blob: a1fba5fb9dbe0630ddbf42c53f6221b6bb2b6d31 [file] [log] [blame]
Jeff Dikea5ed1ff2007-05-06 14:50:58 -07001/*
Jeff Dikeba180fd2007-10-16 01:27:00 -07002 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003 * Licensed under the GPL
4 */
5
Jeff Dikeba180fd2007-10-16 01:27:00 -07006#include <signal.h>
Jeff Dikeedea1382008-02-04 22:30:46 -08007#include "kern_util.h"
Jeff Dike9226b832008-02-04 22:30:40 -08008#include "longjmp.h"
Jeff Dike9226b832008-02-04 22:30:40 -08009#include "sysdep/ptrace.h"
Al Viro5ade8872011-08-18 20:07:39 +010010#include <generated/asm-offsets.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070011
Linus Torvalds1da177e2005-04-16 15:20:36 -070012/* Set during early boot */
WANG Cong99764fa2008-07-23 21:28:49 -070013static int host_has_cmov = 1;
Karol Swietlicki235a6f02008-02-04 22:30:38 -080014static jmp_buf cmov_test_return;
15
Al Viro5ade8872011-08-18 20:07:39 +010016#define TASK_PID(task) *((int *) &(((char *) (task))[HOST_TASK_PID]))
17
Karol Swietlicki235a6f02008-02-04 22:30:38 -080018static void cmov_sigill_test_handler(int sig)
19{
20 host_has_cmov = 0;
21 longjmp(cmov_test_return, 1);
22}
23
Jeff Dike9226b832008-02-04 22:30:40 -080024void arch_check_bugs(void)
Karol Swietlicki235a6f02008-02-04 22:30:38 -080025{
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}
Linus Torvalds1da177e2005-04-16 15:20:36 -070045
Jeff Dike9226b832008-02-04 22:30:40 -080046void arch_examine_signal(int sig, struct uml_pt_regs *regs)
Linus Torvalds1da177e2005-04-16 15:20:36 -070047{
48 unsigned char tmp[2];
49
Jeff Dikeba180fd2007-10-16 01:27:00 -070050 /*
51 * This is testing for a cmov (0x0f 0x4x) instruction causing a
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 * SIGILL in init.
53 */
Jeff Dikeba180fd2007-10-16 01:27:00 -070054 if ((sig != SIGILL) || (TASK_PID(get_current()) != 1))
Jeff Dike9226b832008-02-04 22:30:40 -080055 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -070056
Jeff Dike9226b832008-02-04 22:30:40 -080057 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
Jeff Dikeba180fd2007-10-16 01:27:00 -070063 if ((tmp[0] != 0x0f) || ((tmp[1] & 0xf0) != 0x40))
Jeff Dike9226b832008-02-04 22:30:40 -080064 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -070065
Jeff Dikeba180fd2007-10-16 01:27:00 -070066 if (host_has_cmov == 0)
Jeff Dike9226b832008-02-04 22:30:40 -080067 printk(UM_KERN_ERR "SIGILL caused by cmov, which this "
68 "processor doesn't implement. Boot a filesystem "
69 "compiled for older processors");
Jeff Dikeba180fd2007-10-16 01:27:00 -070070 else if (host_has_cmov == 1)
Jeff Dike9226b832008-02-04 22:30:40 -080071 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);
Linus Torvalds1da177e2005-04-16 15:20:36 -070076}