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SubjectRe: Remaining randconfig objtool warnings, linux-next-20200428
On Thu, Apr 30, 2020 at 12:46:57AM +0200, Arnd Bergmann wrote:
> On Wed, Apr 29, 2020 at 8:55 PM Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> >
> > On Tue, Apr 28, 2020 at 11:10:44AM -0500, Josh Poimboeuf wrote:
> > > > ==> build/x86/0xE0F2ACFF_defconfig/log <==
> > > > kernel/time/posix-stubs.o: warning: objtool: __x64_sys_timer_create()+0x23: sibling call from callable instruction with modified stack frame
> >
> > This one is fixed with the following cleanup:
> >
> > From: Josh Poimboeuf <jpoimboe@redhat.com>
> > Subject: [PATCH] linkage: Convert syscall alias macros to C
> >
> > There's no need to use inline asm to create ELF alias symbols.
> > Annotated C function declarations can be used instead.
> >
> > This also makes the ordering of the ELF symbol table more logical, with
> > the real function now always coming before the aliases. This makes it
> > easier for objtool, objdump and other tools to differentiate them.
> >
> > This fixes the following warning:
> >
> > kernel/time/posix-stubs.o: warning: objtool: __x64_sys_timer_create()+0x23: sibling call from callable instruction with modified stack frame
> >
> > Reported-by: Arnd Bergmann <arnd@arndb.de>
> > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> > ---
> > include/linux/linkage.h | 14 ++++----------
> > 1 file changed, 4 insertions(+), 10 deletions(-)
>
> Unfortunately, this patch leads to new warnings when
> CONFIG_POSIX_TIMERS is disabled:
>
> In file included from /git/arm-soc/kernel/time/posix-stubs.c:9:
> /git/arm-soc/kernel/time/posix-stubs.c:35:37: error: conflicting types
> for 'sys_timer_create'
> 35 | #define SYS_NI(name) SYSCALL_ALIAS(sys_##name, sys_ni_posix_timers)
> | ^~~~
> /git/arm-soc/include/linux/linkage.h:26:63: note: in definition of
> macro 'SYSCALL_ALIAS'
> 26 | #define SYSCALL_ALIAS(alias, name) __alias(name) typeof(name) alias
> | ^~~~~
> /git/arm-soc/kernel/time/posix-stubs.c:42:1: note: in expansion of
> macro 'SYS_NI'
> 42 | SYS_NI(timer_create);
> | ^~~~~~
> In file included from /git/arm-soc/kernel/time/posix-stubs.c:13:
> /git/arm-soc/include/linux/syscalls.h:616:17: note: previous
> declaration of 'sys_timer_create' was here
> 616 | asmlinkage long sys_timer_create(clockid_t which_clock,
> | ^~~~~~~~~~~~~~~~
>
> We can probably move those SYS_NI() instances to kernel/sys_ni.c,
> which does not include the header, but it's still a bit ugly. I'll try
> that tomorrow
> unless you come up with a better suggestion first.

Oh I guess arm32 doesn't have SYS_NI defined. All this syscall aliasing
stuff is a total mystery to me.

--
Josh

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