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>

1 files changed, 36 insertions, 0 deletions

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index d7230bf68ad1..93ac58dbf07c 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
  *-----------------
  */
@@ -91,6 +117,7 @@
         .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
@@ -426,6 +453,7 @@ el0_da:
         mrs     x26, far_el1
         // enable interrupts before calling the main handler
         enable_dbg_and_irq
+        ct_user_exit
         bic     x0, x26, #(0xff << 56)
         mov     x1, x25
         mov     x2, sp
@@ -438,6 +466,7 @@ el0_ia:
         mrs     x26, far_el1
         // enable interrupts before calling the main handler
         enable_dbg_and_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
          */
         enable_dbg
+        ct_user_exit
         mov     x0, x25
         mov     x1, sp
         adr     lr, ret_to_user
@@ -457,6 +487,7 @@ el0_fpsimd_exc:
          * Floating Point or Advanced SIMD exception
          */
         enable_dbg
+        ct_user_exit
         mov     x0, x25
         mov     x1, sp
         adr     lr, ret_to_user
@@ -479,6 +510,7 @@ el0_undef:
          */
         // enable interrupts before calling the main handler
         enable_dbg_and_irq
+        ct_user_exit
         mov     x0, sp
         adr     lr, ret_to_user
         b       do_undefinstr
@@ -492,9 +524,11 @@ el0_dbg:
         mov     x2, sp
         bl      do_debug_exception
         enable_dbg
+        ct_user_exit
         b       ret_to_user
 el0_inv:
         enable_dbg
+        ct_user_exit
         mov     x0, sp
         mov     x1, #BAD_SYNC
         mrs     x2, esr_el1
@@ -511,6 +545,7 @@ el0_irq_naked:
         bl      trace_hardirqs_off
 #endif
 
+        ct_user_exit
         irq_handler
 
 #ifdef CONFIG_TRACE_IRQFLAGS
@@ -615,6 +650,7 @@ el0_svc:
 el0_svc_naked:                                  // compat entry point
         stp     x0, scno, [sp, #S_ORIG_X0]      // save the original x0 and syscall number
         enable_dbg_and_irq
+        ct_user_exit 1
 
         ldr     x16, [tsk, #TI_FLAGS]           // check for syscall hooks
         tst     x16, #_TIF_SYSCALL_WORK