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Subject[PATCH 14/19] ARC: entry.S: move some code around for cache locality in return path
Date
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
arch/arc/kernel/entry-compact.S | 2 +
arch/arc/kernel/entry.S | 98 +++++++++++++++++++++--------------------
2 files changed, 52 insertions(+), 48 deletions(-)

diff --git a/arch/arc/kernel/entry-compact.S b/arch/arc/kernel/entry-compact.S
index bf611ec9a017..abc62cd10a8c 100644
--- a/arch/arc/kernel/entry-compact.S
+++ b/arch/arc/kernel/entry-compact.S
@@ -391,3 +391,5 @@ not_level1_interrupt:
EXCEPTION_EPILOGUE
debug_marker_syscall:
rtie
+
+END(ret_from_exception)
diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S
index 75cdc56351d9..603266eb75e1 100644
--- a/arch/arc/kernel/entry.S
+++ b/arch/arc/kernel/entry.S
@@ -24,6 +24,55 @@
*------------------------------------------------------------------
*/

+;################### Special Sys Call Wrappers ##########################
+
+ENTRY(sys_clone_wrapper)
+ SAVE_CALLEE_SAVED_USER
+ 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
+END(sys_clone_wrapper)
+
+ENTRY(ret_from_fork)
+ ; when the forked child comes here from the __switch_to function
+ ; r0 has the last task pointer.
+ ; put last task in scheduler queue
+ bl @schedule_tail
+
+ ld r9, [sp, PT_status32]
+ brne r9, 0, 1f
+
+ jl.d [r14] ; kernel thread entry point
+ mov r0, r13 ; (see PF_KTHREAD block in copy_thread)
+
+1:
+ ; Return to user space
+ ; 1. Any forked task (Reach here via BRne above)
+ ; 2. First ever init task (Reach here via return from JL above)
+ ; This is the historic "kernel_execve" use-case, to return to init
+ ; user mode, in a round about way since that is always done from
+ ; a kernel thread which is executed via JL above but always returns
+ ; out whenever kernel_execve (now inline do_fork()) is involved
+ b ret_from_exception
+END(ret_from_fork)
+
+#ifdef CONFIG_ARC_DW2_UNWIND
+; Workaround for bug 94179 (STAR ):
+; Despite -fasynchronous-unwind-tables, linker is not making dwarf2 unwinder
+; section (.debug_frame) as loadable. So we force it here.
+; This also fixes STAR 9000487933 where the prev-workaround (objcopy --setflag)
+; would not work after a clean build due to kernel build system dependencies.
+.section .debug_frame, "wa",@progbits
+
+; Reset to .text as this file is included in entry-<isa>.S
+.section .text, "ax",@progbits
+#endif
+
;################### Non TLB Exception Handling #############################

; ---------------------------------------------
@@ -338,53 +387,6 @@ resume_kernel_mode:
#endif

b .Lrestore_regs
-END(ret_from_exception)
-
-ENTRY(ret_from_fork)
- ; when the forked child comes here from the __switch_to function
- ; r0 has the last task pointer.
- ; put last task in scheduler queue
- bl @schedule_tail
-
- ld r9, [sp, PT_status32]
- brne r9, 0, 1f
-
- jl.d [r14] ; kernel thread entry point
- mov r0, r13 ; (see PF_KTHREAD block in copy_thread)
-
-1:
- ; Return to user space
- ; 1. Any forked task (Reach here via BRne above)
- ; 2. First ever init task (Reach here via return from JL above)
- ; This is the historic "kernel_execve" use-case, to return to init
- ; user mode, in a round about way since that is always done from
- ; a kernel thread which is executed via JL above but always returns
- ; out whenever kernel_execve (now inline do_fork()) is involved
- b ret_from_exception
-END(ret_from_fork)

-;################### Special Sys Call Wrappers ##########################
-
-ENTRY(sys_clone_wrapper)
- SAVE_CALLEE_SAVED_USER
- 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
-END(sys_clone_wrapper)
-
-#ifdef CONFIG_ARC_DW2_UNWIND
-; Workaround for bug 94179 (STAR ):
-; Despite -fasynchronous-unwind-tables, linker is not making dwarf2 unwinder
-; section (.debug_frame) as loadable. So we force it here.
-; This also fixes STAR 9000487933 where the prev-workaround (objcopy --setflag)
-; would not work after a clean build due to kernel build system dependencies.
-.section .debug_frame, "wa",@progbits
+##### DONT ADD CODE HERE - .Lrestore_regs actually follows in entry-<isa>.S

-; Reset to .text as this file is included in entry-<isa>.S
-.section .text, "ax",@progbits
-#endif
--
1.9.1


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