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-rw-r--r--arch/arm64/kernel/syscall.c139
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