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-rw-r--r--arch/arm64/kernel/ftrace.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index 07b298120182..65a51331088e 100644
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -103,10 +103,15 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
* to be revisited if support for multiple ftrace entry points
* is added in the future, but for now, the pr_err() below
* deals with a theoretical issue only.
+ *
+ * Note that PLTs are place relative, and plt_entries_equal()
+ * checks whether they point to the same target. Here, we need
+ * to check if the actual opcodes are in fact identical,
+ * regardless of the offset in memory so use memcmp() instead.
*/
trampoline = get_plt_entry(addr, mod->arch.ftrace_trampoline);
- if (!plt_entries_equal(mod->arch.ftrace_trampoline,
- &trampoline)) {
+ if (memcmp(mod->arch.ftrace_trampoline, &trampoline,
+ sizeof(trampoline))) {
if (plt_entry_is_initialized(mod->arch.ftrace_trampoline)) {
pr_err("ftrace: far branches to multiple entry points unsupported inside a single module\n");
return -EINVAL;