On Mon, Oct 8, 2018 at 7:01 PM Kieran Bingham kieran.bingham+renesas@ideasonboard.com wrote:
On 06/10/18 23:06, Masahiro Yamada wrote:
On Sun, Oct 7, 2018 at 6:58 AM Masahiro Yamada yamada.masahiro@socionext.com wrote:
Hi Miguel,
On Sun, Oct 7, 2018 at 6:18 AM Miguel Ojeda miguel.ojeda.sandonis@gmail.com wrote:
On Fri, Oct 5, 2018 at 10:35 AM Arnd Bergmann arnd@arndb.de wrote:
Building any configuration with 'make W=1' produces a warning:
kernel/bounds.c:16:6: warnign: no previous prototype for 'foo' [-Wmissing-prototypes]
When also passing -Werror, this prevents us from building any other files. Nobody ever calls the function, but we can't make it 'static' either since we want the compiler output.
Calling it 'main' instead however avoids the warning, because gcc does not insist on having a declaration for main.
I think marking the function as static __used should do the trick and would be less confusing.
I tried __used, but I still see the warning.
masahiro@grover:~/ref/linux$ git diff diff --git a/kernel/bounds.c b/kernel/bounds.c index c373e88..aee0101 100644 --- a/kernel/bounds.c +++ b/kernel/bounds.c @@ -13,7 +13,7 @@ #include <linux/log2.h> #include <linux/spinlock_types.h>
-void foo(void) +void __used foo(void) { /* The enum constants to put into include/generated/bounds.h */ DEFINE(NR_PAGEFLAGS, __NR_PAGEFLAGS); masahiro@grover:~/ref/linux$ make W=1 prepare CC kernel/bounds.s kernel/bounds.c:16:13: warning: no previous prototype for ‘foo’ [-Wmissing-prototypes] void __used foo(void) ^ CC arch/x86/kernel/asm-offsets.s
Sorry, I forgot to add 'static'.
Adding both static and __used worked for me, and I like the idea.
Aha - I'd also tried converting to static in my earlier attempts, but didn't realise we had __used!
updating as "static __used" causes the following diff:
diff -Nurp bounds.s.foo bounds.s.static-used --- bounds.s.foo 2018-10-05 10:20:53.269941404 +0100 +++ bounds.s.static-used 2018-10-08 10:51:18.079309049 +0100 @@ -110,7 +110,6 @@ #NO_APP .align 2 .p2align 3,,7
.global foo .type foo, %functionfoo: stp x29, x30, [sp, -16]! //,,,
I'd say this is a pretty good alternative fix - however I see Arnd's version is already on it's way though akpm's tree...
https://ozlabs.org/~akpm/mmots/broken-out/kbuild-fix-kernel-boundsc-w%3D1-wa...
Anyway, as long as one of the variants gets there I'll be happy :)
I will leave it to Arnd.
When we fix arch/{mips,sparc}/kernel/asm-offsets.c, 'static __used' is just additions.
The 'main(void)' solution would require a little bit restructuring.
FWIW, with my quick analysis, the following should be fixed as well:
arch/alpha/kernel/asm-offsets.c arch/c6x/kernel/asm-offsets.c arch/ia64/kernel/asm-offsets.c arch/ia64/kernel/nr-irqs.c arch/mips/kernel/asm-offsets.c arch/riscv/kernel/asm-offsets.c arch/sparc/kernel/asm-offsets.c arch/x86/kernel/asm-offsets.c arch/x86/um/shared/sysdep/kernel-offsets.h samples/bpf/syscall_nrs.c