#valgrind 3.27.0 released!

New options for helgrind (--show-events and --track-destroy), new SSE4.1 instruction for x86, support for s390x z/Architecture features from 15th edition, integrated binutils objdump for s390x disassembly, new linux syscalls, address space manager tracking linux kernel lightweight guard pages, freebsd 16.0-CURRENT, macOS up to version 13 Ventura (Intel), new client requests (VALGRIND_REPLACES_MALLOC, VALGRIND_GET_TOOLNAME).

https://gnu.wildebeest.org/blog/mjw/2026/04/20/anticipating-valgrind-3-27-0/

#Valgrind 3.27.0 released.

https://valgrind.org/docs/manual/dist.news.html

Anticipating #valgrind 3.27.0.

There are two new client requests (macros defined in valgrind.h) https://valgrind.org/docs/manual/manual-core-adv.html#manual-core-adv.clientreq

- VALGRIND_REPLACES_MALLOC Returns 1 if the tool replaces malloc (e.g., memcheck). Returns 0 if the tool does not replace malloc (e.g., cachegrind and callgrind) or if the executable is not running under VALGRIND.

- VALGRIND_GET_TOOLNAME Get the running tool name as a string. Takes two arguments, an input buffer pointer and the length of that buffer.

Anticipating #valgrind 3.27.0.

Paul Floyd @paulf had more commits than all others combined for this release. Paul takes care of the alternative toolchains, Solaris/illumos, FreeBSD and Darwin/MacOS ports.

Tested Oracle Solaris 11.4, OpenIndiana Hipster and OmniOS.

FreeBSD works on both amd64 and arm64, support for 16.0-CURRENT has been added.

Supported MacOS versions, 10.13 (bug fixes), 10.14, 10.15, 11.0 (Intel only), 12.0 (Intel only), 13.0 (Intel only, preliminary). No arm64 support yet

Anticipating #valgrind 3.27.0.

Martin also added Valgrind address space manager support for tracking linux kernel lightweight guard pages, created through madvise (MADV_GUARD_INSTALL).

These guard pages are very low overhead for the kernel because they aren't tracked as separate VMAs and don't show up in the process proc maps. But Valgrind does still need to know whether the addresses are accessible. A new --max-guard-pages option controls the memory Valgrind reserves for tracking these pages.

Anticipating #valgrind 3.27.0.

Martin Cermak maintains the Linux Test Program (LTP) valgrind integration, which checks our syscall wrappers work correctly. And he makes sure newer linux syscalls are wrapped. Valgrind 3.27.0 adds support for file_getattr, file_setattr, lsm_get_self_attr, lsm_set_self_attr, lsm_list_modules. And corrects various syscall and ioctl corner cases.

Anticipating #valgrind 3.27.0.

Andreas also showed there are still meaningful optimizations to be made on how memcheck tracks undefinedness bits as outlined in the original "Using Valgrind to detect undefined value errors with bit-precision" https://valgrind.org/docs/memcheck2005.pdf paper.

His optimization of memcheck instrumenting a bitwise AND/OR with a constant is clever and simplifies the generated code: https://sourceware.org/cgit/valgrind/commit/?id=8514763a215f863bc52400991eba332df115eaea

Anticipating #valgrind 3.27.0.

Andreas Arnez and Florian Krohm did a lot of work on the s390x support.

Andreas added support for new s390x z/Architecture features from the 15th edition. This enables running binaries compiled with -march=arch15 or -march=z17 and exploiting the new MSA extensions 10-13.

Florian Krohm integrated binutils objdump for s390x disassembly in VEX. And did a lot of s390x code and facilities cleanups.

s390x machine models older than z196 are no longer supported.

Anticipating #valgrind 3.27.0.

Valgrind has separate VEX IR translators for AMD64 and x86 (32 bit) code. While the AMD64 translator has seen support for new encodings and instruction sets, the x86 translator has not.

Alexandra Hájková decided to port the SSE4.1 instruction set from the AMD64 translator to the x86 translator and add backend support. This is ongoing work, see the bug dependency tree https://bugs.kde.org/showdependencytree.cgi?id=518222

But many more 32bit programs using SSE4.1 should now run under Valgrind.