cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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bugs_32.c (1858B)

      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 */
     13static int host_has_cmov = 1;
     14static jmp_buf cmov_test_return;
     15
     16static void cmov_sigill_test_handler(int sig)
     17{
     18	host_has_cmov = 0;
     19	longjmp(cmov_test_return, 1);
     20}
     21
     22void 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
     44void 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}