In cases of duplicate symbols, sympos will be used to disambiguate instead
of val. By default sympos will be 0, and patching will only succeed if
the symbol is unique. Specifying a positive value will ensure that
occurrence of the symbol in kallsyms for the patched object will be used
for patching if it is valid.
Remove klp_verify_callback, klp_verify_args and klp_verify_vmlinux_symbol
as they are no longer used.
>From the klp_reloc structure remove val, as it can be refactored as a
local variable in klp_write_object_relocations.
Signed-off-by: Chris J Arges <chris.j.ar...@canonical.com>
---
include/linux/livepatch.h | 5 ++-
kernel/livepatch/core.c | 81 +++++++++++++----------------------------------
2 files changed, 24 insertions(+), 62 deletions(-)
diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index b60e8ab..a882865 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -67,8 +67,7 @@ struct klp_func {
/**
* struct klp_reloc - relocation structure for live patching
* @loc: address where the relocation will be written
- * @val: address of the referenced symbol (optional,
- * vmlinux patches only)
+ * @sympos: position in kallsyms to disambiguate symbols (optional)
* @type: ELF relocation type
* @name: name of the referenced symbol (for lookup/verification)
* @addend: offset from the referenced symbol
@@ -76,7 +75,7 @@ struct klp_func {
*/
struct klp_reloc {
unsigned long loc;
- unsigned long val;
+ unsigned long sympos;
unsigned long type;
const char *name;
int addend;
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index ebeaa48..5cfe7b5 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -202,45 +202,6 @@ static int klp_find_object_symbol(const char *objname,
const char *name,
return -EINVAL;
}
-struct klp_verify_args {
- const char *name;
- const unsigned long addr;
-};
-
-static int klp_verify_callback(void *data, const char *name,
- struct module *mod, unsigned long addr)
-{
- struct klp_verify_args *args = data;
-
- if (!mod &&
- !strcmp(args->name, name) &&
- args->addr == addr)
- return 1;
-
- return 0;
-}
-
-static int klp_verify_vmlinux_symbol(const char *name, unsigned long addr)
-{
- struct klp_verify_args args = {
- .name = name,
- .addr = addr,
- };
- int ret;
-
- mutex_lock(&module_mutex);
- ret = kallsyms_on_each_symbol(klp_verify_callback, &args);
- mutex_unlock(&module_mutex);
-
- if (!ret) {
- pr_err("symbol '%s' not found at specified address 0x%016lx,
kernel mismatch?\n",
- name, addr);
- return -EINVAL;
- }
-
- return 0;
-}
-
/*
* external symbols are located outside the parent object (where the parent
* object is either vmlinux or the kmod being patched).
@@ -268,6 +229,7 @@ static int klp_write_object_relocations(struct module *pmod,
struct klp_object *obj)
{
int ret;
+ unsigned long val;
struct klp_reloc *reloc;
if (WARN_ON(!klp_is_object_loaded(obj)))
@@ -277,29 +239,30 @@ static int klp_write_object_relocations(struct module
*pmod,
return -EINVAL;
for (reloc = obj->relocs; reloc->name; reloc++) {
- if (!klp_is_module(obj)) {
- ret = klp_verify_vmlinux_symbol(reloc->name,
- reloc->val);
- if (ret)
- return ret;
- } else {
- /* module, reloc->val needs to be discovered */
- if (reloc->external)
- ret = klp_find_external_symbol(pmod,
- reloc->name,
- &reloc->val);
- else
- ret = klp_find_object_symbol(obj->mod->name,
- reloc->name,
- 0, &reloc->val);
- if (ret)
- return ret;
- }
+ /* discover the address of the referenced symbol */
+ if (reloc->external) {
+ /*
+ * external symbols aren't specified by the user
+ * therefore sympos should not be used
+ */
+ if (reloc->sympos) {
+ pr_err("symbol '%s' is external and has sympos
%lu\n",
+ reloc->name, reloc->sympos);
+ return -EINVAL;
+ }
+ ret = klp_find_external_symbol(pmod, reloc->name, &val);
+ } else
+ ret = klp_find_object_symbol(obj->mod->name,
+ reloc->name,
+ reloc->sympos,
+ &val);
+ if (ret)
+ return ret;
ret = klp_write_module_reloc(pmod, reloc->type, reloc->loc,
- reloc->val + reloc->addend);
+ val + reloc->addend);
if (ret) {
pr_err("relocation failed for symbol '%s' at 0x%016lx
(%d)\n",
- reloc->name, reloc->val, ret);
+ reloc->name, val, ret);
return ret;
}
}
--
1.9.1
--
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