bpftools: fix cross for riscv64-linux (#371240)

pkgs/by-name/bp/bpftools/package.nix

@@ -1,6 +1,7 @@
 {
   lib,
   stdenv,
+  fetchpatch,
   linuxHeaders,
   buildPackages,
   libopcodes,
@@ -25,6 +26,25 @@ stdenv.mkDerivation rec {
   patches = [
     # fix unknown type name '__vector128' on ppc64le
     ./include-asm-types-for-ppc64le.patch
+    # fix build for riscv64
+    (fetchpatch {
+      # libbpf: Add missing per-arch include path
+      # https://patchwork.kernel.org/project/linux-riscv/patch/20240927131355.350918-1-bjorn@kernel.org/
+      url = "https://patchwork.kernel.org/project/linux-riscv/patch/20240927131355.350918-1-bjorn@kernel.org/raw/";
+      hash = "sha256-edXY/ejHW5L7rGgY5B2GmVZxUgnLdBadNhBOSAgcL7M=";
+    })
+    (fetchpatch {
+      # selftests: bpf: Add missing per-arch include path
+      # https://patchwork.kernel.org/project/linux-riscv/patch/20240927131355.350918-2-bjorn@kernel.org/
+      url = "https://patchwork.kernel.org/project/linux-riscv/patch/20240927131355.350918-2-bjorn@kernel.org/raw/";
+      hash = "sha256-7yNWE/L/qd3vcLtJYoSyGxB3ytySlr20R0D3t5ni2Fc=";
+    })
+    (fetchpatch {
+      # tools: Override makefile ARCH variable if defined, but empty
+      # https://patchwork.kernel.org/project/linux-riscv/patch/20241127101748.165693-1-bjorn@kernel.org/
+      url = "https://patchwork.kernel.org/project/linux-riscv/patch/20241127101748.165693-1-bjorn@kernel.org/raw/";
+      hash = "sha256-y8N71Hm1XfX9g3S6PzW2m7Lxp6wQQMfQE9L0QNt8cYY=";
+    })
   ];
 
   depsBuildBuild = [ buildPackages.stdenv.cc ];
@@ -68,6 +88,9 @@ stdenv.mkDerivation rec {
     "bpf_dbg"
   ];
 
+  # needed for cross to riscv64
+  makeFlags = [ "ARCH=${stdenv.hostPlatform.linuxArch}" ];
+
   installPhase = ''
     make -C bpftool install
     install -Dm755 -t $out/bin bpf_asm