From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- tools/testing/vsock/README | 86 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 86 insertions(+) create mode 100644 tools/testing/vsock/README (limited to 'tools/testing/vsock/README') diff --git a/tools/testing/vsock/README b/tools/testing/vsock/README new file mode 100644 index 000000000..680ce666c --- /dev/null +++ b/tools/testing/vsock/README @@ -0,0 +1,86 @@ +AF_VSOCK test suite +------------------- +These tests exercise net/vmw_vsock/ host<->guest sockets for VMware, KVM, and +Hyper-V. + +The following tests are available: + + * vsock_test - core AF_VSOCK socket functionality + * vsock_diag_test - vsock_diag.ko module for listing open sockets + +The following prerequisite steps are not automated and must be performed prior +to running tests: + +1. Build the kernel, make headers_install, and build these tests. +2. Install the kernel and tests on the host. +3. Install the kernel and tests inside the guest. +4. Boot the guest and ensure that the AF_VSOCK transport is enabled. + +Invoke test binaries in both directions as follows: + + # host=server, guest=client + (host)# $TEST_BINARY --mode=server \ + --control-port=1234 \ + --peer-cid=3 + (guest)# $TEST_BINARY --mode=client \ + --control-host=$HOST_IP \ + --control-port=1234 \ + --peer-cid=2 + + # host=client, guest=server + (guest)# $TEST_BINARY --mode=server \ + --control-port=1234 \ + --peer-cid=2 + (host)# $TEST_BINARY --mode=client \ + --control-port=$GUEST_IP \ + --control-port=1234 \ + --peer-cid=3 + +Some tests are designed to produce kernel memory leaks. Leaks detection, +however, is deferred to Kernel Memory Leak Detector. It is recommended to enable +kmemleak (CONFIG_DEBUG_KMEMLEAK=y) and explicitly trigger a scan after each test +suite run, e.g. + + # echo clear > /sys/kernel/debug/kmemleak + # $TEST_BINARY ... + # echo "wait for any grace periods" && sleep 2 + # echo scan > /sys/kernel/debug/kmemleak + # echo "wait for kmemleak" && sleep 5 + # echo scan > /sys/kernel/debug/kmemleak + # cat /sys/kernel/debug/kmemleak + +For more information see Documentation/dev-tools/kmemleak.rst. + +vsock_perf utility +------------------- +'vsock_perf' is a simple tool to measure vsock performance. It works in +sender/receiver modes: sender connect to peer at the specified port and +starts data transmission to the receiver. After data processing is done, +it prints several metrics(see below). + +Usage: +# run as sender +# connect to CID 2, port 1234, send 1G of data, tx buf size is 1M +./vsock_perf --sender 2 --port 1234 --bytes 1G --buf-size 1M + +Output: +tx performance: A Gbits/s + +Output explanation: +A is calculated as "number of bits to send" / "time in tx loop" + +# run as receiver +# listen port 1234, rx buf size is 1M, socket buf size is 1G, SO_RCVLOWAT is 64K +./vsock_perf --port 1234 --buf-size 1M --vsk-size 1G --rcvlowat 64K + +Output: +rx performance: A Gbits/s +total in 'read()': B sec +POLLIN wakeups: C +average in 'read()': D ns + +Output explanation: +A is calculated as "number of received bits" / "time in rx loop". +B is time, spent in 'read()' system call(excluding 'poll()') +C is number of 'poll()' wake ups with POLLIN bit set. +D is B / C, e.g. average amount of time, spent in single 'read()'. -- cgit v1.3.1