Use a regset for NT_ARM_VFP.

This includes adding support for NT_ARM_VFP for 32-bit binaries
running under aarch64 kernels both for ptrace(), and coredumps via the
kernel and gcore.

Reviewed by:	andrew, markj
Sponsored by:	University of Cambridge, Google, Inc.
Differential Revision:	https://reviews.freebsd.org/D34448

sys/arm/arm/elf_machdep.c

@@ -145,19 +145,9 @@ elf32_arm_abi_supported(struct image_params *imgp, int32_t *osrel __unused,
 }
 
 void
-elf32_dump_thread(struct thread *td, void *dst, size_t *off)
+elf32_dump_thread(struct thread *td __unused, void *dst __unused,
+    size_t *off __unused)
 {
-#ifdef VFP
-	mcontext_vfp_t vfp;
-
-	if (dst != NULL) {
-		get_vfpcontext(td, &vfp);
-		*off = elf32_populate_note(NT_ARM_VFP, &vfp, dst, sizeof(vfp),
-		    NULL);
-	} else
-		*off = elf32_populate_note(NT_ARM_VFP, NULL, NULL, sizeof(vfp),
-		    NULL);
-#endif
 }
 
 bool

sys/arm/arm/ptrace_machdep.c

@@ -28,12 +28,45 @@
 __FBSDID("$FreeBSD$");
 
 #include <sys/types.h>
+#include <sys/elf.h>
 #include <sys/proc.h>
 #include <sys/ptrace.h>
+#include <sys/reg.h>
 #ifdef VFP
 #include <machine/vfp.h>
 #endif
 
+#ifdef VFP
+static bool
+get_arm_vfp(struct regset *rs, struct thread *td, void *buf, size_t *sizep)
+{
+	if (buf != NULL) {
+		KASSERT(*sizep == sizeof(mcontext_vfp_t),
+		    ("%s: invalid size", __func__));
+		get_vfpcontext(td, buf);
+	}
+	*sizep = sizeof(mcontext_vfp_t);
+	return (true);
+}
+
+static bool
+set_arm_vfp(struct regset *rs, struct thread *td, void *buf,
+    size_t size)
+{
+	KASSERT(size == sizeof(mcontext_vfp_t), ("%s: invalid size", __func__));
+	set_vfpcontext(td, buf);
+	return (true);
+}
+
+static struct regset regset_arm_vfp = {
+	.note = NT_ARM_VFP,
+	.size = sizeof(mcontext_vfp_t),
+	.get = get_arm_vfp,
+	.set = set_arm_vfp,
+};
+ELF_REGSET(regset_arm_vfp);
+#endif
+
 int
 cpu_ptrace(struct thread *td, int req, void *addr, int data)
 {