x86: fix broken math-emu with lazy allocation of fpu area

Fix the math emulation that got broken with the recent lazy allocation of FPU
area. init_fpu() need to be added for the math-emulation path aswell
for the FPU area allocation.

math emulation enabled kernel booted fine with this, in the presence
of "no387 nofxsr" boot param.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: hpa@zytor.com
Cc: mingo@elte.hu
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 8 insertions, 5 deletions

diff --git a/arch/x86/math-emu/fpu_entry.c b/arch/x86/math-emu/fpu_entry.c
index 6e38d877ea77..c7b06feb139b 100644
--- a/arch/x86/math-emu/fpu_entry.c
+++ b/arch/x86/math-emu/fpu_entry.c
@@ -30,6 +30,7 @@
 #include <asm/uaccess.h>
 #include <asm/desc.h>
 #include <asm/user.h>
+#include <asm/i387.h>
 
 #include "fpu_system.h"
 #include "fpu_emu.h"
@@ -146,6 +147,13 @@ asmlinkage void math_emulate(long arg)
         unsigned long code_limit = 0;   /* Initialized to stop compiler warnings */
         struct desc_struct code_descriptor;
 
+        if (!used_math()) {
+                if (init_fpu(current)) {
+                        do_group_exit(SIGKILL);
+                        return;
+                }
+        }
+
 #ifdef RE_ENTRANT_CHECKING
         if (emulating) {
                 printk("ERROR: wm-FPU-emu is not RE-ENTRANT!\n");
@@ -153,11 +161,6 @@ asmlinkage void math_emulate(long arg)
         RE_ENTRANT_CHECK_ON;
 #endif /* RE_ENTRANT_CHECKING */
 
-        if (!used_math()) {
-                finit();
-                set_used_math();
-        }
-
         SETUP_DATA_AREA(arg);
 
         FPU_ORIG_EIP = FPU_EIP;