module: fix module loading failure of large kernel modules for parisc

When creating the final layout of a kernel module in memory, allow the
module loader to reserve some additional memory in front of a given section.
This is currently only needed for the parisc port which needs to put the
stub entries there to fulfill the 17/22bit PCREL relocations with large
kernel modules like xfs.

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (renamed fn)

2 files changed, 16 insertions, 3 deletions

diff --git a/include/linux/moduleloader.h b/include/linux/moduleloader.h
index eb1033957486..c1f40c2f7ffb 100644
--- a/include/linux/moduleloader.h
+++ b/include/linux/moduleloader.h
@@ -13,6 +13,9 @@ int module_frob_arch_sections(Elf_Ehdr *hdr,
                               char *secstrings,
                               struct module *mod);
 
+/* Additional bytes needed by arch in front of individual sections */
+unsigned int arch_mod_section_prepend(struct module *mod, unsigned int section);
+
 /* Allocator used for allocating struct module, core sections and init
    sections.  Returns NULL on failure. */
 void *module_alloc(unsigned long size);
diff --git a/kernel/module.c b/kernel/module.c
index d3d254571bda..4299aefc20b8 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1578,11 +1578,21 @@ static int simplify_symbols(Elf_Shdr *sechdrs,
         return ret;
 }
 
+/* Additional bytes needed by arch in front of individual sections */
+unsigned int __weak arch_mod_section_prepend(struct module *mod,
+                                             unsigned int section)
+{
+        /* default implementation just returns zero */
+        return 0;
+}
+
 /* Update size with this section: return offset. */
-static long get_offset(unsigned int *size, Elf_Shdr *sechdr)
+static long get_offset(struct module *mod, unsigned int *size,
+                       Elf_Shdr *sechdr, unsigned int section)
 {
         long ret;
 
+        *size += arch_mod_section_prepend(mod, section);
         ret = ALIGN(*size, sechdr->sh_addralign ?: 1);
         *size = ret + sechdr->sh_size;
         return ret;
@@ -1622,7 +1632,7 @@ static void layout_sections(struct module *mod,
                             || strncmp(secstrings + s->sh_name,
                                        ".init", 5) == 0)
                                 continue;
-                        s->sh_entsize = get_offset(&mod->core_size, s);
+                        s->sh_entsize = get_offset(mod, &mod->core_size, s, i);
                         DEBUGP("\t%s\n", secstrings + s->sh_name);
                 }
                 if (m == 0)
@@ -1640,7 +1650,7 @@ static void layout_sections(struct module *mod,
                             || strncmp(secstrings + s->sh_name,
                                        ".init", 5) != 0)
                                 continue;
-                        s->sh_entsize = (get_offset(&mod->init_size, s)
+                        s->sh_entsize = (get_offset(mod, &mod->init_size, s, i)
                                          | INIT_OFFSET_MASK);
                         DEBUGP("\t%s\n", secstrings + s->sh_name);
                 }