From patchwork Thu Oct 12 03:50:30 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Namhyung Kim X-Patchwork-Id: 13418215 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 1FF30EA3; Thu, 12 Oct 2023 03:51:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="bWvj/1R3" Received: from mail-pl1-x632.google.com (mail-pl1-x632.google.com [IPv6:2607:f8b0:4864:20::632]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5D35BCC; Wed, 11 Oct 2023 20:51:24 -0700 (PDT) Received: by mail-pl1-x632.google.com with SMTP id d9443c01a7336-1c60f1a2652so4037085ad.0; Wed, 11 Oct 2023 20:51:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1697082684; x=1697687484; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:sender:from:to:cc:subject:date :message-id:reply-to; bh=iJAPgps5vTes2Y2qx7RQDKoRh92FtNMtdWH/CZXcwx0=; b=bWvj/1R3SWPRqd2i3KlTv8jDqSzj9TljduYQGyEpLscC8Lk2nwEuyTPxggWCk2IhmW rqeCeztkeqAfvkNV9jI2TZM35d7OKUJEyYxcMG8Cwc6WZC3o3vxapoI6lFaU6RoZyQXj YxIMR33ul3z4xRa1PjEUhXnWDCDP6Q5XLFjlRwzeKszIDyPhdOodZdDQEMJVzXcjcTlt CXwZBHkkzX0dmEu56tm6QVXZ9LRJHXw0GJK2fGg2qmBS3+fMoYdOVqIdQFT5rlFXlvKD vjKfAgO9QbGJ1r5WRSkWHCu/J3BatqTVMgZ0AYxhQ31xr0+UaMyfXqzd/OusbwX8XuM9 2K9Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1697082684; x=1697687484; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:sender:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=iJAPgps5vTes2Y2qx7RQDKoRh92FtNMtdWH/CZXcwx0=; b=wcvcXDZ1WDEd9T6PE2EaI1CQjpNcTT11emSn4yu486T37YfIkoOigNPKQiR+4nla4D dBCMbcwhJOnmzjRoHIBLu+ZrmRNDAohwXLErRA4rSXMBsRN1DvB7ksgMiD9NGdivCdzQ 65Oz3RdeJiI+V8o2m6S3VQTARP1J5uSh1uMf2C8VRtg5uS7lq4iuyHKv2WRNN+i6NA4/ Nk7l4xD7KBU7bKVRB8xy1HGOlcr+WFoNXjoUFMLwVEGI0CzFEm/K76vPHUOauFQIIvJD 6EpCMEXRlvGPS4hho8XM4XXYX5PrBvB6sIfaZu7puJnHQqXiUmNAlCjXVmAZs7mHkJ5O mmuA== X-Gm-Message-State: AOJu0YwuaDuXvqh/qENHpDeiaiXhMG0xX5e7kEvIie8QouS2+5cvKaN0 fl9EmK2Fp2SDy35WfQlRnb0= X-Google-Smtp-Source: AGHT+IHA2NlxKsGKl2muwRYeArO/59rj3wAkwqkfeISU9JvT2XBOHWaXkyl4VroGUHqIQaihm5Lruw== X-Received: by 2002:a17:903:2449:b0:1b6:a37a:65b7 with SMTP id l9-20020a170903244900b001b6a37a65b7mr31662151pls.23.1697082683762; Wed, 11 Oct 2023 20:51:23 -0700 (PDT) Received: from bangji.hsd1.ca.comcast.net ([2601:647:6780:42e0:b1b9:d490:2f5e:be06]) by smtp.gmail.com with ESMTPSA id w8-20020a170902d70800b001bc18e579aesm711374ply.101.2023.10.11.20.51.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Oct 2023 20:51:23 -0700 (PDT) Sender: Namhyung Kim From: Namhyung Kim To: Arnaldo Carvalho de Melo , Jiri Olsa , Peter Zijlstra Cc: Ian Rogers , Adrian Hunter , Ingo Molnar , LKML , linux-perf-users@vger.kernel.org, Linus Torvalds , Stephane Eranian , Masami Hiramatsu , linux-toolchains@vger.kernel.org, linux-trace-devel@vger.kernel.org Subject: [PATCH 07/48] perf dwarf-aux: Add die_find_variable_by_reg() helper Date: Wed, 11 Oct 2023 20:50:30 -0700 Message-ID: <20231012035111.676789-8-namhyung@kernel.org> X-Mailer: git-send-email 2.42.0.655.g421f12c284-goog In-Reply-To: <20231012035111.676789-1-namhyung@kernel.org> References: <20231012035111.676789-1-namhyung@kernel.org> Precedence: bulk X-Mailing-List: linux-trace-devel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-1.5 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_EF,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net The die_find_variable_by_reg() will search for a variable or a parameter sub-DIE in the given scope DIE where the location matches to the given register. For the simpliest and most common case, memory access usually happens with a base register and an offset to the field so the register would hold a pointer in a variable or function parameter. Then we can find one if it has a location expression at the (instruction) address. So this function