powerpc/rust: Add target.json for ppc64le

Based on the x86 and arm64 versions, as well as output from:

  $ rustc +nightly -Z unstable-options --target=powerpc64le-unknown-linux-gnu --print target-spec-json

Notably disables altivec, vsx and hard-float.

The very cryptic data-layout:

  "data-layout": "e-m:e-i64:64-n32:64-S128",

Has the following meaning:

  e:     little endian
  m:e    ELF name mangling
  i64:64 64-bit integers 64-bit aligned
  n32:64 Native integer widths, 32-bit and 64-bit.
  S128   16-byte stack alignment

Those all come from the rustc output, with the exception of the stack
alignment. We obviously do have 8-bit & 16-bit integer types, but I'm
not sure if there's any need to specify that.

ppc64le only for now. We'll eventually need to come up with some way to
change the target.json that's used based on more than just $(ARCH).

Signed-off-by: Michael Ellerman <[email protected]>

Author: mpe

arch/powerpc/rust/target.json

@@ -0,0 +1,30 @@
+{
+  "arch": "powerpc64",
+  "code-mode": "kernel",
+  "cpu": "ppc64le",
+  "data-layout": "e-m:e-i64:64-n32:64",
+  "env": "gnu",
+  "features": "-altivec,-vsx,-hard-float",
+  "function-sections": false,
+  "is-builtin": true,
+  "linker-flavor": "gcc",
+  "linker-is-gnu": true,
+  "llvm-target": "powerpc64le-elf",
+  "max-atomic-width": 64,
+  "os": "none",
+  "panic-strategy": "abort",
+  "position-independent-executables": true,
+  "pre-link-args": {
+    "gcc": [
+      "-Wl,--as-needed",
+      "-Wl,-z,noexecstack",
+      "-m64"
+    ]
+  },
+  "relocation-model": "static",
+  "relro-level": "full",
+  "target-family": "unix",
+  "target-mcount": "_mcount",
+  "target-endian": "little",
+  "target-pointer-width": "64"
+}