MIPS: kernel: signal: Prevent save/restore FPU context in user memory

EVA does not have FPU specific instructions for reading or writing
FPU registers from userspace memory.

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c
index fd61700409bc15e362e31b11e180be6f4c9347da..33133d3df3e5a5bdb5a62647522b0946c874ba6d 100644 (file)
--- a/arch/mips/kernel/signal.c
+++ b/arch/mips/kernel/signal.c
@@ -6,6 +6,7 @@
  * Copyright (C) 1991, 1992  Linus Torvalds
  * Copyright (C) 1994 - 2000  Ralf Baechle
  * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
+ * Copyright (C) 2014, Imagination Technologies Ltd.
  */
 #include <linux/cache.h>
 #include <linux/context_tracking.h>
@@ -140,6 +141,7 @@ static int protected_save_fp_context(struct sigcontext __user *sc,
 {
        int err;
        bool save_msa = cpu_has_msa && (used_math & USEDMATH_MSA);
+#ifndef CONFIG_EVA
        while (1) {
                lock_fpu_owner();
                if (is_fpu_owner()) {
@@ -162,6 +164,17 @@ static int protected_save_fp_context(struct sigcontext __user *sc,
                if (err)
                        break;  /* really bad sigcontext */
        }
+#else
+       /*
+        * EVA does not have FPU EVA instructions so saving fpu context directly
+        * does not work.
+        */
+       disable_msa();
+       lose_fpu(1);
+       err = save_fp_context(sc); /* this might fail */
+       if (save_msa && !err)
+               err = copy_msa_to_sigcontext(sc);
+#endif
        return err;
 }
 
@@ -170,6 +183,7 @@ static int protected_restore_fp_context(struct sigcontext __user *sc,
 {
        int err, tmp __maybe_unused;
        bool restore_msa = cpu_has_msa && (used_math & USEDMATH_MSA);
+#ifndef CONFIG_EVA
        while (1) {
                lock_fpu_owner();
                if (is_fpu_owner()) {
@@ -197,6 +211,17 @@ static int protected_restore_fp_context(struct sigcontext __user *sc,
                if (err)
                        break;  /* really bad sigcontext */
        }
+#else
+       /*
+        * EVA does not have FPU EVA instructions so restoring fpu context
+        * directly does not work.
+        */
+       enable_msa();
+       lose_fpu(0);
+       err = restore_fp_context(sc); /* this might fail */
+       if (restore_msa && !err)
+               err = copy_msa_from_sigcontext(sc);
+#endif
        return err;
 }
 
@@ -685,6 +710,7 @@ asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
 }
 
 #ifdef CONFIG_SMP
+#ifndef CONFIG_EVA
 static int smp_save_fp_context(struct sigcontext __user *sc)
 {
        return raw_cpu_has_fpu
@@ -698,10 +724,12 @@ static int smp_restore_fp_context(struct sigcontext __user *sc)
               ? _restore_fp_context(sc)
               : copy_fp_from_sigcontext(sc);
 }
+#endif /* CONFIG_EVA */
 #endif
 
 static int signal_setup(void)
 {
+#ifndef CONFIG_EVA
 #ifdef CONFIG_SMP
        /* For now just do the cpu_has_fpu check when the functions are invoked */
        save_fp_context = smp_save_fp_context;
@@ -714,6 +742,10 @@ static int signal_setup(void)
                save_fp_context = copy_fp_from_sigcontext;
                restore_fp_context = copy_fp_to_sigcontext;
        }
+#endif /* CONFIG_SMP */
+#else
+       save_fp_context = copy_fp_from_sigcontext;;
+       restore_fp_context = copy_fp_to_sigcontext;
 #endif
 
        return 0;