summaryrefslogtreecommitdiff
path: root/arch/arm64/kernel/ftrace.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/arm64/kernel/ftrace.c')
-rw-r--r--arch/arm64/kernel/ftrace.c27
1 files changed, 18 insertions, 9 deletions
diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index 50986e388d2b..6eefd5873aef 100644
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -76,7 +76,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
if (offset < -SZ_128M || offset >= SZ_128M) {
#ifdef CONFIG_ARM64_MODULE_PLTS
- struct plt_entry trampoline;
+ struct plt_entry trampoline, *dst;
struct module *mod;
/*
@@ -104,24 +104,33 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
* is added in the future, but for now, the pr_err() below
* deals with a theoretical issue only.
*/
+ dst = mod->arch.ftrace_trampoline;
trampoline = get_plt_entry(addr);
- if (!plt_entries_equal(mod->arch.ftrace_trampoline,
- &trampoline)) {
- if (!plt_entries_equal(mod->arch.ftrace_trampoline,
- &(struct plt_entry){})) {
+ if (!plt_entries_equal(dst, &trampoline)) {
+ if (!plt_entries_equal(dst, &(struct plt_entry){})) {
pr_err("ftrace: far branches to multiple entry points unsupported inside a single module\n");
return -EINVAL;
}
/* point the trampoline to our ftrace entry point */
module_disable_ro(mod);
- *mod->arch.ftrace_trampoline = trampoline;
+ *dst = trampoline;
module_enable_ro(mod, true);
- /* update trampoline before patching in the branch */
- smp_wmb();
+ /*
+ * Ensure updated trampoline is visible to instruction
+ * fetch before we patch in the branch. Although the
+ * architecture doesn't require an IPI in this case,
+ * Neoverse-N1 erratum #1542419 does require one
+ * if the TLB maintenance in module_enable_ro() is
+ * skipped due to rodata_enabled. It doesn't seem worth
+ * it to make it conditional given that this is
+ * certainly not a fast-path.
+ */
+ flush_icache_range((unsigned long)&dst[0],
+ (unsigned long)&dst[1]);
}
- addr = (unsigned long)(void *)mod->arch.ftrace_trampoline;
+ addr = (unsigned long)dst;
#else /* CONFIG_ARM64_MODULE_PLTS */
return -EINVAL;
#endif /* CONFIG_ARM64_MODULE_PLTS */