tests, tools: every inline-asm LVO call lists all four scratch registers; CI gate (#70) - #86
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…ers; CI gate (#70) An LVO may destroy d0, d1, a0 and a1. An extended asm statement that lists one of them only as an input lets GCC reuse a value the call has overwritten, which is how #68 passed a stale recvfrom address. tools/check-lvo-clobbers.sh (python in check-lvo-clobbers.py) scans src/ and tests/ for asm statements whose template calls through a6 and reports each one whose outputs and clobbers leave out a scratch register. It reads register declarations through object-like macros (BSD_SCRATCH, NETDEV_REG_A1) from the file and its "..." includes, and skips top-level asm. Output is key=value, exit 1 on any site. It is wired into stage_host next to check-lvo-matrix.sh, registered in check-gates-wired.sh, and added to the shellcheck list. Validation: 58c5c4f (the tree the issue scanned): 415 statements, 31 flagged. All 16 shipped sites match the issue's missing sets exactly, and tests/sockopt/sockopt_test.c:332 (pre-#68) is flagged missing=a1. src/tools/toolsock.c alone: 22 statements, 0 flagged. The issue's 77 included 46 false positives: 43 BSD_SCRATCH macro sites, apidrill's TH() macro, and the top-level asm in genet.c and netdev_cache.c. The 14 real test sites on main are fixed: a register that is also an input becomes an output (dummy "=r", or "+r" as in #71), one that is not becomes a clobber. udpdrill's recvfrom and getsockopt helpers had the #68 shape (a1). before (7fa3df3): statements=415 files=50 flagged=14 after: statements=415 files=50 flagged=0 Fixes #70 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Fixes #70
Steps 2 and 3 of #70: the scanner is a CI gate, and the remaining test sites are fixed.
Gate.
tools/check-lvo-clobbers.shrunstools/check-lvo-clobbers.pyover src/ and tests/. It flags every extended asm statement that calls through a6 and does not list d0, d1, a0 and a1 as outputs or clobbers. It reads register declarations through object-like macros (BSD_SCRATCH,NETDEV_REG_A1) from the file and from its"..."includes, and it skips top-level asm. Output is key=value, and the exit code is 1 on any flagged site. The gate runs instage_hostnext tocheck-lvo-matrix.sh, is registered incheck-gates-wired.sh, and is on the shellcheck list.Validation
src/tools/toolsock.calonetests/sockopt/sockopt_test.c:332(pre-sockopt_test: the recvfrom helper declares a1 clobbered #68) is flaggedmissing=a1.BSD_SCRATCHmacro sites in ipv6_socket_test, sockopt_test and udpdrillTH()macro, which lists all eight registersFixes (14 test sites). A missing register that is also an input becomes an output: a dummy
"=r", or"+r"as in #71. A missing register that is not an input becomes a clobber.Repro:
tools/check-lvo-clobbers.sh; echo $?🤖 Generated with Claude Code