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SubjectRe: Remaining randconfig objtool warnings, linux-next-20200428
On Thu, Apr 30, 2020 at 02:46:30PM -0500, Josh Poimboeuf wrote:
> > Yup, makes sense. I think I've been getting confused by the syscall
> > wrappers.
> >
> > > How hard would it be to change objtool instead of changing the sources?

So I just realized this is an objtool bug after all. Or at least a new
GCC quirk. The quick fix is:

sed -si 's/cold./cold/' tools/objtool/check.c

However... after studying how all this works, I'm actually thinking that
it makes sense to move the SYS_NI usage into kernel/sys_ni.c, like you
originally suggested. That seems cleaner to me: all the syscall
aliasing code together in one file. SYS_NI is similar to COND_SYSCALL,
except it has a custom ENOSYS handler. Having "NI" in the name is
another clue it belongs in sys_ni.c.

Alternatively, I could do the x86-specific SYSCALL_ALIAS, which is easy
enough, but I really prefer the sys_ni.c approach.

Either of those would allow the removal of some hacky objtool code,
which only ever existed in the first place because of posix-stubs.c and
that inline asm SYSCALL_ALIAS macro.

One of objtool's goals is to standardize ELF data, and it seems
reasonable to require the use of C-based aliases. And I think it would
be a nice cleanup anyway.

--
Josh

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