[PATCH RFC POC 11/50] MIPS: commit fds on syscall exit

[Christian Brauner]

Add TIF_FD_SLOTS to the syscall exit work. The return path rereads
the flags after the system call and calls syscall_trace_leave() for
any of the exit work bits which commits the reservations before audit
and the ptrace exit stop.

Signed-off-by: Christian Brauner (Amutable) <brauner at kernel.org>
---
 arch/mips/include/asm/thread_info.h | 5 ++++-
 arch/mips/kernel/ptrace.c           | 4 ++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/mips/include/asm/thread_info.h b/arch/mips/include/asm/thread_info.h
index 2707dad260dd..79c81696e9c1 100644
--- a/arch/mips/include/asm/thread_info.h
+++ b/arch/mips/include/asm/thread_info.h
@@ -114,6 +114,7 @@ register unsigned long current_stack_pointer __asm__("sp");
 #define TIF_NOTIFY_RESUME	5	/* callback before returning to user */
 #define TIF_UPROBE		6	/* breakpointed or singlestepping */
 #define TIF_NOTIFY_SIGNAL	7	/* signal notifications exist */
+#define TIF_FD_SLOTS		8	/* syscall prepared descriptors */
 #define TIF_RESTORE_SIGMASK	9	/* restore signal mask in do_signal() */
 #define TIF_USEDFPU		16	/* FPU was used by this task this quantum (SMP) */
 #define TIF_MEMDIE		18	/* is terminating due to OOM killer */
@@ -152,6 +153,7 @@ register unsigned long current_stack_pointer __asm__("sp");
 #define _TIF_USEDMSA		(1<<TIF_USEDMSA)
 #define _TIF_MSA_CTX_LIVE	(1<<TIF_MSA_CTX_LIVE)
 #define _TIF_SYSCALL_TRACEPOINT	(1<<TIF_SYSCALL_TRACEPOINT)
+#define _TIF_FD_SLOTS		(1<<TIF_FD_SLOTS)
 
 #define _TIF_WORK_SYSCALL_ENTRY	(_TIF_NOHZ | _TIF_SYSCALL_TRACE |	\
 				 _TIF_SYSCALL_AUDIT | \
@@ -159,7 +161,8 @@ register unsigned long current_stack_pointer __asm__("sp");
 
 /* work to do in syscall_trace_leave() */
 #define _TIF_WORK_SYSCALL_EXIT	(_TIF_NOHZ | _TIF_SYSCALL_TRACE |	\
-				 _TIF_SYSCALL_AUDIT | _TIF_SYSCALL_TRACEPOINT)
+				 _TIF_SYSCALL_AUDIT | _TIF_SYSCALL_TRACEPOINT | \
+				 _TIF_FD_SLOTS)
 
 /* work to do on interrupt/exception return */
 #define _TIF_WORK_MASK		\
diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index 17dc7249b8ca..d68eab59bcc2 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -17,6 +17,7 @@
 #include <linux/compiler.h>
 #include <linux/context_tracking.h>
 #include <linux/elf.h>
+#include <linux/file.h>
 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/sched/task_stack.h>
@@ -1364,6 +1365,9 @@ asmlinkage void syscall_trace_leave(struct pt_regs *regs)
 	 */
 	user_exit();
 
+	if (test_thread_flag(TIF_FD_SLOTS))
+		fd_slots_commit(regs);
+
 	audit_syscall_exit(regs);
 
 	if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))

-- 
2.53.0