[sanitizer] Asm implementation of syscall() for arm32.

[eugenis]

Summary

These will be used in an ifunc resolver, when the binary may not be
completely relocated, and syscall() function from libc could not be
used.

[eugenis]

vitalybuka added a reviewer: eugenis.

Do you want me to review my own patch? :)

compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cc

 #endif  // SANITIZER_LINUX && defined(__NR_getrandom)
 
 namespace __sanitizer {
 
 #if SANITIZER_LINUX && defined(__x86_64__)
 #include "sanitizer_syscall_linux_x86_64.inc"
 #elif SANITIZER_LINUX && defined(__aarch64__)
 #include "sanitizer_syscall_linux_aarch64.inc"
+#elif SANITIZER_LINUX && defined(__arm__)
+#include "sanitizer_syscall_linux_arm.inc"
 #else
 #include "sanitizer_syscall_generic.inc"
 #endif
 
 // --------------- sanitizer_libc.h
 #if !SANITIZER_S390
 uptr internal_mmap(void *addr, uptr length, int prot, int flags, int fd,
                    OFF_T offset) {

compiler-rt/trunk/lib/sanitizer_common/sanitizer_syscall_linux_arm.inc

+//===-- sanitizer_syscall_linux_arm.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/arm.
+//
+//===----------------------------------------------------------------------===//
+
+#define SYSCALL(name) __NR_ ## name
+
+static uptr __internal_syscall(u32 nr) {
+  register u32 r8 asm("r7") = nr;
+  register u32 r0 asm("r0");
+  asm volatile("swi #0"
+               : "=r"(r0)
+               : "r"(r8)
+               : "memory", "cc");
+  return r0;
+}
+#define __internal_syscall0(n) \
+  (__internal_syscall)(n)
+
+static uptr __internal_syscall(u32 nr, u32 arg1) {
+  register u32 r8 asm("r7") = nr;
+  register u32 r0 asm("r0") = arg1;
+  asm volatile("swi #0"
+               : "=r"(r0)
+               : "r"(r8), "0"(r0)
+               : "memory", "cc");
+  return r0;
+}
+#define __internal_syscall1(n, a1) \
+  (__internal_syscall)(n, (u32)(a1))
+
+static uptr __internal_syscall(u32 nr, u32 arg1, long arg2) {
+  register u32 r8 asm("r7") = nr;
+  register u32 r0 asm("r0") = arg1;
+  register u32 r1 asm("r1") = arg2;
+  asm volatile("swi #0"
+               : "=r"(r0)
+               : "r"(r8), "0"(r0), "r"(r1)
+               : "memory", "cc");
+  return r0;
+}
+#define __internal_syscall2(n, a1, a2) \
+  (__internal_syscall)(n, (u32)(a1), (long)(a2))
+
+static uptr __internal_syscall(u32 nr, u32 arg1, long arg2, long arg3) {
+  register u32 r8 asm("r7") = nr;
+  register u32 r0 asm("r0") = arg1;
+  register u32 r1 asm("r1") = arg2;
+  register u32 r2 asm("r2") = arg3;
+  asm volatile("swi #0"
+               : "=r"(r0)
+               : "r"(r8), "0"(r0), "r"(r1), "r"(r2)
+               : "memory", "cc");
+  return r0;
+}
+#define __internal_syscall3(n, a1, a2, a3) \
+  (__internal_syscall)(n, (u32)(a1), (long)(a2), (long)(a3))
+
+static uptr __internal_syscall(u32 nr, u32 arg1, long arg2, long arg3,
+                               u32 arg4) {
+  register u32 r8 asm("r7") = nr;
+  register u32 r0 asm("r0") = arg1;
+  register u32 r1 asm("r1") = arg2;
+  register u32 r2 asm("r2") = arg3;
+  register u32 r3 asm("r3") = arg4;
+  asm volatile("swi #0"
+               : "=r"(r0)
+               : "r"(r8), "0"(r0), "r"(r1), "r"(r2), "r"(r3)
+               : "memory", "cc");
+  return r0;
+}
+#define __internal_syscall4(n, a1, a2, a3, a4) \
+  (__internal_syscall)(n, (u32)(a1), (long)(a2), (long)(a3), (long)(a4))
+
+static uptr __internal_syscall(u32 nr, u32 arg1, long arg2, long arg3,
+                               u32 arg4, long arg5) {
+  register u32 r8 asm("r7") = nr;
+  register u32 r0 asm("r0") = arg1;
+  register u32 r1 asm("r1") = arg2;
+  register u32 r2 asm("r2") = arg3;
+  register u32 r3 asm("r3") = arg4;
+  register u32 r4 asm("r4") = arg5;
+  asm volatile("swi #0"
+               : "=r"(r0)
+               : "r"(r8), "0"(r0), "r"(r1), "r"(r2), "r"(r3), "r"(r4)
+               : "memory", "cc");
+  return r0;
+}
+#define __internal_syscall5(n, a1, a2, a3, a4, a5) \
+  (__internal_syscall)(n, (u32)(a1), (long)(a2), (long)(a3), (long)(a4), \
+                       (u32)(a5))
+
+static uptr __internal_syscall(u32 nr, u32 arg1, long arg2, long arg3,
+                               u32 arg4, long arg5, long arg6) {
+  register u32 r8 asm("r7") = nr;
+  register u32 r0 asm("r0") = arg1;
+  register u32 r1 asm("r1") = arg2;
+  register u32 r2 asm("r2") = arg3;
+  register u32 r3 asm("r3") = arg4;
+  register u32 r4 asm("r4") = arg5;
+  register u32 r5 asm("r5") = arg6;
+  asm volatile("swi #0"
+               : "=r"(r0)
+               : "r"(r8), "0"(r0), "r"(r1), "r"(r2), "r"(r3), "r"(r4), "r"(r5)
+               : "memory", "cc");
+  return r0;
+}
+#define __internal_syscall6(n, a1, a2, a3, a4, a5, a6) \
+  (__internal_syscall)(n, (u32)(a1), (long)(a2), (long)(a3), (long)(a4), \
+                       (u32)(a5), (long)(a6))
+
+#define __SYSCALL_NARGS_X(a1, a2, a3, a4, a5, a6, a7, a8, n, ...) n
+#define __SYSCALL_NARGS(...) \
+  __SYSCALL_NARGS_X(__VA_ARGS__, 7, 6, 5, 4, 3, 2, 1, 0, )
+#define __SYSCALL_CONCAT_X(a, b) a##b
+#define __SYSCALL_CONCAT(a, b) __SYSCALL_CONCAT_X(a, b)
+#define __SYSCALL_DISP(b, ...) \
+  __SYSCALL_CONCAT(b, __SYSCALL_NARGS(__VA_ARGS__))(__VA_ARGS__)
+
+#define internal_syscall(...) __SYSCALL_DISP(__internal_syscall, __VA_ARGS__)
+
+#define internal_syscall_ptr internal_syscall
+#define internal_syscall64 internal_syscall
+
+// Helper function used to avoid cobbler errno.
+bool internal_iserror(uptr retval, int *rverrno) {
+  if (retval >= (uptr)-4095) {
+    if (rverrno)
+      *rverrno = -retval;
+    return true;
+  }
+  return false;
+}