1 files changed, 199 insertions, 0 deletions
diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
new file mode 100644
index 000000000000..87efb38b7081
--- /dev/null
+++ b/include/linux/entry-common.h
@@ -0,0 +1,199 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LINUX_ENTRYCOMMON_H
+#define __LINUX_ENTRYCOMMON_H
+
+#include <linux/irq-entry-common.h>
+#include <linux/livepatch.h>
+#include <linux/ptrace.h>
+#include <linux/resume_user_mode.h>
+#include <linux/seccomp.h>
+#include <linux/sched.h>
+
+#include <asm/entry-common.h>
+#include <asm/syscall.h>
+
+#ifndef _TIF_UPROBE
+# define _TIF_UPROBE			(0)
+#endif
+
+/*
+ * SYSCALL_WORK flags handled in syscall_enter_from_user_mode()
+ */
+#ifndef ARCH_SYSCALL_WORK_ENTER
+# define ARCH_SYSCALL_WORK_ENTER	(0)
+#endif
+
+/*
+ * SYSCALL_WORK flags handled in syscall_exit_to_user_mode()
+ */
+#ifndef ARCH_SYSCALL_WORK_EXIT
+# define ARCH_SYSCALL_WORK_EXIT		(0)
+#endif
+
+#define SYSCALL_WORK_ENTER	(SYSCALL_WORK_SECCOMP |			\
+				 SYSCALL_WORK_SYSCALL_TRACEPOINT |	\
+				 SYSCALL_WORK_SYSCALL_TRACE |		\
+				 SYSCALL_WORK_SYSCALL_EMU |		\
+				 SYSCALL_WORK_SYSCALL_AUDIT |		\
+				 SYSCALL_WORK_SYSCALL_USER_DISPATCH |	\
+				 ARCH_SYSCALL_WORK_ENTER)
+
+#define SYSCALL_WORK_EXIT	(SYSCALL_WORK_SYSCALL_TRACEPOINT |	\
+				 SYSCALL_WORK_SYSCALL_TRACE |		\
+				 SYSCALL_WORK_SYSCALL_AUDIT |		\
+				 SYSCALL_WORK_SYSCALL_USER_DISPATCH |	\
+				 SYSCALL_WORK_SYSCALL_EXIT_TRAP	|	\
+				 ARCH_SYSCALL_WORK_EXIT)
+
+long syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long work);
+
+/**
+ * syscall_enter_from_user_mode_work - Check and handle work before invoking
+ *				       a syscall
+ * @regs:	Pointer to currents pt_regs
+ * @syscall:	The syscall number
+ *
+ * Invoked from architecture specific syscall entry code with interrupts
+ * enabled after invoking enter_from_user_mode(), enabling interrupts and
+ * extra architecture specific work.
+ *
+ * Returns: The original or a modified syscall number
+ *
+ * If the returned syscall number is -1 then the syscall should be
+ * skipped. In this case the caller may invoke syscall_set_error() or
+ * syscall_set_return_value() first.  If neither of those are called and -1
+ * is returned, then the syscall will fail with ENOSYS.
+ *
+ * It handles the following work items:
+ *
+ *  1) syscall_work flag dependent invocations of
+ *     ptrace_report_syscall_entry(), __secure_computing(), trace_sys_enter()
+ *  2) Invocation of audit_syscall_entry()
+ */
+static __always_inline long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall)
+{
+	unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
+
+	if (work & SYSCALL_WORK_ENTER)
+		syscall = syscall_trace_enter(regs, syscall, work);
+
+	return syscall;
+}
+
+/**
+ * syscall_enter_from_user_mode - Establish state and check and handle work
+ *				  before invoking a syscall
+ * @regs:	Pointer to currents pt_regs
+ * @syscall:	The syscall number
+ *
+ * Invoked from architecture specific syscall entry code with interrupts
+ * disabled. The calling code has to be non-instrumentable. When the
+ * function returns all state is correct, interrupts are enabled and the
+ * subsequent functions can be instrumented.
