Add a NT_ARM_VFP ELF core note to hold VFP registers for each thread.

The core note matches the format and layout of NT_ARM_VFP on Linux.
Debuggers use the AT_HWCAP flags to determine how many VFP registers
are actually used and their format.

Reviewed by:	mmel (earlier version w/o gcore)
MFC after:	1 month
Differential Revision:	https://reviews.freebsd.org/D12293

1 files changed, 31 insertions, 0 deletions

diff --git a/usr.bin/gcore/elfcore.c b/usr.bin/gcore/elfcore.c
index ff1010001c3f..ae52d61c9281 100644
--- a/usr.bin/gcore/elfcore.c
+++ b/usr.bin/gcore/elfcore.c
@@ -109,6 +109,9 @@ static void *elf_note_prpsinfo(void *, size_t *);
 static void *elf_note_prstatus(void *, size_t *);
 static void *elf_note_thrmisc(void *, size_t *);
 static void *elf_note_ptlwpinfo(void *, size_t *);
+#if defined(__arm__)
+static void *elf_note_arm_vfp(void *, size_t *);
+#endif
 #if defined(__i386__) || defined(__amd64__)
 static void *elf_note_x86_xstate(void *, size_t *);
 #endif
@@ -368,6 +371,9 @@ elf_putnotes(pid_t pid, struct sbuf *sb, size_t *sizep)
 		elf_putnote(NT_FPREGSET, elf_note_fpregset, tids + i, sb);
 		elf_putnote(NT_THRMISC, elf_note_thrmisc, tids + i, sb);
 		elf_putnote(NT_PTLWPINFO, elf_note_ptlwpinfo, tids + i, sb);
+#if defined(__arm__)
+		elf_putnote(NT_ARM_VFP, elf_note_arm_vfp, tids + i, sb);
+#endif
 #if defined(__i386__) || defined(__amd64__)
 		elf_putnote(NT_X86_XSTATE, elf_note_x86_xstate, tids + i, sb);
 #endif
@@ -718,6 +724,31 @@ elf_note_ptlwpinfo(void *arg, size_t *sizep)
 	return (p);
 }
 
+#if defined(__arm__)
+static void *
+elf_note_arm_vfp(void *arg, size_t *sizep)
+{
+	lwpid_t tid;
+	struct vfpreg *vfp;
+	static bool has_vfp = true;
+	struct vfpreg info;
+
+	tid = *(lwpid_t *)arg;
+	if (has_vfp) {
+		if (ptrace(PT_GETVFPREGS, tid, (void *)&info, 0) != 0)
+			has_vfp = false;
+	}
+	if (!has_vfp) {
+		*sizep = 0;
+		return (NULL);
+	}
+	vfp = calloc(1, sizeof(*vfp));
+	memcpy(vfp, &info, sizeof(*vfp));
+	*sizep = sizeof(*vfp);
+	return (vfp);
+}
+#endif
+
 #if defined(__i386__) || defined(__amd64__)
 static void *
 elf_note_x86_xstate(void *arg, size_t *sizep)