commit 59da21398e680e8100625d689c8bebee6a139e93
author Martin Schwidefsky <schwidefsky@de.ibm.com> Thu Nov 27 11:05:55 2008 +0100
committer Martin Schwidefsky <schwidefsky@de.ibm.com> Thu Nov 27 11:06:56 2008 +0100
tree 7d93f87d2942dac06367af8b3a269e9f6d557b29
parent ed313489badef16d700f5a3be50e8fd8f8294bc8

[S390] fix system call parameter functions.

syscall_get_nr() currently returns a valid result only if the call
chain of the traced process includes do_syscall_trace_enter(). But
collect_syscall() can be called for any sleeping task, the result of
syscall_get_nr() in general is completely bogus.

To make syscall_get_nr() work for any sleeping task the traps field
in pt_regs is replace with svcnr - the system call number the process
is executing. If svcnr == 0 the process is not on a system call path.

The syscall_get_arguments and syscall_set_arguments use regs->gprs[2]
for the first system call parameter. This is incorrect since gprs[2]
may have been overwritten with the system call number if the call
chain includes do_syscall_trace_enter. Use regs->orig_gprs2 instead.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/signal.c

diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c
index 4f7fc30..8e6812a 100644
--- a/arch/s390/kernel/signal.c
+++ b/arch/s390/kernel/signal.c
@@ -160,7 +160,7 @@
 	current->thread.fp_regs.fpc &= FPC_VALID_MASK;
 
 	restore_fp_regs(&current->thread.fp_regs);
-	regs->trap = -1;	/* disable syscall checks */
+	regs->svcnr = 0;	/* disable syscall checks */
 	return 0;
 }
 
@@ -445,7 +445,7 @@
 		oldset = &current->blocked;
 
 	/* Are we from a system call? */
-	if (regs->trap == __LC_SVC_OLD_PSW) {
+	if (regs->svcnr) {
 		continue_addr = regs->psw.addr;
 		restart_addr = continue_addr - regs->ilc;
 		retval = regs->gprs[2];
@@ -462,7 +462,7 @@
 		case -ERESTART_RESTARTBLOCK:
 			regs->gprs[2] = -EINTR;
 		}
-		regs->trap = -1;	/* Don't deal with this again. */
+		regs->svcnr = 0;	/* Don't deal with this again. */
 	}
 
 	/* Get signal to deliver.  When running under ptrace, at this point