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Subject[rfc 45/45] Modules: Hack to handle symbols that have a zero value
The module subsystem cannot handle symbols that are zero. It prints out
a message that these symbols are unresolved. Define a constant

UNRESOLVED

that is used to hold the value used for unresolved symbols. Set it to 1
(its hopefully unlikely that a symbol will have the value 1). This is necessary
so that the pda variable which is placed at offset 0 of the per cpu
segment is handled correctly.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

---
kernel/module.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)

Index: linux-2.6/kernel/module.c
===================================================================
--- linux-2.6.orig/kernel/module.c 2007-11-19 17:08:40.563625526 -0800
+++ linux-2.6/kernel/module.c 2007-11-19 17:08:40.855625732 -0800
@@ -62,6 +62,7 @@ extern int module_sysfs_initialized;
/* If this is set, the section belongs in the init part of the module */
#define INIT_OFFSET_MASK (1UL << (BITS_PER_LONG-1))

+#define UNRESOLVED 1
/* List of modules, protected by module_mutex or preempt_disable
* (add/delete uses stop_machine). */
static DEFINE_MUTEX(module_mutex);
@@ -285,7 +286,7 @@ static unsigned long __find_symbol(const
}
}
DEBUGP("Failed to find symbol %s\n", name);
- return 0;
+ return UNRESOLVED;
}

/* Search for module by name: must hold module_mutex. */
@@ -755,7 +756,7 @@ void __symbol_put(const char *symbol)
const unsigned long *crc;

preempt_disable();
- if (!__find_symbol(symbol, &owner, &crc, 1))
+ if (__find_symbol(symbol, &owner, &crc, 1) == UNRESOLVED)
BUG();
module_put(owner);
preempt_enable();
@@ -899,7 +900,7 @@ static inline int check_modstruct_versio
const unsigned long *crc;
struct module *owner;

- if (!__find_symbol("struct_module", &owner, &crc, 1))
+ if (__find_symbol("struct_module", &owner, &crc, 1) == UNRESOLVED)
BUG();
return check_version(sechdrs, versindex, "struct_module", mod,
crc);
@@ -952,7 +953,7 @@ static unsigned long resolve_symbol(Elf_
/* use_module can fail due to OOM, or module unloading */
if (!check_version(sechdrs, versindex, name, mod, crc) ||
!use_module(mod, owner))
- ret = 0;
+ ret = UNRESOLVED;
}
return ret;
}
@@ -1345,14 +1346,14 @@ static int verify_export_symbols(struct
const unsigned long *crc;

for (i = 0; i < mod->num_syms; i++)
- if (__find_symbol(mod->syms[i].name, &owner, &crc, 1)) {
+ if (__find_symbol(mod->syms[i].name, &owner, &crc, 1) != UNRESOLVED) {
name = mod->syms[i].name;
ret = -ENOEXEC;
goto dup;
}

for (i = 0; i < mod->num_gpl_syms; i++)
- if (__find_symbol(mod->gpl_syms[i].name, &owner, &crc, 1)) {
+ if (__find_symbol(mod->gpl_syms[i].name, &owner, &crc, 1)!= UNRESOLVED) {
name = mod->gpl_syms[i].name;
ret = -ENOEXEC;
goto dup;
@@ -1402,7 +1403,7 @@ static int simplify_symbols(Elf_Shdr *se
strtab + sym[i].st_name, mod);

/* Ok if resolved. */
- if (sym[i].st_value != 0)
+ if (sym[i].st_value != UNRESOLVED)
break;
/* Ok if weak. */
if (ELF_ST_BIND(sym[i].st_info) == STB_WEAK)
--
-
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