MIPS: Don't assume 64-bit FP registers for dump_{,task_}fpu

This code assumed that saved FP registers are 64 bits wide, an
assumption which will no longer be true once MSA is introduced. This
patch modifies the code to copy the lower 64 bits of each register in
turn, which is safe for any FP register width >= 64 bits.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6425/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/process.c

@@ -157,7 +157,13 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
 /* Fill in the fpu structure for a core dump.. */
 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
 {
-	memcpy(r, &current->thread.fpu, sizeof(current->thread.fpu));
+	int i;
+
+	for (i = 0; i < NUM_FPU_REGS; i++)
+		memcpy(&r[i], &current->thread.fpu.fpr[i], sizeof(*r));
+
+	memcpy(&r[NUM_FPU_REGS], &current->thread.fpu.fcr31,
+	       sizeof(current->thread.fpu.fcr31));
 
 	return 1;
 }
@@ -192,7 +198,13 @@ int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
 
 int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr)
 {
-	memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu));
+	int i;
+
+	for (i = 0; i < NUM_FPU_REGS; i++)
+		memcpy(&fpr[i], &t->thread.fpu.fpr[i], sizeof(*fpr));
+
+	memcpy(&fpr[NUM_FPU_REGS], &t->thread.fpu.fcr31,
+	       sizeof(t->thread.fpu.fcr31));
 
 	return 1;
 }