From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753561AbeFDHDi (ORCPT ); Mon, 4 Jun 2018 03:03:38 -0400 Received: from mail.kernel.org ([198.145.29.99]:55694 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753511AbeFDHDe (ORCPT ); Mon, 4 Jun 2018 03:03:34 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Arnd Bergmann , kbuild test robot , Josh Poimboeuf , "Peter Zijlstra (Intel)" , David Laight , Linus Torvalds , Randy Dunlap , Thomas Gleixner , damian , Ingo Molnar Subject: [PATCH 4.16 02/47] objtool: Support GCC 8 switch tables Date: Mon, 4 Jun 2018 08:58:14 +0200 Message-Id: <20180604065549.574831400@linuxfoundation.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180604065549.468488465@linuxfoundation.org> References: <20180604065549.468488465@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Josh Poimboeuf commit fd35c88b74170d9335530d9abf271d5d73eb5401 upstream. With GCC 8, some issues were found with the objtool switch table detection. 1) In the .rodata section, immediately after the switch table, there can be another object which contains a pointer to the function which had the switch statement. In this case objtool wrongly considers the function pointer to be part of the switch table. Fix it by: a) making sure there are no pointers to the beginning of the function; and b) making sure there are no gaps in the switch table. Only the former was needed, the latter adds additional protection for future optimizations. 2) In find_switch_table(), case 1 and case 2 are missing the check to ensure that the .rodata switch table data is anonymous, i.e. that it isn't already associated with an ELF symbol. Fix it by adding the same find_symbol_containing() check which is used for case 3. This fixes the following warnings with GCC 8: drivers/block/virtio_blk.o: warning: objtool: virtio_queue_rq()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+72 net/ipv6/icmp.o: warning: objtool: icmpv6_rcv()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+64 drivers/usb/core/quirks.o: warning: objtool: quirks_param_set()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+48 drivers/mtd/nand/raw/nand_hynix.o: warning: objtool: hynix_nand_decode_id()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+24 drivers/mtd/nand/raw/nand_samsung.o: warning: objtool: samsung_nand_decode_id()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+32 drivers/gpu/drm/nouveau/nvkm/subdev/top/gk104.o: warning: objtool: gk104_top_oneinit()+0x0: stack state mismatch: cfa1=7+8 cfa2=7+64 Reported-by: Arnd Bergmann Reported-by: kbuild test robot Signed-off-by: Josh Poimboeuf Acked-by: Peter Zijlstra (Intel) Cc: David Laight Cc: Greg KH Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Randy Dunlap Cc: Thomas Gleixner Cc: damian Link: http://lkml.kernel.org/r/20180510224849.xwi34d6tzheb5wgw@treble Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- tools/objtool/check.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -806,17 +806,28 @@ static int add_switch_table(struct objto struct rela *rela = table; struct instruction *alt_insn; struct alternative *alt; + struct symbol *pfunc = insn->func->pfunc; + unsigned int prev_offset = 0; list_for_each_entry_from(rela, &file->rodata->rela->rela_list, list) { if (rela == next_table) break; + /* Make sure the switch table entries are consecutive: */ + if (prev_offset && rela->offset != prev_offset + 8) + break; + + /* Detect function pointers from contiguous objects: */ + if (rela->sym->sec == pfunc->sec && + rela->addend == pfunc->offset) + break; + alt_insn = find_insn(file, rela->sym->sec, rela->addend); if (!alt_insn) break; /* Make sure the jmp dest is in the function or subfunction: */ - if (alt_insn->func->pfunc != insn->func->pfunc) + if (alt_insn->func->pfunc != pfunc) break; alt = malloc(sizeof(*alt)); @@ -827,6 +838,13 @@ static int add_switch_table(struct objto alt->insn = alt_insn; list_add_tail(&alt->list, &insn->alts); + prev_offset = rela->offset; + } + + if (!prev_offset) { + WARN_FUNC("can't find switch jump table", + insn->sec, insn->offset); + return -1; } return 0; @@ -883,7 +901,9 @@ static struct rela *find_switch_table(st struct instruction *orig_insn = insn; text_rela = find_rela_by_dest_range(insn->sec, insn->offset, insn->len); - if (text_rela && text_rela->sym == file->rodata->sym) { + if (text_rela && text_rela->sym == file->rodata->sym && + !find_symbol_containing(file->rodata, text_rela->addend)) { + /* case 1 */ rodata_rela = find_rela_by_dest(file->rodata, text_rela->addend);