ci: init

.github/workflows/llvm-18.yml

@@ -0,0 +1,102 @@
+name: Test workflow with LLVM 18
+
+on:
+  push:
+    branches:
+    - public-approved
+  workflow_dispatch:
+
+env:
+  MCDC_HOME: /home/github-runner/mcdc-workdir
+
+jobs:
+  find_runner:
+    name: Find an available self-hosted runner
+    runs-on: self-hosted
+    # Enforce this same runner for all later jobs that depend on this one
+    # FIXME this requires each runner has a label the same as its name
+    outputs:
+      runner_name: ${{ runner.name }}
+    # Dummy, do nothing
+    steps:
+    - uses: actions/checkout@v4
+
+  install_deps:
+    name: 1. Install dependencies
+    needs: find_runner
+    # Enforce the same runner
+    runs-on: ${{ needs.find_runner.outputs.runner_name }}
+    outputs:
+      runner_name: ${{ runner.name }}
+    steps:
+    - uses: actions/checkout@v4
+    - name: Install dependencies
+      run: ./ci/1_install_deps.sh
+
+  pull_source:
+    name: 2. Pull the source code and apply patches
+    needs: install_deps
+    # Enforce the same runner
+    runs-on: ${{ needs.install_deps.outputs.runner_name }}
+    outputs:
+      runner_name: ${{ runner.name }}
+    steps:
+    - uses: actions/checkout@v4
+    - name: Create a workspace from clean slate
+      run: |
+        rm -rf $MCDC_HOME
+        mkdir -p $MCDC_HOME
+    - name: Pull the source code and apply patches
+      run: ./ci/2_pull_source.sh
+
+  get_llvm:
+    name: 3. Get LLVM
+    needs: pull_source
+    # Enforce the same runner
+    runs-on: ${{ needs.pull_source.outputs.runner_name }}
+    outputs:
+      runner_name: ${{ runner.name }}
+    steps:
+    - uses: actions/checkout@v4
+    - name: Build from source
+      run: ./ci/3_get_llvm.sh
+    - name: Print LLVM build resource usage
+      run: |
+        cat /tmp/time.log
+        du -sh $MCDC_HOME/llvm-project
+
+  build_kernel:
+    name: 4. Build the kernel
+    needs: get_llvm
+    # Enforce the same runner
+    runs-on: ${{ needs.get_llvm.outputs.runner_name }}
+    outputs:
+      runner_name: ${{ runner.name }}
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up LLVM path
+      run: echo "$MCDC_HOME/llvm-project/build/bin" >> $GITHUB_PATH
+    - name: Build the kernel
+      run: ./ci/4_build_kernel.sh
+    - name: Print full kernel build log
+      run: cat /tmp/make.log
+    - name: Print kernel build resource usage
+      run: |
+        cat /tmp/time.log
+        du -sh $MCDC_HOME/linux
+
+  boot_kernel_and_collect_coverage:
+    name: 5. Boot the kernel and collect coverage
+    needs: build_kernel
+    # Enforce the same runner
+    runs-on: ${{ needs.build_kernel.outputs.runner_name }}
+    outputs:
+      runner_name: ${{ runner.name }}
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up LLVM path
+      run: echo "$MCDC_HOME/llvm-project/build/bin" >> $GITHUB_PATH
+    - name: Boot the kernel and collect coverage
+      run: ./ci/5_boot_kernel_and_collect_coverage.sh
+    - name: Print the index of coverage report
+      run: cat $MCDC_HOME/analysis/text-coverage-reports/index.txt

ci/1_install_deps.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+# For building LLVM from source (optional)
+sudo apt-get -yq install cmake ninja-build mold
+
+# For building the kernel
+sudo apt-get -yq install git bc libncurses-dev wget busybox \
+    libssl-dev libelf-dev dwarves flex bison build-essential
+
+# For booting the kernel
+sudo apt-get -yq install qemu-system-x86

ci/2_pull_source.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+
+cd $MCDC_HOME
+
+# This meta repository
+git clone https://github.com/xlab-uiuc/linux-mcdc.git
+# LLVM if we want to build it from source (optional)
+git clone https://github.com/llvm/llvm-project.git --branch llvmorg-18.1.7 --depth 5
+# Linux kernel
+git clone https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git --branch v5.15.153 --depth 5
+
+# Apply kernel patches
+cd $MCDC_HOME/linux
+git apply $MCDC_HOME/linux-mcdc/patches/v0.4/0001-clang_instr_profile-add-Clang-s-Source-based-Code-Co.patch
+git apply $MCDC_HOME/linux-mcdc/patches/v0.4/0002-kbuild-clang_instr_profile-disable-instrumentation-i.patch
+git apply $MCDC_HOME/linux-mcdc/patches/v0.4/0003-clang_instr_profile-add-Clang-s-MC-DC-support.patch

