diff options
author | Max Filippov <jcmvbkbc@gmail.com> | 2018-12-21 17:26:20 +0100 |
---|---|---|
committer | Max Filippov <jcmvbkbc@gmail.com> | 2019-01-26 11:02:13 +0100 |
commit | 32a7726c4f4aadfabdb82440d84f88a5a2c8fe13 (patch) | |
tree | 5cdf2947f361d0d90c3322f3121316f93870bd5c /arch | |
parent | xtensa: SMP: fix ccount_timer_shutdown (diff) | |
download | linux-32a7726c4f4aadfabdb82440d84f88a5a2c8fe13.tar.xz linux-32a7726c4f4aadfabdb82440d84f88a5a2c8fe13.zip |
xtensa: SMP: fix secondary CPU initialization
- add missing memory barriers to the secondary CPU synchronization spin
loops; add comment to the matching memory barrier in the boot_secondary
and __cpu_die functions;
- use READ_ONCE/WRITE_ONCE to access cpu_start_id/cpu_start_ccount
instead of reading/writing them directly;
- re-initialize cpu_running every time before starting secondary CPU to
flush possible previous CPU startup results.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/xtensa/kernel/head.S | 5 | ||||
-rw-r--r-- | arch/xtensa/kernel/smp.c | 34 |
2 files changed, 25 insertions, 14 deletions
diff --git a/arch/xtensa/kernel/head.S b/arch/xtensa/kernel/head.S index da08e75100ab..7f009719304e 100644 --- a/arch/xtensa/kernel/head.S +++ b/arch/xtensa/kernel/head.S @@ -276,12 +276,13 @@ should_never_return: movi a2, cpu_start_ccount 1: + memw l32i a3, a2, 0 beqi a3, 0, 1b movi a3, 0 s32i a3, a2, 0 - memw 1: + memw l32i a3, a2, 0 beqi a3, 0, 1b wsr a3, ccount @@ -317,11 +318,13 @@ ENTRY(cpu_restart) rsr a0, prid neg a2, a0 movi a3, cpu_start_id + memw s32i a2, a3, 0 #if XCHAL_DCACHE_IS_WRITEBACK dhwbi a3, 0 #endif 1: + memw l32i a2, a3, 0 dhi a3, 0 bne a2, a0, 1b diff --git a/arch/xtensa/kernel/smp.c b/arch/xtensa/kernel/smp.c index 932d64689bac..c9fc2c4f71b3 100644 --- a/arch/xtensa/kernel/smp.c +++ b/arch/xtensa/kernel/smp.c @@ -195,9 +195,11 @@ static int boot_secondary(unsigned int cpu, struct task_struct *ts) int i; #ifdef CONFIG_HOTPLUG_CPU - cpu_start_id = cpu; - system_flush_invalidate_dcache_range( - (unsigned long)&cpu_start_id, sizeof(cpu_start_id)); + WRITE_ONCE(cpu_start_id, cpu); + /* Pairs with the third memw in the cpu_restart */ + mb(); + system_flush_invalidate_dcache_range((unsigned long)&cpu_start_id, + sizeof(cpu_start_id)); #endif smp_call_function_single(0, mx_cpu_start, (void *)cpu, 1); @@ -206,18 +208,21 @@ static int boot_secondary(unsigned int cpu, struct task_struct *ts) ccount = get_ccount(); while (!ccount); - cpu_start_ccount = ccount; + WRITE_ONCE(cpu_start_ccount, ccount); - while (time_before(jiffies, timeout)) { + do { + /* + * Pairs with the first two memws in the + * .Lboot_secondary. + */ mb(); - if (!cpu_start_ccount) - break; - } + ccount = READ_ONCE(cpu_start_ccount); + } while (ccount && time_before(jiffies, timeout)); - if (cpu_start_ccount) { + if (ccount) { smp_call_function_single(0, mx_cpu_stop, - (void *)cpu, 1); - cpu_start_ccount = 0; + (void *)cpu, 1); + WRITE_ONCE(cpu_start_ccount, 0); return -EIO; } } @@ -237,6 +242,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle) pr_debug("%s: Calling wakeup_secondary(cpu:%d, idle:%p, sp: %08lx)\n", __func__, cpu, idle, start_info.stack); + init_completion(&cpu_running); ret = boot_secondary(cpu, idle); if (ret == 0) { wait_for_completion_timeout(&cpu_running, @@ -298,8 +304,10 @@ void __cpu_die(unsigned int cpu) unsigned long timeout = jiffies + msecs_to_jiffies(1000); while (time_before(jiffies, timeout)) { system_invalidate_dcache_range((unsigned long)&cpu_start_id, - sizeof(cpu_start_id)); - if (cpu_start_id == -cpu) { + sizeof(cpu_start_id)); + /* Pairs with the second memw in the cpu_restart */ + mb(); + if (READ_ONCE(cpu_start_id) == -cpu) { platform_cpu_kill(cpu); return; } |