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_constants.h" 8#include "kern_util.h" 9#include "longjmp.h" 10#include "task.h" 11#include "user.h" 12#include "sysdep/ptrace.h" 13 14/* Set during early boot */ 15static int host_has_cmov = 1; 16static jmp_buf cmov_test_return; 17 18static void cmov_sigill_test_handler(int sig) 19{ 20 host_has_cmov = 0; 21 longjmp(cmov_test_return, 1); 22} 23 24void arch_check_bugs(void) 25{ 26 struct sigaction old, new; 27 28 printk(UM_KERN_INFO "Checking for host processor cmov support..."); 29 new.sa_handler = cmov_sigill_test_handler; 30 31 /* Make sure that SIGILL is enabled after the handler longjmps back */ 32 new.sa_flags = SA_NODEFER; 33 sigemptyset(&new.sa_mask); 34 sigaction(SIGILL, &new, &old); 35 36 if (setjmp(cmov_test_return) == 0) { 37 unsigned long foo = 0; 38 __asm__ __volatile__("cmovz %0, %1" : "=r" (foo) : "0" (foo)); 39 printk(UM_KERN_CONT "Yes\n"); 40 } else 41 printk(UM_KERN_CONT "No\n"); 42 43 sigaction(SIGILL, &old, &new); 44} 45 46void arch_examine_signal(int sig, struct uml_pt_regs *regs) 47{ 48 unsigned char tmp[2]; 49 50 /* 51 * This is testing for a cmov (0x0f 0x4x) instruction causing a 52 * SIGILL in init. 53 */ 54 if ((sig != SIGILL) || (TASK_PID(get_current()) != 1)) 55 return; 56 57 if (copy_from_user_proc(tmp, (void *) UPT_IP(regs), 2)) { 58 printk(UM_KERN_ERR "SIGILL in init, could not read " 59 "instructions!\n"); 60 return; 61 } 62 63 if ((tmp[0] != 0x0f) || ((tmp[1] & 0xf0) != 0x40)) 64 return; 65 66 if (host_has_cmov == 0) 67 printk(UM_KERN_ERR "SIGILL caused by cmov, which this " 68 "processor doesn't implement. Boot a filesystem " 69 "compiled for older processors"); 70 else if (host_has_cmov == 1) 71 printk(UM_KERN_ERR "SIGILL caused by cmov, which this " 72 "processor claims to implement"); 73 else 74 printk(UM_KERN_ERR "Bad value for host_has_cmov (%d)", 75 host_has_cmov); 76} 77