Add support for usermode (vdso-like) gettimeofday(2) and

clock_gettime(2) on ARMv7 and ARMv8 systems which have architectural
generic timer hardware. It is similar how the RDTSC timer is used in
userspace on x86.

Fix a permission problem where generic timer access from EL0 (or
userspace on v7) was not properly initialized on APs.

For ARMv7, mark the stack non-executable. The shared page is added for
all arms (including ARMv8 64bit), and the signal trampoline code is
moved to the page.

Reviewed by:	andrew
Discussed with:	emaste, mmel
Sponsored by:	The FreeBSD Foundation
Differential revision:	https://reviews.freebsd.org/D4209

5 files changed, 33 insertions, 4 deletions

diff --git a/sys/arm64/arm64/elf_machdep.c b/sys/arm64/arm64/elf_machdep.c
index 2506de3..9ba2541 100644
--- a/sys/arm64/arm64/elf_machdep.c
+++ b/sys/arm64/arm64/elf_machdep.c
@@ -80,12 +80,15 @@ static struct sysentvec elf64_freebsd_sysvec = {
 	.sv_setregs	= exec_setregs,
 	.sv_fixlimit	= NULL,
 	.sv_maxssiz	= NULL,
-	.sv_flags	= SV_ABI_FREEBSD | SV_LP64,
+	.sv_flags	= SV_SHP | SV_TIMEKEEP | SV_ABI_FREEBSD | SV_LP64,
 	.sv_set_syscall_retval = cpu_set_syscall_retval,
 	.sv_fetch_syscall_args = cpu_fetch_syscall_args,
 	.sv_syscallnames = syscallnames,
+	.sv_shared_page_base = SHAREDPAGE,
+	.sv_shared_page_len = PAGE_SIZE,
 	.sv_schedtail	= NULL,
 };
+INIT_SYSENTVEC(elf64_sysvec, &elf64_freebsd_sysvec);
 
 static Elf64_Brandinfo freebsd_brand_info = {
 	.brand		= ELFOSABI_FREEBSD,
diff --git a/sys/arm64/arm64/machdep.c b/sys/arm64/arm64/machdep.c
index e92a99f..f7e1456 100644
--- a/sys/arm64/arm64/machdep.c
+++ b/sys/arm64/arm64/machdep.c
@@ -56,6 +56,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/sysent.h>
 #include <sys/sysproto.h>
 #include <sys/ucontext.h>
+#include <sys/vdso.h>
 
 #include <vm/vm.h>
 #include <vm/vm_kern.h>
@@ -72,6 +73,7 @@ __FBSDID("$FreeBSD$");
 #include <machine/devmap.h>
 #include <machine/machdep.h>
 #include <machine/metadata.h>
+#include <machine/md_var.h>
 #include <machine/pcb.h>
 #include <machine/reg.h>
 #include <machine/vmparam.h>
@@ -505,6 +507,7 @@ sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
 	struct trapframe *tf;
 	struct sigframe *fp, frame;
 	struct sigacts *psp;
+	struct sysentvec *sysent;
 	int code, onstack, sig;
 
 	td = curthread;
@@ -563,7 +566,12 @@ sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
 
 	tf->tf_elr = (register_t)catcher;
 	tf->tf_sp = (register_t)fp;
-	tf->tf_lr = (register_t)(PS_STRINGS - *(p->p_sysent->sv_szsigcode));
+	sysent = p->p_sysent;
+	if (sysent->sv_sigcode_base != 0)
+		tf->tf_lr = (register_t)sysent->sv_sigcode_base;
+	else
+		tf->tf_lr = (register_t)(sysent->sv_psstrings -
+		    *(sysent->sv_szsigcode));
 
 	CTR3(KTR_SIG, "sendsig: return td=%p pc=%#x sp=%#x", td, tf->tf_elr,
 	    tf->tf_sp);
@@ -875,6 +883,17 @@ initarm(struct arm64_bootparams *abp)
 	early_boot = 0;
 }
 
+uint32_t (*arm_cpu_fill_vdso_timehands)(struct vdso_timehands *,
+    struct timecounter *);
+
+uint32_t
+cpu_fill_vdso_timehands(struct vdso_timehands *vdso_th, struct timecounter *tc)
+{
+
+	return (arm_cpu_fill_vdso_timehands != NULL ?
+	    arm_cpu_fill_vdso_timehands(vdso_th, tc) : 0);
+}
+
 #ifdef DDB
 #include <ddb/ddb.h>
 
diff --git a/sys/arm64/include/md_var.h b/sys/arm64/include/md_var.h
index 8545591..d6cecfc 100644
--- a/sys/arm64/include/md_var.h
+++ b/sys/arm64/include/md_var.h
@@ -46,4 +46,9 @@ void dump_add_page(vm_paddr_t);
 void dump_drop_page(vm_paddr_t);
 int minidumpsys(struct dumperinfo *);
 
+struct vdso_timehands;
+struct timecounter;
+extern uint32_t (*arm_cpu_fill_vdso_timehands)(struct vdso_timehands *,
+    struct timecounter *);
+
 #endif /* !_MACHINE_MD_VAR_H_ */
diff --git a/sys/arm64/include/vdso.h b/sys/arm64/include/vdso.h
index 5a8f7f5..285e986 100644
--- a/sys/arm64/include/vdso.h
+++ b/sys/arm64/include/vdso.h
@@ -29,6 +29,7 @@
 #define	_MACHINE_VDSO_H_
 
 #define	VDSO_TIMEHANDS_MD			\
-	uint32_t	th_res[8];
+	uint32_t	th_physical;		\
+	uint32_t	th_res[7];
 
 #endif /* !_MACHINE_VDSO_H_ */
diff --git a/sys/arm64/include/vmparam.h b/sys/arm64/include/vmparam.h
index e3c1d74..2752ee1 100644
--- a/sys/arm64/include/vmparam.h
+++ b/sys/arm64/include/vmparam.h
@@ -194,7 +194,8 @@ extern vm_paddr_t dmap_phys_base;
 #define	VM_MAXUSER_ADDRESS	(VM_MAX_USER_ADDRESS)
 
 #define	KERNBASE		(VM_MIN_KERNEL_ADDRESS)
-#define	USRSTACK		(VM_MAX_USER_ADDRESS)
+#define	SHAREDPAGE		(VM_MAXUSER_ADDRESS - PAGE_SIZE)
+#define	USRSTACK		SHAREDPAGE
 
 /*
  * How many physical pages per kmem arena virtual page.