+ *
+ * This is the combination of enter_from_user_mode() and
+ * syscall_enter_from_user_mode_work() to be used when there is no
+ * architecture specific work to be done between the two.
+ *
+ * Returns: The original or a modified syscall number. See
+ * syscall_enter_from_user_mode_work() for further explanation.
+ */
+static __always_inline long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall)
+{
+	long ret;
+
+	enter_from_user_mode(regs);
+
+	instrumentation_begin();
+	local_irq_enable();
+	ret = syscall_enter_from_user_mode_work(regs, syscall);
+	instrumentation_end();
+
+	return ret;
+}
+
+/**
+ * syscall_exit_work - Handle work before returning to user mode
+ * @regs:	Pointer to current pt_regs
+ * @work:	Current thread syscall work
+ *
+ * Do one-time syscall specific work.
+ */
+void syscall_exit_work(struct pt_regs *regs, unsigned long work);
+
+/**
+ * syscall_exit_to_user_mode_work - Handle work before returning to user mode
+ * @regs:	Pointer to currents pt_regs
+ *
+ * Same as step 1 and 2 of syscall_exit_to_user_mode() but without calling
+ * exit_to_user_mode() to perform the final transition to user mode.
+ *
+ * Calling convention is the same as for syscall_exit_to_user_mode() and it
+ * returns with all work handled and interrupts disabled. The caller must
+ * invoke exit_to_user_mode() before actually switching to user mode to
+ * make the final state transitions. Interrupts must stay disabled between
+ * return from this function and the invocation of exit_to_user_mode().
+ */
+static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs *regs)
+{
+	unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
+	unsigned long nr = syscall_get_nr(current, regs);
+
+	CT_WARN_ON(ct_state() != CT_STATE_KERNEL);
+
+	if (IS_ENABLED(CONFIG_PROVE_LOCKING)) {
+		if (WARN(irqs_disabled(), "syscall %lu left IRQs disabled", nr))
+			local_irq_enable();
+	}
+
+	rseq_debug_syscall_return(regs);
+
+	/*
+	 * Do one-time syscall specific work. If these work items are
+	 * enabled, we want to run them exactly once per syscall exit with
+	 * interrupts enabled.
+	 */
+	if (unlikely(work & SYSCALL_WORK_EXIT))
+		syscall_exit_work(regs, work);
+	local_irq_disable_exit_to_user();
+	syscall_exit_to_user_mode_prepare(regs);
+}
+
+/**
+ * syscall_exit_to_user_mode - Handle work before returning to user mode
+ * @regs:	Pointer to currents pt_regs
+ *
+ * Invoked with interrupts enabled and fully valid regs. Returns with all
+ * work handled, interrupts disabled such that the caller can immediately
+ * switch to user mode. Called from architecture specific syscall and ret
+ * from fork code.
+ *
+ * The call order is:
+ *  1) One-time syscall exit work:
+ *	- rseq syscall exit
+ *      - audit
+ *	- syscall tracing
+ *	- ptrace (single stepping)
+ *
+ *  2) Preparatory work
+ *	- Exit to user mode loop (common TIF handling). Invokes
+ *	  arch_exit_to_user_mode_work() for architecture specific TIF work
+ *	- Architecture specific one time work arch_exit_to_user_mode_prepare()
+ *	- Address limit and lockdep checks
+ *
+ *  3) Final transition (lockdep, tracing, context tracking, RCU), i.e. the
+ *     functionality in exit_to_user_mode().
+ *
+ * This is a combination of syscall_exit_to_user_mode_work() (1,2) and
+ * exit_to_user_mode(). This function is preferred unless there is a
+ * compelling architectural reason to use the separate functions.
+ */
+static __always_inline void syscall_exit_to_user_mode(struct pt_regs *regs)
+{
+	instrumentation_begin();
+	syscall_exit_to_user_mode_work(regs);
+	instrumentation_end();
+	exit_to_user_mode();
+}
+
+#endif