From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f53.google.com (mail-ej1-f53.google.com [209.85.218.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 810DC1BBBDD for ; Tue, 27 Aug 2024 12:40:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724762435; cv=none; b=KnL6BsR8OhuY+oAJgyDtu+lWXZ+7sLRdWP42y9WDimFtxx+5a67tPTr2hfX2nNx+OuZjt3uyZgQsyPt9XdwkIJSzdkv5Tsb9LJl1hR3i4T80lda3PNlwKDh6Lqg01CJDSHTge7XIkrGzchP9yXDL3+ulesQ5xIWHxLah6QlIbMs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724762435; c=relaxed/simple; bh=/PsGYidPx6+ERZmAziEKQOOY4l7eHfRbQ5ZJvgTJFS0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=bUqKoVldlSWqRZ9U0zxuanqnra/kWr/fDfyrHG9ncRaMs89PkhDKogTFpz9++x/eINPCoMV9Bl+TBAVS0r6IyBHzmVLBNYtq6VyqKvgm+7XNtbLfLZ4bFyWTBA4WiBI9UzdA5RNYyCJXT+6ZsMLWbgkI5A2YCFEhPrWXR+W8z7M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b=B2vXf//I; arc=none smtp.client-ip=209.85.218.53 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b="B2vXf//I" Received: by mail-ej1-f53.google.com with SMTP id a640c23a62f3a-a86e5e9ff05so100243066b.1 for ; Tue, 27 Aug 2024 05:40:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1724762432; x=1725367232; darn=lists.linux.dev; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=9zVOTmoRZ3AzmWugvFPF8grdlifA6e7LOITutJp+jd0=; b=B2vXf//IGDlZoOvEvsmIXtjH6CTJSmgEfMtf94SDlY7K8IwmEXfNP+pAq5yENztWjd uK5WHg1qcrv9n0DaMuthEHu+JDzaxNP8qX0uovWqQUsbyqqS/mh9jn0IodgtrS3Gy71k S0UW1NCAR26kJSvPv29d77MKMIWOgVESYtwV3qcJAXZ1ApXKZ+gQzBrF7XmDHomKLbrA 1EsYT8R2oRrLHpFCeS8Qo9FGaGfjN19akSDM2nzq2pWyMStttOY809GVKWDSYfg+6zyZ sxs6/iqQDRUveP5jil6V0gmrT/Zp9+5tDMmSMHssjzckV+LHjDK7HtUyEBvPgxHVhYsB KZaQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1724762432; x=1725367232; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=9zVOTmoRZ3AzmWugvFPF8grdlifA6e7LOITutJp+jd0=; b=lV1xb/jIFDZuP6F5GS1evjgjQPI22MMqsM8borIOOc38iYtfQVxuJUk/jmCkihNUgn qUmTy2IO4T/YRtWlCXLF1rKX5N5SQyNei90osx5jozKPJ4y1uGrFwI4SH8wruwHw6+ES TWChivhyD/WcXHn5pMWpjtPqAGaAdhTOvhcgNSWZ4BpaiJ+r4TiIZBZq1fXmEpS7kNSU fWU/97W3q+YtfIdFvd4RL0VjcQUIG1u7UVS93iRejSIY4BpkxV2Ku73zdI799P/OFieX Tk8sBEFJ9qRLqqWABKnUwrizbpDiNImss7u+0MMM2C5G50STBLLaJ292H0rppsPkp/uU N78Q== X-Forwarded-Encrypted: i=1; AJvYcCXq/4GDkAD7ucrsfJVll6v1nqCaBgAuoElJxtj0s4vmTHfVGWwY6dvk+cUYzd1bhU7hZLg6KA==@lists.linux.dev X-Gm-Message-State: AOJu0YwFkVuVVODsJoKnZ6qbb8PJ6xD5vkGYb4E3qlxRo5NylqcdqIIb nPepJOqKSCsJJ4+Cn8y1Hc4Z1dYOmQJFaRQLXVFampqqiX+bMUPBbz3zlP0CIQc= X-Google-Smtp-Source: AGHT+IH6McW6hyGl6MR/gJhPXCODeA+z498UhPFdaJ7K9nt2nnEpjKiqvYziIFRATCpbd9fKRid2WA== X-Received: by 2002:a17:906:6a23:b0:a7a:8e98:890d with SMTP id a640c23a62f3a-a86e39c9e11mr232226966b.16.1724762431563; Tue, 27 Aug 2024 05:40:31 -0700 (PDT) Received: from [10.100.51.161] ([193.86.92.181]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a86e549cf94sm105628966b.80.2024.08.27.05.40.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 27 Aug 2024 05:40:31 -0700 (PDT) Message-ID: Date: Tue, 27 Aug 2024 14:40:30 +0200 Precedence: bulk X-Mailing-List: asahi@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 03/19] gendwarfksyms: Add address matching To: Sami Tolvanen Cc: Masahiro Yamada , Luis Chamberlain , Miguel Ojeda , Greg Kroah-Hartman , Matthew Maurer , Alex Gaynor , Wedson Almeida Filho , Gary Guo , Petr Pavlu , Neal Gompa , Hector Martin , Janne Grunau , Asahi Linux , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-modules@vger.kernel.org, rust-for-linux@vger.kernel.org References: <20240815173903.4172139-21-samitolvanen@google.com> <20240815173903.4172139-24-samitolvanen@google.com> Content-Language: en-US From: Petr Pavlu In-Reply-To: <20240815173903.4172139-24-samitolvanen@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/15/24 19:39, Sami Tolvanen wrote: > The compiler may choose not to emit type information in DWARF for all > aliases, but it's possible for each alias to be exported separately. > To ensure we find type