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Merge pull request #448 from jpoimboe/static-local-fixes 

improve static local variable correlation
This commit is contained in:
Seth Jennings 2014-10-06 23:56:24 -05:00
parent 5ebe1f6a6e 2a29d8704e
commit 8e9aa2b559
2 changed files with 121 additions and 34 deletions
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109
kpatch-build/create-diff-object.c
View File

@ -932,6 +932,58 @@ void kpatch_rename_mangled_functions(struct kpatch_elf *base,
}
}
static char *kpatch_section_function_name(struct section *sec)
{
if (is_rela_section(sec))
sec = sec->base;
return sec->sym ? sec->sym->name : sec->name;
}
/*
* Given a static local variable symbol and a section which references it in
* the patched object, find a corresponding usage of a similarly named symbol
* in the base object.
*/
static struct symbol *kpatch_find_static_twin(struct section *sec,
struct symbol *sym)
{
struct rela *rela;
struct symbol *basesym;
if (!sec->twin)
return NULL;
/*
* Ensure there are no other orphaned static variables with the
* same name in the function. This is possible if the
* variables are in different scopes or if one of them is part of an
* inlined function.
*/
list_for_each_entry(rela, &sec->relas, list) {
if (rela->sym == sym || rela->sym->twin)
continue;
if (!kpatch_mangled_strcmp(rela->sym->name, sym->name))
ERROR("found another static local variable matching %s in patched %s",
sym->name, kpatch_section_function_name(sec));
}
/* find the base object's corresponding variable */
basesym = NULL;
list_for_each_entry(rela, &sec->twin->relas, list) {
if (rela->sym->twin)
continue;
if (kpatch_mangled_strcmp(rela->sym->name, sym->name))
continue;
if (basesym && basesym != rela->sym)
ERROR("found two static local variables matching %s in orig %s",
sym->name, kpatch_section_function_name(sec));
basesym = rela->sym;
}
return basesym;
}
/*
* gcc renames static local variables by appending a period and a number. For
* example, __foo could be renamed to __foo.31452. Unfortunately this number
@ -941,7 +993,7 @@ void kpatch_rename_mangled_functions(struct kpatch_elf *base,
void kpatch_correlate_static_local_variables(struct kpatch_elf *base,
struct kpatch_elf *patched)
{
struct symbol *sym, *basesym;
struct symbol *sym, *basesym, *tmpsym;
struct section *tmpsec, *sec;
struct rela *rela;
int bundled, basebundled;
@ -958,12 +1010,16 @@ void kpatch_correlate_static_local_variables(struct kpatch_elf *base,
continue;
/*
* Find the first function which uses the static variable.
* For each function which uses the variable in the patched
* object, look for a corresponding use in the function's twin
* in the base object.
*
* It's possible for multiple functions to use the same static
* variable if the containing function is inlined, but we only
* need to find one of them to do the correlation.
* local variable if the variable is defined in an inlined
* function.
*/
sec = NULL;
basesym = NULL;
list_for_each_entry(tmpsec, &patched->sections, list) {
if (!is_rela_section(tmpsec) ||
!is_text_section(tmpsec->base) ||
@ -972,45 +1028,30 @@ void kpatch_correlate_static_local_variables(struct kpatch_elf *base,
list_for_each_entry(rela, &tmpsec->relas, list) {
if (rela->sym != sym)
continue;
tmpsym = kpatch_find_static_twin(tmpsec, sym);
if (basesym && tmpsym && basesym != tmpsym)
ERROR("found two twins for static local variable %s: %s and %s",
sym->name, basesym->name,
tmpsym->name);
if (tmpsym && !basesym)
basesym = tmpsym;
sec = tmpsec;
goto done;
break;
}
}
done:
if (!sec)
ERROR("static local variable %s not used", sym->name);
if (!sec->twin)
if (!basesym) {
log_normal("WARNING: unable to correlate static local variable %s used by %s, assuming variable is new\n",
sym->name,
kpatch_section_function_name(sec));
continue;
/*
* Ensure there are no other orphaned static variables with the
* same name in the function. This is possible if the
* variables are in different scopes (using C braces).
*/
list_for_each_entry(rela, &sec->relas, list) {
if (rela->sym == sym || rela->sym->twin)
continue;
if (!kpatch_mangled_strcmp(rela->sym->name, sym->name))
ERROR("found another static local variable matching %s in patched %s",
sym->name, sec->name);
}
/* find the base object's corresponding variable */
basesym = NULL;
list_for_each_entry(rela, &sec->twin->relas, list) {
if (rela->sym->twin)
continue;
if (kpatch_mangled_strcmp(rela->sym->name, sym->name))
continue;
if (basesym && basesym != rela->sym)
ERROR("found two static local variables matching %s in orig %s",
sym->name, sec->name);
basesym = rela->sym;
}
if (!basesym)
continue;
bundled = sym == sym->sec->sym;
basebundled = basesym == basesym->sec->sym;

46
test/integration/gcc-static-local-var-5.patch Normal file
View File

@ -0,0 +1,46 @@
Index: src/kernel/audit.c
===================================================================
--- src.orig/kernel/audit.c
+++ src/kernel/audit.c
@@ -211,6 +211,12 @@ void audit_panic(const char *message)
}
}
+void kpatch_audit_foo(void)
+{
+ if (!jiffies)
+ printk("kpatch audit foo\n");
+}
+
static inline int audit_rate_check(void)
{
static unsigned long last_check = 0;
@@ -221,6 +227,7 @@ static inline int audit_rate_check(void)
unsigned long elapsed;
int retval = 0;
+ kpatch_audit_foo();
if (!audit_rate_limit) return 1;
spin_lock_irqsave(&lock, flags);
@@ -240,6 +247,11 @@ static inline int audit_rate_check(void)
return retval;
}
+noinline void kpatch_audit_check(void)
+{
+ audit_rate_check();
+}
+
/**
* audit_log_lost - conditionally log lost audit message event
* @message: the message stating reason for lost audit message
@@ -286,6 +298,8 @@ static int audit_log_config_change(char
struct audit_buffer *ab;
int rc = 0;
+ kpatch_audit_check();
+
ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
if (unlikely(!ab))
return rc;