[v6,0/7] plugins: access values during a memory read/write

Message

Pierrick Bouvier July 6, 2024, 7:13 p.m. UTC

This series allows plugins to know which value is read/written during a memory
access.

For every memory access, we know copy this value before calling mem callbacks,
and those can query it using new API function:
- qemu_plugin_mem_get_value

Mem plugin was extended to print accesses, and a new test was added to check
functionality work as expected. A bug was found where callbacks were not
called as expected.

This will open new use cases for plugins, such as tracking specific values in
memory.

Needs review:
Patch 7: tests/tcg/x86_64: add test for plugin memory access

v6
- fix big endian offset for plugin_gen_mem_callbacks_i32

v5
- fixed width output for mem values in mem plugin
- move plugin_mem_value to CPUNegativeOffset
- tcg/tcg-op-ldst.c: only store word size mem access (do not set upper bits)

v4
- fix prototype for stubs qemu_plugin_vcpu_mem_cb (inverted low/high parameters
  names)
- link gitlab bugs resolved (thanks @Anton Kochkov for reporting)
  https://gitlab.com/qemu-project/qemu/-/issues/1719
  https://gitlab.com/qemu-project/qemu/-/issues/2152

v3
- simplify API: return an algebraic data type for value accessed
  this can be easily extended when QEMU will support wider accesses
- fix Makefile test (use quiet-command instead of manually run the command)
- rename upper/lower to high/low
- reorder functions parameters and code to low/high instead of high/low, to
  follow current convention in QEMU codebase

v2
- fix compilation on aarch64 (missing undef in accel/tcg/atomic_template.h)

v3
- add info when printing memory accesses (insn_vaddr,mem_vaddr,mem_hwaddr)

Pierrick Bouvier (7):
  plugins: fix mem callback array size
  plugins: save value during memory accesses
  plugins: extend API to get latest memory value accessed
  tests/tcg: add mechanism to run specific tests with plugins
  tests/tcg: allow to check output of plugins
  tests/plugin/mem: add option to print memory accesses
  tests/tcg/x86_64: add test for plugin memory access

 accel/tcg/atomic_template.h                 | 66 +++++++++++++--
 include/hw/core/cpu.h                       |  4 +
 include/qemu/plugin.h                       |  4 +
 include/qemu/qemu-plugin.h                  | 32 ++++++++
 accel/tcg/plugin-gen.c                      |  3 +-
 plugins/api.c                               | 33 ++++++++
 plugins/core.c                              |  6 ++
 tcg/tcg-op-ldst.c                           | 66 +++++++++++++--
 tests/plugin/mem.c                          | 69 +++++++++++++++-
 tests/tcg/x86_64/test-plugin-mem-access.c   | 89 +++++++++++++++++++++
 accel/tcg/atomic_common.c.inc               | 13 ++-
 accel/tcg/ldst_common.c.inc                 | 38 +++++----
 plugins/qemu-plugins.symbols                |  1 +
 tests/tcg/Makefile.target                   | 10 ++-
 tests/tcg/x86_64/Makefile.target            |  7 ++
 tests/tcg/x86_64/check-plugin-mem-access.sh | 48 +++++++++++
 16 files changed, 455 insertions(+), 34 deletions(-)
 create mode 100644 tests/tcg/x86_64/test-plugin-mem-access.c
 create mode 100755 tests/tcg/x86_64/check-plugin-mem-access.sh