linux/export: fix reference to exported functions for parisc64

commit 08700ec upstream.

John David Anglin reported parisc has been broken since commit
ddb5cdb ("kbuild: generate KSYMTAB entries by modpost").

Like ia64, parisc64 uses a function descriptor. The function
references must be prefixed with P%.

Also, symbols prefixed $$ from the library have the symbol type
STT_LOPROC instead of STT_FUNC. They should be handled as functions
too.

Fixes: ddb5cdb ("kbuild: generate KSYMTAB entries by modpost")
Reported-by: John David Anglin <dave.anglin@bell.net>
Tested-by: John David Anglin <dave.anglin@bell.net>
Tested-by: Helge Deller <deller@gmx.de>
Closes: https://lore.kernel.org/linux-parisc/1901598a-e11d-f7dd-a5d9-9a69d06e6b6e@bell.net/T/#u
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/export-internal.h

@@ -52,6 +52,8 @@
 
 #ifdef CONFIG_IA64
 #define KSYM_FUNC(name)		@fptr(name)
+#elif defined(CONFIG_PARISC) && defined(CONFIG_64BIT)
+#define KSYM_FUNC(name)		P%name
 #else
 #define KSYM_FUNC(name)		name
 #endif

scripts/mod/modpost.c

@@ -1226,6 +1226,15 @@ static void check_export_symbol(struct module *mod, struct elf_info *elf,
 	 */
 	s->is_func = (ELF_ST_TYPE(sym->st_info) == STT_FUNC);
 
+	/*
+	 * For parisc64, symbols prefixed $$ from the library have the symbol type
+	 * STT_LOPROC. They should be handled as functions too.
+	 */
+	if (elf->hdr->e_ident[EI_CLASS] == ELFCLASS64 &&
+	    elf->hdr->e_machine == EM_PARISC &&
+	    ELF_ST_TYPE(sym->st_info) == STT_LOPROC)
+		s->is_func = true;
+
 	if (match(secname, PATTERNS(INIT_SECTIONS)))
 		warn("%s: %s: EXPORT_SYMBOL used for init symbol. Remove __init or EXPORT_SYMBOL.\n",
 		     mod->name, name);