1 files changed, 74 insertions, 0 deletions

diff --git a/arch/um/sys-x86/bugs_32.c b/arch/um/sys-x86/bugs_32.c
new file mode 100644
index 000000000000..7058e1fa903b
--- /dev/null
+++ b/arch/um/sys-x86/bugs_32.c
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#include <signal.h>
+#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);
+}