Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752860AbcDUUBn (ORCPT ); Thu, 21 Apr 2016 16:01:43 -0400 Received: from mail-ob0-f176.google.com ([209.85.214.176]:33480 "EHLO mail-ob0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751697AbcDUUBl (ORCPT ); Thu, 21 Apr 2016 16:01:41 -0400 MIME-Version: 1.0 In-Reply-To: <1460987025-30360-3-git-send-email-dsafonov@virtuozzo.com> References: <1460388169-13340-1-git-send-email-dsafonov@virtuozzo.com> <1460987025-30360-1-git-send-email-dsafonov@virtuozzo.com> <1460987025-30360-3-git-send-email-dsafonov@virtuozzo.com> From: Andy Lutomirski Date: Thu, 21 Apr 2016 13:01:20 -0700 Message-ID: Subject: Re: [PATCHv5 3/3] selftest/x86: add mremap vdso 32-bit test To: Dmitry Safonov Cc: "linux-kernel@vger.kernel.org" , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , X86 ML , Andrew Morton , "linux-mm@kvack.org" , Dmitry Safonov <0x7f454c46@gmail.com>, Shuah Khan , linux-kselftest@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4878 Lines: 144 On Mon, Apr 18, 2016 at 6:43 AM, Dmitry Safonov wrote: > Should print on success: > [root@localhost ~]# ./test_mremap_vdso_32 > AT_SYSINFO_EHDR is 0xf773f000 > [NOTE] Moving vDSO: [f773f000, f7740000] -> [a000000, a001000] > [OK] > Or segfault if landing was bad (before patches): > [root@localhost ~]# ./test_mremap_vdso_32 > AT_SYSINFO_EHDR is 0xf774f000 > [NOTE] Moving vDSO: [f774f000, f7750000] -> [a000000, a001000] > Segmentation fault (core dumped) > > Cc: Shuah Khan > Cc: linux-kselftest@vger.kernel.org > Suggested-by: Andy Lutomirski > Signed-off-by: Dmitry Safonov > --- > v5: initial version > > tools/testing/selftests/x86/Makefile | 2 +- > tools/testing/selftests/x86/test_mremap_vdso.c | 72 ++++++++++++++++++++++++++ > 2 files changed, 73 insertions(+), 1 deletion(-) > create mode 100644 tools/testing/selftests/x86/test_mremap_vdso.c > > diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile > index b47ebd170690..c7162b511ab0 100644 > --- a/tools/testing/selftests/x86/Makefile > +++ b/tools/testing/selftests/x86/Makefile > @@ -7,7 +7,7 @@ include ../lib.mk > TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt ptrace_syscall \ > check_initial_reg_state sigreturn ldt_gdt iopl > TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault test_syscall_vdso unwind_vdso \ > - test_FCMOV test_FCOMI test_FISTTP \ > + test_FCMOV test_FCOMI test_FISTTP test_mremap_vdso \ > vdso_restorer > > TARGETS_C_32BIT_ALL := $(TARGETS_C_BOTHBITS) $(TARGETS_C_32BIT_ONLY) > diff --git a/tools/testing/selftests/x86/test_mremap_vdso.c b/tools/testing/selftests/x86/test_mremap_vdso.c > new file mode 100644 > index 000000000000..a470790e2118 > --- /dev/null > +++ b/tools/testing/selftests/x86/test_mremap_vdso.c > @@ -0,0 +1,72 @@ > +/* > + * 32-bit test to check vdso mremap. > + * > + * Copyright (c) 2016 Dmitry Safonov > + * Suggested-by: Andrew Lutomirski > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms and conditions of the GNU General Public License, > + * version 2, as published by the Free Software Foundation. > + * > + * This program is distributed in the hope it will be useful, but > + * WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + * General Public License for more details. > + */ > +/* > + * Can be built statically: > + * gcc -Os -Wall -static -m32 test_mremap_vdso.c > + */ > +#define _GNU_SOURCE > +#include > +#include > +#include > +#include > + > +#include > +#include > +#include > + > +#if !defined(__i386__) > +int main(int argc, char **argv, char **envp) > +{ > + printf("[SKIP]\tNot a 32-bit x86 userspace\n"); > + return 0; What's wrong with testing on 64-bit systems? > +} > +#else > + > +#define PAGE_SIZE 4096 > +#define VDSO_SIZE PAGE_SIZE The vdso is frequently bigger than a page. > + > +int main(int argc, char **argv, char **envp) > +{ > + unsigned long vdso_addr, dest_addr; > + void *new_addr; > + const char *ok_string = "[OK]\n"; > + > + vdso_addr = getauxval(AT_SYSINFO_EHDR); > + printf("\tAT_SYSINFO_EHDR is 0x%lx\n", vdso_addr); > + if (!vdso_addr || vdso_addr == -ENOENT) { > + printf("[FAIL]\tgetauxval failed\n"); > + return 1; Let's make this [WARN] and return 0. The vdso is optional, and getauxval is missing on many systems. > + } > + > + /* to low for stack, to high for lib/data/code mappings */ > + dest_addr = 0x0a000000; This could be make reliable -- map a big enough area PROT_NONE and use that address. > + printf("[NOTE]\tMoving vDSO: [%lx, %lx] -> [%lx, %lx]\n", > + vdso_addr, vdso_addr + VDSO_SIZE, > + dest_addr, dest_addr + VDSO_SIZE); fflush(stdout), please, for the benefit of test harnesses that use pipes. --Andy > + new_addr = mremap((void *)vdso_addr, VDSO_SIZE, VDSO_SIZE, > + MREMAP_FIXED|MREMAP_MAYMOVE, dest_addr); > + if ((unsigned long)new_addr == (unsigned long)-1) { > + printf("[FAIL]\tmremap failed (%d): %m\n", errno); > + return 1; > + } > + > + asm volatile ("int $0x80" : : "a" (__NR_write), "b" (STDOUT_FILENO), > + "c" (ok_string), "d" (strlen(ok_string))); > + asm volatile ("int $0x80" : : "a" (__NR_exit), "b" (0)); > + > + return 0; > +} > +#endif > -- > 2.8.0 > -- Andy Lutomirski AMA Capital Management, LLC