From 5c48b108ecbf6505d929e64d50dace13ac2bdf34 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 18 Aug 2011 20:06:39 +0100 Subject: um: take arch/um/sys-x86 to arch/x86/um Signed-off-by: Al Viro Signed-off-by: Richard Weinberger --- arch/x86/um/bugs_32.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+) create mode 100644 arch/x86/um/bugs_32.c (limited to 'arch/x86/um/bugs_32.c') diff --git a/arch/x86/um/bugs_32.c b/arch/x86/um/bugs_32.c new file mode 100644 index 000000000000..7058e1fa903b --- /dev/null +++ b/arch/x86/um/bugs_32.c @@ -0,0 +1,74 @@ +/* + * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) + * Licensed under the GPL + */ + +#include +#include "kern_util.h" +#include "longjmp.h" +#include "task.h" +#include "sysdep/ptrace.h" + +/* Set during early boot */ +static int host_has_cmov = 1; +static jmp_buf cmov_test_return; + +static void cmov_sigill_test_handler(int sig) +{ + host_has_cmov = 0; + longjmp(cmov_test_return, 1); +} + +void arch_check_bugs(void) +{ + struct sigaction old, new; + + printk(UM_KERN_INFO "Checking for host processor cmov support..."); + new.sa_handler = cmov_sigill_test_handler; + + /* Make sure that SIGILL is enabled after the handler longjmps back */ + new.sa_flags = SA_NODEFER; + sigemptyset(&new.sa_mask); + sigaction(SIGILL, &new, &old); + + if (setjmp(cmov_test_return) == 0) { + unsigned long foo = 0; + __asm__ __volatile__("cmovz %0, %1" : "=r" (foo) : "0" (foo)); + printk(UM_KERN_CONT "Yes\n"); + } else + printk(UM_KERN_CONT "No\n"); + + sigaction(SIGILL, &old, &new); +} + +void arch_examine_signal(int sig, struct uml_pt_regs *regs) +{ + unsigned char tmp[2]; + + /* + * This is testing for a cmov (0x0f 0x4x) instruction causing a + * SIGILL in init. + */ + if ((sig != SIGILL) || (TASK_PID(get_current()) != 1)) + return; + + if (copy_from_user_proc(tmp, (void *) UPT_IP(regs), 2)) { + printk(UM_KERN_ERR "SIGILL in init, could not read " + "instructions!\n"); + return; + } + + if ((tmp[0] != 0x0f) || ((tmp[1] & 0xf0) != 0x40)) + return; + + if (host_has_cmov == 0) + printk(UM_KERN_ERR "SIGILL caused by cmov, which this " + "processor doesn't implement. Boot a filesystem " + "compiled for older processors"); + else if (host_has_cmov == 1) + printk(UM_KERN_ERR "SIGILL caused by cmov, which this " + "processor claims to implement"); + else + printk(UM_KERN_ERR "Bad value for host_has_cmov (%d)", + host_has_cmov); +} -- cgit v1.2.3