only handles such a simple case for now. In this case, the expression would have a DW_OP_regN operation where N < 32. If the register index (N) is greater than or equal to 32, DW_OP_regx operation with an operand which saves the value for the N would be used. It would reject expressions with more operations. Cc: Masami Hiramatsu Signed-off-by: Namhyung Kim Acked-by: Masami Hiramatsu (Google) --- tools/perf/util/dwarf-aux.c | 67 +++++++++++++++++++++++++++++++++++++ tools/perf/util/dwarf-aux.h | 12 +++++++ 2 files changed, 79 insertions(+) diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c index 10aa32334d6f..652e6e7368a2 100644 --- a/tools/perf/util/dwarf-aux.c +++ b/tools/perf/util/dwarf-aux.c @@ -1245,6 +1245,73 @@ int die_get_var_range(Dwarf_Die *sp_die, Dwarf_Die *vr_die, struct strbuf *buf) out: return ret; } + +/* Interval parameters for __die_find_var_reg_cb() */ +struct find_var_data { + /* Target instruction address */ + Dwarf_Addr pc; + /* Target register */ + unsigned reg; +}; + +/* Max number of registers DW_OP_regN supports */ +#define DWARF_OP_DIRECT_REGS 32 + +/* Only checks direct child DIEs in the given scope. */ +static int __die_find_var_reg_cb(Dwarf_Die *die_mem, void *arg) +{ + struct find_var_data *data = arg; + int tag = dwarf_tag(die_mem); + ptrdiff_t off = 0; + Dwarf_Attribute attr; + Dwarf_Addr base, start, end; + Dwarf_Op *ops; + size_t nops; + + if (tag != DW_TAG_variable && tag != DW_TAG_formal_parameter) + return DIE_FIND_CB_SIBLING; + + if (dwarf_attr(die_mem, DW_AT_location, &attr) == NULL) + return DIE_FIND_CB_SIBLING; + + while ((off = dwarf_getlocations(&attr, off, &base, &start, &end, &ops, &nops)) > 0) { + /* Assuming the location list is sorted by address */ + if (end < data->pc) + continue; + if (start > data->pc) + break; + + /* Only match with a simple case */ + if (data->reg < DWARF_OP_DIRECT_REGS) { + if (ops->atom == (DW_OP_reg0 + data->reg) && nops == 1) + return DIE_FIND_CB_END; + } else { + if (ops->atom == DW_OP_regx && ops->number == data->reg && + nops == 1) + return DIE_FIND_CB_END; + } + } + return DIE_FIND_CB_SIBLING; +} + +/** + * die_find_variable_by_reg - Find a variable saved in a register + * @sc_die: a scope DIE + * @pc: the program address to find + * @reg: the register number to find + * @die_mem: a buffer to save the resulting DIE + * + * Find the variable DIE accessed by the given register. + */ +Dwarf_Die *die_find_variable_by_reg(Dwarf_Die *sc_die, Dwarf_Addr pc, int reg, + Dwarf_Die *die_mem) +{ + struct find_var_data data = { + .pc = pc, + .reg = reg, + }; + return die_find_child(sc_die, __die_find_var_reg_cb, &data, die_mem); +} #endif /* diff --git a/tools/perf/util/dwarf-aux.h b/tools/perf/util/dwarf-aux.h index f9d765f80fb0..b6f430730bd1 100644 --- a/tools/perf/util/dwarf-aux.h +++ b/tools/perf/util/dwarf-aux.h @@ -137,6 +137,10 @@ int die_get_scopes(Dwarf_Die *cu_die, Dwarf_Addr pc, Dwarf_Die **scopes); /* Get byte offset range of given variable DIE */ int die_get_var_range(Dwarf_Die *sp_die, Dwarf_Die *vr_die, struct strbuf *buf); +/* Find a variable saved in the 'reg' at given address */ +Dwarf_Die *die_find_variable_by_reg(Dwarf_Die *sc_die, Dwarf_Addr pc, int reg, + Dwarf_Die *die_mem); + #else /* HAVE_DWARF_GETLOCATIONS_SUPPORT */ static inline int die_get_var_range(Dwarf_Die *sp_die __maybe_unused, @@ -146,6 +150,14 @@ static inline int die_get_var_range(Dwarf_Die *sp_die __maybe_unused, return -ENOTSUP; } +static inline Dwarf_Die *die_find_variable_by_reg(Dwarf_Die *sc_die __maybe_unused, + Dwarf_Addr pc __maybe_unused, + int reg __maybe_unused, + Dwarf_Die *die_mem __maybe_unused) +{ + return NULL; +} + #endif /* HAVE_DWARF_GETLOCATIONS_SUPPORT */ #endif /* _DWARF_AUX_H */