[libc-commits] [libc] [libc] check a few syscall #'s to avoid wrong syscalls (PR #123100)

[via libc-commits]

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@@ -0,0 +1,44 @@
+//===-------------- Simple checks for cross compilation -------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_LINUX_CROSS_COMPILE_CLIPPY_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_LINUX_CROSS_COMPILE_CLIPPY_H
+
+#include "src/__support/macros/properties/architectures.h"
+#include <sys/syscall.h>
+
+#define MSG                                                                    \
+  "Looks like you may be using the host kernel headers to cross "              \
+  "compile. This is bad because the syscall numbers frequently (but not "      \
+  "always) differ between architectures.  What frequently happens as a "       \
+  "result are crashes in startup."
+
+// https://github.com/hrw/syscalls-table is super helpful for trying to find
+// syscalls with unique numbers.
+
+#ifdef LIBC_TARGET_ARCH_IS_AARCH64
+static_assert(__NR_renameat == 38, MSG);
+#elif defined(LIBC_TARGET_ARCH_IS_ARM)
+static_assert(__NR_renameat == 329, MSG);
+#elif defined(LIBC_TARGET_ARCH_IS_X86_32)
+static_assert(__NR_renameat == 302, MSG);
+#elif defined(LIBC_TARGET_ARCH_IS_X86_64)
+static_assert(__NR_renameat == 264, MSG);
+#elif defined(LIBC_TARGET_ARCH_IS_RISCV64)
+static_assert(__NR_riscv_flush_icache == 259, MSG);
+static_assert(__NR_renameat2 == 276, MSG);
+#elif defined(LIBC_TARGET_ARCH_IS_RISCV32)
+static_assert(__NR_riscv_flush_icache == 259, MSG);
+#ifdef __NR_iodestroy
+#error MSG
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lntue wrote:

Can you add the comment about at the moment, riscv32 is missing `iodestroy`, so that we will know / notice if it changes in the future?

https://github.com/llvm/llvm-project/pull/123100