1 files changed, 53 insertions, 12 deletions
diff --git a/libgo/go/runtime/os_linux.go b/libgo/go/runtime/os_linux.go
index 04c690bd42f..ad334869ed1 100644
--- a/libgo/go/runtime/os_linux.go
+++ b/libgo/go/runtime/os_linux.go
@@ -86,9 +86,13 @@ func futexwakeup(addr *uint32, cnt uint32) {
 const (
 	_AT_NULL   = 0  // End of vector
 	_AT_PAGESZ = 6  // System physical page size
+	_AT_HWCAP  = 16 // hardware capability bit vector
 	_AT_RANDOM = 25 // introduced in 2.6.29
+	_AT_HWCAP2 = 26 // hardware capability bit vector 2
 )
 
+var procAuxv = []byte("/proc/self/auxv\x00")
+
 func sysargs(argc int32, argv **byte) {
 	n := argc + 1
 
@@ -102,7 +106,50 @@ func sysargs(argc int32, argv **byte) {
 
 	// now argv+n is auxv
 	auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*sys.PtrSize))
-	for i := 0; auxv[i] != _AT_NULL; i += 2 {
+	if sysauxv(auxv[:]) == 0 {
+		// In some situations we don't get a loader-provided
+		// auxv, such as when loaded as a library on Android.
+		// Fall back to /proc/self/auxv.
+		fd := open(&procAuxv[0], 0 /* O_RDONLY */, 0)
+		if fd < 0 {
+			// On Android, /proc/self/auxv might be unreadable (issue 9229), so we fallback to
+			// try using mincore to detect the physical page size.
+			// mincore should return EINVAL when address is not a multiple of system page size.
+			const size = 256 << 10 // size of memory region to allocate
+			p := mmap(nil, size, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_PRIVATE, -1, 0)
+			if uintptr(p) < 4096 {
+				return
+			}
+			var n uintptr
+			for n = 4 << 10; n < size; n <<= 1 {
+				err := mincore(unsafe.Pointer(uintptr(p)+n), 1, &addrspace_vec[0])
+				if err == 0 {
+					physPageSize = n
+					break
+				}
+			}
+			if physPageSize == 0 {
+				physPageSize = size
+			}
+			munmap(p, size)
+			return
+		}
+		var buf [128]uintptr
+		n := read(fd, noescape(unsafe.Pointer(&buf[0])), int32(unsafe.Sizeof(buf)))
+		closefd(fd)
+		if n < 0 {
+			return
+		}
+		// Make sure buf is terminated, even if we didn't read
+		// the whole file.
+		buf[len(buf)-2] = _AT_NULL
+		sysauxv(buf[:])
+	}
+}
+
+func sysauxv(auxv []uintptr) int {
+	var i int
+	for ; auxv[i] != _AT_NULL; i += 2 {
 		tag, val := auxv[i], auxv[i+1]
 		switch tag {
 		case _AT_RANDOM:
@@ -111,20 +158,14 @@ func sysargs(argc int32, argv **byte) {
 			startupRandomData = (*[16]byte)(unsafe.Pointer(val))[:]
 
 		case _AT_PAGESZ:
-			// Check that the true physical page size is
-			// compatible with the runtime's assumed
-			// physical page size.
-			if sys.PhysPageSize < val {
-				print("runtime: kernel page size (", val, ") is larger than runtime page size (", sys.PhysPageSize, ")\n")
-				exit(1)
-			}
-			if sys.PhysPageSize%val != 0 {
-				print("runtime: runtime page size (", sys.PhysPageSize, ") is not a multiple of kernel page size (", val, ")\n")
-				exit(1)
-			}
+			physPageSize = val
 		}
 
 		// Commented out for gccgo for now.
 		// archauxv(tag, val)
 	}
+	return i / 2
 }
+
+// Temporary for gccgo until we port mem_GOOS.go.
+var addrspace_vec [1]byte