Re: [PATCH] parisc: fix module loading failure of large kernel modules (take 4)

Rusty Russell
2009-01-01T00:52:20Z

On Thursday 01 January 2009 00:43:56 Helge Deller wrote:
> Rusty Russell wrote:
> > Not quite what I had in mind... let me show you:
> > ...
> > Otherwise I'd have called it "arch_module_extra_size()".
>
> This would mean that I can increase the section size in the arch-specific function
> by returning a bigger value than sh_size.
> This would give me space at the end of the section, but not at the beginning
> (which is what I need), as sh_entsize (the offset into memory) will stay the
> same as before.

Ah, OK. I assumed that extra room at the end was sufficient.

So I've taken your previous patch and renamed the function to
arch_mod_section_prepend(). If we decide not to kill those bad gcc versions,
I'll stick it in some other random file (lib/weak.c? Blech...)

BTW, this is very late for this merge window. I would have liked to see
this a month ago :(

Subject: module: fix module loading failure of large kernel modules for parisc
Date: Wed, 31 Dec 2008 12:31:18 +0100
From: Helge Deller <deller@gmx.de>

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)

diff --git a/include/linux/moduleloader.h b/include/linux/moduleloader.h
--- a/include/linux/moduleloader.h
+++ b/include/linux/moduleloader.h
@@ -12,6 +12,9 @@ int module_frob_arch_sections(Elf_Ehdr *
Elf_Shdr *sechdrs,
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. */
diff --git a/kernel/module.c b/kernel/module.c
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1588,11 +1588,21 @@ static int simplify_symbols(Elf_Shdr *se
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;
@@ -1632,7 +1642,7 @@ static void layout_sections(struct modul
|| 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)
@@ -1650,7 +1660,7 @@ static void layout_sections(struct modul
|| 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);
}