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 <li...@roeck-us.net>
Signed-off-by: Masahiro Yamada <masahi...@kernel.org>
---

 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

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