[PATCH] PPC32: Don't oops on out-of-range system call

This patch fixes a bug on PPC where the kernel will oops if a process
does a system call and the system call number is out of range.

While fixing that, I noticed that if the process is being ptraced, an
out-of-range system call will not get traced on the way in but will on
the way out.  This patch fixes that too, by making it get traced on
the way in as well as the way out.  It turned out to be less change,
and fewer instructions overall, to do that than to make the
out-of-range system call not be traced at all.

diff --git a/arch/ppc/kernel/entry.S b/arch/ppc/kernel/entry.S
index 772e723812c9655c078d23d427d3b2147f12d225..2df04db0b2121f6d22abe4b6cba1dee102ffb398 100644 (file)
--- a/arch/ppc/kernel/entry.S
+++ b/arch/ppc/kernel/entry.S
@@ -170,8 +170,6 @@ _GLOBAL(DoSyscall)
 #ifdef SHOW_SYSCALLS
        bl      do_show_syscall
 #endif /* SHOW_SYSCALLS */
-       cmpli   0,r0,NR_syscalls
-       bge-    66f
        rlwinm  r10,r1,0,0,18   /* current_thread_info() */
        lwz     r11,TI_FLAGS(r10)
        rlwinm  r11,r11,0,~_TIF_FORCE_NOERROR
@@ -179,9 +177,11 @@ _GLOBAL(DoSyscall)
        andi.   r11,r11,_TIF_SYSCALL_TRACE
        bne-    syscall_dotrace
 syscall_dotrace_cont:
+       cmpli   0,r0,NR_syscalls
        lis     r10,sys_call_table@h
        ori     r10,r10,sys_call_table@l
        slwi    r0,r0,2
+       bge-    66f
        lwzx    r10,r10,r0      /* Fetch system call handler [ptr] */
        mtlr    r10
        addi    r9,r1,STACK_FRAME_OVERHEAD
@@ -200,7 +200,7 @@ ret_from_syscall:
        andi.   r11,r11,_TIF_FORCE_NOERROR
        bne     30f
        neg     r3,r3
-22:    lwz     r10,_CCR(r1)    /* Set SO bit in CR */
+       lwz     r10,_CCR(r1)    /* Set SO bit in CR */
        oris    r10,r10,0x1000
        stw     r10,_CCR(r1)
 
@@ -233,8 +233,8 @@ syscall_exit_cont:
        SYNC
        RFI
 
-66:    li      r3,ENOSYS
-       b       22b
+66:    li      r3,-ENOSYS
+       b       ret_from_syscall
 
        .globl  ret_from_fork
 ret_from_fork: