Messages in this thread | | | Subject | Re: [PATCHv5 3/3] selftest/x86: add mremap vdso 32-bit test | From | Dmitry Safonov <> | Date | Fri, 22 Apr 2016 14:34:23 +0300 |
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On 04/21/2016 11:01 PM, Andy Lutomirski wrote: > On Mon, Apr 18, 2016 at 6:43 AM, Dmitry Safonov <dsafonov@virtuozzo.com> 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 <shuahkh@osg.samsung.com> >> Cc: linux-kselftest@vger.kernel.org >> Suggested-by: Andy Lutomirski <luto@kernel.org> >> Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com> >> --- >> 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 <stdio.h> >> +#include <errno.h> >> +#include <unistd.h> >> +#include <string.h> >> + >> +#include <sys/mman.h> >> +#include <sys/auxv.h> >> +#include <sys/syscall.h> >> + >> +#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?
Ok, will drop this.
>> +} >> +#else >> + >> +#define PAGE_SIZE 4096 >> +#define VDSO_SIZE PAGE_SIZE > The vdso is frequently bigger than a page.
Ok, will enlarge this. Are two pages big enough?
>> + >> +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.
Ok
>> + } >> + >> + /* 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.
Oh, that's good, will do.
>> + 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.
Will add.
>> + 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 >> > >
-- Regards, Dmitry Safonov
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