projects / linux-block.git / blame
| Commit | Line | Data |
|---|---|---|
| 2025cf9e | 1 | // SPDX-License-Identifier: GPL-2.0-only |
| a9c909ce AL |
2 | /* |
| 3 | * syscall_nt.c - checks syscalls with NT set | |
| 4 | * Copyright (c) 2014-2015 Andrew Lutomirski | |
| 5 | * | |
| a9c909ce AL |
6 | * Some obscure user-space code requires the ability to make system calls |
| 7 | * with FLAGS.NT set. Make sure it works. | |
| 8 | */ | |
| 9 | ||
| 10 | #include <stdio.h> | |
| 11 | #include <unistd.h> | |
| a318beea AL |
12 | #include <string.h> |
| 13 | #include <signal.h> | |
| 14 | #include <err.h> | |
| a9c909ce AL |
15 | #include <sys/syscall.h> |
| 16 | #include <asm/processor-flags.h> | |
| 17 | ||
| 18 | #ifdef __x86_64__ | |
| 19 | # define WIDTH "q" | |
| 20 | #else | |
| 21 | # define WIDTH "l" | |
| 22 | #endif | |
| 23 | ||
| a318beea AL |
24 | static unsigned int nerrs; |
| 25 | ||
| a9c909ce AL |
26 | static unsigned long get_eflags(void) |
| 27 | { | |
| 28 | unsigned long eflags; | |
| 29 | asm volatile ("pushf" WIDTH "\n\tpop" WIDTH " %0" : "=rm" (eflags)); | |
| 30 | return eflags; | |
| 31 | } | |
| 32 | ||
| 33 | static void set_eflags(unsigned long eflags) | |
| 34 | { | |
| 35 | asm volatile ("push" WIDTH " %0\n\tpopf" WIDTH | |
| 36 | : : "rm" (eflags) : "flags"); | |
| 37 | } | |
| 38 | ||
| a318beea AL |
39 | static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *), |
| 40 | int flags) | |
| a9c909ce | 41 | { |
| a318beea AL |
42 | struct sigaction sa; |
| 43 | memset(&sa, 0, sizeof(sa)); | |
| 44 | sa.sa_sigaction = handler; | |
| 45 | sa.sa_flags = SA_SIGINFO | flags; | |
| 46 | sigemptyset(&sa.sa_mask); | |
| 47 | if (sigaction(sig, &sa, 0)) | |
| 48 | err(1, "sigaction"); | |
| 49 | } | |
| 50 | ||
| 51 | static void sigtrap(int sig, siginfo_t *si, void *ctx_void) | |
| 52 | { | |
| 53 | } | |
| 54 | ||
| 55 | static void do_it(unsigned long extraflags) | |
| 56 | { | |
| 57 | unsigned long flags; | |
| 58 | ||
| 59 | set_eflags(get_eflags() | extraflags); | |
| a9c909ce | 60 | syscall(SYS_getpid); |
| a318beea AL |
61 | flags = get_eflags(); |
| 62 | if ((flags & extraflags) == extraflags) { | |
| 63 | printf("[OK]\tThe syscall worked and flags are still set\n"); | |
| a9c909ce | 64 | } else { |
| a318beea AL |
65 | printf("[FAIL]\tThe syscall worked but flags were cleared (flags = 0x%lx but expected 0x%lx set)\n", |
| 66 | flags, extraflags); | |
| 67 | nerrs++; | |
| a9c909ce AL |
68 | } |
| 69 | } | |
| a318beea AL |
70 | |
| 71 | int main(void) | |
| 72 | { | |
| 73 | printf("[RUN]\tSet NT and issue a syscall\n"); | |
| 74 | do_it(X86_EFLAGS_NT); | |
| 75 | ||
| 76 | /* | |
| 77 | * Now try it again with TF set -- TF forces returns via IRET in all | |
| 78 | * cases except non-ptregs-using 64-bit full fast path syscalls. | |
| 79 | */ | |
| 80 | ||
| 81 | sethandler(SIGTRAP, sigtrap, 0); | |
| 82 | ||
| 83 | printf("[RUN]\tSet NT|TF and issue a syscall\n"); | |
| 84 | do_it(X86_EFLAGS_NT | X86_EFLAGS_TF); | |
| 85 | ||
| 86 | return nerrs == 0 ? 0 : 1; | |
| 87 | } |