1 files changed, 118 insertions, 0 deletions
diff --git a/arch/arm64/kernel/sys_compat.c b/arch/arm64/kernel/sys_compat.c
new file mode 100644
index 0000000000..df14336c3a
--- /dev/null
+++ b/arch/arm64/kernel/sys_compat.c
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Based on arch/arm/kernel/sys_arm.c
+ *
+ * Copyright (C) People who wrote linux/arch/i386/kernel/sys_i386.c
+ * Copyright (C) 1995, 1996 Russell King.
+ * Copyright (C) 2012 ARM Ltd.
+ */
+
+#include <linux/compat.h>
+#include <linux/cpufeature.h>
+#include <linux/sched.h>
+#include <linux/sched/signal.h>
+#include <linux/slab.h>
+#include <linux/syscalls.h>
+#include <linux/uaccess.h>
+
+#include <asm/cacheflush.h>
+#include <asm/system_misc.h>
+#include <asm/tlbflush.h>
+#include <asm/unistd.h>
+
+static long
+__do_compat_cache_op(unsigned long start, unsigned long end)
+{
+	long ret;
+
+	do {
+		unsigned long chunk = min(PAGE_SIZE, end - start);
+
+		if (fatal_signal_pending(current))
+			return 0;
+
+		if (cpus_have_const_cap(ARM64_WORKAROUND_1542419)) {
+			/*
+			 * The workaround requires an inner-shareable tlbi.
+			 * We pick the reserved-ASID to minimise the impact.
+			 */
+			__tlbi(aside1is, __TLBI_VADDR(0, 0));
+			dsb(ish);
+		}
+
+		ret = caches_clean_inval_user_pou(start, start + chunk);
+		if (ret)
+			return ret;
+
+		cond_resched();
+		start += chunk;
+	} while (start < end);
+
+	return 0;
+}
+
+static inline long
+do_compat_cache_op(unsigned long start, unsigned long end, int flags)
+{
+	if (end < start || flags)
+		return -EINVAL;
+
+	if (!access_ok((const void __user *)start, end - start))
+		return -EFAULT;
+
+	return __do_compat_cache_op(start, end);
+}
+/*
+ * Handle all unrecognised system calls.
+ */
+long compat_arm_syscall(struct pt_regs *regs, int scno)
+{
+	unsigned long addr;
+
+	switch (scno) {
+	/*
+	 * Flush a region from virtual address 'r0' to virtual address 'r1'
+	 * _exclusive_.  There is no alignment requirement on either address;
+	 * user space does not need to know the hardware cache layout.
+	 *
+	 * r2 contains flags.  It should ALWAYS be passed as ZERO until it
+	 * is defined to be something else.  For now we ignore it, but may
+	 * the fires of hell burn in your belly if you break this rule. ;)
+	 *
+	 * (at a later date, we may want to allow this call to not flush
+	 * various aspects of the cache.  Passing '0' will guarantee that
+	 * everything necessary gets flushed to maintain consistency in
+	 * the specified region).
+	 */
+	case __ARM_NR_compat_cacheflush:
+		return do_compat_cache_op(regs->regs[0], regs->regs[1], regs->regs[2]);
+
+	case __ARM_NR_compat_set_tls:
+		current->thread.uw.tp_value = regs->regs[0];
+
+		/*
+		 * Protect against register corruption from context switch.
+		 * See comment in tls_thread_flush.
+		 */
+		barrier();
+		write_sysreg(regs->regs[0], tpidrro_el0);
+		return 0;
+
+	default:
+		/*
+		 * Calls 0xf0xxx..0xf07ff are defined to return -ENOSYS
+		 * if not implemented, rather than raising SIGILL. This
+		 * way the calling program can gracefully determine whether
+		 * a feature is supported.
+		 */
+		if (scno < __ARM_NR_COMPAT_END)
+			return -ENOSYS;
+		break;
+	}
+
+	addr = instruction_pointer(regs) - (compat_thumb_mode(regs) ? 2 : 4);
+
+	arm64_notify_die("Oops - bad compat syscall(2)", regs,
+			 SIGILL, ILL_ILLTRP, addr, 0);
+	return 0;
+}