score: add generic sys_call_table

This adds back a sys_call_table to the score architecture, which
got lost in the conversion to the generic unistd.h file.
It's rather worrying that the code got submitted without a
system call table, which evidently means that it got zero
testing.

Since the system call table has a different layout from the old
one (which was modeled after the mips-o32 one), I also try to
fix the entry.S path to use it. In the modified calling conventions,
all system call arguments are passed as registers r4 through r9,
instead of r4 through r7 plus stack for the fifth and sixth argument.

This matches what other architectures to when they normally pass
arguments on the stack.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 3 insertions, 44 deletions

diff --git a/arch/score/kernel/entry.S b/arch/score/kernel/entry.S
index 0af89b2f16b..2f169175bbd 100644
--- a/arch/score/kernel/entry.S
+++ b/arch/score/kernel/entry.S
@@ -400,6 +400,8 @@ ENTRY(handle_sys)
         sw      r4, [r0, PT_ORIG_R4]    #for restart syscall
         sw      r7, [r0, PT_ORIG_R7]    #for restart syscall
         sw      r27, [r0, PT_IS_SYSCALL] # it from syscall
+        sw      r8, [r0, 16]            # argument 5 from user r8
+        sw      r9, [r0, 20]            # argument 6 from user r9
 
         lw      r9, [r0, PT_EPC]        # skip syscall on return
         addi    r9, 4
@@ -408,19 +410,14 @@ ENTRY(handle_sys)
         cmpi.c  r27, __NR_syscalls      # check syscall number
         bgtu    illegal_syscall
 
-        slli    r8, r27, 3              # get syscall routine
+        slli    r8, r27, 2              # get syscall routine
         la      r11, sys_call_table
         add     r11, r11, r8
         lw      r10, [r11]              # get syscall entry
-        lw      r11, [r11, 4]           # get number of args
 
         cmpz.c  r10
         beq     illegal_syscall
 
-        cmpi.c  r11, 4                  # more than 4 arguments?
-        bgtu    stackargs
-
-stack_done:
         lw      r8, [r28, TI_FLAGS]
         li      r9, _TIF_SYSCALL_TRACE
         and.c   r8, r8, r9
@@ -475,44 +472,6 @@ syscall_trace_entry:
 1:      sw      r4, [r0, PT_R2]         # result
         j       syscall_exit
 
-stackargs:
-        lw      r8, [r0, PT_R0]
-        andri.c r9, r8, 3               # test whether user sp is align a word
-        bne     bad_stack
-        subi    r11, 5
-        slli    r9, r11, 2
-        add.c   r9, r9, r8
-
-        bmi     bad_stack
-        la      r9, 3f                  # calculate branch address
-        slli    r11, r11, 3
-        sub     r9, r9, r11
-        br      r9
-
-2:      lw      r9, [r8, 20]            # argument 6 from usp
-        sw      r9, [r0, 20]
-
-3:      lw      r9, [r8, 16]            # argument 5 from usp
-        sw      r9, [r0, 16]
-        j       stack_done
-
-        .section __ex_table,"a"
-        .word   2b, bad_stack
-        .word   3b, bad_stack
-        .previous
-
-        /*
-         * The stackpointer for a call with more than 4 arguments is bad.
-         * We probably should handle this case a bit more drastic.
-         */
-bad_stack:
-        neg     r27, r27                # error
-        sw      r27, [r0, PT_ORIG_R4]
-        sw      r27, [r0, PT_R4]
-        ldi     r8, 1                   # set error flag
-        sw      r8, [r0, PT_R7]
-        j       syscall_return
-
 illegal_syscall:
         ldi     r4, -ENOSYS             # error
         sw      r4, [r0, PT_ORIG_R4]