Add adjustable stack size and call depth (#12728)

programs/bpf/rust/call_depth/Cargo.toml

@@ -0,0 +1,26 @@
+
+# Note: This crate must be built using do.sh
+
+[package]
+name = "solana-bpf-rust-call-depth"
+version = "1.4.0"
+description = "Solana BPF test program written in Rust"
+authors = ["Solana Maintainers <maintainers@solana.foundation>"]
+repository = "https://github.com/solana-labs/solana"
+license = "Apache-2.0"
+homepage = "https://solana.com/"
+edition = "2018"
+
+[dependencies]
+solana-sdk = { path = "../../../../sdk/", version = "1.4.0", default-features = false }
+
+[features]
+program = ["solana-sdk/program"]
+default = ["program", "solana-sdk/default"]
+
+[lib]
+name = "solana_bpf_rust_call_depth"
+crate-type = ["cdylib"]
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]

programs/bpf/rust/call_depth/Xargo.toml

@@ -0,0 +1,2 @@
+[target.bpfel-unknown-unknown.dependencies.std]
+features = []

programs/bpf/rust/call_depth/src/lib.rs

@@ -0,0 +1,27 @@
+//! @brief Example Rust-based BPF program that tests call depth and stack usage
+
+use solana_sdk::{entrypoint::SUCCESS, info};
+
+#[inline(never)]
+pub fn recurse(data: &mut [u8]) {
+    if data.len() <= 1 {
+        return;
+    }
+    recurse(&mut data[1..]);
+    info!(line!(), 0, 0, 0, data[0]);
+}
+
+/// # Safety
+#[inline(never)]
+#[no_mangle]
+pub unsafe extern "C" fn entrypoint(input: *mut u8) -> u64 {
+    info!("Call depth");
+    let depth = *(input.add(16) as *mut u8);
+    info!(line!(), 0, 0, 0, depth);
+    let mut data = Vec::with_capacity(depth as usize);
+    for i in 0_u8..depth {
+        data.push(i);
+    }
+    recurse(&mut data);
+    SUCCESS
+}