riscv: Introduce set_compat_task() in asm/compat.h

In order to have all task compat bit access directly in compat.h, introduce
set_compat_task() to set/reset those when needed.

Also, since it's only used on an if/else scenario, simplify the macro using
it.

Signed-off-by: Leonardo Bras <leobras@redhat.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Link: https://lore.kernel.org/r/20240103160024.70305-7-leobras@redhat.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

riscv: Introduce is_compat_thread() into compat.h

task_user_regset_view() makes use of a function very similar to
is_compat_task(), but pointing to a any thread.

In arm64 asm/compat.h there is a function very similar to that:
is_compat_thread(struct thread_info *thread)

Copy this function to riscv asm/compat.h and make use of it into
task_user_regset_view().

Also, introduce a compile-time test for CONFIG_COMPAT and simplify the
function code by removing the #ifdef.

Signed-off-by: Leonardo Bras <leobras@redhat.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Andy Chiu <andy.chiu@sifive.com>
Link: https://lore.kernel.org/r/20240103160024.70305-6-leobras@redhat.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

riscv: add compile-time test into is_compat_task()

Currently several places will test for CONFIG_COMPAT before testing
is_compat_task(), probably in order to avoid a run-time test into the task
structure.

Since is_compat_task() is an inlined function, it would be helpful to add a
compile-time test of CONFIG_COMPAT, making sure it always returns zero when
the option is not enabled during the kernel build.

With this, the compiler is able to understand in build-time that
is_compat_task() will always return 0, and optimize-out some of the extra
code introduced by the option.

This will also allow removing a lot #ifdefs that were introduced, and make
the code more clean.

Signed-off-by: Leonardo Bras <leobras@redhat.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Andy Chiu <andy.chiu@sifive.com>
Link: https://lore.kernel.org/r/20240103160024.70305-5-leobras@redhat.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

riscv: compat: Add basic compat data type implementation

Implement riscv asm/compat.h for struct compat_xxx,
is_compat_task, compat_user_regset, regset convert.

The rv64 compat.h has inherited most of the structs
from the generic one.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20220405071314.3225832-10-guoren@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>