diff options
Diffstat (limited to 'arch/arm64/kernel/alternative.c')
| -rw-r--r-- | arch/arm64/kernel/alternative.c | 30 |
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(®ion); + /* 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, ®ion, NULL); + stop_machine(__apply_alternatives_multi_stop, NULL, cpu_online_mask); } void apply_alternatives(void *start, size_t length) |