1 files changed, 139 insertions, 0 deletions
diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
new file mode 100644
index 000000000000..032d22312881
--- /dev/null
+++ b/arch/arm64/kernel/syscall.c
@@ -0,0 +1,139 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/compiler.h>
+#include <linux/context_tracking.h>
+#include <linux/errno.h>
+#include <linux/nospec.h>
+#include <linux/ptrace.h>
+#include <linux/syscalls.h>
+
+#include <asm/daifflags.h>
+#include <asm/fpsimd.h>
+#include <asm/syscall.h>
+#include <asm/thread_info.h>
+#include <asm/unistd.h>
+
+long compat_arm_syscall(struct pt_regs *regs);
+
+long sys_ni_syscall(void);
+
+asmlinkage long do_ni_syscall(struct pt_regs *regs)
+{
+#ifdef CONFIG_COMPAT
+	long ret;
+	if (is_compat_task()) {
+		ret = compat_arm_syscall(regs);
+		if (ret != -ENOSYS)
+			return ret;
+	}
+#endif
+
+	return sys_ni_syscall();
+}
+
+static long __invoke_syscall(struct pt_regs *regs, syscall_fn_t syscall_fn)
+{
+	return syscall_fn(regs);
+}
+
+static void invoke_syscall(struct pt_regs *regs, unsigned int scno,
+			   unsigned int sc_nr,
+			   const syscall_fn_t syscall_table[])
+{
+	long ret;
+
+	if (scno < sc_nr) {
+		syscall_fn_t syscall_fn;
+		syscall_fn = syscall_table[array_index_nospec(scno, sc_nr)];
+		ret = __invoke_syscall(regs, syscall_fn);
+	} else {
+		ret = do_ni_syscall(regs);
+	}
+
+	regs->regs[0] = ret;
+}
+
+static inline bool has_syscall_work(unsigned long flags)
+{
+	return unlikely(flags & _TIF_SYSCALL_WORK);
+}
+
+int syscall_trace_enter(struct pt_regs *regs);
+void syscall_trace_exit(struct pt_regs *regs);
+
+static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
+			   const syscall_fn_t syscall_table[])
+{
+	unsigned long flags = current_thread_info()->flags;
+
+	regs->orig_x0 = regs->regs[0];
+	regs->syscallno = scno;
+
+	local_daif_restore(DAIF_PROCCTX);
+	user_exit();
+
+	if (has_syscall_work(flags)) {
+		/* set default errno for user-issued syscall(-1) */
+		if (scno == NO_SYSCALL)
+			regs->regs[0] = -ENOSYS;
+		scno = syscall_trace_enter(regs);
+		if (scno == NO_SYSCALL)
+			goto trace_exit;
+	}
+
+	invoke_syscall(regs, scno, sc_nr, syscall_table);
+
+	/*
+	 * The tracing status may have changed under our feet, so we have to
+	 * check again. However, if we were tracing entry, then we always trace
+	 * exit regardless, as the old entry assembly did.
+	 */
+	if (!has_syscall_work(flags) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) {
+		local_daif_mask();
+		flags = current_thread_info()->flags;
+		if (!has_syscall_work(flags)) {
+			/*
+			 * We're off to userspace, where interrupts are
+			 * always enabled after we restore the flags from
+			 * the SPSR.
+			 */
+			trace_hardirqs_on();
+			return;
+		}
+		local_daif_restore(DAIF_PROCCTX);
+	}
+
+trace_exit:
+	syscall_trace_exit(regs);
+}
+
+static inline void sve_user_discard(void)
+{
+	if (!system_supports_sve())
+		return;
+
+	clear_thread_flag(TIF_SVE);
+
+	/*
+	 * task_fpsimd_load() won't be called to update CPACR_EL1 in
+	 * ret_to_user unless TIF_FOREIGN_FPSTATE is still set, which only
+	 * happens if a context switch or kernel_neon_begin() or context
+	 * modification (sigreturn, ptrace) intervenes.
+	 * So, ensure that CPACR_EL1 is already correct for the fast-path case.
+	 */
+	sve_user_disable();
+}
+
+asmlinkage void el0_svc_handler(struct pt_regs *regs)
+{
+	sve_user_discard();
+	el0_svc_common(regs, regs->regs[8], __NR_syscalls, sys_call_table);
+}
+
+#ifdef CONFIG_COMPAT
+asmlinkage void el0_svc_compat_handler(struct pt_regs *regs)
+{
+	el0_svc_common(regs, regs->regs[7], __NR_compat_syscalls,
+		       compat_sys_call_table);
+}
+#endif