parisc: Fix and enable seccomp filter support
The seccomp filter support requires careful handling of task registers. This
includes reloading of the return value (%r28) and proper syscall exit if
secure_computing() returned -1.
Additionally we need to sign-extend the syscall number from signed 32bit to
signed 64bit in do_syscall_trace_enter() since the ptrace interface only allows
storing 32bit values in compat mode.
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: stable@vger.kernel.org # v4.5
diff --git a/arch/parisc/kernel/syscall.S b/arch/parisc/kernel/syscall.S
index fbafa0d..c976ebf 100644
--- a/arch/parisc/kernel/syscall.S
+++ b/arch/parisc/kernel/syscall.S
@@ -329,6 +329,7 @@
ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
LDREG TI_TASK(%r1), %r1
+ LDREG TASK_PT_GR28(%r1), %r28 /* Restore return value */
LDREG TASK_PT_GR26(%r1), %r26 /* Restore the users args */
LDREG TASK_PT_GR25(%r1), %r25
LDREG TASK_PT_GR24(%r1), %r24
@@ -342,6 +343,7 @@
stw %r21, -56(%r30) /* 6th argument */
#endif
+ cmpib,COND(=),n -1,%r20,tracesys_exit /* seccomp may have returned -1 */
comiclr,>>= __NR_Linux_syscalls, %r20, %r0
b,n .Ltracesys_nosys