ARM: linux-user: Expose VFP registers to signal handlers

For ARM linux-user mode signal handlers, fill in the ucontext with
VFP register contents in the same way that the kernel does. We only
do this for v2 format sigframe (2.6.12 and above); this is actually
bug-for-bug compatible with the older kernels, which don't save and
restore VFP registers either.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Riku Voipio <riku.voipio@nokia.com>

linux-user/signal.c

@@ -1112,6 +1112,26 @@ struct target_ucontext_v2 {
     abi_ulong tuc_regspace[128] __attribute__((__aligned__(8)));
 };
 
+struct target_user_vfp {
+    uint64_t fpregs[32];
+    abi_ulong fpscr;
+};
+
+struct target_user_vfp_exc {
+    abi_ulong fpexc;
+    abi_ulong fpinst;
+    abi_ulong fpinst2;
+};
+
+struct target_vfp_sigframe {
+    abi_ulong magic;
+    abi_ulong size;
+    struct target_user_vfp ufp;
+    struct target_user_vfp_exc ufp_exc;
+} __attribute__((__aligned__(8)));
+
+#define TARGET_VFP_MAGIC 0x56465001
+
 struct sigframe_v1
 {
     struct target_sigcontext sc;
@@ -1255,11 +1275,29 @@ setup_return(CPUState *env, struct target_sigaction *ka,
 	return 0;
 }
 
+static abi_ulong *setup_sigframe_v2_vfp(abi_ulong *regspace, CPUState *env)
+{
+    int i;
+    struct target_vfp_sigframe *vfpframe;
+    vfpframe = (struct target_vfp_sigframe *)regspace;
+    __put_user(TARGET_VFP_MAGIC, &vfpframe->magic);
+    __put_user(sizeof(*vfpframe), &vfpframe->size);
+    for (i = 0; i < 32; i++) {
+        __put_user(env->vfp.regs[i], &vfpframe->ufp.fpregs[i]);
+    }
+    __put_user(vfp_get_fpscr(env), &vfpframe->ufp.fpscr);
+    __put_user(env->vfp.xregs[ARM_VFP_FPEXC], &vfpframe->ufp_exc.fpexc);
+    __put_user(env->vfp.xregs[ARM_VFP_FPINST], &vfpframe->ufp_exc.fpinst);
+    __put_user(env->vfp.xregs[ARM_VFP_FPINST2], &vfpframe->ufp_exc.fpinst2);
+    return (abi_ulong*)(vfpframe+1);
+}
+
 static void setup_sigframe_v2(struct target_ucontext_v2 *uc,
                               target_sigset_t *set, CPUState *env)
 {
     struct target_sigaltstack stack;
     int i;
+    abi_ulong *regspace;
 
     /* Clear all the bits of the ucontext we don't use.  */
     memset(uc, 0, offsetof(struct target_ucontext_v2, tuc_mcontext));
@@ -1271,7 +1309,14 @@ static void setup_sigframe_v2(struct target_ucontext_v2 *uc,
     memcpy(&uc->tuc_stack, &stack, sizeof(stack));
 
     setup_sigcontext(&uc->tuc_mcontext, env, set->sig[0]);
-    /* FIXME: Save coprocessor signal frame.  */
+    /* Save coprocessor signal frame.  */
+    regspace = uc->tuc_regspace;
+    if (arm_feature(env, ARM_FEATURE_VFP)) {
+        regspace = setup_sigframe_v2_vfp(regspace, env);
+    }
+    /* Write terminating magic word */
+    __put_user(0, regspace);
+
     for(i = 0; i < TARGET_NSIG_WORDS; i++) {
         __put_user(set->sig[i], &uc->tuc_sigmask.sig[i]);
     }