 2026 10:31:41 -0700 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH dwarves 1/9] dwarf_loader: Reduce parameter checking with clang DW_AT_calling_convention attr To: Jiri Olsa Cc: Alan Maguire , Arnaldo Carvalho de Melo , dwarves@vger.kernel.org, Alexei Starovoitov , Andrii Nakryiko , bpf@vger.kernel.org, kernel-team@fb.com References: <20260305225455.1151066-1-yonghong.song@linux.dev> <20260305225500.1151338-1-yonghong.song@linux.dev> Content-Language: en-GB X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yonghong Song In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 3/19/26 5:32 AM, Jiri Olsa wrote: > On Thu, Mar 05, 2026 at 02:55:00PM -0800, Yonghong Song wrote: > > SNIP > >> --- >> dwarf_loader.c | 71 +++++++++++++++++++++++++++++++++++++++++++------- >> dwarves.h | 2 ++ >> 2 files changed, 63 insertions(+), 10 deletions(-) >> >> diff --git a/dwarf_loader.c b/dwarf_loader.c >> index 16fb7be..610b69e 100644 >> --- a/dwarf_loader.c >> +++ b/dwarf_loader.c >> @@ -1190,6 +1190,10 @@ static ptrdiff_t __dwarf_getlocations(Dwarf_Attribute *attr, >> return ret; >> } >> >> +struct func_info { >> + bool signature_changed; >> +}; >> + >> /* For DW_AT_location 'attr': >> * - if first location is DW_OP_regXX with expected number, return the register; >> * otherwise save the register for later return >> @@ -1252,7 +1256,8 @@ out: >> } >> >> static struct parameter *parameter__new(Dwarf_Die *die, struct cu *cu, >> - struct conf_load *conf, int param_idx) >> + struct conf_load *conf, int param_idx, >> + struct func_info *info) >> { >> struct parameter *parm = tag__alloc(cu, sizeof(*parm)); >> >> @@ -1265,6 +1270,8 @@ static struct parameter *parameter__new(Dwarf_Die *die, struct cu *cu, >> parm->idx = param_idx; >> if (param_idx >= cu->nr_register_params || param_idx < 0) >> return parm; >> + if (cu->producer_clang && !info->signature_changed) >> + return parm; > should you check for info != NULL? We should be okay. I audited that if info is NULL, then param_idx must be < 0. > >> /* Parameters which use DW_AT_abstract_origin to point at >> * the original parameter definition (with no name in the DIE) >> * are the result of later DWARF generation during compilation >> @@ -1337,7 +1344,7 @@ static int formal_parameter_pack__load_params(struct formal_parameter_pack *pack >> continue; >> } >> >> - struct parameter *param = parameter__new(die, cu, conf, -1); >> + struct parameter *param = parameter__new(die, cu, conf, -1, NULL); >> >> if (param == NULL) >> return -1; >> @@ -1502,6 +1509,29 @@ static struct ftype *ftype__new(Dwarf_Die *die, struct cu *cu) >> return ftype; >> } >> > SNIP > >> int param_idx = 0; >> Dwarf_Die child; >> @@ -2320,7 +2353,7 @@ static int die__process_function(Dwarf_Die *die, struct ftype *ftype, >> continue; >> } >> case DW_TAG_formal_parameter: >> - tag = die__create_new_parameter(die, ftype, lexblock, cu, conf, param_idx++); >> + tag = die__create_new_parameter(die, ftype, lexblock, cu, conf, param_idx++, info); >> break; >> case DW_TAG_variable: >> tag = die__create_new_variable(die, cu, conf, 0); >> @@ -2391,9 +2424,10 @@ out_enomem: >> static struct tag *die__create_new_function(Dwarf_Die *die, struct cu *cu, struct conf_load *conf) >> { >> struct function *function = function__new(die, cu, conf); >> + struct func_info info = { function->signature_changed }; > would it be easier to add signature_changed to struct ftype or pass > function pointer directly to die__process_function ? > > (after reading the rest of the patches, seems like func_info is needed > anyway, so maybe not worth it) Right, there are additional fields in func_info struct. > >> >> if (function != NULL && >> - die__process_function(die, &function->proto, &function->lexblock, cu, conf) != 0) { >> + die__process_function(die, &function->proto, &function->lexblock, cu, conf, &info) != 0) { >> function__delete(function, cu); >> function = NULL; >> } >> @@ -3045,6 +3079,21 @@ static unsigned long long dwarf_tag__orig_id(const struct tag *tag, >> return cu->extra_dbg_info ? dtag->id : 0; >> } >> >> +static bool attr_producer_clang(Dwarf_Die *die) >> +{ >> + Dwarf_Attribute attr; >> + const char *producer; >> + >> + if (dwarf_attr(die, DW_AT_producer, &attr) == NULL) >> + return false; >> + >> + producer = dwarf_formstring(&attr); >> + if (!producer) >> + return false; >> + > nit you could call attr_string(die, DW_AT_producer, NULL) to get the string Good point. Will fix it in the next revision. > > jirka > >> + return !!strstr(producer, "clang"); >> +} >> + > SNIP >