From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Tue, 08 Sep 2009 18:17:14 +0200 (CEST) Received: from ru.mvista.com ([213.79.90.228]:22052 "EHLO buildserver.ru.mvista.com" rhost-flags-OK-FAIL-OK-FAIL) by ftp.linux-mips.org with ESMTP id S1492691AbZIHQRG (ORCPT ); Tue, 8 Sep 2009 18:17:06 +0200 Received: from [192.168.11.243] (unknown [10.150.0.9]) by buildserver.ru.mvista.com (Postfix) with ESMTP id 11D568814; Tue, 8 Sep 2009 18:06:33 +0500 (SAMST) Message-ID: <4AA656D8.9040608@ru.mvista.com> Date: Tue, 08 Sep 2009 17:06:32 +0400 From: Maxim Uvarov User-Agent: Thunderbird 2.0.0.23 (X11/20090817) MIME-Version: 1.0 To: linux-mips@linux-mips.org Cc: ralf@linux-mips.org Subject: [MIPS] TLB handler fix for vmalloc'ed addresses Content-Type: multipart/mixed; boundary="------------060200050905030006090904" Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 23994 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: muvarov@ru.mvista.com Precedence: bulk X-list: linux-mips This is a multi-part message in MIME format. --------------060200050905030006090904 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Patch is attached. Best regards, Maxim Uvarov. --------------060200050905030006090904 Content-Type: text/x-patch; name="mips_tlb_fixup.patch" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="mips_tlb_fixup.patch" TLB exception handler incorrecly handles situation with wrong vmalloc'ed addresses. This patch adds verifications for vmalloc'ed addresses (similar to x86_64 implementation). So the code now traps inside do_page_fault() on access to the wrong area. Signed-off-by: Maxim Uvarov Test case: #include #include #include #include #include static struct task_struct *ts; static int example_thread(void *dummy) { void *ptr; ptr = vmalloc(16*1024*1024); for(;;) { msleep(100); } } static void run_vmalloc(void *unused) { ts=kthread_run(example_thread,NULL,"vtest"); } int init_module (void) { run_vmalloc(NULL); return 0; } void cleanup_module (void) { /*Nothing*/} Originally kernel trapped on BUG() inside exit_mmap() and it was impossible to see what has happened. After this patch applied, nice back trace will be generated: CPU 0 Unable to handle kernel paging request at virtual address c00000000036a148 Oops[#1]: Cpu 0 $ 0 : 0000000000000000 ffffffff81940000 0000000000000000 00000000ffff05a7 $ 4 : 0000000000000000 ffffffffffffffff ffffffff81a0b7d0 ffffffff811983e4 $ 8 : ffffffff817407b0 0000000000000000 0000000000000000 0000000000000000 $12 : a80000003374bfe0 0000000000008c00 ffffffff811e9df8 0000000000000000 $16 : ffffffff81164a68 a8000000352a3c50 c00000000036a0e8 0000000000000000 $20 : 0000000000000000 0000000000000000 0000000000000000 0000000000000000 $24 : 0000000000000002 a8000000337bb1a0 $28 : a800000033748000 a80000003374bf70 a80000003374bf70 c00000000036a148 Hi : 0000000000000000 Lo : 000000000000a311 epc : c00000000036a148 0xc00000000036a148 Tainted: P ra : c00000000036a148 0xc00000000036a148 <-- dead in kernel module vtest Status: 10008ce3 KX SX UX KERNEL EXL IE Cause : 00000008 BadVA : c00000000036a148 PrId : 000d0408 Modules linked in: Process vtest (pid: 723, threadinfo=a800000033748000, task=a800000034530340) Stack : 0000000000000000 a80000003374bf90 ffffffff81176530 ffffffff81176488 ffffffffffffffff ffffffffffffffff 0000000000000000 0000000000000000 0000000000000000 a80000003374bfd0 ffffffff81125024 0000000000000000 0000000000000000 0000000000000000 5a5a5a5a5a5a5a5a 5a5a5a5a5a5a5a5a 5a5a5a5a5a5a5a5a 5a5a5a5a5a5a5aa5 Call Trace: [] kthread+0x198/0x1f0 [] kthread+0xf0/0x1f0 [] kernel_thread_helper+0x14/0x20 Code: (Bad address in epc) Index: linux-2.6.21/arch/mips/mm/fault.c =================================================================== --- linux-2.6.21.orig/arch/mips/mm/fault.c +++ linux-2.6.21/arch/mips/mm/fault.c @@ -282,22 +282,32 @@ vmalloc_fault: pte_t *pte_k; pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset; - pgd_k = init_mm.pgd + offset; + pgd_k = pgd_offset_k(address); if (!pgd_present(*pgd_k)) goto no_context; - set_pgd(pgd, *pgd_k); + if (unlikely(!pgd_present(*pgd))) + set_pgd(pgd, *pgd_k); + else if (pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_k)) + goto no_context; pud = pud_offset(pgd, address); pud_k = pud_offset(pgd_k, address); if (!pud_present(*pud_k)) goto no_context; + if (pud_none(*pud) || + pud_page_vaddr(*pud) != pud_page_vaddr(*pud_k)) + goto no_context; pmd = pmd_offset(pud, address); pmd_k = pmd_offset(pud_k, address); if (!pmd_present(*pmd_k)) goto no_context; - set_pmd(pmd, *pmd_k); + if (!pmd_present(*pmd)) + set_pmd(pmd, *pmd_k); + else + if (pmd_page(*pmd) != pmd_page(*pmd_k)) + goto no_context; pte_k = pte_offset_kernel(pmd_k, address); if (!pte_present(*pte_k)) --------------060200050905030006090904--