From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 9AE343438A0; Sat, 12 Sep 2026 05:47:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789192033; cv=none; b=RJ7zXrOF3aq65K8mzB/rHO+Twq7c6pqkcgoiitXiwrKLL4z9KKUd1s6IxLaMBtgNF6+RJiAiede+1SgGL6kFvKwvZX78qPuPpcap9stP5VPpQ3VgsTwoAEvVXAU9E6ujlqyZLALol4H2La8jd0cmv+zb8lig0YbqFZWkqRzoB0c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789192033; c=relaxed/simple; bh=9rTPBRQNFbhkPpWu07uefnMLUJIgUw0iqFOmDICck7Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EGMBE7BVNjZgFG4Uf+T9NiCcQMgMe1e7zoMTelMsfQqT8uWMTXWDoeol4p43WVpyReI5smiHfL5X69VBc4r3WEb+QPP3RCjRiZ4ABAaB3/D3BSScimUA3ZMC/f1Cm/3fv+lkHDwVXjcatLIRtTHDfih5nQZEjwI9gOEJUfbLYeM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=kExom4ei; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="kExom4ei" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DA7511F0089D; Sat, 12 Sep 2026 05:47:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789192031; bh=/lbcpL34xjVfLdT41e2SVefAYol68GxosbShhiJAp/s=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=kExom4eiDy6NqWDOFMkx8p3L1m9z2e+hhx2452ObCDnAuAlCY8rL9ZSHm4lgya3PA gXxTFfjuCXjmWCUKfpJliLtd0+AY+jwjhVNIZA9q9JtNjJgSOKx99UR6RLRfWH2bIw hr5zLy8Dedm2epBtKbNI2Z77uHAv9O3fdurwZYMNYLQj2brLDuLWROD3pE2sksvrqz t4v9NdQqeeiI1dTDeoqi9ouoheRQqBJDyg+2CvvT8kvW+gGYny1O+1aJ6WDP/9264V 2OABpyFJDGWVjShN0+IK0DtmFCM4DTdN/89ygfS9g/M+W6VkAY/gbR0zYGgvNMFkuP 8RuWQjNVPfrrg== From: Namhyung Kim To: Arnaldo Carvalho de Melo Cc: Ian Rogers , Jiri Olsa , Adrian Hunter , James Clark , Peter Zijlstra , Ingo Molnar , LKML , linux-perf-users@vger.kernel.org, Zecheng Li , Yanbo Zhao , Tengda Wu , Shuai Xue , Masami Hiramatsu Subject: [PATCH 2/4] perf dwarf-aux: Add die_has_flex_array() helper Date: Fri, 11 Sep 2026 22:47:04 -0700 Message-ID: <20260912054706.1475583-3-namhyung@kernel.org> X-Mailer: git-send-email 2.55.0.1032.g73a4cd73de-goog In-Reply-To: <20260912054706.1475583-1-namhyung@kernel.org> References: <20260912054706.1475583-1-namhyung@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The die_has_flex_array() returns true when the given type is a struct and contains an array at the end of the struct. Cc: Masami Hiramatsu Signed-off-by: Namhyung Kim --- tools/perf/util/dwarf-aux.c | 57 +++++++++++++++++++++++++++++++++++++ tools/perf/util/dwarf-aux.h | 3 ++ 2 files changed, 60 insertions(+) diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c index d7160f87ac7d7ab3..98d018798fa750ae 100644 --- a/tools/perf/util/dwarf-aux.c +++ b/tools/perf/util/dwarf-aux.c @@ -2180,3 +2180,60 @@ Dwarf_Die *die_deref_ptr_type(Dwarf_Die *ptr_die, int offset, return die_get_member_type(&type_die, offset, die_mem); } + +static bool __die_find_last_member(Dwarf_Die *parent_die, Dwarf_Die *die_mem) +{ + Dwarf_Die tmp_die; + bool found = false; + + if (dwarf_child(parent_die, &tmp_die)) + return false; + + do { + if (dwarf_tag(&tmp_die) == DW_TAG_member) { + memcpy(die_mem, &tmp_die, sizeof(tmp_die)); + found = true; + } + } while (dwarf_siblingof(&tmp_die, &tmp_die) == 0); + + return found; +} + +/** + * die_has_flex_array - Check if the given type has a flex-array at the end + * @parent_die: a pointer to type DIE + * + * This function returns %true iff @parent_die is a struct type and has an + * array at the end. Note that the flex-array has no element, it should have + * no size and the parent size doesn't include the flex-array. So it should + * locate at the offset of the parent size. + * + * For simplicity, it assumes the parent size of aligned with the flex-array. + */ +bool die_has_flex_array(Dwarf_Die *parent_die) +{ + Dwarf_Die die_mem, type_die; + Dwarf_Word size, loc; + + if (dwarf_tag(parent_die) != DW_TAG_structure_type) + return false; + + if (dwarf_aggregate_size(parent_die, &size) < 0) + return false; + + /* get the member field at the end of the struct */ + if (!__die_find_last_member(parent_die, &die_mem)) + return false; + + /* get the type of the member */ + if (die_get_real_type(&die_mem, &type_die) == NULL) + return false; + + if (dwarf_tag(&type_die) == DW_TAG_array_type) + return die_get_data_member_location(&die_mem, &loc) == 0 && loc == size; + + if (dwarf_tag(&type_die) == DW_TAG_structure_type) + return die_has_flex_array(&type_die); + + return false; +} diff --git a/tools/perf/util/dwarf-aux.h b/tools/perf/util/dwarf-aux.h index 161f0bf980b6ee6a..9b662db710220522 100644 --- a/tools/perf/util/dwarf-aux.h +++ b/tools/perf/util/dwarf-aux.h @@ -189,4 +189,7 @@ void die_collect_global_vars(Dwarf_Die *cu_die, struct die_var_type **var_types) /* Get the frame base information from CFA */ int die_get_cfa(Dwarf *dwarf, u64 pc, int *preg, int *poffset); +/* Check whether given type has a flex array */ +bool die_has_flex_array(Dwarf_Die *parent_die); + #endif /* _DWARF_AUX_H */ -- 2.55.0.1032.g73a4cd73de-goog