[Wenzel]

Fixes #245.

Summary

src/arch/arm.rs reads the magic index from r10 and arguments from r9/r8/r7. The arm32 harness put the testcase buffer in r10 and never set an index, so every start/stop was rejected with index is not configured (index 2129111884 = 0x7ee7ab4c, the reporter's stack buffer; see mov sl, r7 before orr r1,r1,r1 in their disassembly). #217 fixed the aarch64 registers but not arm32.

 HARNESS_START(buf, size_ptr)
-  __orr_extended2(1, buf, size_ptr)                 // r10=buf, r9=size_ptr
+  __orr_extended3(1, DEFAULT_INDEX, buf, size_ptr)  // r10=0,   r9=buf, r8=size_ptr
 HARNESS_STOP()
-  __orr(4)                                          // r10 = whatever was left
+  __orr_extended1(4, DEFAULT_INDEX)
+HARNESS_{START,START_WITH_MAXIMUM_SIZE,START_WITH_MAXIMUM_SIZE_AND_PTR,STOP,ASSERT}_INDEX  // new on arm32

• harness/tsffs-gcc-arm32.h: ported from the aarch64 header (same macro set and register order). __orr_extended4 saves/restores r7 instead of clobbering it (Thumb frame pointer).
• harness/tsffs-gcc-aarch64.h: add missing x8/x7 clobbers to __orr_extended3/__orr_extended4.
• harness/tsffs.h: regenerated with build.sh; harness/test.c no longer skips the *_INDEX tests on arm.
• tests/arm32_harness_abi_latest.rs: new test. Public Simics has no ARM CPU model, so it compiles every HARNESS_* macro with clang -target arm-unknown-linux-gnueabi -O2, decodes each function with goblin + yaxpeax-arm (existing deps), constant-propagates up to the magic orr rN,rN,rN, and asserts the magic number, r10 index, and r9/r8/r7 arguments.

Evidence

• Before (old header, non-_INDEX macros only):

  assertion `left == right` failed: start: index register r10
    left: Some(4096)   // buffer pointer 0x1000
   right: Some(0)
  

  Old header with the full test: clang fails, HARNESS_START_INDEX etc. undeclared.
• After: test test_arm32_harness_abi_latest ... ok

Also: cargo build -r, cargo clippy --test arm32_harness_abi_latest -- -D warnings, and harness/build.sh pass (Simics 7.70.0). Thumb -O0 build of harness/test.c emits no warnings.

Merge Danger

Door: two-way

Blast Radius: arm32 harness users

Targets must be rebuilt with the new header; the TSFFS module is unchanged. Not run end to end in Simics on an ARM target (no public ARM package). Thumb-mode encoding of the orr magic instruction was not verified against Simics.

[Copilot]

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Copilot review overview

6 open issues

• Using push/pop inside inline asm is unsafe here because it temporarily moves sp and writes… · New
• env!(\"CARGO_TARGET_TMPDIR\") is evaluated at compile time and will fail compilation if that env… · New
• env!(\"CARGO_TARGET_TMPDIR\") is evaluated at compile time and will fail compilation if that env… · New
• This can panic or slice out-of-bounds if a STT_FUNC symbol is undefined/special (st_shndx like… · New
• This can panic or slice out-of-bounds if a STT_FUNC symbol is undefined/special (st_shndx like… · New
• Dropping the unsigned suffix changes the constant’s type to (signed) int, which can trigger… · New

What changed in this PR

Fixes the ARM32 harness ABI by ensuring the magic index is passed in r10 (and arguments in r9/r8/r7) to match what src/arch/arm.rs expects, and adds an integration test that verifies the generated ARM32 harness code without requiring an ARM Simics model.

Changes:

• Update ARM32 harness macros to pass DEFAULT_INDEX in r10 and add *_INDEX macro variants.
• Fix AArch64 harness inline-asm clobbers for __orr_extended3/__orr_extended4.
• Add a new Rust test that cross-compiles harness macros for ARM32 and validates register values via disassembly and constant propagation.

File	Description
tests/​arm32_harness_abi_latest.rs	Adds a cross-compile + disassembly-based ABI test for ARM32 harness macros/register placement.
harness/​tsffs.h	Regenerates umbrella header to reflect ARM32 macro ABI fixes and AArch64 clobber updates.
harness/​tsffs-gcc-arm32.h	Fixes ARM32 register assignment (index in r10) and introduces *_INDEX harness macros.
harness/​tsffs-gcc-aarch64.h	Adds missing x8/x7 clobbers for correctness under optimization.
harness/​test.c	Stops skipping _INDEX harness tests on ARM now that ARM32 supports them.

_{Review effort: Lite}