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/multiarch: add test for plugin memory access

v7
- renamed variable for adding plugins tests in Makefile
- do not run any command when plugin output should not be checked (thanks Alex)
- add LICENSE + summary for tests/tcg/multiarch/test-plugin-mem-access.c
- test for mem access is now multiarch (tested on aarch64, x86_64, i386)

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 (6):
  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/multiarch: 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 ++++
 plugins/api.c                                 |  33 ++++
 plugins/core.c                                |   6 +
 tcg/tcg-op-ldst.c                             |  66 ++++++-
 tests/plugin/mem.c                            |  69 ++++++-
 tests/tcg/multiarch/test-plugin-mem-access.c  | 175 ++++++++++++++++++
 accel/tcg/atomic_common.c.inc                 |  13 +-
 accel/tcg/ldst_common.c.inc                   |  38 ++--
 plugins/qemu-plugins.symbols                  |   1 +
 tests/tcg/Makefile.target                     |  12 +-
 tests/tcg/multiarch/Makefile.target           |   7 +
 .../tcg/multiarch/check-plugin-mem-access.sh  |  30 +++
 15 files changed, 524 insertions(+), 32 deletions(-)
 create mode 100644 tests/tcg/multiarch/test-plugin-mem-access.c
 create mode 100755 tests/tcg/multiarch/check-plugin-mem-access.sh

-- 
2.39.2

Pierrick Bouvier <pierrick.bouvier@linaro.org> writes:

> 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

Queued to patches 1-5 to plugins/next, thanks.

You can send the re-spun version of 6 once the review comments have been
done.

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro

On 9/5/24 08:21, Alex Bennée wrote:
> Pierrick Bouvier <pierrick.bouvier@linaro.org> writes:
> 
>> 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
> 
> Queued to patches 1-5 to plugins/next, thanks.
> 
> You can send the re-spun version of 6 once the review comments have been
> done.
> 

Thanks Alex,

right now, my try to make check-tcg are blocked with the cross 
containers who don't compile, so I'll wait for this to be resolved.
I still wonder if having a simple aarch64/x64 test is not enough, and 
covering 99.9% of the bug we could introduce in the future on this.