Re: [PATCH v17 09/47] arm64, dept: add support CONFIG_ARCH_HAS_DEPT_SUPPORT to arm64

dept needs to notice every entrance from user to kernel mode to treat
every kernel context independently when tracking wait-event dependencies.
Roughly, system call and user oriented fault are the cases.

Make dept aware of the entrances of arm64 and add support
CONFIG_ARCH_HAS_DEPT_SUPPORT to arm64.

Signed-off-by: Byungchul Park <byungchul@sk.com>
---
 arch/arm64/Kconfig          | 1 +
 arch/arm64/kernel/syscall.c | 7 +++++++
 arch/arm64/mm/fault.c       | 7 +++++++
 3 files changed, 15 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index e9bbfacc35a6..a8fab2c052dc 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig

@@ -281,6 +281,7 @@ config ARM64
 	select USER_STACKTRACE_SUPPORT
 	select VDSO_GETRANDOM
 	select VMAP_STACK
+	select ARCH_HAS_DEPT_SUPPORT
 	help
 	  ARM 64-bit (AArch64) Linux support.
 

diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
index c442fcec6b9e..bbd306335179 100644
--- a/arch/arm64/kernel/syscall.c
+++ b/arch/arm64/kernel/syscall.c

@@ -7,6 +7,7 @@
 #include <linux/ptrace.h>
 #include <linux/randomize_kstack.h>
 #include <linux/syscalls.h>
+#include <linux/dept.h>
 
 #include <asm/debug-monitors.h>
 #include <asm/exception.h>

@@ -96,6 +97,12 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
 	 * (Similarly for HVC and SMC elsewhere.)
 	 */
 
+	/*
+	 * This is a system call from user mode.  Make dept work with a
+	 * new kernel mode context.
+	 */
+	dept_update_cxt();