ci/3_get_llvm.sh

@@ -0,0 +1,123 @@
+#!/bin/bash
+
+cd $MCDC_HOME/llvm-project
+
+# Patches that improve llvm-cov text output
+
+cat > /tmp/llvm_cov_divider.patch << EOF
+diff --git a/llvm/tools/llvm-cov/CoverageReport.cpp b/llvm/tools/llvm-cov/CoverageReport.cpp
+index 49a35f2a9..00aea4039 100644
+--- a/llvm/tools/llvm-cov/CoverageReport.cpp
++++ b/llvm/tools/llvm-cov/CoverageReport.cpp
+@@ -102,8 +102,25 @@ void adjustColumnWidths(ArrayRef<StringRef> Files,
+
+ /// Prints a horizontal divider long enough to cover the given column
+ /// widths.
+-void renderDivider(ArrayRef<size_t> ColumnWidths, raw_ostream &OS) {
+-  size_t Length = std::accumulate(ColumnWidths.begin(), ColumnWidths.end(), 0);
++void renderDivider(raw_ostream &OS, const CoverageViewOptions &Options, bool isFileReport) {
++  size_t Length;
++  if (isFileReport) {
++    Length = std::accumulate(std::begin(FileReportColumns), std::end(FileReportColumns), 0);
++    if (!Options.ShowRegionSummary)
++      Length -= (FileReportColumns[1] + FileReportColumns[2] + FileReportColumns[3]);
++    if (!Options.ShowInstantiationSummary)
++      Length -= (FileReportColumns[7] + FileReportColumns[8] + FileReportColumns[9]);
++    if (!Options.ShowBranchSummary)
++      Length -= (FileReportColumns[13] + FileReportColumns[14] + FileReportColumns[15]);
++    if (!Options.ShowMCDCSummary)
++      Length -= (FileReportColumns[16] + FileReportColumns[17] + FileReportColumns[18]);
++  } else {
++    Length = std::accumulate(std::begin(FunctionReportColumns), std::end(FunctionReportColumns), 0);
++    if (!Options.ShowBranchSummary)
++      Length -= (FunctionReportColumns[7] + FunctionReportColumns[8] + FunctionReportColumns[9]);
++    if (!Options.ShowMCDCSummary)
++      Length -= (FunctionReportColumns[10] + FunctionReportColumns[11] + FunctionReportColumns[12]);
++  }
+   for (size_t I = 0; I < Length; ++I)
+     OS << '-';
+ }
+@@ -405,7 +422,7 @@ void CoverageReport::renderFunctionReports(ArrayRef<std::string> Files,
+          << column("Miss", FunctionReportColumns[11], Column::RightAlignment)
+          << column("Cover", FunctionReportColumns[12], Column::RightAlignment);
+     OS << "\n";
+-    renderDivider(FunctionReportColumns, OS);
++    renderDivider(OS, Options, false);
+     OS << "\n";
+     FunctionCoverageSummary Totals("TOTAL");
+     for (const auto &F : Functions) {
+@@ -418,7 +435,7 @@ void CoverageReport::renderFunctionReports(ArrayRef<std::string> Files,
+       render(Function, DC, OS);
+     }
+     if (Totals.ExecutionCount) {
+-      renderDivider(FunctionReportColumns, OS);
++      renderDivider(OS, Options, false);
+       OS << "\n";
+       render(Totals, DC, OS);
+     }
+@@ -544,7 +561,7 @@ void CoverageReport::renderFileReports(
+                  Column::RightAlignment)
+        << column("Cover", FileReportColumns[18], Column::RightAlignment);
+   OS << "\n";
+-  renderDivider(FileReportColumns, OS);
++  renderDivider(OS, Options, true);
+   OS << "\n";
+
+   std::vector<const FileCoverageSummary *> EmptyFiles;
+@@ -563,7 +580,7 @@ void CoverageReport::renderFileReports(
+       render(*FCS, OS);
+   }
+
+-  renderDivider(FileReportColumns, OS);
++  renderDivider(OS, Options, true);
+   OS << "\n";
+   render(Totals, OS);
+ }
+
+EOF
+git apply /tmp/llvm_cov_divider.patch
+cat > /tmp/llvm_cov_final_new_line.patch << EOF
+diff --git a/llvm/tools/llvm-cov/SourceCoverageViewText.cpp b/llvm/tools/llvm-cov/SourceCoverageViewText.cpp
+index cab60c2d9..2aa588e6d 100644
+--- a/llvm/tools/llvm-cov/SourceCoverageViewText.cpp
++++ b/llvm/tools/llvm-cov/SourceCoverageViewText.cpp
+@@ -43,7 +43,8 @@ Error CoveragePrinterText::createIndexFile(
+   Report.renderFileReports(OSRef, SourceFiles, Filters);
+
+   Opts.colored_ostream(OSRef, raw_ostream::CYAN) << "\n"
+-                                                 << Opts.getLLVMVersionString();
++                                                 << Opts.getLLVMVersionString()
++                                                 << "\n";
+
+   return Error::success();
+ }
+@@ -84,7 +85,8 @@ struct CoveragePrinterTextDirectory::Reporter : public DirectoryCoverageReport {
+
+     Options.colored_ostream(OSRef, raw_ostream::CYAN)
+         << "\n"
+-        << Options.getLLVMVersionString();
++        << Options.getLLVMVersionString()
++        << "\n";
+
+     return Error::success();
+   }
+EOF
+git apply /tmp/llvm_cov_final_new_line.patch
+cat > /tmp/llvm_cov_trim_abs_path.patch << EOF
+diff --git a/llvm/tools/llvm-cov/CoverageReport.cpp b/llvm/tools/llvm-cov/CoverageReport.cpp
+index 49a35f2a9..dc9f2f9c5 100644
+--- a/llvm/tools/llvm-cov/CoverageReport.cpp
++++ b/llvm/tools/llvm-cov/CoverageReport.cpp
+@@ -216,7 +216,7 @@ void CoverageReport::render(const FileCoverageSummary &File,
+   if (IsDir)
+     FileName += sys::path::get_separator();
+
+-  OS << column(FileName, FileReportColumns[0], Column::NoTrim);
++  OS << column(FileName, FileReportColumns[0], Column::RightTrim);
+
+   if (Options.ShowRegionSummary) {
+     OS << format("%*u", FileReportColumns[1],
+EOF
+git apply /tmp/llvm_cov_trim_abs_path.patch
+
+/usr/bin/time -v -o /tmp/time.log $MCDC_HOME/linux-mcdc/scripts/build-llvm.sh

