[PATCH RFC POC 14/50] parisc: commit fds on syscall exit

[Christian Brauner]

Add TIF_FD_SLOTS and test it in syscall_exit once the return value
has been saved to pt_regs. A task that reserved descriptors calls
do_syscall_trace_exit() and then continues with the usual reschedule and
signal checks. The traced path already ends up there.

Signed-off-by: Christian Brauner (Amutable) <brauner@xxxxxxxxxx>
---
 arch/parisc/include/asm/thread_info.h |  2 ++
 arch/parisc/kernel/entry.S            | 12 ++++++++++++
 arch/parisc/kernel/ptrace.c           |  4 ++++
 3 files changed, 18 insertions(+)

diff --git a/arch/parisc/include/asm/thread_info.h b/arch/parisc/include/asm/thread_info.h
index b283738bb6da..14a40c53689f 100644
--- a/arch/parisc/include/asm/thread_info.h
+++ b/arch/parisc/include/asm/thread_info.h
@@ -52,6 +52,7 @@ struct thread_info {
 #define TIF_SECCOMP		11	/* secure computing */
 #define TIF_SYSCALL_TRACEPOINT	12	/* syscall tracepoint instrumentation */
 #define TIF_NONBLOCK_WARNING	13	/* warned about wrong O_NONBLOCK usage */
+#define TIF_FD_SLOTS		14	/* syscall prepared descriptors */
 
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
@@ -65,6 +66,7 @@ struct thread_info {
 #define _TIF_BLOCKSTEP		(1 << TIF_BLOCKSTEP)
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
 #define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
+#define _TIF_FD_SLOTS		(1 << TIF_FD_SLOTS)
 
 #define _TIF_USER_WORK_MASK     (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | \
                                  _TIF_NEED_RESCHED | _TIF_NOTIFY_SIGNAL)
diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S
index e04c5d806c10..c5807cf6fbd8 100644
--- a/arch/parisc/kernel/entry.S
+++ b/arch/parisc/kernel/entry.S
@@ -1732,6 +1732,8 @@ syscall_check_resched:
 	/* check for reschedule */
 	mfctl	%cr30,%r19
 	LDREG	TASK_TI_FLAGS(%r19),%r19	/* long */
+	/* descriptors reserved by the syscall are committed in do_syscall_trace_exit */
+	bb,<,n	%r19, 31-TIF_FD_SLOTS, syscall_do_fd_slots /* forward */
 	bb,<,n	%r19, 31-TIF_NEED_RESCHED, syscall_do_resched /* forward */
 
 	.import do_signal,code
@@ -1765,6 +1767,16 @@ syscall_do_signal:
 
 	b,n     syscall_check_sig
 
+syscall_do_fd_slots:
+	mfctl	%cr30,%r1
+#ifdef CONFIG_64BIT
+	ldo	-16(%r30),%r29			/* Reference param save area */
+#endif
+	ldo	TASK_REGS(%r1),%r26		/* struct pt_regs *regs */
+	BL	do_syscall_trace_exit,%r2
+	nop
+	b,n	syscall_check_resched
+
 syscall_restore:
 	mfctl	%cr30,%r1
 
diff --git a/arch/parisc/kernel/ptrace.c b/arch/parisc/kernel/ptrace.c
index 1d9e210702e1..f142766792af 100644
--- a/arch/parisc/kernel/ptrace.c
+++ b/arch/parisc/kernel/ptrace.c
@@ -9,6 +9,7 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/file.h>
 #include <linux/sched.h>
 #include <linux/mm.h>
 #include <linux/smp.h>
@@ -381,6 +382,9 @@ void do_syscall_trace_exit(struct pt_regs *regs)
 	int stepping = test_thread_flag(TIF_SINGLESTEP) ||
 		test_thread_flag(TIF_BLOCKSTEP);
 
+	if (test_thread_flag(TIF_FD_SLOTS))
+		fd_slots_commit(regs);
+
 	audit_syscall_exit(regs);
 
 #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS

-- 
2.53.0