From 27efb0a2422308cb6ba1170bbaa32546fce5a85b Mon Sep 17 00:00:00 2001
From: John Baldwin <jhb@FreeBSD.org>
Date: Thu, 14 Sep 2017 15:07:48 +0000
Subject: [PATCH] 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
---
 sys/arm/arm/elf_machdep.c | 17 +++++++++++++++--
 sys/sys/elf_common.h      |  1 +
 usr.bin/gcore/elfcore.c   | 31 +++++++++++++++++++++++++++++++
 3 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/sys/arm/arm/elf_machdep.c b/sys/arm/arm/elf_machdep.c
index 26e3754d3c8c..fba35eb159c6 100644
--- a/sys/arm/arm/elf_machdep.c
+++ b/sys/arm/arm/elf_machdep.c
@@ -45,6 +45,9 @@ __FBSDID("$FreeBSD$");
 
 #include <machine/elf.h>
 #include <machine/md_var.h>
+#ifdef VFP
+#include <machine/vfp.h>
+#endif
 
 static boolean_t elf32_arm_abi_supported(struct image_params *);
 
@@ -127,9 +130,19 @@ elf32_arm_abi_supported(struct image_params *imgp)
 }
 
 void
-elf32_dump_thread(struct thread *td __unused, void *dst __unused,
-    size_t *off __unused)
+elf32_dump_thread(struct thread *td, void *dst, size_t *off)
 {
+#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
 }
 
 /*
diff --git a/sys/sys/elf_common.h b/sys/sys/elf_common.h
index c66bbae499eb..8634e0a9d5db 100644
--- a/sys/sys/elf_common.h
+++ b/sys/sys/elf_common.h
@@ -757,6 +757,7 @@ typedef struct {
 #define	NT_PTLWPINFO		17	/* Thread ptrace miscellaneous info. */
 #define	NT_PPC_VMX	0x100	/* PowerPC Altivec/VMX registers */
 #define	NT_X86_XSTATE	0x202	/* x86 XSAVE extended state. */
+#define	NT_ARM_VFP	0x400	/* ARM VFP registers */
 
 /* Symbol Binding - ELFNN_ST_BIND - st_info */
 #define	STB_LOCAL	0	/* Local symbol */
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)