ci/4_build_kernel.sh

@@ -0,0 +1,35 @@
+#!/bin/bash
+
+cd $MCDC_HOME/linux
+make LLVM=1 defconfig
+
+./scripts/config -e CONFIG_9P_FS_POSIX_ACL
+./scripts/config -e CONFIG_9P_FS
+./scripts/config -e CONFIG_NET_9P_VIRTIO
+./scripts/config -e CONFIG_NET_9P
+./scripts/config -e CONFIG_PCI
+./scripts/config -e CONFIG_VIRTIO_PCI
+./scripts/config -e CONFIG_OVERLAY_FS
+./scripts/config -e CONFIG_DEBUG_FS
+./scripts/config -e CONFIG_CONFIGFS_FS
+./scripts/config -e CONFIG_MAGIC_SYSRQ
+make LLVM=1 olddefconfig
+
+./scripts/config -e CONFIG_KUNIT
+./scripts/config -e CONFIG_KUNIT_ALL_TESTS
+make LLVM=1 olddefconfig
+
+./scripts/config -e CONFIG_INSTR_PROFILE_CLANG
+./scripts/config -e CONFIG_SCC_CLANG
+./scripts/config -e CONFIG_MCDC_CLANG
+make LLVM=1 olddefconfig
+
+./scripts/config -d CONFIG_DRM_I915
+make LLVM=1 olddefconfig
+
+cat << EOF
+Building the kernel with output suppressed. The log tail will be displayed once
+the process finishes. See the full log in the next step.
+EOF
+/usr/bin/time -v -o /tmp/time.log make LLVM=1 -j$(nproc) >& /tmp/make.log
+tail -n 200 /tmp/make.log

ci/5_boot_kernel_and_collect_coverage.sh

@@ -0,0 +1,31 @@
+#!/bin/bash
+
+GUEST_COMMANDS="true"
+GUEST_COMMANDS="$GUEST_COMMANDS; uname -a"
+GUEST_COMMANDS="$GUEST_COMMANDS; ls /sys/kernel/debug/clang_instr_profile"
+GUEST_COMMANDS="$GUEST_COMMANDS; cp /sys/kernel/debug/clang_instr_profile/profraw ."
+
+cd $MCDC_HOME/linux
+$MCDC_HOME/linux-mcdc/scripts/q -c "$GUEST_COMMANDS"
+
+file profraw |& tee /tmp/file.log
+if ! grep "LLVM raw profile data, version 9" /tmp/file.log > /dev/null; then
+    printf "\nUnexpected profraw\n"
+    exit 1
+fi
+
+mkdir -p $MCDC_HOME/analysis
+mv profraw $MCDC_HOME/analysis
+cd $MCDC_HOME/analysis
+
+llvm-profdata merge profraw -o profdata
+llvm-cov show --show-mcdc                                                      \
+              --show-mcdc-summary                                              \
+              --show-region-summary=false                                      \
+              --show-branch-summary=false                                      \
+              --format=text                                                    \
+              -use-color                                                       \
+              -show-directory-coverage                                         \
+              -output-dir=text-coverage-reports                                \
+              -instr-profile profdata                                          \
+              $MCDC_HOME/linux/vmlinux