1 files changed, 25 insertions, 21 deletions

diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index 0bc10cd4cbed..d6c22f8aa06d 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -298,7 +298,6 @@ static int userspace_tramp(void *data)
 		.seccomp = using_seccomp,
 		.stub_start = STUB_START,
 	};
-	struct iomem_region *iomem;
 	int ret;
 
 	if (using_seccomp) {
@@ -332,12 +331,6 @@ static int userspace_tramp(void *data)
 
 	fcntl(init_data.stub_data_fd, F_SETFD, 0);
 
-	/* In SECCOMP mode, these FDs are passed when needed */
-	if (!using_seccomp) {
-		for (iomem = iomem_regions; iomem; iomem = iomem->next)
-			fcntl(iomem->fd, F_SETFD, 0);
-	}
-
 	/* dup2 signaling FD/socket to STDIN */
 	if (dup2(tramp_data->sockpair[0], 0) < 0)
 		exit(3);
@@ -553,7 +546,7 @@ extern unsigned long tt_extra_sched_jiffies;
 void userspace(struct uml_pt_regs *regs)
 {
 	int err, status, op;
-	siginfo_t si_ptrace;
+	siginfo_t si_local;
 	siginfo_t *si;
 	int sig;
 
@@ -564,6 +557,13 @@ void userspace(struct uml_pt_regs *regs)
 		struct mm_id *mm_id = current_mm_id();
 
 		/*
+		 * At any given time, only one CPU thread can enter the
+		 * turnstile to operate on the same stub process, including
+		 * executing stub system calls (mmap and munmap).
+		 */
+		enter_turnstile(mm_id);
+
+		/*
 		 * When we are in time-travel mode, userspace can theoretically
 		 * do a *lot* of work without being scheduled. The problem with
 		 * this is that it will prevent kernel bookkeeping (primarily
@@ -630,9 +630,10 @@ void userspace(struct uml_pt_regs *regs)
 			}
 
 			if (proc_data->si_offset > sizeof(proc_data->sigstack) - sizeof(*si))
-				panic("%s - Invalid siginfo offset from child",
-				      __func__);
-			si = (void *)&proc_data->sigstack[proc_data->si_offset];
+				panic("%s - Invalid siginfo offset from child", __func__);
+
+			si = &si_local;
+			memcpy(si, &proc_data->sigstack[proc_data->si_offset], sizeof(*si));
 
 			regs->is_user = 1;
 
@@ -728,8 +729,8 @@ void userspace(struct uml_pt_regs *regs)
 				case SIGFPE:
 				case SIGWINCH:
 					ptrace(PTRACE_GETSIGINFO, pid, 0,
-					       (struct siginfo *)&si_ptrace);
-					si = &si_ptrace;
+					       (struct siginfo *)&si_local);
+					si = &si_local;
 					break;
 				default:
 					si = NULL;
@@ -740,6 +741,8 @@ void userspace(struct uml_pt_regs *regs)
 			}
 		}
 
+		exit_turnstile(mm_id);
+
 		UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
 
 		if (sig) {
@@ -809,10 +812,9 @@ void switch_threads(jmp_buf *me, jmp_buf *you)
 
 static jmp_buf initial_jmpbuf;
 
-/* XXX Make these percpu */
-static void (*cb_proc)(void *arg);
-static void *cb_arg;
-static jmp_buf *cb_back;
+static __thread void (*cb_proc)(void *arg);
+static __thread void *cb_arg;
+static __thread jmp_buf *cb_back;
 
 int start_idle_thread(void *stack, jmp_buf *switch_buf)
 {
@@ -866,10 +868,10 @@ void initial_thread_cb_skas(void (*proc)(void *), void *arg)
 	cb_arg = arg;
 	cb_back = &here;
 
-	block_signals_trace();
+	initial_jmpbuf_lock();
 	if (UML_SETJMP(&here) == 0)
 		UML_LONGJMP(&initial_jmpbuf, INIT_JMP_CALLBACK);
-	unblock_signals_trace();
+	initial_jmpbuf_unlock();
 
 	cb_proc = NULL;
 	cb_arg = NULL;
@@ -878,8 +880,9 @@ void initial_thread_cb_skas(void (*proc)(void *), void *arg)
 
 void halt_skas(void)
 {
-	block_signals_trace();
+	initial_jmpbuf_lock();
 	UML_LONGJMP(&initial_jmpbuf, INIT_JMP_HALT);
+	/* unreachable */
 }
 
 static bool noreboot;
@@ -899,6 +902,7 @@ __uml_setup("noreboot", noreboot_cmd_param,
 
 void reboot_skas(void)
 {
-	block_signals_trace();
+	initial_jmpbuf_lock();
 	UML_LONGJMP(&initial_jmpbuf, noreboot ? INIT_JMP_HALT : INIT_JMP_REBOOT);
+	/* unreachable */
 }