From dff606546d91cfe239bd033eefe62fdc6931cb78 Mon Sep 17 00:00:00 2001
From: jhb <jhb@FreeBSD.org>
Date: Thu, 14 Sep 2017 14:30:43 +0000
Subject: [PATCH] Add AT_HWCAP flags for VFP settings for FreeBSD/arm.

These flags match the meaning and value of flags in Linux, though
Linux has many more flags.

Reviewed by:	stevek, Michal Meloun <meloun-miracle-cz> (earlier version)
MFC after:	1 month
Differential Revision:	https://reviews.freebsd.org/D12291
---
 sys/arm/arm/elf_machdep.c | 3 +++
 sys/arm/arm/vfp.c         | 9 ++++++++-
 sys/arm/include/elf.h     | 6 ++++++
 sys/arm/include/md_var.h  | 1 +
 4 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/sys/arm/arm/elf_machdep.c b/sys/arm/arm/elf_machdep.c
index a962ee882e1c..26e3754d3c8c 100644
--- a/sys/arm/arm/elf_machdep.c
+++ b/sys/arm/arm/elf_machdep.c
@@ -48,6 +48,8 @@ __FBSDID("$FreeBSD$");
 
 static boolean_t elf32_arm_abi_supported(struct image_params *);
 
+u_long elf_hwcap;
+
 struct sysentvec elf32_freebsd_sysvec = {
 	.sv_size	= SYS_MAXSYSCALL,
 	.sv_table	= sysent,
@@ -86,6 +88,7 @@ struct sysentvec elf32_freebsd_sysvec = {
 	.sv_schedtail	= NULL,
 	.sv_thread_detach = NULL,
 	.sv_trap	= NULL,
+	.sv_hwcap	= &elf_hwcap,
 };
 INIT_SYSENTVEC(elf32_sysvec, &elf32_freebsd_sysvec);
 
diff --git a/sys/arm/arm/vfp.c b/sys/arm/arm/vfp.c
index 5a403a692c0c..6b8fcaef7a0b 100644
--- a/sys/arm/arm/vfp.c
+++ b/sys/arm/arm/vfp.c
@@ -33,9 +33,11 @@ __FBSDID("$FreeBSD$");
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/proc.h>
+#include <sys/imgact_elf.h>
 #include <sys/kernel.h>
 
 #include <machine/armreg.h>
+#include <machine/elf.h>
 #include <machine/frame.h>
 #include <machine/md_var.h>
 #include <machine/pcb.h>
@@ -115,6 +117,7 @@ vfp_init(void)
 		vfp_exists = 1;
 		is_d32 = 0;
 		PCPU_SET(vfpsid, fpsid);	/* save the fpsid */
+		elf_hwcap |= HWCAP_VFP;
 
 		vfp_arch =
 		    (fpsid & VFPSID_SUBVERSION2_MASK) >> VFPSID_SUBVERSION_OFF;
@@ -122,9 +125,13 @@ vfp_init(void)
 		if (vfp_arch >= VFP_ARCH3) {
 			tmp = fmrx(mvfr0);
 			PCPU_SET(vfpmvfr0, tmp);
+			elf_hwcap |= HWCAP_VFPv3;
 
-			if ((tmp & VMVFR0_RB_MASK) == 2)
+			if ((tmp & VMVFR0_RB_MASK) == 2) {
+				elf_hwcap |= HWCAP_VFPD32;
 				is_d32 = 1;
+			} else
+				elf_hwcap |= HWCAP_VFPv3D16;
 
 			tmp = fmrx(mvfr1);
 			PCPU_SET(vfpmvfr1, tmp);
diff --git a/sys/arm/include/elf.h b/sys/arm/include/elf.h
index 4dc0d456892b..f4f57b87f4f1 100644
--- a/sys/arm/include/elf.h
+++ b/sys/arm/include/elf.h
@@ -115,4 +115,10 @@ __ElfType(Auxinfo);
 
 #define	ET_DYN_LOAD_ADDR	0x12000
 
+/* Flags passed in AT_HWCAP. */
+#define	HWCAP_VFP		0x00000040
+#define	HWCAP_VFPv3		0x00000200
+#define	HWCAP_VFPv3D16		0x00000400
+#define	HWCAP_VFPD32		0x00080000
+
 #endif /* !_MACHINE_ELF_H_ */
diff --git a/sys/arm/include/md_var.h b/sys/arm/include/md_var.h
index 642124d9d214..46d834b9ba36 100644
--- a/sys/arm/include/md_var.h
+++ b/sys/arm/include/md_var.h
@@ -38,6 +38,7 @@ extern char sigcode[];
 extern int szsigcode;
 extern uint32_t *vm_page_dump;
 extern int vm_page_dump_size;
+extern u_long elf_hwcap;
 
 extern int (*_arm_memcpy)(void *, void *, int, int);
 extern int (*_arm_bzero)(void *, int, int);