SIMD-0094: deprecate executable update for bpf loader

proposals/0094-deprecate-executable-update.md

@@ -0,0 +1,67 @@
+---
+simd: '0094'
+title: Deprecate executable update in bpf loader
+authors:
+  - Haoran Yi
+category: Standard
+type: Core
+status: Draft
+created: 2023-12-13
+feature: (fill in with feature tracking issues once accepted)
+extends: 0162
+---
+
+## Summary
+
+Deprecate executable update during bpf program deployment.
+
+## Motivation
+
+Currently, when a program is deployed, the "executable" flag on the account is
+set to true for legacy reasons. However, (a) old bpf loaders, such as v1 and v2,
+are disabled on mainnet (SIMD-0093); (b) we are going to remove accounts
+executable checks for runtime execution (SIMD-0162). (c) the future bpf
+loader-v4 no longer need "executable" flag.
+
+Because of these above reasons, "executable" flag becomes irrelevant and
+provides no functional benefit for runtime execution. Therefore, we want to
+deprecate its update during bpf program deployment for loader-v3.
+
+## Alternatives Considered
+
+None
+
+## New Terminology
+
+None
+
+## Detailed Design
+
+When the feature - "deprecate executable update" is activated, the bpf loader-V3
+will no longer update *executable* flag to true after program deployment.
+
+The "executable" flag remains false after program deployment.
+
+## Impact
+
+This will affect the following scenarios.
+
+- program accounts hash after deployment. Since this change is guarded by a
+  feature, program accounts hash change won't break consensus.
+- any dapps that depend on `is_executable` to be true on the serialized
+  instruction accounts. Existing program deployed on chain will work fine.
+  However, if the program is redeployed, it may be broken. Before redeployment,
+  dapps developer will need to check and update the program if it depends on
+  `is_executable`.
+- CPI won't ignore changes made by caller to instruction accounts (Currently CPI
+  ignores changes made by the caller to instruction accounts which has the
+  `is_executable` flag set). For correctness, this change will be fine. It just
+  becomes a bit less efficient with more checks.
+
+## Security Considerations
+
+None
+
+## Backwards Compatibility
+
+Incompatible.