diff options
| author | Julia Suvorova <jusual@mail.ru> | 2019-02-01 14:55:46 +0000 |
|---|---|---|
| committer | Peter Maydell <peter.maydell@linaro.org> | 2019-02-01 14:55:46 +0000 |
| commit | 42f6ed919325413392bea247a1e6f135deb469cd (patch) | |
| tree | e0c08124c77ac0a831e03234dfde0bac665fe679 /include/qom/cpu.h | |
| parent | ef682cdb4aded5c65a018e175482e875de66059d (diff) | |
arm: Clarify the logic of set_pc()
Until now, the set_pc logic was unclear, which raised questions about
whether it should be used directly, applying a value to PC or adding
additional checks, for example, set the Thumb bit in Arm cpu. Let's set
the set_pc logic for “Configure the PC, as was done in the ELF file”
and implement synchronize_with_tb hook for preserving PC to cpu_tb_exec.
Signed-off-by: Julia Suvorova <jusual@mail.ru>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20190129121817.7109-1-jusual@mail.ru
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'include/qom/cpu.h')
| -rw-r--r-- | include/qom/cpu.h | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/include/qom/cpu.h b/include/qom/cpu.h index 4c2feb9c17..1d6099e5d4 100644 --- a/include/qom/cpu.h +++ b/include/qom/cpu.h @@ -103,9 +103,21 @@ struct TranslationBlock; * @get_arch_id: Callback for getting architecture-dependent CPU ID. * @get_paging_enabled: Callback for inquiring whether paging is enabled. * @get_memory_mapping: Callback for obtaining the memory mappings. - * @set_pc: Callback for setting the Program Counter register. + * @set_pc: Callback for setting the Program Counter register. This + * should have the semantics used by the target architecture when + * setting the PC from a source such as an ELF file entry point; + * for example on Arm it will also set the Thumb mode bit based + * on the least significant bit of the new PC value. + * If the target behaviour here is anything other than "set + * the PC register to the value passed in" then the target must + * also implement the synchronize_from_tb hook. * @synchronize_from_tb: Callback for synchronizing state from a TCG - * #TranslationBlock. + * #TranslationBlock. This is called when we abandon execution + * of a TB before starting it, and must set all parts of the CPU + * state which the previous TB in the chain may not have updated. + * This always includes at least the program counter; some targets + * will need to do more. If this hook is not implemented then the + * default is to call @set_pc(tb->pc). * @handle_mmu_fault: Callback for handling an MMU fault. * @get_phys_page_debug: Callback for obtaining a physical address. * @get_phys_page_attrs_debug: Callback for obtaining a physical address and the |