From patchwork Fri Dec 6 13:07:25 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xi Ruoyao X-Patchwork-Id: 848374 Received: from xry111.site (xry111.site [89.208.246.23]) (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 93E7C1C1F19; Fri, 6 Dec 2024 13:08:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=89.208.246.23 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733490484; cv=none; b=l5MWu9URYgBMUhdYUm8Ts8xYGFEWZu34DcZd850yLXyEcV9WIeU8yTygR9x3IDMUYoNU7keGJjf8Zbe+FyHye8BK8W7pvyLg5HFh3uTmX66nI2YUZ8+O2tjN+l0x8ohiP6HAc8zhXJ0fvNx0/aEZFz/H92iBkIJt85VYvuMzfNQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733490484; c=relaxed/simple; bh=1ixYuV9vn+tvWWMjI9qcrLzeMtCAsGWYRbir1E1avq8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=s+eHmZG0oyRzO9E6fyf2PjZSp0hStPyh1eYjXpoe6AkQqCvilAMzElZv4R405NX4OmiH/p17nelMD+kS75XjStoc3SGHm14S7+Pxsn74qxNDH87VAc2baLRNqqgsroadzNeorq4tlZJZe7memahRX81bSjV6wYUDH8dV+NguPRY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=xry111.site; spf=pass smtp.mailfrom=xry111.site; dkim=pass (1024-bit key) header.d=xry111.site header.i=@xry111.site header.b=E7JWWcnG; arc=none smtp.client-ip=89.208.246.23 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=xry111.site Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=xry111.site Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=xry111.site header.i=@xry111.site header.b="E7JWWcnG" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=xry111.site; s=default; t=1733490481; bh=XnKm59ylPYPwoM2DkN4Cx3zBQck18EMZi4AXKvhtbWo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=E7JWWcnG1+tJLydCqLAwS1NH5On7Gx6kfN9sRI2Ava1ePlhNZ1oVGZUUMpr2Mfb3x T+PMUlh7kW9ltKamp7Ssg+cSNOukT1ZHR04gyTjbj+BIeRycG2ti5+on178Di/xb7n 7DnQSmJU5jRYDj9mk4pGWk0QPUy60JrD/h+AoKDU= Received: from stargazer.. (unknown [113.200.174.114]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (secp384r1) server-digest SHA384) (Client did not present a certificate) (Authenticated sender: xry111@xry111.site) by xry111.site (Postfix) with ESMTPSA id 14E6C6748E; Fri, 6 Dec 2024 08:07:59 -0500 (EST) From: Xi Ruoyao To: Shuah Khan , Fangrui Song , linux-kselftest@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Xi Ruoyao Subject: [PATCH v3] selftests/vDSO: support DT_GNU_HASH Date: Fri, 6 Dec 2024 21:07:25 +0800 Message-ID: <20241206130724.7944-2-xry111@xry111.site> X-Mailer: git-send-email 2.47.1 In-Reply-To: <297cfe11-0418-4633-8c15-4ffc7d290a3d@linuxfoundation.org> References: <297cfe11-0418-4633-8c15-4ffc7d290a3d@linuxfoundation.org> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Fangrui Song glibc added support for DT_GNU_HASH in 2006 and DT_HASH has been obsoleted for more than one decade in many Linux distributions. Many vDSOs support DT_GNU_HASH. This patch adds selftests support. Signed-off-by: Fangrui Song Tested-by: Xi Ruoyao Signed-off-by: Xi Ruoyao # rebase --- tools/testing/selftests/vDSO/parse_vdso.c | 110 ++++++++++++++++------ 1 file changed, 82 insertions(+), 28 deletions(-) base-commit: 40384c840ea1944d7c5a392e8975ed088ecf0b37 diff --git a/tools/testing/selftests/vDSO/parse_vdso.c b/tools/testing/selftests/vDSO/parse_vdso.c index 28f35620c499..2fe5e983cb22 100644 --- a/tools/testing/selftests/vDSO/parse_vdso.c +++ b/tools/testing/selftests/vDSO/parse_vdso.c @@ -53,6 +53,7 @@ static struct vdso_info /* Symbol table */ ELF(Sym) *symtab; const char *symstrings; + ELF(Word) *gnu_hash; ELF_HASH_ENTRY *bucket, *chain; ELF_HASH_ENTRY nbucket, nchain; @@ -81,6 +82,16 @@ static unsigned long elf_hash(const char *name) return h; } +static uint32_t gnu_hash(const char *name) +{ + const unsigned char *s = (void *)name; + uint32_t h = 5381; + + for (; *s; s++) + h += h * 32 + *s; + return h; +} + void vdso_init_from_sysinfo_ehdr(uintptr_t base) { size_t i; @@ -123,6 +134,7 @@ void vdso_init_from_sysinfo_ehdr(uintptr_t base) */ ELF_HASH_ENTRY *hash = 0; vdso_info.symstrings = 0; + vdso_info.gnu_hash = 0; vdso_info.symtab = 0; vdso_info.versym = 0; vdso_info.verdef = 0; @@ -143,6 +155,11 @@ void vdso_init_from_sysinfo_ehdr(uintptr_t base) ((uintptr_t)dyn[i].d_un.d_ptr + vdso_info.load_offset); break; + case DT_GNU_HASH: + vdso_info.gnu_hash = + (ELF(Word) *)((uintptr_t)dyn[i].d_un.d_ptr + + vdso_info.load_offset); + break; case DT_VERSYM: vdso_info.versym = (ELF(Versym) *) ((uintptr_t)dyn[i].d_un.d_ptr @@ -155,17 +172,27 @@ void vdso_init_from_sysinfo_ehdr(uintptr_t base) break; } } - if (!vdso_info.symstrings || !vdso_info.symtab || !hash) + if (!vdso_info.symstrings || !vdso_info.symtab || + (!hash && !vdso_info.gnu_hash)) return; /* Failed */ if (!vdso_info.verdef) vdso_info.versym = 0; /* Parse the hash table header. */ - vdso_info.nbucket = hash[0]; - vdso_info.nchain = hash[1]; - vdso_info.bucket = &hash[2]; - vdso_info.chain = &hash[vdso_info.nbucket + 2]; + if (vdso_info.gnu_hash) { + vdso_info.nbucket = vdso_info.gnu_hash[0]; + /* The bucket array is located after the header (4 uint32) and the bloom + * filter (size_t array of gnu_hash[2] elements). + */ + vdso_info.bucket = vdso_info.gnu_hash + 4 + + sizeof(size_t) / 4 * vdso_info.gnu_hash[2]; + } else { + vdso_info.nbucket = hash[0]; + vdso_info.nchain = hash[1]; + vdso_info.bucket = &hash[2]; + vdso_info.chain = &hash[vdso_info.nbucket + 2]; + } /* That's all we need. */ vdso_info.valid = true; @@ -209,6 +236,26 @@ static bool vdso_match_version(ELF(Versym) ver, && !strcmp(name, vdso_info.symstrings + aux->vda_name); } +static bool check_sym(ELF(Sym) *sym, ELF(Word) i, const char *name, + const char *version, unsigned long ver_hash) +{ + /* Check for a defined global or weak function w/ right name. */ + if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC) + return false; + if (ELF64_ST_BIND(sym->st_info) != STB_GLOBAL && + ELF64_ST_BIND(sym->st_info) != STB_WEAK) + return false; + if (strcmp(name, vdso_info.symstrings + sym->st_name)) + return false; + + /* Check symbol version. */ + if (vdso_info.versym && + !vdso_match_version(vdso_info.versym[i], version, ver_hash)) + return false; + + return true; +} + void *vdso_sym(const char *version, const char *name) { unsigned long ver_hash; @@ -216,29 +263,36 @@ void *vdso_sym(const char *version, const char *name) return 0; ver_hash = elf_hash(version); - ELF(Word) chain = vdso_info.bucket[elf_hash(name) % vdso_info.nbucket]; - - for (; chain != STN_UNDEF; chain = vdso_info.chain[chain]) { - ELF(Sym) *sym = &vdso_info.symtab[chain]; - - /* Check for a defined global or weak function w/ right name. */ - if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC) - continue; - if (ELF64_ST_BIND(sym->st_info) != STB_GLOBAL && - ELF64_ST_BIND(sym->st_info) != STB_WEAK) - continue; - if (sym->st_shndx == SHN_UNDEF) - continue; - if (strcmp(name, vdso_info.symstrings + sym->st_name)) - continue; - - /* Check symbol version. */ - if (vdso_info.versym - && !vdso_match_version(vdso_info.versym[chain], - version, ver_hash)) - continue; - - return (void *)(vdso_info.load_offset + sym->st_value); + ELF(Word) i; + + if (vdso_info.gnu_hash) { + uint32_t h1 = gnu_hash(name), h2, *hashval; + + i = vdso_info.bucket[h1 % vdso_info.nbucket]; + if (i == 0) + return 0; + h1 |= 1; + hashval = vdso_info.bucket + vdso_info.nbucket + + (i - vdso_info.gnu_hash[1]); + for (;; i++) { + ELF(Sym) *sym = &vdso_info.symtab[i]; + h2 = *hashval++; + if (h1 == (h2 | 1) && + check_sym(sym, i, name, version, ver_hash)) + return (void *)(vdso_info.load_offset + + sym->st_value); + if (h2 & 1) + break; + } + } else { + i = vdso_info.bucket[elf_hash(name) % vdso_info.nbucket]; + for (; i; i = vdso_info.chain[i]) { + ELF(Sym) *sym = &vdso_info.symtab[i]; + if (sym->st_shndx != SHN_UNDEF && + check_sym(sym, i, name, version, ver_hash)) + return (void *)(vdso_info.load_offset + + sym->st_value); + } } return 0;