1*4882a593Smuzhiyun /*
2*4882a593Smuzhiyun * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3*4882a593Smuzhiyun * Licensed under the GPL
4*4882a593Smuzhiyun */
5*4882a593Smuzhiyun
6*4882a593Smuzhiyun #include <signal.h>
7*4882a593Smuzhiyun #include <kern_util.h>
8*4882a593Smuzhiyun #include <longjmp.h>
9*4882a593Smuzhiyun #include <sysdep/ptrace.h>
10*4882a593Smuzhiyun #include <generated/asm-offsets.h>
11*4882a593Smuzhiyun
12*4882a593Smuzhiyun /* Set during early boot */
13*4882a593Smuzhiyun static int host_has_cmov = 1;
14*4882a593Smuzhiyun static jmp_buf cmov_test_return;
15*4882a593Smuzhiyun
cmov_sigill_test_handler(int sig)16*4882a593Smuzhiyun static void cmov_sigill_test_handler(int sig)
17*4882a593Smuzhiyun {
18*4882a593Smuzhiyun host_has_cmov = 0;
19*4882a593Smuzhiyun longjmp(cmov_test_return, 1);
20*4882a593Smuzhiyun }
21*4882a593Smuzhiyun
arch_check_bugs(void)22*4882a593Smuzhiyun void arch_check_bugs(void)
23*4882a593Smuzhiyun {
24*4882a593Smuzhiyun struct sigaction old, new;
25*4882a593Smuzhiyun
26*4882a593Smuzhiyun printk(UM_KERN_INFO "Checking for host processor cmov support...");
27*4882a593Smuzhiyun new.sa_handler = cmov_sigill_test_handler;
28*4882a593Smuzhiyun
29*4882a593Smuzhiyun /* Make sure that SIGILL is enabled after the handler longjmps back */
30*4882a593Smuzhiyun new.sa_flags = SA_NODEFER;
31*4882a593Smuzhiyun sigemptyset(&new.sa_mask);
32*4882a593Smuzhiyun sigaction(SIGILL, &new, &old);
33*4882a593Smuzhiyun
34*4882a593Smuzhiyun if (setjmp(cmov_test_return) == 0) {
35*4882a593Smuzhiyun unsigned long foo = 0;
36*4882a593Smuzhiyun __asm__ __volatile__("cmovz %0, %1" : "=r" (foo) : "0" (foo));
37*4882a593Smuzhiyun printk(UM_KERN_CONT "Yes\n");
38*4882a593Smuzhiyun } else
39*4882a593Smuzhiyun printk(UM_KERN_CONT "No\n");
40*4882a593Smuzhiyun
41*4882a593Smuzhiyun sigaction(SIGILL, &old, &new);
42*4882a593Smuzhiyun }
43*4882a593Smuzhiyun
arch_examine_signal(int sig,struct uml_pt_regs * regs)44*4882a593Smuzhiyun void arch_examine_signal(int sig, struct uml_pt_regs *regs)
45*4882a593Smuzhiyun {
46*4882a593Smuzhiyun unsigned char tmp[2];
47*4882a593Smuzhiyun
48*4882a593Smuzhiyun /*
49*4882a593Smuzhiyun * This is testing for a cmov (0x0f 0x4x) instruction causing a
50*4882a593Smuzhiyun * SIGILL in init.
51*4882a593Smuzhiyun */
52*4882a593Smuzhiyun if ((sig != SIGILL) || (get_current_pid() != 1))
53*4882a593Smuzhiyun return;
54*4882a593Smuzhiyun
55*4882a593Smuzhiyun if (copy_from_user_proc(tmp, (void *) UPT_IP(regs), 2)) {
56*4882a593Smuzhiyun printk(UM_KERN_ERR "SIGILL in init, could not read "
57*4882a593Smuzhiyun "instructions!\n");
58*4882a593Smuzhiyun return;
59*4882a593Smuzhiyun }
60*4882a593Smuzhiyun
61*4882a593Smuzhiyun if ((tmp[0] != 0x0f) || ((tmp[1] & 0xf0) != 0x40))
62*4882a593Smuzhiyun return;
63*4882a593Smuzhiyun
64*4882a593Smuzhiyun if (host_has_cmov == 0)
65*4882a593Smuzhiyun printk(UM_KERN_ERR "SIGILL caused by cmov, which this "
66*4882a593Smuzhiyun "processor doesn't implement. Boot a filesystem "
67*4882a593Smuzhiyun "compiled for older processors");
68*4882a593Smuzhiyun else if (host_has_cmov == 1)
69*4882a593Smuzhiyun printk(UM_KERN_ERR "SIGILL caused by cmov, which this "
70*4882a593Smuzhiyun "processor claims to implement");
71*4882a593Smuzhiyun else
72*4882a593Smuzhiyun printk(UM_KERN_ERR "Bad value for host_has_cmov (%d)",
73*4882a593Smuzhiyun host_has_cmov);
74*4882a593Smuzhiyun }
75