information for the aliases as well, read > {section, address} tuples from the symbol table and match symbols also > by address. > > Signed-off-by: Sami Tolvanen > --- > scripts/gendwarfksyms/gendwarfksyms.c | 2 + > scripts/gendwarfksyms/gendwarfksyms.h | 7 ++ > scripts/gendwarfksyms/symbols.c | 161 +++++++++++++++++++++++++- > 3 files changed, 165 insertions(+), 5 deletions(-) > > diff --git a/scripts/gendwarfksyms/gendwarfksyms.c b/scripts/gendwarfksyms/gendwarfksyms.c > index d209b237766b..e2f8ee5a4bf3 100644 > --- a/scripts/gendwarfksyms/gendwarfksyms.c > +++ b/scripts/gendwarfksyms/gendwarfksyms.c > @@ -118,6 +118,8 @@ int main(int argc, const char **argv) > return -1; > } > > + check(symbol_read_symtab(fd)); > + > dwfl = dwfl_begin(&callbacks); > if (!dwfl) { > error("dwfl_begin failed for '%s': %s", object_files[n], > diff --git a/scripts/gendwarfksyms/gendwarfksyms.h b/scripts/gendwarfksyms/gendwarfksyms.h > index 03f3e408a839..cb9106dfddb9 100644 > --- a/scripts/gendwarfksyms/gendwarfksyms.h > +++ b/scripts/gendwarfksyms/gendwarfksyms.h > @@ -61,6 +61,10 @@ extern bool debug; > /* > * symbols.c > */ > +struct symbol_addr { > + uint32_t section; > + Elf64_Addr address; > +}; > > static inline u32 name_hash(const char *name) > { > @@ -69,10 +73,13 @@ static inline u32 name_hash(const char *name) > > struct symbol { > const char *name; > + struct symbol_addr addr; > + struct hlist_node addr_hash; > struct hlist_node name_hash; > }; > > extern int symbol_read_exports(FILE *file); > +extern int symbol_read_symtab(int fd); > extern struct symbol *symbol_get(const char *name); > > /* > diff --git a/scripts/gendwarfksyms/symbols.c b/scripts/gendwarfksyms/symbols.c > index 673ad9cf9e77..f96acb941196 100644 > --- a/scripts/gendwarfksyms/symbols.c > +++ b/scripts/gendwarfksyms/symbols.c > @@ -6,11 +6,43 @@ > #include "gendwarfksyms.h" > > #define SYMBOL_HASH_BITS 15 > + > +/* struct symbol_addr -> struct symbol */ > +static DEFINE_HASHTABLE(symbol_addrs, SYMBOL_HASH_BITS); > +/* name -> struct symbol */ > static DEFINE_HASHTABLE(symbol_names, SYMBOL_HASH_BITS); > > +static inline u32 symbol_addr_hash(const struct symbol_addr *addr) > +{ > + return jhash(addr, sizeof(struct symbol_addr), 0); I would be careful and avoid including the padding between symbol_addr.section and symbol_addr.address in the hash calculation. > +} > + > typedef int (*symbol_callback_t)(struct symbol *, void *arg); > > -static int for_each(const char *name, symbol_callback_t func, void *data) > +static int __for_each_addr(struct symbol *sym, symbol_callback_t func, > + void *data) > +{ > + struct hlist_node *tmp; > + struct symbol *match = NULL; > + int processed = 0; > + > + hash_for_each_possible_safe(symbol_addrs, match, tmp, addr_hash, > + symbol_addr_hash(&sym->addr)) { > + if (match == sym) > + continue; /* Already processed */ > + > + if (match->addr.section == sym->addr.section && > + match->addr.address == sym->addr.address) { > + check(func(match, data)); > + ++processed; > + } > + } > + > + return processed; > +} > + > +static int for_each(const char *name, bool name_only, symbol_callback_t func, > + void *data) > { > struct hlist_node *tmp; > struct symbol *match; > @@ -23,9 +55,13 @@ static int for_each(const char *name, symbol_callback_t func, void *data) > if (strcmp(match->name, name)) > continue; > > + /* Call func for the match, and all address matches */ > if (func) > check(func(match, data)); > > + if (!name_only && match->addr.section != SHN_UNDEF) > + return checkp(__for_each_addr(match, func, data)) + 1; > + > return 1; > } > > @@ -34,7 +70,7 @@ static int for_each(const char *name, symbol_callback_t func, void *data) > > static bool is_exported(const char *name) > { > - return checkp(for_each(name, NULL, NULL)) > 0; > + return checkp(for_each(name, true, NULL, NULL)) > 0; > } > > int symbol_read_exports(FILE *file) > @@ -57,13 +93,14 @@ int symbol_read_exports(FILE *file) > if (is_exported(name)) > continue; /* Ignore duplicates */ > > - sym = malloc(sizeof(struct symbol)); > + sym = calloc(1, sizeof(struct symbol)); > if (!sym) { > - error("malloc failed"); > + error("calloc failed"); > return -1; > } > > sym->name = name; > + sym->addr.section = SHN_UNDEF; > name = NULL; > > hash_add(symbol_names, &sym->name_hash, name_hash(sym->name)); > @@ -91,6 +128,120 @@ struct symbol *symbol_get(const char *name) > { > struct symbol *sym = NULL; > > - for_each(name, get_symbol, &sym); > + for_each(name, false, get_symbol, &sym); > return sym; > } > + > +typedef int (*elf_symbol_callback_t)(const char *name, GElf_Sym *sym, > + Elf32_Word xndx, void *arg); > + > +static int elf_for_each_symbol(int fd, elf_symbol_callback_t func, void *arg) > +{ > + size_t sym_size; > + GElf_Shdr shdr_mem; > + GElf_Shdr *shdr; > + Elf_Data *xndx_data = NULL; > + Elf_Scn *scn; > + Elf *elf; > + > + if (elf_version(EV_CURRENT) != EV_CURRENT) { > + error("elf_version failed: %s", elf_errmsg(-1)); > + return -1; > + } > + > + elf = elf_begin(fd, ELF_C_READ_MMAP, NULL); > + if (!elf) { > + error("elf_begin failed: %s", elf_errmsg(-1)); > + return -1; > + } > + > + sym_size = gelf_getclass(elf) == ELFCLASS32 ? sizeof(Elf32_Sym) : > + sizeof(Elf64_Sym); > + > + scn = elf_nextscn(elf, NULL); > + > + while (scn) { > + shdr = gelf_getshdr(scn, &shdr_mem); > + > + if (shdr && shdr->sh_type == SHT_SYMTAB_SHNDX) { > + xndx_data = elf_getdata(scn, NULL); > + break; > + } > + > + scn = elf_nextscn(elf, scn); > + } > + > + scn = elf_nextscn(elf, NULL); > + > + while (scn) { > + shdr = gelf_getshdr(scn, &shdr_mem); > + > + if (shdr && shdr->sh_type == SHT_SYMTAB) { > + Elf_Data *data = elf_getdata(scn, NULL); > + unsigned int nsyms = data->d_size / sym_size; I think strictly speaking this should be: size_t nsyms = shdr->sh_size / shdr->sh_entsize; .. and the code could check that shdr->sh_entsize is same as what gelf_fsize(elf, ELF_T_SYM, 1, EV_CURRENT) returns. > + unsigned int n; > + > + for (n = 0; n < nsyms; ++n) { The first symbol in the symbol table is always undefined, the loop can start from 1. Alternatively, since elf_for_each_symbol() ends up in the entire series being used only with process_symbol() which skips symbols with the local binding, the function could be renamed to elf_for_each_global_symbol() and start the loop from shdr->sh_info. > + const char *name = NULL; > + Elf32_Word xndx = 0; > + GElf_Sym sym_mem; > + GElf_Sym *sym; > + > + sym = gelf_getsymshndx(data, xndx_data, n, > + &sym_mem, &xndx); > + > + if (sym->st_shndx != SHN_XINDEX) > + xndx = sym->st_shndx; > + > + name = elf_strptr(elf, shdr->sh_link, > + sym->st_name); > + > + /* Skip empty symbol names */ > + if (name && *name && > + checkp(func(name, sym, xndx, arg)) > 0) > + break; > + } > + } > + > + scn = elf_nextscn(elf, scn); > + } > + > + return check(elf_end(elf)); > +} > + > +static int set_symbol_addr(struct symbol *sym, void *arg) > +{ > + struct symbol_addr *addr = arg; > + > + if (sym->addr.section == SHN_UNDEF) { > + sym->addr.section = addr->section; > + sym->addr.address = addr->address; > + hash_add(symbol_addrs, &sym->addr_hash, > + symbol_addr_hash(&sym->addr)); > + > + debug("%s -> { %u, %lx }", sym->name, sym->addr.section, > + sym->addr.address); > + } else { > + warn("multiple addresses for symbol %s?", sym->name); > + } > + > + return 0; > +} > + > +static int process_symbol(const char *name, GElf_Sym *sym, Elf32_Word xndx, > + void *arg) > +{ > + struct symbol_addr addr = { .section = xndx, .address = sym->st_value }; > + > + /* Set addresses for exported symbols */ > + if (GELF_ST_BIND(sym->st_info) != STB_LOCAL && > + addr.section != SHN_UNDEF) > + checkp(for_each(name, true, set_symbol_addr, &addr)); > + > + return 0; > +} > + > +int symbol_read_symtab(int fd) > +{ > + return elf_for_each_symbol(fd, process_symbol, NULL); > +} -- Thanks, Petr