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