osdtrace: recover by-value param location from the SysV-AMD64 ABI; add Resolute amd64v3 DWARF JSONs

.github/workflows/pr-build.yaml

@@ -11,14 +11,35 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-22.04, ubuntu-24.04, ubuntu-latest]
+        os: [ubuntu-22.04, ubuntu-24.04, ubuntu-26.04, ubuntu-latest]
+        # Which apt architecture variant the cell's ceph packages come from.
+        # "default" means whatever the runner image defaults to: baseline
+        # amd64 on 22.04/24.04, but amd64v3 on 26.04 (cloud images enable
+        # APT::Architecture-Variants "amd64v3" out of the box).  The extra
+        # (ubuntu-26.04, amd64) cell disables the variant so the Resolute
+        # baseline-amd64 reference DWARF JSONs get CI coverage too;
+        # dwarf-compare's build-id keying selects the matching reference
+        # automatically in both cells.
+        ceph-variant: [default]
+        include:
+          - os: ubuntu-26.04
+            ceph-variant: amd64
     steps:
       - name: Checkout code and submodules
         uses: actions/checkout@v4
         with:
           submodules: recursive
           fetch-depth: 0
 
+      - name: Force baseline amd64 packages (disable amd64v3 variant)
+        if: matrix.ceph-variant == 'amd64'
+        run: |
+            # apt.conf.d files parse in lexical order and #clear erases the
+            # option wherever an earlier file set it, so zz- wins over the
+            # cloud image's enablement snippet.
+            echo '#clear APT::Architecture-Variants;' | sudo tee /etc/apt/apt.conf.d/zz-disable-arch-variants
+            sudo apt-get update
+
       - name: Ensure submodules are updated
         run: |
             sudo apt-get update
@@ -30,19 +51,27 @@ jobs:
       - name: Unit test - verify dwarf output is consistent
         run: ./tests/dwarf-compare.sh
 
+      # The remaining functional tests deploy MicroCeph (a snap) and trace its
+      # bundled ceph -- independent of the host apt variant -- so they only
+      # run in the default cell; the amd64 variant cell exists purely to give
+      # dwarf-compare coverage of the baseline-amd64 reference JSONs.
       - name: Uninstall pre-installed Ceph packages
+        if: matrix.ceph-variant != 'amd64'
         run: |
           # Remove any pre-installed Ceph packages that might conflict with MicroCeph
           sudo apt-get remove --purge -y ceph ceph-common ceph-osd python3-ceph-argparse python3-ceph-common 'ceph-libboost*' || true
           sudo apt-get autoremove -y || true
 
       - name: Functional test - verify osdtrace and radostrace with MicroCeph
+        if: matrix.ceph-variant != 'amd64'
         run: sudo ./tests/functional-test-microceph.sh
 
       - name: Embedded DWARF data test - verify integrity and E2E
+        if: matrix.ceph-variant != 'amd64'
         run: sudo ./tests/functional-test-embedded-dwarf.sh
 
       - name: Functional test - radostrace tracing a qemu VM on an RBD disk
+        if: matrix.ceph-variant != 'amd64'
         run: sudo ./tests/functional-test-qemu-rbd.sh
 
   build-ubuntu-cephadm:
@@ -51,7 +80,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-22.04, ubuntu-24.04]
+        os: [ubuntu-22.04, ubuntu-24.04, ubuntu-26.04]
         release: [quincy, reef, squid, tentacle]
     steps:
       - name: Checkout code and submodules

doc/dwarf-json-files.md

@@ -75,10 +75,26 @@ Available versions include:
 - Ubuntu 20.04: Ceph 15.2.17, 17.2.x series
 - Ubuntu 22.04: Ceph 17.2.x, 19.2.x series
 - Ubuntu 24.04: Ceph 19.2.x series
+- Ubuntu 26.04: Ceph 20.2.x series (Tentacle), including `amd64v3`
+  architecture-variant builds
 
 File naming format: `<version>_dwarf.json`
 - Example: `17.2.6-0ubuntu0.22.04.2_dwarf.json`
 
+When more than one build of the same package version is checked in — a
+different architecture or microarchitecture variant — the filename carries an
+architecture suffix to keep the builds distinct. Ubuntu 26.04's `amd64v3`
+package variant (`APT::Architecture-Variants "amd64v3"`) keeps the same
+version string and `dpkg` architecture as the baseline `amd64` build but is
+compiled for `-march=x86-64-v3`, so it has different function addresses and a
+different ELF build-id and needs its own DWARF JSON:
+- Example: `osd-20.2.0-0ubuntu2_amd64v3_dwarf.json`
+- Example: `20.2.0-0ubuntu2_amd64v3_dwarf.json`
+
+The embedded-DWARF path matches the target by ELF build-id, so it selects the
+right variant automatically; the suffix only disambiguates the checked-in
+files and the `-i` import path.
+
 ### CentOS Stream
 
 Location: `files/centos-stream/{radostrace,osdtrace}/`