Re: [PATCH 2/6] contrib/plugins/cache: fix warning when compiling on 32bits host

[Richard Henderson <richard.henderson@linaro.org>]

On 8/15/24 21:46, Alex Bennée wrote:
> Thomas Huth <thuth@redhat.com> writes:
> 
>> On 15/08/2024 01.36, Pierrick Bouvier wrote:
>>> Found on debian stable (i386).
>>> ../contrib/plugins/cache.c: In function 'vcpu_tb_trans':
>>> ../contrib/plugins/cache.c:477:30: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
>>>     477 |             effective_addr = (uint64_t) qemu_plugin_insn_haddr(insn);
>>>         |
>>> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
>>> ---
>>>    contrib/plugins/cache.c | 6 +++---
>>>    1 file changed, 3 insertions(+), 3 deletions(-)
>>> diff --git a/contrib/plugins/cache.c b/contrib/plugins/cache.c
>>> index 512ef6776b7..82ed734d6d4 100644
>>> --- a/contrib/plugins/cache.c
>>> +++ b/contrib/plugins/cache.c
>>> @@ -471,12 +471,12 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
>>>        n_insns = qemu_plugin_tb_n_insns(tb);
>>>        for (i = 0; i < n_insns; i++) {
>>>            struct qemu_plugin_insn *insn = qemu_plugin_tb_get_insn(tb, i);
>>> -        uint64_t effective_addr;
>>> +        uintptr_t effective_addr;
>>>              if (sys) {
>>> -            effective_addr = (uint64_t) qemu_plugin_insn_haddr(insn);
>>> +            effective_addr = (uintptr_t) qemu_plugin_insn_haddr(insn);
>>>            } else {
>>> -            effective_addr = (uint64_t) qemu_plugin_insn_vaddr(insn);
>>> +            effective_addr = (uintptr_t)
>>> qemu_plugin_insn_vaddr(insn);
>>>            }
>>
>> Is this the right fix? I assume effective_addr stores an address of
>> the guest, so if the guest is 64-bit and the host is 32-bit, you now
>> lose the upper bits of the address...?
> 
> I think the problem is higher up, it was a mistake to have:
> 
>    void *qemu_plugin_insn_haddr(const struct qemu_plugin_insn *insn);
> 
> return *void.

No, not a bug.  This is a host addr, right there in the name.
Returning uint64_t would be a bug.


r~