[PATCH v1 4/4] arm64/syscalls: Specific usage of verify_pre_usermode_state

[Thomas Garnier]

Implement specific usage of verify_pre_usermode_state for user-mode
returns for arm64.
---
Based on next-20170308
---
 arch/arm64/Kconfig        | 1 +
 arch/arm64/kernel/entry.S | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 896eba61e5ed..da54774838d8 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -24,6 +24,7 @@ config ARM64
        select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
        select ARCH_WANT_FRAME_POINTERS
        select ARCH_HAS_UBSAN_SANITIZE_ALL
+       select ARCH_NO_SYSCALL_VERIFY_PRE_USERMODE_STATE
        select ARM_AMBA
        select ARM_ARCH_TIMER
        select ARM_GIC
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 43512d4d7df2..b3d1d9e5c7c1 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -744,6 +744,7 @@ ENDPROC(cpu_switch_to)
 ret_fast_syscall:
        disable_irq                             // disable interrupts
        str     x0, [sp, #S_X0]                 // returned x0
+       bl      verify_pre_usermode_state
        ldr     x1, [tsk, #TSK_TI_FLAGS]        // re-check for syscall tracing
        and     x2, x1, #_TIF_SYSCALL_WORK
        cbnz    x2, ret_fast_syscall_trace
@@ -771,6 +772,7 @@ work_pending:
  */
 ret_to_user:
        disable_irq                             // disable interrupts
+       bl      verify_pre_usermode_state
        ldr     x1, [tsk, #TSK_TI_FLAGS]
        and     x2, x1, #_TIF_WORK_MASK
        cbnz    x2, work_pending
-- 
2.12.0.246.ga2ecc84866-goog