Re: [PATCH v6 06/11] target/arm: Factor out code for setting MTE TCF0 field

[Gustavo Romero <gustavo.romero@linaro.org>]

Hi Alex,

On 6/28/24 9:14 AM, Alex Bennée wrote:
> Gustavo Romero <gustavo.romero@linaro.org> writes:
> 
>> Factor out the code used for setting the MTE TCF0 field from the prctl
>> code into a convenient function. Other subsystems, like gdbstub, need to
>> set this field as well, so keep it as a separate function to avoid
>> duplication and ensure consistency in how this field is set across the
>> board.
>>
>> Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>
>> ---
>>   linux-user/aarch64/meson.build       |  2 ++
>>   linux-user/aarch64/mte_user_helper.c | 34 ++++++++++++++++++++++++++++
>>   linux-user/aarch64/mte_user_helper.h | 25 ++++++++++++++++++++
>>   linux-user/aarch64/target_prctl.h    | 22 ++----------------
>>   4 files changed, 63 insertions(+), 20 deletions(-)
>>   create mode 100644 linux-user/aarch64/mte_user_helper.c
>>   create mode 100644 linux-user/aarch64/mte_user_helper.h
>>
>> diff --git a/linux-user/aarch64/meson.build b/linux-user/aarch64/meson.build
>> index 248c578d15..f75bb3cd75 100644
>> --- a/linux-user/aarch64/meson.build
>> +++ b/linux-user/aarch64/meson.build
>> @@ -9,3 +9,5 @@ vdso_le_inc = gen_vdso.process('vdso-le.so',
>>                                  extra_args: ['-r', '__kernel_rt_sigreturn'])
>>   
>>   linux_user_ss.add(when: 'TARGET_AARCH64', if_true: [vdso_be_inc, vdso_le_inc])
>> +
>> +linux_user_ss.add(when: 'TARGET_AARCH64', if_true: [files('mte_user_helper.c')])
>> diff --git a/linux-user/aarch64/mte_user_helper.c b/linux-user/aarch64/mte_user_helper.c
>> new file mode 100644
>> index 0000000000..8be6deaf03
>> --- /dev/null
>> +++ b/linux-user/aarch64/mte_user_helper.c
>> @@ -0,0 +1,34 @@
>> +/*
>> + * ARM MemTag convenience functions.
>> + *
>> + * This code is licensed under the GNU GPL v2 or later.
>> + *
>> + * SPDX-License-Identifier: LGPL-2.1-or-later
>> + */
>> +
>> +#include <sys/prctl.h>
> 
> Aside from missing the osdep Phillipe pointed out including prctl.h here
> is very suspect as its a system header. I assume if we need
> PR_MTE_TCF_SYNC we should hoist the definition that linux-user uses into
> a common header.
Other .c files include <sys/prctl.h> for other PR_ definitions. For example,
syscall.c and elfload.c. Is this really a problem? I see that would be a
problem when trying to build, for instance, aarch64-linux-user target on a
BSD host, but we don't support it. Building *-linux-user target is only
supported on Linux host, no?


Cheers,
Gustavo