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-rw-r--r--arch/x86/um/bugs_32.c74
1 files changed, 74 insertions, 0 deletions
diff --git a/arch/x86/um/bugs_32.c b/arch/x86/um/bugs_32.c
new file mode 100644
index 0000000..7058e1f
--- /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 <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);
+}
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