diff options
| -rw-r--r-- | tools/testing/selftests/x86/Makefile | 2 | ||||
| -rw-r--r-- | tools/testing/selftests/x86/syscall_nt.c | 54 |
2 files changed, 55 insertions, 1 deletions
diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile index 986e7cbf118f..29089b24d18b 100644 --- a/tools/testing/selftests/x86/Makefile +++ b/tools/testing/selftests/x86/Makefile @@ -4,7 +4,7 @@ include ../lib.mk .PHONY: all all_32 all_64 warn_32bit_failure clean -TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs ldt_gdt +TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs ldt_gdt syscall_nt TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault sigreturn TARGETS_C_32BIT_ALL := $(TARGETS_C_BOTHBITS) $(TARGETS_C_32BIT_ONLY) diff --git a/tools/testing/selftests/x86/syscall_nt.c b/tools/testing/selftests/x86/syscall_nt.c new file mode 100644 index 000000000000..60c06af4646a --- /dev/null +++ b/tools/testing/selftests/x86/syscall_nt.c @@ -0,0 +1,54 @@ +/* + * syscall_nt.c - checks syscalls with NT set + * Copyright (c) 2014-2015 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. + * + * Some obscure user-space code requires the ability to make system calls + * with FLAGS.NT set. Make sure it works. + */ + +#include <stdio.h> +#include <unistd.h> +#include <sys/syscall.h> +#include <asm/processor-flags.h> + +#ifdef __x86_64__ +# define WIDTH "q" +#else +# define WIDTH "l" +#endif + +static unsigned long get_eflags(void) +{ + unsigned long eflags; + asm volatile ("pushf" WIDTH "\n\tpop" WIDTH " %0" : "=rm" (eflags)); + return eflags; +} + +static void set_eflags(unsigned long eflags) +{ + asm volatile ("push" WIDTH " %0\n\tpopf" WIDTH + : : "rm" (eflags) : "flags"); +} + +int main() +{ + printf("[RUN]\tSet NT and issue a syscall\n"); + set_eflags(get_eflags() | X86_EFLAGS_NT); + syscall(SYS_getpid); + if (get_eflags() & X86_EFLAGS_NT) { + printf("[OK]\tThe syscall worked and NT is still set\n"); + return 0; + } else { + printf("[FAIL]\tThe syscall worked but NT was cleared\n"); + return 1; + } +} |