arm64: enable context tracking

Backport of the following patch to 3.14 LSK:

commit 6c81fe7925cc4c42de49e17be21eb86d1173c3a7
Author: Larry Bassel <larry.bassel@linaro.org>
Date:   Fri May 30 12:34:15 2014 -0700

    arm64: enable context tracking

    Make calls to ct_user_enter when the kernel is exited
    and ct_user_exit when the kernel is entered (in el0_da,
    el0_ia, el0_svc, el0_irq and all of the "error" paths).

    These macros expand to function calls which will only work
    properly if el0_sync and related code has been rearranged
    (in a previous patch of this series).

    The calls to ct_user_exit are made after hw debugging has been
    enabled (enable_dbg_and_irq).

    The call to ct_user_enter is made at the beginning of the
    kernel_exit macro.

    This patch is based on earlier work by Kevin Hilman.
    Save/restore optimizations were also done by Kevin.

    Acked-by: Will Deacon <will.deacon@arm.com>
    Reviewed-by: Kevin Hilman <khilman@linaro.org>
    Tested-by: Kevin Hilman <khilman@linaro.org>
    Signed-off-by: Larry Bassel <larry.bassel@linaro.org>
    Signed-off-by: Kevin Hilman <khilman@linaro.org>
    Signed-off-by: Will Deacon <will.deacon@arm.com>
    Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Signed-off-by: Larry Bassel <larry.bassel@linaro.org>

1 files changed, 37 insertions, 1 deletions

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index c779ef357e43..e59b7b3500fc 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -30,6 +30,32 @@
 #include <asm/unistd32.h>
 
 /*
+ * Context tracking subsystem.  Used to instrument transitions
+ * between user and kernel mode.
+ */
+	.macro ct_user_exit, syscall = 0
+#ifdef CONFIG_CONTEXT_TRACKING
+	bl	context_tracking_user_exit
+	.if \syscall == 1
+	/*
+	 * Save/restore needed during syscalls.  Restore syscall arguments from
+	 * the values already saved on stack during kernel_entry.
+	 */
+	ldp	x0, x1, [sp]
+	ldp	x2, x3, [sp, #S_X2]
+	ldp	x4, x5, [sp, #S_X4]
+	ldp	x6, x7, [sp, #S_X6]
+	.endif
+#endif
+	.endm
+
+	.macro ct_user_enter
+#ifdef CONFIG_CONTEXT_TRACKING
+	bl	context_tracking_user_enter
+#endif
+	.endm
+
+/*
  * Bad Abort numbers
  *-----------------
  */
@@ -88,6 +114,7 @@
 	.macro	kernel_exit, el, ret = 0
 	ldp	x21, x22, [sp, #S_PC]		// load ELR, SPSR
 	.if	\el == 0
+	ct_user_enter
 	ldr	x23, [sp, #S_SP]		// load return stack pointer
 	.endif
 	.if	\ret
@@ -424,6 +451,7 @@ el0_da:
 	enable_dbg
 	// enable interrupts before calling the main handler
 	enable_irq
+	ct_user_exit
 	bic	x0, x26, #(0xff << 56)
 	mov	x1, x25
 	mov	x2, sp
@@ -439,6 +467,7 @@ el0_ia:
 	enable_dbg
 	// enable interrupts before calling the main handler
 	enable_irq
+	ct_user_exit
 	mov	x0, x26
 	orr	x1, x25, #1 << 24		// use reserved ISS bit for instruction aborts
 	mov	x2, sp
@@ -448,6 +477,7 @@ el0_fpsimd_acc:
 	/*
 	 * Floating Point or Advanced SIMD access
 	 */
+	ct_user_exit
 	mov	x0, x25
 	mov	x1, sp
 	adr	lr, ret_from_exception
@@ -456,6 +486,7 @@ el0_fpsimd_exc:
 	/*
 	 * Floating Point or Advanced SIMD exception
 	 */
+	ct_user_exit
 	mov	x0, x25
 	mov	x1, sp
 	adr	lr, ret_from_exception
@@ -479,9 +510,10 @@ el0_undef:
 	/*
 	 * Undefined instruction
 	 */
-	mov	x0, sp
 	// enable interrupts before calling the main handler
+	ct_user_exit
 	enable_irq
+	mov	x0, sp
 	adr	lr, ret_from_exception
 	b	do_undefinstr
 el0_dbg:
@@ -489,12 +521,14 @@ el0_dbg:
 	 * Debug exception handling
 	 */
 	tbnz	x24, #0, el0_inv		// EL0 only
+	ct_user_exit
 	mrs	x0, far_el1
 	disable_step x1
 	mov	x1, x25
 	mov	x2, sp
 	b	do_debug_exception
 el0_inv:
+	ct_user_exit
 	mov	x0, sp
 	mov	x1, #BAD_SYNC
 	mrs	x2, esr_el1
@@ -513,6 +547,7 @@ el0_irq_naked:
 	bl	trace_hardirqs_off
 #endif
 
+	ct_user_exit
 	irq_handler
 	get_thread_info tsk
 
@@ -635,6 +670,7 @@ el0_svc_naked:					// compat entry point
 	isb
 	enable_dbg
 	enable_irq
+	ct_user_exit 1
 
 	get_thread_info tsk
 	ldr	x16, [tsk, #TI_FLAGS]		// check for syscall hooks