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SubjectRe: [PATCH] scripts/kallsyms: skip ppc compiler stub *.long_branch.* / *.plt_branch.*
On Wed, Sep 23, 2020 at 5:43 AM Guenter Roeck <linux@roeck-us.net> wrote:
>
> On Wed, Sep 23, 2020 at 02:48:56AM +0900, Masahiro Yamada wrote:
> > PowerPC allmodconfig often fails to build as follows:
> >
> > LD .tmp_vmlinux.kallsyms1
> > KSYM .tmp_vmlinux.kallsyms1.o
> > LD .tmp_vmlinux.kallsyms2
> > KSYM .tmp_vmlinux.kallsyms2.o
> > LD .tmp_vmlinux.kallsyms3
> > KSYM .tmp_vmlinux.kallsyms3.o
> > LD vmlinux
> > SORTTAB vmlinux
> > SYSMAP System.map
> > Inconsistent kallsyms data
> > Try make KALLSYMS_EXTRA_PASS=1 as a workaround
> > make[2]: *** [../Makefile:1162: vmlinux] Error 1
> >
> > Setting KALLSYMS_EXTRA_PASS=1 does not help.
> >
> > This is caused by the compiler inserting stubs such as *.long_branch.*
> > and *.plt_branch.*
> >
> > $ powerpc-linux-nm -n .tmp_vmlinux.kallsyms2
> > [ snip ]
> > c00000000210c000 T __init_begin
> > c00000000210c000 T _sinittext
> > c00000000210c010 t 00000075.plt_branch.da9:19
> > c00000000210c020 t 00000075.plt_branch.1677:5
> > c00000000210c030 t 00000075.long_branch.memmove
> > c00000000210c034 t 00000075.plt_branch.9e0:5
> > c00000000210c044 t 00000075.plt_branch.free_initrd_mem
> > ...
> >
> > Actually, the problem mentioned in scripts/link-vmlinux.sh comments;
> > "In theory it's possible this results in even more stubs, but unlikely"
> > is happening here, and ends up with another kallsyms step required.
> >
> > scripts/kallsyms.c already ignores various compiler stubs. Let's do
> > similar to make kallsysms for PowerPC always succeed in 2 steps.
> >
> > Reported-by: Guenter Roeck <linux@roeck-us.net>
> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
>
> Tested-by: Guenter Roeck <linux@roeck-us.net>
>
> Thanks,
> Guenter
>
> > ---
> >
> > scripts/kallsyms.c | 16 +++++++++++++++-
> > 1 file changed, 15 insertions(+), 1 deletion(-)
> >
> > diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
> > index 0096cd965332..306b9b38150f 100644
> > --- a/scripts/kallsyms.c
> > +++ b/scripts/kallsyms.c
> > @@ -120,17 +120,25 @@ static bool is_ignored_symbol(const char *name, char type)
> > NULL
> > };
> >
> > + static const char * const ignored_matches[] = {
> > + ".long_branch.", /* ppc stub */
> > + ".plt_branch.", /* ppc stub */
> > + NULL
> > + };
> > +
> > const char * const *p;
> >
> > - /* Exclude symbols which vary between passes. */
> > + /* ignore symbol names that exactly match to a particular string. */
> > for (p = ignored_symbols; *p; p++)
> > if (!strcmp(name, *p))
> > return true;
> >
> > + /* ignore symbol names that start with a particular string. */
> > for (p = ignored_prefixes; *p; p++)
> > if (!strncmp(name, *p, strlen(*p)))
> > return true;
> >
> > + /* ignore symbol names that end with a particular string. */
> > for (p = ignored_suffixes; *p; p++) {
> > int l = strlen(name) - strlen(*p);
> >
> > @@ -138,6 +146,12 @@ static bool is_ignored_symbol(const char *name, char type)
> > return true;
> > }
> >
> > + /* ignore symbol names that contain a particular string. */
> > + for (p = ignored_matches; *p; p++) {
> > + if (strstr(name, *p))
> > + return true;
> > + }
> > +
> > if (type == 'U' || type == 'u')
> > return true;
> > /* exclude debugging symbols */
> > --
> > 2.25.1
> >

Applied to linux-kbuild/fixes.



--
Best Regards
Masahiro Yamada

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