Add TIF_FD_SLOTS and test it on the untraced return from a system call in all three entry paths. A task that reserved descriptors calls syscall_trace_leave(), which commits them before the ptrace exit stop. The traced paths already end up there.
Signed-off-by: Christian Brauner (Amutable) <[email protected]> --- arch/m68k/68000/entry.S | 10 ++++++++++ arch/m68k/coldfire/entry.S | 12 ++++++++++++ arch/m68k/include/asm/thread_info.h | 2 ++ arch/m68k/kernel/entry.S | 2 ++ arch/m68k/kernel/ptrace.c | 3 +++ 5 files changed, 29 insertions(+) diff --git a/arch/m68k/68000/entry.S b/arch/m68k/68000/entry.S index c257cc415c47..479032af2f2f 100644 --- a/arch/m68k/68000/entry.S +++ b/arch/m68k/68000/entry.S @@ -89,6 +89,16 @@ ENTRY(system_call) jbsr %a0@ movel %d0,%sp@(PT_OFF_D0) /* save the return value*/ + /* descriptors reserved by the syscall are committed in syscall_trace_leave */ + getthreadinfo + btst #(TIF_FD_SLOTS%8),%a2@(TINFO_FLAGS+(31-TIF_FD_SLOTS)/8) + jeq ret_from_exception + subql #4,%sp /* dummy return address */ + SAVE_SWITCH_STACK + jbsr syscall_trace_leave + RESTORE_SWITCH_STACK + addql #4,%sp + ret_from_exception: btst #5,%sp@(PT_OFF_SR) /* check if returning to kernel*/ jeq Luser_return /* if so, skip resched, signals*/ diff --git a/arch/m68k/coldfire/entry.S b/arch/m68k/coldfire/entry.S index 4ea08336e2fb..43e47d4c0018 100644 --- a/arch/m68k/coldfire/entry.S +++ b/arch/m68k/coldfire/entry.S @@ -78,6 +78,18 @@ ENTRY(system_call) movel %d3,%a0 jbsr %a0@ movel %d0,%sp@(PT_OFF_D0) /* save the return value */ + + /* descriptors reserved by the syscall are committed in syscall_trace_leave */ + movel %sp,%d2 /* get thread_info pointer */ + andl #-THREAD_SIZE,%d2 /* at start of kernel stack */ + movel %d2,%a0 + btst #(TIF_FD_SLOTS%8),%a0@(TINFO_FLAGS+(31-TIF_FD_SLOTS)/8) + jeq ret_from_exception + subql #4,%sp /* dummy return address */ + SAVE_SWITCH_STACK + jbsr syscall_trace_leave + RESTORE_SWITCH_STACK + addql #4,%sp jra ret_from_exception 1: movel #-ENOSYS,%d2 /* strace needs -ENOSYS in PT_OFF_D0 */ diff --git a/arch/m68k/include/asm/thread_info.h b/arch/m68k/include/asm/thread_info.h index 5cb3ace55622..861b6f523bda 100644 --- a/arch/m68k/include/asm/thread_info.h +++ b/arch/m68k/include/asm/thread_info.h @@ -62,6 +62,7 @@ static inline struct thread_info *current_thread_info(void) #define TIF_NOTIFY_RESUME 5 /* callback before returning to user */ #define TIF_SIGPENDING 6 /* signal pending */ #define TIF_NEED_RESCHED 7 /* rescheduling necessary */ +#define TIF_FD_SLOTS 12 /* syscall prepared descriptors */ #define TIF_SECCOMP 13 /* seccomp syscall filtering active */ #define TIF_DELAYED_TRACE 14 /* single step a syscall */ #define TIF_SYSCALL_TRACE 15 /* syscall trace active */ @@ -71,6 +72,7 @@ static inline struct thread_info *current_thread_info(void) #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) +#define _TIF_FD_SLOTS (1 << TIF_FD_SLOTS) #define _TIF_SECCOMP (1 << TIF_SECCOMP) #define _TIF_DELAYED_TRACE (1 << TIF_DELAYED_TRACE) #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) diff --git a/arch/m68k/kernel/entry.S b/arch/m68k/kernel/entry.S index 338b474910f7..9e4471f68165 100644 --- a/arch/m68k/kernel/entry.S +++ b/arch/m68k/kernel/entry.S @@ -229,6 +229,8 @@ ret_from_syscall: syscall_exit_work: btst #5,%sp@(PT_OFF_SR) | check if returning to kernel bnes 1b | if so, skip resched, signals + btst #4,%a1@(TINFO_FLAGS+2) | TIF_FD_SLOTS: commit descriptors + jne do_trace_exit lslw #1,%d0 jcs do_trace_exit jmi do_delayed_trace diff --git a/arch/m68k/kernel/ptrace.c b/arch/m68k/kernel/ptrace.c index 4575f6487a9a..07103e6ddeb0 100644 --- a/arch/m68k/kernel/ptrace.c +++ b/arch/m68k/kernel/ptrace.c @@ -11,6 +11,7 @@ */ #include <linux/kernel.h> +#include <linux/file.h> #include <linux/sched.h> #include <linux/sched/task_stack.h> #include <linux/mm.h> @@ -289,6 +290,8 @@ asmlinkage int syscall_trace_enter(void) asmlinkage void syscall_trace_leave(void) { + if (test_thread_flag(TIF_FD_SLOTS)) + fd_slots_commit(task_pt_regs(current)); if (test_thread_flag(TIF_SYSCALL_TRACE)) ptrace_report_syscall_exit(task_pt_regs(current), 0); } -- 2.53.0
