mirror of
https://github.com/ratspeak/C6-Reticulum-ASM
synced 2026-08-12 18:07:18 -04:00
33914bb7ec
Word-by-word copy from .data's LMA (__data_load_start) to its VMA (__data_start..__data_end). On qemu-virt LMA == VMA so the loop is identity; on the C6 it pulls flash → SRAM. Same asm shape, target- selected behaviour driven entirely by the linker script. toolchain/qemu-virt.ld: defines __data_load_start = LOADADDR(.data) so the symbol resolves at link time on either target. Static disassembly checks: three auipc/addi pairs for the bounds, matched lw/sw word pair, two increments per iteration, ret, no callee-saved writes.
62 lines
2.7 KiB
Python
62 lines
2.7 KiB
Python
"""Tests for src/boot/_init_data.S.
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Static disassembly checks (per @verify: kat-only). On qemu-virt the
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function is semantically identity (LMA == VMA), but the asm shape — load,
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store, increment-both, branch — is the same as on the C6 where it
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performs a real flash → SRAM copy. The tests assert the shape; the
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integration check (a non-zero .data initialiser observed at runtime)
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lands when _main wires up the boot chain.
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"""
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from __future__ import annotations
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import re
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import pytest
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from harness import build
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@pytest.fixture(scope="module")
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def artifacts() -> build.BuildArtifacts:
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return build.build("qemu-virt")
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def test_loads_three_bounds(artifacts: build.BuildArtifacts) -> None:
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"""Three la pairs at the head: __data_start, __data_end, __data_load_start."""
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body = build.objdump_disassemble(artifacts.elf, symbol="_init_data")
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instrs = [line for line in body.splitlines() if re.match(r"^\s*[0-9a-f]{8}:", line)]
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assert len(instrs) >= 9, body
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for i, reg in enumerate(("t0", "t1", "t2")):
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assert "auipc" in instrs[2 * i] and f"{reg}," in instrs[2 * i], instrs[2 * i]
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assert "addi" in instrs[2 * i + 1] and f"{reg}," in instrs[2 * i + 1], instrs[2 * i + 1]
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def test_load_store_word_pair(artifacts: build.BuildArtifacts) -> None:
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body = build.objdump_disassemble(artifacts.elf, symbol="_init_data")
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# The word load is from the LMA cursor (t2), the word store goes to the
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# VMA cursor (t0). Match the canonical forms; objdump may compress.
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assert re.search(r"\blw\b\s+t3,0\(t2\)", body), body
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assert re.search(r"\bsw\b\s+t3,0\(t0\)", body), body
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def test_loop_advances_both_cursors(artifacts: build.BuildArtifacts) -> None:
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body = build.objdump_disassemble(artifacts.elf, symbol="_init_data")
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# Two `addi … 4` increments per iteration — one for t0, one for t2.
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addi_count = len(re.findall(r"\baddi\s+(t0|t2),", body)) + \
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len(re.findall(r"\baddi\s+(t0|t2),", body))
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# The la prologue also uses addi for low-12-bit fixups; subtract the
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# known three la pairs (3 addi). Increments contribute 2 more.
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addi_total = len(re.findall(r"\baddi\b", body))
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assert addi_total >= 5, body # 3 (la fixups) + 2 (increments)
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def test_function_returns(artifacts: build.BuildArtifacts) -> None:
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body = build.objdump_disassemble(artifacts.elf, symbol="_init_data")
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assert "ret" in body or "jalr\tzero" in body, body
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def test_does_not_touch_callee_saved(artifacts: build.BuildArtifacts) -> None:
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body = build.objdump_disassemble(artifacts.elf, symbol="_init_data")
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for match in re.findall(r"\b(s\d+)\b,", body):
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pytest.fail(f"_init_data writes callee-saved register {match}: {body}")
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