[PATCH -next] openrisc: Define __ro_after_init to avoid crash

[Guenter Roeck]

openrisc qemu tests fail with the following crash.

Unable to handle kernel access at virtual address 0xc0300c34

Oops#: 0001
CPU #: 0
   PC: c016c710    SR: 0000ae67    SP: c1017e04
   GPR00: 00000000 GPR01: c1017e04 GPR02: c0300c34 GPR03: c0300c34
   GPR04: 00000000 GPR05: c0300cb0 GPR06: c0300c34 GPR07: 000000ff
   GPR08: c107f074 GPR09: c0199ef4 GPR10: c1016000 GPR11: 00000000
   GPR12: 00000000 GPR13: c107f044 GPR14: c0473774 GPR15: 07ce0000
   GPR16: 00000000 GPR17: c107ed8a GPR18: 00009600 GPR19: c107f044
   GPR20: c107ee74 GPR21: 00000003 GPR22: c0473770 GPR23: 00000033
   GPR24: 000000bf GPR25: 00000019 GPR26: c046400c GPR27: 00000001
   GPR28: c0464028 GPR29: c1018000 GPR30: 00000006 GPR31: ccf37483
     RES: 00000000 oGPR11: ffffffff
     Process swapper (pid: 1, stackpage=c1001960)

     Stack: Stack dump [0xc1017cf8]:
     sp + 00: 0xc1017e04
     sp + 04: 0xc0300c34
     sp + 08: 0xc0300c34
     sp + 12: 0x00000000
...

Bisect points to commit d2ec3f77de8e ("pty: make ptmx file ops read-only
after init"). Fix by defining __ro_after_init for the openrisc
architecture, similar to parisc.

Fixes: d2ec3f77de8e ("pty: make ptmx file ops read-only after init")
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
 arch/openrisc/include/asm/cache.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/openrisc/include/asm/cache.h b/arch/openrisc/include/asm/cache.h
index 4ce7a01a252d..5f55da9cbfd5 100644
--- a/arch/openrisc/include/asm/cache.h
+++ b/arch/openrisc/include/asm/cache.h
@@ -23,6 +23,8 @@
  * they shouldn't be hard-coded!
  */
 
+#define __ro_after_init __read_mostly
+
 #define L1_CACHE_BYTES 16
 #define L1_CACHE_SHIFT 4
 
-- 
2.5.0