microblaze: Support ptrace syscall tracing.

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>

1 files changed, 60 insertions, 12 deletions

diff --git a/arch/microblaze/kernel/entry.S b/arch/microblaze/kernel/entry.S
index c7353e79f4a2..acc1f05d1e2c 100644
--- a/arch/microblaze/kernel/entry.S
+++ b/arch/microblaze/kernel/entry.S
@@ -308,38 +308,69 @@ C_ENTRY(_user_exception):
         swi     r12, r1, PTO+PT_R0;
         tovirt(r1,r1)
 
-        la      r15, r0, ret_from_trap-8
 /* where the trap should return need -8 to adjust for rtsd r15, 8*/
 /* Jump to the appropriate function for the system call number in r12
  * (r12 is not preserved), or return an error if r12 is not valid. The LP
  * register should point to the location where
  * the called function should return.  [note that MAKE_SYS_CALL uses label 1] */
-        /* See if the system call number is valid.  */
+
+        # Step into virtual mode.
+        set_vms;
+        addik   r11, r0, 3f
+        rtid    r11, 0
+        nop
+3:
+        add     r11, r0, CURRENT_TASK    /* Get current task ptr into r11 */
+        lwi     r11, r11, TS_THREAD_INFO /* get thread info */
+        lwi     r11, r11, TI_FLAGS       /* get flags in thread info */
+        andi    r11, r11, _TIF_WORK_SYSCALL_MASK
+        beqi    r11, 4f
+
+        addik   r3, r0, -ENOSYS
+        swi     r3, r1, PTO + PT_R3
+        brlid   r15, do_syscall_trace_enter
+        addik   r5, r1, PTO + PT_R0
+
+        # do_syscall_trace_enter returns the new syscall nr.
+        addk    r12, r0, r3
+        lwi     r5, r1, PTO+PT_R5;
+        lwi     r6, r1, PTO+PT_R6;
+        lwi     r7, r1, PTO+PT_R7;
+        lwi     r8, r1, PTO+PT_R8;
+        lwi     r9, r1, PTO+PT_R9;
+        lwi     r10, r1, PTO+PT_R10;
+4:
+/* Jump to the appropriate function for the system call number in r12
+ * (r12 is not preserved), or return an error if r12 is not valid.
+ * The LP register should point to the location where the called function
+ * should return.  [note that MAKE_SYS_CALL uses label 1] */
+        /* See if the system call number is valid */
         addi    r11, r12, -__NR_syscalls;
-        bgei    r11,1f;
+        bgei    r11,5f;
         /* Figure out which function to use for this system call.  */
         /* Note Microblaze barrel shift is optional, so don't rely on it */
         add     r12, r12, r12;                  /* convert num -> ptr */
         add     r12, r12, r12;
 
         /* Trac syscalls and stored them to r0_ram */
-        lwi     r3, r12, 0x400 + TOPHYS(r0_ram)
+        lwi     r3, r12, 0x400 + r0_ram
         addi    r3, r3, 1
-        swi     r3, r12, 0x400 + TOPHYS(r0_ram)
+        swi     r3, r12, 0x400 + r0_ram
+
+        # Find and jump into the syscall handler.
+        lwi     r12, r12, sys_call_table
+        /* where the trap should return need -8 to adjust for rtsd r15, 8 */
+        la      r15, r0, ret_from_trap-8
+        bra     r12
 
-        lwi     r12, r12, TOPHYS(sys_call_table); /* Function ptr */
-        /* Make the system call.  to r12*/
-        set_vms;
-        rtid    r12, 0;
-        nop;
         /* The syscall number is invalid, return an error.  */
-1:      VM_ON;  /* RETURN() expects virtual mode*/
+5:
         addi    r3, r0, -ENOSYS;
         rtsd    r15,8;          /* looks like a normal subroutine return */
         or      r0, r0, r0
 
 
-/* Entry point used to return from a syscall/trap.  */
+/* Entry point used to return from a syscall/trap */
 /* We re-enable BIP bit before state restore */
 C_ENTRY(ret_from_trap):
         set_bip;                        /*  Ints masked for state restore*/
@@ -349,6 +380,23 @@ C_ENTRY(ret_from_trap):
 
         /* We're returning to user mode, so check for various conditions that
          * trigger rescheduling. */
+        # FIXME: Restructure all these flag checks.
+        add     r11, r0, CURRENT_TASK;  /* Get current task ptr into r11 */
+        lwi     r11, r11, TS_THREAD_INFO;       /* get thread info */
+        lwi     r11, r11, TI_FLAGS;             /* get flags in thread info */
+        andi    r11, r11, _TIF_WORK_SYSCALL_MASK
+        beqi    r11, 1f
+
+        swi     r3, r1, PTO + PT_R3
+        swi     r4, r1, PTO + PT_R4
+        brlid   r15, do_syscall_trace_leave
+        addik   r5, r1, PTO + PT_R0
+        lwi     r3, r1, PTO + PT_R3
+        lwi     r4, r1, PTO + PT_R4
+1:
+
+        /* We're returning to user mode, so check for various conditions that
+         * trigger rescheduling. */
         /* Get current task ptr into r11 */
         add     r11, r0, CURRENT_TASK;  /* Get current task ptr into r11 */
         lwi     r11, r11, TS_THREAD_INFO;       /* get thread info */