[libc] [llvm] [libc] Implement pkey_alloc/free/get/set/mprotect for x86_64 linux (PR #162362)

[Jackson Stogel via llvm-commits]

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@@ -0,0 +1,45 @@
+//===---------- Linux implementation of the Linux pkey_mprotect function --===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/sys/mman/pkey_mprotect.h"
+
+#include "hdr/errno_macros.h" // For ENOSYS
+#include "hdr/types/size_t.h"
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/common.h"
+#include "src/__support/libc_errno.h"
+#include "src/__support/macros/config.h"
+#include "src/sys/mman/mprotect.h"
+
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(int, pkey_mprotect,
+                   (void *addr, size_t len, int prot, int pkey)) {
+  // Fall back to mprotect if pkey is -1
+  // to maintain compatibility with kernel versions that don't support pkey.
+  if (pkey == -1) {
+    return LIBC_NAMESPACE::mprotect(addr, len, prot);
----------------
jtstogel wrote:

Good catch, thanks. I added a file mprotect_common.h that just exposes the syscall wrapper. WDYT of that vs just duplicating the syscall line?

https://github.com/llvm/llvm-project/pull/162362