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Commit 91dc182c authored by Dave C Boutcher's avatar Dave C Boutcher Committed by Paul Mackerras
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[PATCH] powerpc: special-case ibm,suspend-me RTAS call 



Handle the ibm,suspend-me RTAS call specially.  It needs
to be wrapped in a set of synchronization hypervisor calls
(H_Join).  When the H_Join calls are made on all CPUs, the
intent is that only one will return with H_Continue, meaning
that he is the "last man standing".  That CPU then issues the
ibm,suspend-me call.  What is interesting, of course, is that
the CPU running when the rtas syscall is made, may NOT be the
CPU that ultimately executes the ibm,suspend-me rtas call.

Signed-off-by: default avatarDave Boutcher <sleddog@us.ibm.com>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent 91f62a24

arch/powerpc/kernel/rtas.c

+95 −1
Original line number Diff line number Diff line
@@ -36,6 +36,11 @@ struct rtas_t rtas = { 
	.lock = SPIN_LOCK_UNLOCKED

};



struct rtas_suspend_me_data {

	long waiting;

	struct rtas_args *args;

};



EXPORT_SYMBOL(rtas);



DEFINE_SPINLOCK(rtas_data_buf_lock);
@@ -556,6 +561,80 @@ void rtas_os_term(char *str) 
	} while (status == RTAS_BUSY);

}



static int ibm_suspend_me_token = RTAS_UNKNOWN_SERVICE;

#ifdef CONFIG_PPC_PSERIES

static void rtas_percpu_suspend_me(void *info)

{

	long rc;

	long flags;

	struct rtas_suspend_me_data *data =

		(struct rtas_suspend_me_data *)info;



	/*

	 * We use "waiting" to indicate our state.  As long

	 * as it is >0, we are still trying to all join up.

	 * If it goes to 0, we have successfully joined up and

	 * one thread got H_Continue.  If any error happens,

	 * we set it to <0.

	 */

	local_irq_save(flags);

	do {

		rc = plpar_hcall_norets(H_JOIN);

		smp_rmb();

	} while (rc == H_Success && data->waiting > 0);

	if (rc == H_Success)

		goto out;



	if (rc == H_Continue) {

		data->waiting = 0;

		rtas_call(ibm_suspend_me_token, 0, 1,

			  data->args->args);

	} else {

		data->waiting = -EBUSY;

		printk(KERN_ERR "Error on H_Join hypervisor call\n");

	}



out:

	/* before we restore interrupts, make sure we don't

	 * generate a spurious soft lockup errors

	 */

	touch_softlockup_watchdog();

	local_irq_restore(flags);

	return;

}



static int rtas_ibm_suspend_me(struct rtas_args *args)

{

	int i;



	struct rtas_suspend_me_data data;



	data.waiting = 1;

	data.args = args;



	/* Call function on all CPUs.  One of us will make the

	 * rtas call

	 */

	if (on_each_cpu(rtas_percpu_suspend_me, &data, 1, 0))

		data.waiting = -EINVAL;



	if (data.waiting != 0)

		printk(KERN_ERR "Error doing global join\n");



	/* Prod each CPU.  This won't hurt, and will wake

	 * anyone we successfully put to sleep with H_Join

	 */

	for_each_cpu(i)

		plpar_hcall_norets(H_PROD, i);



	return data.waiting;

}

#else /* CONFIG_PPC_PSERIES */

static int rtas_ibm_suspend_me(struct rtas_args *args)

{

	return -ENOSYS;

}

#endif



asmlinkage int ppc_rtas(struct rtas_args __user *uargs)

{
@@ -563,6 +642,7 @@ asmlinkage int ppc_rtas(struct rtas_args __user *uargs) 
	unsigned long flags;

	char *buff_copy, *errbuf = NULL;

	int nargs;

	int rc;



	if (!capable(CAP_SYS_ADMIN))

		return -EPERM;
@@ -581,6 +661,17 @@ asmlinkage int ppc_rtas(struct rtas_args __user *uargs) 
			   nargs * sizeof(rtas_arg_t)) != 0)

		return -EFAULT;



	if (args.token == RTAS_UNKNOWN_SERVICE)

		return -EINVAL;



	/* Need to handle ibm,suspend_me call specially */

	if (args.token == ibm_suspend_me_token) {

		rc = rtas_ibm_suspend_me(&args);

		if (rc)

			return rc;

		goto copy_return;

	}



	buff_copy = get_errorlog_buffer();



	spin_lock_irqsave(&rtas.lock, flags);
@@ -604,6 +695,7 @@ asmlinkage int ppc_rtas(struct rtas_args __user *uargs) 
		kfree(buff_copy);

	}



 copy_return:

	/* Copy out args. */

	if (copy_to_user(uargs->args + nargs,

			 args.args + nargs,
@@ -675,8 +767,10 @@ void __init rtas_initialize(void) 
	 * the stop-self token if any

	 */

#ifdef CONFIG_PPC64

	if (_machine == PLATFORM_PSERIES_LPAR)

	if (_machine == PLATFORM_PSERIES_LPAR) {

		rtas_region = min(lmb.rmo_size, RTAS_INSTANTIATE_MAX);

		ibm_suspend_me_token = rtas_token("ibm,suspend-me");

	}

#endif

	rtas_rmo_buf = lmb_alloc_base(RTAS_RMOBUF_MAX, PAGE_SIZE, rtas_region);