ARC: ptrace support
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S
index 69d0d37..76697ae 100644
--- a/arch/arc/kernel/entry.S
+++ b/arch/arc/kernel/entry.S
@@ -7,6 +7,13 @@
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
+ * vineetg: Feb 2011 (ptrace low level code fixes)
+ * -traced syscall return code (r0) was not saved into pt_regs for restoring
+ * into user reg-file when traded task rets to user space.
+ * -syscalls needing arch-wrappers (mainly for passing sp as pt_regs)
+ * were not invoking post-syscall trace hook (jumping directly into
+ * ret_from_system_call)
+ *
* vineetg: Nov 2010:
* -Vector table jumps (@8 bytes) converted into branches (@4 bytes)
* -To maintain the slot size of 8 bytes/vector, added nop, which is
@@ -347,6 +354,50 @@
b ret_from_exception
ARC_EXIT EV_Extension
+;######################### System Call Tracing #########################
+
+tracesys:
+ ; save EFA in case tracer wants the PC of traced task
+ ; using ERET won't work since next-PC has already committed
+ lr r12, [efa]
+ GET_CURR_TASK_FIELD_PTR TASK_THREAD, r11
+ st r12, [r11, THREAD_FAULT_ADDR]
+
+ ; PRE Sys Call Ptrace hook
+ mov r0, sp ; pt_regs needed
+ bl @syscall_trace_entry
+
+ ; Tracing code now returns the syscall num (orig or modif)
+ mov r8, r0
+
+ ; Do the Sys Call as we normally would.
+ ; Validate the Sys Call number
+ cmp r8, NR_syscalls
+ mov.hi r0, -ENOSYS
+ bhi tracesys_exit
+
+ ; Restore the sys-call args. Mere invocation of the hook abv could have
+ ; clobbered them (since they are in scratch regs). The tracer could also
+ ; have deliberately changed the syscall args: r0-r7
+ ld r0, [sp, PT_r0]
+ ld r1, [sp, PT_r1]
+ ld r2, [sp, PT_r2]
+ ld r3, [sp, PT_r3]
+ ld r4, [sp, PT_r4]
+ ld r5, [sp, PT_r5]
+ ld r6, [sp, PT_r6]
+ ld r7, [sp, PT_r7]
+ ld.as r9, [sys_call_table, r8]
+ jl [r9] ; Entry into Sys Call Handler
+
+tracesys_exit:
+ st r0, [sp, PT_r0] ; sys call return value in pt_regs
+
+ ;POST Sys Call Ptrace Hook
+ bl @syscall_trace_exit
+ b ret_from_exception ; NOT ret_from_system_call at is saves r0 which
+ ; we'd done before calling post hook above
+
;################### Break Point TRAP ##########################
; ======= (5b) Trap is due to Break-Point =========
@@ -412,6 +463,11 @@
; Before doing anything, return from CPU Exception Mode
FAKE_RET_FROM_EXCPN r11
+ ; If syscall tracing ongoing, invoke pre-pos-hooks
+ GET_CURR_THR_INFO_FLAGS r10
+ btst r10, TIF_SYSCALL_TRACE
+ bnz tracesys ; this never comes back
+
;============ This is normal System Call case ==========
; Sys-call num shd not exceed the total system calls avail
cmp r8, NR_syscalls
@@ -608,6 +664,10 @@
bl @sys_fork
DISCARD_CALLEE_SAVED_USER
+ GET_CURR_THR_INFO_FLAGS r10
+ btst r10, TIF_SYSCALL_TRACE
+ bnz tracesys_exit
+
b ret_from_system_call
ARC_EXIT sys_fork_wrapper
@@ -616,6 +676,10 @@
bl @sys_vfork
DISCARD_CALLEE_SAVED_USER
+ GET_CURR_THR_INFO_FLAGS r10
+ btst r10, TIF_SYSCALL_TRACE
+ bnz tracesys_exit
+
b ret_from_system_call
ARC_EXIT sys_vfork_wrapper
@@ -624,5 +688,9 @@
bl @sys_clone
DISCARD_CALLEE_SAVED_USER
+ GET_CURR_THR_INFO_FLAGS r10
+ btst r10, TIF_SYSCALL_TRACE
+ bnz tracesys_exit
+
b ret_from_system_call
ARC_EXIT sys_clone_wrapper
