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SubjectRe: [PATCH] fix for kallsyms module symbol resolution problem
Date
In message <1057026277.2069.80.camel@mulgrave> you write:
> OK, how about the attached. I think it solves the module_text_address()
> problem too.

Excellent: tested on bk8. Linus, please apply (subsumes previous
patch: if you get a couple of rej's ignore them).

James: I changed the names to s/code/text/ since that's more expected
for toolchain-type people. I frobbed the NOTE: comment a bit, and
moved the m == 0 tests outside the section loop.

Thanks!
Rusty.

================
Name: Identify Code Section Of Modules for kallsyms
Author: James Bottomley
Status: Tested on 2.5.73-bk8
D: Remember the size of the SHF_EXECINSTR sections, which are conveniently
D: at the start of the modules, and use that to more reliably implement
D: module_text_address().

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .5304-linux-2.5.73-bk8/include/linux/module.h .5304-linux-2.5.73-bk8.updated/include/linux/module.h
--- .5304-linux-2.5.73-bk8/include/linux/module.h 2003-06-15 11:30:08.000000000 +1000
+++ .5304-linux-2.5.73-bk8.updated/include/linux/module.h 2003-07-01 14:15:16.000000000 +1000
@@ -217,6 +217,9 @@ struct module
/* Here are the sizes of the init and core sections */
unsigned long init_size, core_size;

+ /* The size of the executable code in each section. */
+ unsigned long init_text_size, core_text_size;
+
/* Arch-specific module values */
struct mod_arch_specific arch;

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .5304-linux-2.5.73-bk8/kernel/module.c .5304-linux-2.5.73-bk8.updated/kernel/module.c
--- .5304-linux-2.5.73-bk8/kernel/module.c 2003-06-15 11:30:11.000000000 +1000
+++ .5304-linux-2.5.73-bk8.updated/kernel/module.c 2003-07-01 14:37:18.000000000 +1000
@@ -1176,6 +1176,9 @@ static void layout_sections(struct modul
const char *secstrings)
{
static unsigned long const masks[][2] = {
+ /* NOTE: all executable code must be the first section
+ * in this array; otherwise modify the text_size
+ * finder in the two loops below */
{ SHF_EXECINSTR | SHF_ALLOC, ARCH_SHF_SMALL },
{ SHF_ALLOC, SHF_WRITE | ARCH_SHF_SMALL },
{ SHF_WRITE | SHF_ALLOC, ARCH_SHF_SMALL },
@@ -1199,6 +1202,8 @@ static void layout_sections(struct modul
s->sh_entsize = get_offset(&mod->core_size, s);
DEBUGP("\t%s\n", secstrings + s->sh_name);
}
+ if (m == 0)
+ mod->core_text_size = mod->core_size;
}

DEBUGP("Init section allocation order:\n");
@@ -1215,6 +1220,8 @@ static void layout_sections(struct modul
| INIT_OFFSET_MASK);
DEBUGP("\t%s\n", secstrings + s->sh_name);
}
+ if (m == 0)
+ mod->init_text_size = mod->init_size;
}
}

@@ -1726,6 +1733,7 @@ sys_init_module(void __user *umod,
module_free(mod, mod->module_init);
mod->module_init = NULL;
mod->init_size = 0;
+ mod->init_text_size = 0;
up(&module_mutex);

return 0;
@@ -1747,9 +1755,9 @@ static const char *get_ksymbol(struct mo

/* At worse, next value is at end of module */
if (within(addr, mod->module_init, mod->init_size))
- nextval = (unsigned long)mod->module_init + mod->init_size;
+ nextval = (unsigned long)mod->module_init+mod->init_text_size;
else
- nextval = (unsigned long)mod->module_core + mod->core_size;
+ nextval = (unsigned long)mod->module_core+mod->core_text_size;

/* Scan for closest preceeding symbol, and next symbol. (ELF
starts real symbols at 1). */
@@ -1757,11 +1765,15 @@ static const char *get_ksymbol(struct mo
if (mod->symtab[i].st_shndx == SHN_UNDEF)
continue;

+ /* We ignore unnamed symbols: they're uninformative
+ * and inserted at a whim. */
if (mod->symtab[i].st_value <= addr
- && mod->symtab[i].st_value > mod->symtab[best].st_value)
+ && mod->symtab[i].st_value > mod->symtab[best].st_value
+ && *(mod->strtab + mod->symtab[i].st_name) != '\0' )
best = i;
if (mod->symtab[i].st_value > addr
- && mod->symtab[i].st_value < nextval)
+ && mod->symtab[i].st_value < nextval
+ && *(mod->strtab + mod->symtab[i].st_name) != '\0')
nextval = mod->symtab[i].st_value;
}

@@ -1910,8 +1924,8 @@ struct module *module_text_address(unsig
struct module *mod;

list_for_each_entry(mod, &modules, list)
- if (within(addr, mod->module_init, mod->init_size)
- || within(addr, mod->module_core, mod->core_size))
+ if (within(addr, mod->module_init, mod->init_text_size)
+ || within(addr, mod->module_core, mod->core_text_size))
return mod;
return NULL;
}
--
Anyone who quotes me in their sig is an idiot. -- Rusty Russell.
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