]>
git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/blob - tools/testing/selftests/x86/syscall_arg_fault.c
2 * syscall_arg_fault.c - tests faults 32-bit fast syscall stack args
3 * Copyright (c) 2015 Andrew Lutomirski
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms and conditions of the GNU General Public License,
7 * version 2, as published by the Free Software Foundation.
9 * This program is distributed in the hope it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
20 #include <sys/signal.h>
21 #include <sys/ucontext.h>
26 /* Our sigaltstack scratch space. */
27 static unsigned char altstack_data
[SIGSTKSZ
];
29 static void sethandler(int sig
, void (*handler
)(int, siginfo_t
*, void *),
33 memset(&sa
, 0, sizeof(sa
));
34 sa
.sa_sigaction
= handler
;
35 sa
.sa_flags
= SA_SIGINFO
| flags
;
36 sigemptyset(&sa
.sa_mask
);
37 if (sigaction(sig
, &sa
, 0))
41 static volatile sig_atomic_t sig_traps
;
42 static sigjmp_buf jmpbuf
;
44 static volatile sig_atomic_t n_errs
;
46 static void sigsegv(int sig
, siginfo_t
*info
, void *ctx_void
)
48 ucontext_t
*ctx
= (ucontext_t
*)ctx_void
;
50 if (ctx
->uc_mcontext
.gregs
[REG_EAX
] != -EFAULT
) {
51 printf("[FAIL]\tAX had the wrong value: 0x%x\n",
52 ctx
->uc_mcontext
.gregs
[REG_EAX
]);
55 printf("[OK]\tSeems okay\n");
58 siglongjmp(jmpbuf
, 1);
61 static void sigill(int sig
, siginfo_t
*info
, void *ctx_void
)
63 printf("[SKIP]\tIllegal instruction\n");
64 siglongjmp(jmpbuf
, 1);
70 .ss_sp
= altstack_data
,
73 if (sigaltstack(&stack
, NULL
) != 0)
74 err(1, "sigaltstack");
76 sethandler(SIGSEGV
, sigsegv
, SA_ONSTACK
);
77 sethandler(SIGILL
, sigill
, SA_ONSTACK
);
80 * Exercise another nasty special case. The 32-bit SYSCALL
81 * and SYSENTER instructions (even in compat mode) each
82 * clobber one register. A Linux system call has a syscall
83 * number and six arguments, and the user stack pointer
84 * needs to live in some register on return. That means
85 * that we need eight registers, but SYSCALL and SYSENTER
86 * only preserve seven registers. As a result, one argument
87 * ends up on the stack. The stack is user memory, which
88 * means that the kernel can fail to read it.
90 * The 32-bit fast system calls don't have a defined ABI:
91 * we're supposed to invoke them through the vDSO. So we'll
92 * fudge it: we set all regs to invalid pointer values and
93 * invoke the entry instruction. The return will fail no
94 * matter what, and we completely lose our program state,
95 * but we can fix it up with a signal handler.
98 printf("[RUN]\tSYSENTER with invalid state\n");
99 if (sigsetjmp(jmpbuf
, 1) == 0) {
101 "movl $-1, %%eax\n\t"
102 "movl $-1, %%ebx\n\t"
103 "movl $-1, %%ecx\n\t"
104 "movl $-1, %%edx\n\t"
105 "movl $-1, %%esi\n\t"
106 "movl $-1, %%edi\n\t"
107 "movl $-1, %%ebp\n\t"
108 "movl $-1, %%esp\n\t"
110 : : : "memory", "flags");
113 printf("[RUN]\tSYSCALL with invalid state\n");
114 if (sigsetjmp(jmpbuf
, 1) == 0) {
116 "movl $-1, %%eax\n\t"
117 "movl $-1, %%ebx\n\t"
118 "movl $-1, %%ecx\n\t"
119 "movl $-1, %%edx\n\t"
120 "movl $-1, %%esi\n\t"
121 "movl $-1, %%edi\n\t"
122 "movl $-1, %%ebp\n\t"
123 "movl $-1, %%esp\n\t"
125 "pushl $0" /* make sure we segfault cleanly */
126 : : : "memory", "flags");