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[209.132.180.67]) by mx.google.com with ESMTP id x63si24996624pff.206.2017.02.03.01.54.43; Fri, 03 Feb 2017 01:54:44 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753145AbdBCJyg (ORCPT + 25 others); Fri, 3 Feb 2017 04:54:36 -0500 Received: from mail-wm0-f44.google.com ([74.125.82.44]:37311 "EHLO mail-wm0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753110AbdBCJyc (ORCPT ); Fri, 3 Feb 2017 04:54:32 -0500 Received: by mail-wm0-f44.google.com with SMTP id v77so19569205wmv.0 for ; Fri, 03 Feb 2017 01:54:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=aSN8JMNpJ6X2oqakYcIBfZ/l1TAPNFVQ4WhqrP6Fq8s=; b=V5dmRt6fpbkN8uh2llk6cK351++pEwL/NhOqx3gUO1l9lXcOcEX1wtcUfO5GkKkm2d cS1vWH9JcSdyJ98YpfS7JSNoyDfd6WLhR6E70hmiAhExdb8jST6NTDvy+FyQXMxFCWMt Z/XDF0JHMHcPcc9VPeLrVKKYeW6q4nvw8PjuY= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=aSN8JMNpJ6X2oqakYcIBfZ/l1TAPNFVQ4WhqrP6Fq8s=; b=j1q4KmZkj65RMUp+lo4msaRms54EvQv1SV5OmHi13O0qCLhWRQ1HeJGOd1Xk3hy/7j +91BNiUjSJXAgDrQGpON27ifAgUsKCMrLXMQS9943MWREYPwqwF7WG1MQzuNJyYrEkDc KIfOHvBCzTVpizV/NyRlixzVLuxe+XU8Vf+raa1kDEZJoNySEdqMm3fRFrOZ3V/wbDwG X3by6jR+dYkVehf0Aw80s1pfpiSxFl0HbodjF8Ra34cZrcga2erZ8/MoI8fGjZIAES4X bOdliW9lyFr5k9x1NtxBDh+vBoF6KTD6UigSnLH8gGczo/Qusz98X1a5WexcZFMHkC1T e/DA== X-Gm-Message-State: AMke39kvd1WD1nHQfFBe+0ZW+N5Nnujs01F43ndKUrzJpHreoAYVVjxj+F2TY1HFlJiOxtXm X-Received: by 10.28.185.77 with SMTP id j74mr623593wmf.76.1486115670956; Fri, 03 Feb 2017 01:54:30 -0800 (PST) Received: from localhost.localdomain ([105.130.17.13]) by smtp.gmail.com with ESMTPSA id l67sm2144562wmf.1.2017.02.03.01.54.28 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Fri, 03 Feb 2017 01:54:30 -0800 (PST) From: Ard Biesheuvel To: linux-kbuild@vger.kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, jeyu@redhat.com, rusty@rustcorp.com.au, mmarek@suse.com, mpe@ellerman.id.au Cc: torvalds@linux-foundation.org, arnd@arndb.de, viro@zeniv.linux.org.uk, linux-arm-kernel@lists.infradead.org, Ard Biesheuvel Subject: [PATCH v5 1/3] kbuild: modversions: add infrastructure for emitting relative CRCs Date: Fri, 3 Feb 2017 09:54:05 +0000 Message-Id: <1486115647-27680-2-git-send-email-ard.biesheuvel@linaro.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1486115647-27680-1-git-send-email-ard.biesheuvel@linaro.org> References: <1486115647-27680-1-git-send-email-ard.biesheuvel@linaro.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This add the kbuild infrastructure that will allow architectures to emit vmlinux symbol CRCs as 32-bit offsets to another location in the kernel where the actual value is stored. This works around problems with CRCs being mistaken for relocatable symbols on kernels that self relocate at runtime (i.e., powerpc with CONFIG_RELOCATABLE=y) For the kbuild side of things, this comes down to the following: - introducing a Kconfig symbol MODULE_REL_CRCS - adding a -R switch to genksyms to instruct it to emit the CRC symbols as references into the .rodata section - making modpost distinguish such references from absolute CRC symbols by the section index (SHN_ABS) - making kallsyms disregard non-absolute symbols with a __crc_ prefix Signed-off-by: Ard Biesheuvel --- init/Kconfig | 4 ++++ scripts/Makefile.build | 2 ++ scripts/genksyms/genksyms.c | 19 ++++++++++++++----- scripts/kallsyms.c | 12 ++++++++++++ scripts/mod/modpost.c | 10 ++++++++++ 5 files changed, 42 insertions(+), 5 deletions(-) -- 2.7.4 diff --git a/init/Kconfig b/init/Kconfig index e1a937348a3e..4dd8bd232a1d 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1987,6 +1987,10 @@ config MODVERSIONS make them incompatible with the kernel you are running. If unsure, say N. +config MODULE_REL_CRCS + bool + depends on MODVERSIONS + config MODULE_SRCVERSION_ALL bool "Source checksum for all modules" help diff --git a/scripts/Makefile.build b/scripts/Makefile.build index eadcd4d359d9..d883116ebaa4 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -164,6 +164,7 @@ cmd_gensymtypes_c = \ $(CPP) -D__GENKSYMS__ $(c_flags) $< | \ $(GENKSYMS) $(if $(1), -T $(2)) \ $(patsubst y,-s _,$(CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX)) \ + $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS)) \ $(if $(KBUILD_PRESERVE),-p) \ -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null)) @@ -337,6 +338,7 @@ cmd_gensymtypes_S = \ $(CPP) -D__GENKSYMS__ $(c_flags) -xc - | \ $(GENKSYMS) $(if $(1), -T $(2)) \ $(patsubst y,-s _,$(CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX)) \ + $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS)) \ $(if $(KBUILD_PRESERVE),-p) \ -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null)) diff --git a/scripts/genksyms/genksyms.c b/scripts/genksyms/genksyms.c index 06121ce524a7..c9235d8340f1 100644 --- a/scripts/genksyms/genksyms.c +++ b/scripts/genksyms/genksyms.c @@ -44,7 +44,7 @@ char *cur_filename, *source_file; int in_source_file; static int flag_debug, flag_dump_defs, flag_reference, flag_dump_types, - flag_preserve, flag_warnings; + flag_preserve, flag_warnings, flag_rel_crcs; static const char *mod_prefix = ""; static int errors; @@ -693,7 +693,10 @@ void export_symbol(const char *name) fputs(">\n", debugfile); /* Used as a linker script. */ - printf("%s__crc_%s = 0x%08lx ;\n", mod_prefix, name, crc); + printf(!flag_rel_crcs ? "%s__crc_%s = 0x%08lx;\n" : + "SECTIONS { .rodata : ALIGN(4) { " + "%s__crc_%s = .; LONG(0x%08lx); } }\n", + mod_prefix, name, crc); } } @@ -730,7 +733,7 @@ void error_with_pos(const char *fmt, ...) static void genksyms_usage(void) { - fputs("Usage:\n" "genksyms [-adDTwqhV] > /path/to/.tmp_obj.ver\n" "\n" + fputs("Usage:\n" "genksyms [-adDTwqhVR] > /path/to/.tmp_obj.ver\n" "\n" #ifdef __GNU_LIBRARY__ " -s, --symbol-prefix Select symbol prefix\n" " -d, --debug Increment the debug level (repeatable)\n" @@ -742,6 +745,7 @@ static void genksyms_usage(void) " -q, --quiet Disable warnings (default)\n" " -h, --help Print this message\n" " -V, --version Print the release version\n" + " -R, --relative-crc Emit section relative symbol CRCs\n" #else /* __GNU_LIBRARY__ */ " -s Select symbol prefix\n" " -d Increment the debug level (repeatable)\n" @@ -753,6 +757,7 @@ static void genksyms_usage(void) " -q Disable warnings (default)\n" " -h Print this message\n" " -V Print the release version\n" + " -R Emit section relative symbol CRCs\n" #endif /* __GNU_LIBRARY__ */ , stderr); } @@ -774,13 +779,14 @@ int main(int argc, char **argv) {"preserve", 0, 0, 'p'}, {"version", 0, 0, 'V'}, {"help", 0, 0, 'h'}, + {"relative-crc", 0, 0, 'R'}, {0, 0, 0, 0} }; - while ((o = getopt_long(argc, argv, "s:dwqVDr:T:ph", + while ((o = getopt_long(argc, argv, "s:dwqVDr:T:phR", &long_opts[0], NULL)) != EOF) #else /* __GNU_LIBRARY__ */ - while ((o = getopt(argc, argv, "s:dwqVDr:T:ph")) != EOF) + while ((o = getopt(argc, argv, "s:dwqVDr:T:phR")) != EOF) #endif /* __GNU_LIBRARY__ */ switch (o) { case 's': @@ -823,6 +829,9 @@ int main(int argc, char **argv) case 'h': genksyms_usage(); return 0; + case 'R': + flag_rel_crcs = 1; + break; default: genksyms_usage(); return 1; diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c index 299b92ca1ae0..5d554419170b 100644 --- a/scripts/kallsyms.c +++ b/scripts/kallsyms.c @@ -219,6 +219,10 @@ static int symbol_valid(struct sym_entry *s) "_SDA2_BASE_", /* ppc */ NULL }; + static char *special_prefixes[] = { + "__crc_", /* modversions */ + NULL }; + static char *special_suffixes[] = { "_veneer", /* arm */ "_from_arm", /* arm */ @@ -259,6 +263,14 @@ static int symbol_valid(struct sym_entry *s) if (strcmp(sym_name, special_symbols[i]) == 0) return 0; + for (i = 0; special_prefixes[i]; i++) { + int l = strlen(special_prefixes[i]); + + if (l <= strlen(sym_name) && + strncmp(sym_name, special_prefixes[i], l) == 0) + return 0; + } + for (i = 0; special_suffixes[i]; i++) { int l = strlen(sym_name) - strlen(special_suffixes[i]); diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 29c89a6bad3d..4dedd0d3d3a7 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -621,6 +621,16 @@ static void handle_modversions(struct module *mod, struct elf_info *info, if (strncmp(symname, CRC_PFX, strlen(CRC_PFX)) == 0) { is_crc = true; crc = (unsigned int) sym->st_value; + if (sym->st_shndx != SHN_UNDEF && sym->st_shndx != SHN_ABS) { + unsigned int *crcp; + + /* symbol points to the CRC in the ELF object */ + crcp = (void *)info->hdr + sym->st_value + + info->sechdrs[sym->st_shndx].sh_offset - + (info->hdr->e_type != ET_REL ? + info->sechdrs[sym->st_shndx].sh_addr : 0); + crc = *crcp; + } sym_update_crc(symname + strlen(CRC_PFX), mod, crc, export); }