[PATCH] s390: put sys_call_table into .rodata section and write protect it

Put s390's syscall tables into .rodata section and write protect this
section to prevent misuse of it.  Suggested by Arjan van de Ven
<arjan@infradead.org>.

Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 7 insertions, 3 deletions

diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 1a434a7004ee..d8948c342caf 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -228,8 +228,9 @@ sysc_do_svc:
 sysc_nr_ok:
         mvc     SP_ARGS(4,%r15),SP_R7(%r15)
 sysc_do_restart:
+        l       %r8,BASED(.Lsysc_table)
         tm      __TI_flags+3(%r9),(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)
-        l       %r8,sys_call_table-system_call(%r7,%r13) # get system call addr.
+        l       %r8,0(%r7,%r8)    # get system call addr.
         bnz     BASED(sysc_tracesys)
         basr    %r14,%r8          # call sys_xxxx
         st      %r2,SP_R2(%r15)   # store return value (change R2 on stack)
@@ -330,9 +331,10 @@ sysc_tracesys:
         basr    %r14,%r1
         clc     SP_R2(4,%r15),BASED(.Lnr_syscalls)
         bnl     BASED(sysc_tracenogo)
+        l       %r8,BASED(.Lsysc_table)
         l       %r7,SP_R2(%r15)        # strace might have changed the 
         sll     %r7,2                  #  system call
-        l       %r8,sys_call_table-system_call(%r7,%r13)
+        l       %r8,0(%r7,%r8)
 sysc_tracego:
         lm      %r3,%r6,SP_R3(%r15)
         l       %r2,SP_ORIG_R2(%r15)
@@ -1009,6 +1011,7 @@ cleanup_io_leave_insn:
 .Ltrace:       .long  syscall_trace
 .Lvfork:       .long  sys_vfork
 .Lschedtail:   .long  schedule_tail
+.Lsysc_table:  .long  sys_call_table
 
 .Lcritical_start:
                .long  __critical_start + 0x80000000
@@ -1017,8 +1020,8 @@ cleanup_io_leave_insn:
 .Lcleanup_critical:
                .long  cleanup_critical
 
+               .section .rodata, "a"
 #define SYSCALL(esa,esame,emu)  .long esa
 sys_call_table:
 #include "syscalls.S"
 #undef SYSCALL
-
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index edad60771673..1ca499fa54b4 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -991,6 +991,7 @@ cleanup_io_leave_insn:
 .Lcritical_end:
                .quad  __critical_end
 
+               .section .rodata, "a"
 #define SYSCALL(esa,esame,emu)  .long esame
 sys_call_table:
 #include "syscalls.S"