casaroli opened a new pull request, #20382:
URL: https://github.com/apache/nuttx/pull/20382
## Summary
Part of the FDPIC series. An architecture that sets
`CONFIG_ARCH_USE_DATA_HEAP` gives a loaded module its data from
`up_dataheap_memalign()`. The ELF loader honours that for every object except
an FDPIC one: an FDPIC object allocates its writable segment on its own, and
that allocation and the two places that free it still use `lib_memalign()` and
`lib_free()`. Its text already honours `CONFIG_ARCH_USE_TEXT_HEAP`.
This makes the FDPIC data allocation, and its frees in `elf_unload.c` and
`elf_remove.c`, use the data heap when it is enabled.
## Impact
Only a build with `CONFIG_FDPIC` and `CONFIG_ARCH_USE_DATA_HEAP` changes.
In the tree that is `mps3-an547`, whose text and data heaps are in SRAM2.
In a flat build the module ran before too, just out of the wrong heap. In a
protected build it did not: the ordinary heap is kernel memory there, so the
module took a data access violation on its first access to its data. Making
`mps3-an547:knsh` run modules also needs its SRAM2 heaps mapped for user code,
which is a separate change.
## Testing
`mps3-an547:nsh` under QEMU with `CONFIG_FDPIC`,
`CONFIG_ARCH_USE_TEXT_HEAP`, `CONFIG_ARCH_USE_DATA_HEAP` and xipfs on a RAM MTD
(the xipfs mount is local to the test, not part of this PR), running `fdpicxip`:
```
before: Loading sections - text: 0x100d848.358 data: 0x1007220.180
Loading sections - text: 0x100d848.358 data: 0x104e480.180
after: Loading sections - text: 0x100d848.358 data: 0x21000000.180
Loading sections - text: 0x100d848.358 data: 0x21000180.180
[inst 1] 11 21 31 41 51 61 71 81
[inst 2] 12 22 32 42 52 62 72 82
=== done ===
```
Both instances share the text in place and run to the end in both cases;
after the change their data is in the SRAM2 data heap.
`tools/checkpatch.sh -g` passes.
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