The test is fairly simplistic: it checks that all registers are preserved across 32-bit syscall via VDSO.
Run-tested: $ ./test_syscall_vdso_32 [RUN] Executing 6-argument 32-bit syscall via VDSO [Ok] Arguments are preserved across syscall [RUN] Executing 6-argument 32-bit syscall via INT 80 [Ok] Arguments are preserved across syscall [RUN] Running tests under ptrace [RUN] Executing 6-argument 32-bit syscall via VDSO [Ok] Arguments are preserved across syscall [RUN] Executing 6-argument 32-bit syscall via INT 80 [Ok] Arguments are preserved across syscall Signed-off-by: Denys Vlasenko <[email protected]> CC: Linus Torvalds <[email protected]> CC: Steven Rostedt <[email protected]> CC: Ingo Molnar <[email protected]> CC: Borislav Petkov <[email protected]> CC: "H. Peter Anvin" <[email protected]> CC: Andy Lutomirski <[email protected]> CC: Oleg Nesterov <[email protected]> CC: Frederic Weisbecker <[email protected]> CC: Alexei Starovoitov <[email protected]> CC: Will Drewry <[email protected]> CC: Kees Cook <[email protected]> CC: [email protected] CC: [email protected] --- Changes in v2: does not fail if VDSO can't be found; tests INT 80 syscall method; tests syscalls under ptrace; switched to /* */ comments tools/testing/selftests/x86/Makefile | 2 +- tools/testing/selftests/x86/test_syscall_vdso.c | 271 ++++++++++++++++++++++++ 2 files changed, 272 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/x86/test_syscall_vdso.c diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile index caa60d5..84effa6 100644 --- a/tools/testing/selftests/x86/Makefile +++ b/tools/testing/selftests/x86/Makefile @@ -5,7 +5,7 @@ include ../lib.mk .PHONY: all all_32 all_64 warn_32bit_failure clean TARGETS_C_BOTHBITS := sigreturn single_step_syscall sysret_ss_attrs -TARGETS_C_32BIT_ONLY := entry_from_vm86 +TARGETS_C_32BIT_ONLY := entry_from_vm86 test_syscall_vdso TARGETS_C_32BIT_ALL := $(TARGETS_C_BOTHBITS) $(TARGETS_C_32BIT_ONLY) BINARIES_32 := $(TARGETS_C_32BIT_ALL:%=%_32) diff --git a/tools/testing/selftests/x86/test_syscall_vdso.c b/tools/testing/selftests/x86/test_syscall_vdso.c new file mode 100644 index 0000000..7112e9d --- /dev/null +++ b/tools/testing/selftests/x86/test_syscall_vdso.c @@ -0,0 +1,271 @@ +/* + * 32-bit syscall ABI conformance test. + * + * Copyright (c) 2015 Denys Vlasenko + * + * 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. + */ +#undef _GNU_SOURCE +#define _GNU_SOURCE 1 +#undef __USE_GNU +#define __USE_GNU 1 +#include <unistd.h> +#include <stdlib.h> +#include <stdio.h> +#include <signal.h> +#include <sys/types.h> +#include <sys/select.h> +#include <sys/time.h> +#include <elf.h> +#include <sys/ptrace.h> +#include <sys/wait.h> + +#if !defined(__i386__) +int main(int argc, char **argv, char **envp) +{ + printf("[SKIP] Not a 32-bit x86\n"); + return 0; +} +#else + +/* + * TODO: check r8..15 for info leaks. + */ + +extern char int80; +asm ( + " .pushsection .text\n" + " .global int80\n" + "int80:\n" + " int $0x80\n" + " ret\n" + " .popsection" +); + +long syscall_addr; +long get_syscall(char **envp) +{ + Elf32_auxv_t *auxv; + while (*envp++ != NULL) + continue; + for (auxv = (void *)envp; auxv->a_type != AT_NULL; auxv++) + if (auxv->a_type == AT_SYSINFO) + return auxv->a_un.a_val; + printf("[WARN]\tAT_SYSINFO not supplied\n"); + return 0; +} + +int nfds; +fd_set rfds; +fd_set wfds; +fd_set efds; +struct timespec timeout; +sigset_t sigmask; +struct { + sigset_t *sp; + int sz; +} sigmask_desc; + +void prep_args() +{ + nfds = 42; + FD_ZERO(&rfds); + FD_ZERO(&wfds); + FD_ZERO(&efds); + FD_SET(0, &rfds); + FD_SET(1, &wfds); + FD_SET(2, &efds); + timeout.tv_sec = 0; + timeout.tv_nsec = 123; + sigemptyset(&sigmask); + sigaddset(&sigmask, SIGINT); + sigaddset(&sigmask, SIGUSR2); + sigaddset(&sigmask, SIGRTMAX); + sigmask_desc.sp = &sigmask; + sigmask_desc.sz = 8; /* bytes */ +} + +static void print_flags(const char *name, unsigned long r) +{ + static const char *bitarray[] = { + "\n" ,"c\n" ,/* Carry Flag */ + "0 " ,"1 " ,/* Bit 1 - always on */ + "" ,"p " ,/* Parity Flag */ + "0 " ,"3? " , + "" ,"a " ,/* Auxiliary