[PATCH v3 04/13] x86/um: nommu: syscall handling

[Johannes Berg]

On Tue, 2024-12-03 at 13:23 +0900, Hajime Tazaki wrote:
> This commit introduces an entry point of syscall interface for !MMU
> mode. It uses an entry function, __kernel_vsyscall, a kernel-wide global
> symbol accessible from any locations.
> 
> Although it isn't in the scope of this commit, it can be also exposed
> via vdso image which is directly accessible from userspace. A standard
> library (i.e., libc) can utilize this entry point to implement syscall
> wrapper; we can also use this by hooking syscall for unmodified userspace
> applications/libraries, which will be implemented in the subsequent
> commit.
> 
> This only supports 64-bit mode of x86 architecture.
> 
> Signed-off-by: Hajime Tazaki <thehajime at gmail.com>
> Signed-off-by: Ricardo Koller <ricarkol at google.com>
> ---
>  arch/x86/um/do_syscall_64.c             | 37 +++++++++++
>  arch/x86/um/entry_64.S                  | 87 +++++++++++++++++++++++++
> 

As I said before, I think it needs to be something obviously nommu.
Maybe in a new directory, or maybe nommu_syscall_64.c or something like
that.

Also needs comment style fixes and I'm not sure about all the
pr_debug(), but I guess they don't matter unless someone defines it? 

johannes