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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-12-15 14:52:16 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-12-15 14:52:16 -0300
commit8d91c1e411f55d7ea91b1183a2e9f8088fb4d5be (patch)
treee9891aa6c295060d065adffd610c4f49ecf884f3 /arch/arm64/kernel/alternative.c
parenta71852147516bc1cb5b0b3cbd13639bfd4022dc8 (diff)
Linux-libre 4.3.2-gnu
Diffstat (limited to 'arch/arm64/kernel/alternative.c')
-rw-r--r--arch/arm64/kernel/alternative.c30
1 files changed, 25 insertions, 5 deletions
diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c
index 221b98312..ab9db0e98 100644
--- a/arch/arm64/kernel/alternative.c
+++ b/arch/arm64/kernel/alternative.c
@@ -85,7 +85,7 @@ static u32 get_alt_insn(struct alt_instr *alt, u32 *insnptr, u32 *altinsnptr)
return insn;
}
-static int __apply_alternatives(void *alt_region)
+static void __apply_alternatives(void *alt_region)
{
struct alt_instr *alt;
struct alt_region *region = alt_region;
@@ -114,19 +114,39 @@ static int __apply_alternatives(void *alt_region)
flush_icache_range((uintptr_t)origptr,
(uintptr_t)(origptr + nr_inst));
}
-
- return 0;
}
-void apply_alternatives_all(void)
+/*
+ * We might be patching the stop_machine state machine, so implement a
+ * really simple polling protocol here.
+ */
+static int __apply_alternatives_multi_stop(void *unused)
{
+ static int patched = 0;
struct alt_region region = {
.begin = __alt_instructions,
.end = __alt_instructions_end,
};
+ /* We always have a CPU 0 at this point (__init) */
+ if (smp_processor_id()) {
+ while (!READ_ONCE(patched))
+ cpu_relax();
+ isb();
+ } else {
+ BUG_ON(patched);
+ __apply_alternatives(&region);
+ /* Barriers provided by the cache flushing */
+ WRITE_ONCE(patched, 1);
+ }
+
+ return 0;
+}
+
+void __init apply_alternatives_all(void)
+{
/* better not try code patching on a live SMP system */
- stop_machine(__apply_alternatives, &region, NULL);
+ stop_machine(__apply_alternatives_multi_stop, NULL, cpu_online_mask);
}
void apply_alternatives(void *start, size_t length)