diff options
Diffstat (limited to 'arch/arm64/kernel/ftrace.c')
| -rw-r--r-- | arch/arm64/kernel/ftrace.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c index 8e4431a8821f..65a51331088e 100644 --- a/arch/arm64/kernel/ftrace.c +++ b/arch/arm64/kernel/ftrace.c @@ -103,12 +103,16 @@ 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 (!plt_entries_equal(mod->arch.ftrace_trampoline, - &(struct plt_entry){})) { + 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; } |