[nolibc] Change internal syscall API to remove reliance on libc's errno.

This change moves to a model where the error value of a system call is
potentially contained in the return value itself rather than being
implicit in errno.  The helper function internal_iserror can be used
to extract the error value from a return value.  On platforms other
than Linux/x86_64 this still uses errno, but other platforms are free
to port their error handling to this new model.

Differential Revision: http://llvm-reviews.chandlerc.com/D756

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@181436 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 87 insertions, 0 deletions

diff --git a/lib/sanitizer_common/sanitizer_syscall_linux_x86_64.inc b/lib/sanitizer_common/sanitizer_syscall_linux_x86_64.inc
new file mode 100644
index 000000000..e084b84ab
--- /dev/null
+++ b/lib/sanitizer_common/sanitizer_syscall_linux_x86_64.inc
@@ -0,0 +1,87 @@
+//===-- sanitizer_syscall_linux_x86_64.inc ----------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Implementations of internal_syscall and internal_iserror for Linux/x86_64.
+//
+//===----------------------------------------------------------------------===//
+
+static uptr internal_syscall(u64 nr) {
+  u64 retval;
+  asm volatile("syscall" : "=a"(retval) : "a"(nr) : "rcx", "r11");
+  return retval;
+}
+
+template <typename T1>
+static uptr internal_syscall(u64 nr, T1 arg1) {
+  u64 retval;
+  asm volatile("syscall" : "=a"(retval) : "a"(nr), "D"((u64)arg1) :
+               "rcx", "r11");
+  return retval;
+}
+
+template <typename T1, typename T2>
+static uptr internal_syscall(u64 nr, T1 arg1, T2 arg2) {
+  u64 retval;
+  asm volatile("syscall" : "=a"(retval) : "a"(nr), "D"((u64)arg1),
+               "S"((u64)arg2) : "rcx", "r11");
+  return retval;
+}
+
+template <typename T1, typename T2, typename T3>
+static uptr internal_syscall(u64 nr, T1 arg1, T2 arg2, T3 arg3) {
+  u64 retval;
+  asm volatile("syscall" : "=a"(retval) : "a"(nr), "D"((u64)arg1),
+               "S"((u64)arg2), "d"((u64)arg3) : "rcx", "r11");
+  return retval;
+}
+
+template <typename T1, typename T2, typename T3, typename T4>
+static uptr internal_syscall(u64 nr, T1 arg1, T2 arg2, T3 arg3, T4 arg4) {
+  u64 retval;
+  asm volatile("mov %5, %%r10;"
+               "syscall" : "=a"(retval) : "a"(nr), "D"((u64)arg1),
+               "S"((u64)arg2), "d"((u64)arg3), "r"((u64)arg4) :
+               "rcx", "r11", "r10");
+  return retval;
+}
+
+template <typename T1, typename T2, typename T3, typename T4, typename T5>
+static uptr internal_syscall(u64 nr, T1 arg1, T2 arg2, T3 arg3, T4 arg4,
+                             T5 arg5) {
+  u64 retval;
+  asm volatile("mov %5, %%r10;"
+               "mov %6, %%r8;"
+               "syscall" : "=a"(retval) : "a"(nr), "D"((u64)arg1),
+               "S"((u64)arg2), "d"((u64)arg3), "r"((u64)arg4), "r"((u64)arg5) :
+               "rcx", "r11", "r10", "r8");
+  return retval;
+}
+
+template <typename T1, typename T2, typename T3, typename T4, typename T5,
+          typename T6>
+static uptr internal_syscall(u64 nr, T1 arg1, T2 arg2, T3 arg3, T4 arg4,
+                             T5 arg5, T6 arg6) {
+  u64 retval;
+  asm volatile("mov %5, %%r10;"
+               "mov %6, %%r8;"
+               "mov %7, %%r9;"
+               "syscall" : "=a"(retval) : "a"(nr), "D"((u64)arg1),
+               "S"((u64)arg2), "d"((u64)arg3), "r"((u64)arg4), "r"((u64)arg5),
+               "r"((u64)arg6) : "rcx", "r11", "r10", "r8", "r9");
+  return retval;
+}
+
+bool internal_iserror(uptr retval, int *rverrno) {
+  if (retval >= (uptr)-4095) {
+    if (rverrno)
+      *rverrno = -retval;
+    return true;
+  }
+  return false;
+}