ci: add Valgrind testing workflow

This patch adds CI testing with Valgrind in three scenarios:
  - Full checks enabled.
  - No leak checks, with memory fill set to `--malloc-fill=0x00`
    and `--free-fill=0x00`.
  - No leak checks, with memory fill set to `--malloc-fill=0xFF`
    and `--free-fill=0xFF`.

.github/actions/setup-valgrind/README.md

@@ -0,0 +1,12 @@
+# Setup environment on Linux
+
+Action setups the environment on Linux runners (install requirements, setup the
+workflow environment, etc) for testing with Valgrind.
+
+## How to use Github Action from Github workflow
+
+Add the following code to the running steps before LuaJIT configuration:
+```
+- uses: ./.github/actions/setup-linux
+  if: ${{ matrix.OS == 'Linux' }}
+```

.github/actions/setup-valgrind/action.yml

@@ -0,0 +1,19 @@
+name: Setup CI environment on Linux
+description: Common part to tweak Linux CI runner environment
+runs:
+  using: composite
+  steps:
+    - name: Setup CI environment
+      uses: ./.github/actions/setup
+    - name: Set CMAKE_BUILD_PARALLEL_LEVEL
+      run: |
+        # Set CMAKE_BUILD_PARALLEL_LEVEL environment variable to
+        # limit the number of parallel jobs for build/test step.
+        NPROC=$(nproc)
+        echo CMAKE_BUILD_PARALLEL_LEVEL=$(($NPROC + 1)) | tee -a $GITHUB_ENV
+      shell: bash
+    - name: Install build and test dependencies
+      run: |
+        apt -y update
+        apt -y install cmake gcc make ninja-build perl valgrind
+      shell: bash

.github/workflows/valgrind-testing.yaml

@@ -0,0 +1,88 @@
+name: Valgrind testing
+
+on:
+  push:
+    branches-ignore:
+      - '**-notest'
+      - 'upstream-**'
+    tags-ignore:
+      - '**'
+
+concurrency:
+  # An update of a developer branch cancels the previously
+  # scheduled workflow run for this branch. However, the default
+  # branch, and long-term branch (tarantool/release/2.11,
+  # tarantool/release/2.10, etc) workflow runs are never canceled.
+  #
+  # We use a trick here: define the concurrency group as 'workflow
+  # run ID' + # 'workflow run attempt' because it is a unique
+  # combination for any run. So it effectively discards grouping.
+  #
+  # XXX: we cannot use `github.sha` as a unique identifier because
+  # pushing a tag may cancel a run that works on a branch push
+  # event.
+  group: ${{ startsWith(github.ref, 'refs/heads/tarantool/')
+    && format('{0}-{1}', github.run_id, github.run_attempt)
+    || format('{0}-{1}', github.workflow, github.ref) }}
+  cancel-in-progress: true
+
+jobs:
+  test-valgrind:
+    strategy:
+      fail-fast: false
+      matrix:
+        # XXX: Let's start with only Linux/x86_64
+        BUILDTYPE: [Debug, Release]
+        VALGRIND_OPTIONS:
+          - --leak-check=full --show-leak-kinds=all --track-origins=yes --verbose
+          - --leak-check=no --malloc-fill=0x00 --free-fill=0x00
+          - --leak-check=no --malloc-fill=0xFF --free-fill=0xFF
+        include:
+          - BUILDTYPE: Debug
+            CMAKEFLAGS: -DCMAKE_BUILD_TYPE=Debug -DLUA_USE_ASSERT=ON -DLUA_USE_APICHECK=ON
+          - BUILDTYPE: Release
+            CMAKEFLAGS: -DCMAKE_BUILD_TYPE=RelWithDebInfo
+
+    runs-on: [self-hosted, regular, Linux, x86_64]
+    name: >
+      LuaJIT with Valgrind (Linux/x86_64)
+      ${{ matrix.BUILDTYPE }}
+      CC: gcc
+      GC64:ON SYSMALLOC:ON
+      leak-check: ${{ matrix.VALGRIND_OPTIONS | regex_replace('--leak-check=([a-zA-Z0-9]+).*', '$1') }} 
+      malloc/free-fill: ${{ matrix.VALGRIND_OPTIONS | regex_replace('.*--malloc-fill=0x([0-9A-Fa-f]+).*', '$1', 'none') }}
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+          submodules: recursive
+      - name: setup Linux for Valgrind
+        uses: ./.github/actions/setup-valgrind
+      - name: configure
+        # XXX: LuaJIT configuration requires a couple of tweaks:
+        # LUAJIT_USE_SYSMALLOC=ON: Unfortunately, internal LuaJIT
+        #   memory allocator is not instrumented yet, so to find
+        #   any memory errors it's better to build LuaJIT with
+        #   system provided memory allocator (i.e. run CMake
+        #   configuration phase with -DLUAJIT_USE_SYSMALLOC=ON).
+        #   For more info, see root CMakeLists.txt.
+        # LUAJIT_ENABLE_GC64=ON: LUAJIT_USE_SYSMALLOC cannot be
+        #   enabled on x64 without GC64, since realloc usually
+        #   doesn't return addresses in the right address range.
+        #   For more info, see root CMakeLists.txt.
+        run: >
+          CC=gcc
+          cmake -S . -B ${{ env.BUILDDIR }}
+          -G Ninja
+          ${{ matrix.CMAKEFLAGS }}
+          -DLUAJIT_USE_VALGRIND=ON
+          -DLUAJIT_ENABLE_GC64=ON
+          -DLUAJIT_USE_SYSMALLOC=ON
+      - name: build
+        run: cmake --build . --parallel
+        working-directory: ${{ env.BUILDDIR }}
+      - name: test
+        env:
+          VALGRIND_OPTIONS: ${{ matrix.VALGRIND_OPTIONS }}
+        run: cmake --build . --parallel --target LuaJIT-test
+        working-directory: ${{ env.BUILDDIR }}