carry Flag */ + "0 " ,"5? " , + "" ,"z " ,/* Zero Flag */ + "" ,"s " ,/* Sign Flag */ + "" ,"t " ,/* Trap Flag */ + "" ,"i " ,/* Interrupt Flag */ + "" ,"d " ,/* Direction Flag */ + "" ,"o " ,/* Overflow Flag */ + "0 " ,"1 " ,/* I/O Privilege Level (2 bits) */ + "0" ,"1" ,/* I/O Privilege Level (2 bits) */ + "" ,"n " ,/* Nested Task */ + "0 " ,"15? ", + "" ,"r " ,/* Resume Flag */ + "" ,"v " ,/* Virtual Mode */ + "" ,"ac " ,/* Alignment Check/Access Control */ + "" ,"vif ",/* Virtual Interrupt Flag */ + "" ,"vip ",/* Virtual Interrupt Pending */ + "" ,"id " ,/* CPUID detection */ + NULL + }; + const char **bitstr; + int bit; + + printf("%s=%016lx ", name, r); + bitstr = bitarray + 42; + bit = 21; + if ((r >> 22) != 0) + printf("(extra bits are set) "); + do { + if (bitstr[(r >> bit) & 1][0]) + printf(bitstr[(r >> bit) & 1]); + bitstr -= 2; + bit--; + } while (bit >= 0); +} + +int run_syscall(void) +{ + long flags, bad_arg; + + prep_args(); + + asm("\n" + /* Try 6-arg syscall: pselect. It should return quickly */ + " push %%ebp\n" + " mov $308, %%eax\n" /* PSELECT */ + " mov nfds, %%ebx\n" /* ebx arg1 */ + " mov $rfds, %%ecx\n" /* ecx arg2 */ + " mov $wfds, %%edx\n" /* edx arg3 */ + " mov $efds, %%esi\n" /* esi arg4 */ + " mov $timeout, %%edi\n" /* edi arg5 */ + " mov $sigmask_desc, %%ebp\n" /* %ebp arg6 */ + " push $0x200ed7\n" /* set almost all flags */ + " popf\n" /* except TF, IOPL, NT, RF, VM, AC, VIF, VIP */ + " call *syscall_addr\n" + /* Check that registers are not clobbered */ + " pushf\n" + " pop %%eax\n" + " cld\n" + " cmp nfds, %%ebx\n" /* ebx arg1 */ + " mov $1, %%ebx\n" + " jne 1f\n" + " cmp $rfds, %%ecx\n" /* ecx arg2 */ + " mov $2, %%ebx\n" + " jne 1f\n" + " cmp $wfds, %%edx\n" /* edx arg3 */ + " mov $3, %%ebx\n" + " jne 1f\n" + " cmp $efds, %%esi\n" /* esi arg4 */ + " mov $4, %%ebx\n" + " jne 1f\n" + " cmp $timeout, %%edi\n" /* edi arg5 */ + " mov $5, %%ebx\n" + " jne 1f\n" + " cmpl $sigmask_desc, %%ebp\n" /* %ebp arg6 */ + " mov $6, %%ebx\n" + " jne 1f\n" + " mov $0, %%ebx\n" + "1:\n" + " pop %%ebp\n" + : "=a" (flags), "=b" (bad_arg) + : + : "cx", "dx", "si", "di" + ); + + /* + * On paravirt kernels, flags are not preserved across syscalls. + * Thus, we do not consider it a bug if some are changed. + * We just show ones which do. + */ + if ((0x200ed7 ^ flags) != 0) { + print_flags("[WARN]\tFlags before", 0x200ed7); + print_flags("[WARN]\tFlags after", flags); + print_flags("[WARN]\tChanged", (0x200ed7 ^ flags)); + } + + if (bad_arg) { + printf("[FAIL]\targ#%ld clobbered\n", bad_arg); + return 1; + } + printf("[Ok]\tArguments are preserved across syscall\n"); + return 0; +} + +int run_syscall_twice() +{ + int exitcode = 0; + long sv; + + if (syscall_addr) { + printf("[RUN]\tExecuting 6-argument 32-bit syscall via VDSO\n"); + exitcode = run_syscall(); + } + sv = syscall_addr; + syscall_addr = (long)&int80; + printf("[RUN]\tExecuting 6-argument 32-bit syscall via INT 80\n"); + exitcode += run_syscall(); + syscall_addr = sv; + return exitcode; +} + +void ptrace_me() +{ + pid_t pid; + + fflush(NULL); + pid = fork(); + if (pid < 0) + exit(1); + if (pid == 0) { + /* child */ + if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) != 0) + exit(0); + raise(SIGSTOP); + return; + } + /* parent */ + printf("[RUN]\tRunning tests under ptrace\n"); + while (1) { + int status; + pid = waitpid(-1, &status, __WALL); + if (pid < 0 || !WIFSTOPPED(status)) + break; + /* + * Note: we do not inject sig = WSTOPSIG(status). + * We probably should, but careful: do not inject SIGTRAP + * generated by syscall entry/exit stops. + * That kills the child. + */ + ptrace(PTRACE_SYSCALL, pid, 0L, 0L /*sig*/); + } + exit(0); +} + +int main(int argc, char **argv, char **envp) +{ + int exitcode = 0; + + /* This only works for non-static builds: + * syscall_addr = dlsym(dlopen("linux-gate.so.1", RTLD_NOW), "__kernel_vsyscall"); + */ + syscall_addr = get_syscall(envp); + + exitcode += run_syscall_twice(); + ptrace_me(); + exitcode += run_syscall_twice(); + + return 0; +} +#endif -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
