cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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io_event_irq.c (5002B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * Copyright 2010 2011 Mark Nelson and Tseng-Hui (Frank) Lin, IBM Corporation
      4 */
      5
      6#include <linux/errno.h>
      7#include <linux/slab.h>
      8#include <linux/export.h>
      9#include <linux/irq.h>
     10#include <linux/interrupt.h>
     11#include <linux/of.h>
     12#include <linux/list.h>
     13#include <linux/notifier.h>
     14
     15#include <asm/machdep.h>
     16#include <asm/rtas.h>
     17#include <asm/irq.h>
     18#include <asm/io_event_irq.h>
     19
     20#include "pseries.h"
     21
     22/*
     23 * IO event interrupt is a mechanism provided by RTAS to return
     24 * information about hardware error and non-error events. Device
     25 * drivers can register their event handlers to receive events.
     26 * Device drivers are expected to use atomic_notifier_chain_register()
     27 * and atomic_notifier_chain_unregister() to register and unregister
     28 * their event handlers. Since multiple IO event types and scopes
     29 * share an IO event interrupt, the event handlers are called one
     30 * by one until the IO event is claimed by one of the handlers.
     31 * The event handlers are expected to return NOTIFY_OK if the
     32 * event is handled by the event handler or NOTIFY_DONE if the
     33 * event does not belong to the handler.
     34 *
     35 * Usage:
     36 *
     37 * Notifier function:
     38 * #include <asm/io_event_irq.h>
     39 * int event_handler(struct notifier_block *nb, unsigned long val, void *data) {
     40 * 	p = (struct pseries_io_event_sect_data *) data;
     41 * 	if (! is_my_event(p->scope, p->event_type)) return NOTIFY_DONE;
     42 * 		:
     43 * 		:
     44 * 	return NOTIFY_OK;
     45 * }
     46 * struct notifier_block event_nb = {
     47 * 	.notifier_call = event_handler,
     48 * }
     49 *
     50 * Registration:
     51 * atomic_notifier_chain_register(&pseries_ioei_notifier_list, &event_nb);
     52 *
     53 * Unregistration:
     54 * atomic_notifier_chain_unregister(&pseries_ioei_notifier_list, &event_nb);
     55 */
     56
     57ATOMIC_NOTIFIER_HEAD(pseries_ioei_notifier_list);
     58EXPORT_SYMBOL_GPL(pseries_ioei_notifier_list);
     59
     60static int ioei_check_exception_token;
     61
     62static char ioei_rtas_buf[RTAS_DATA_BUF_SIZE] __cacheline_aligned;
     63
     64/**
     65 * Find the data portion of an IO Event section from event log.
     66 * @elog: RTAS error/event log.
     67 *
     68 * Return:
     69 * 	pointer to a valid IO event section data. NULL if not found.
     70 */
     71static struct pseries_io_event * ioei_find_event(struct rtas_error_log *elog)
     72{
     73	struct pseries_errorlog *sect;
     74
     75	/* We should only ever get called for io-event interrupts, but if
     76	 * we do get called for another type then something went wrong so
     77	 * make some noise about it.
     78	 * RTAS_TYPE_IO only exists in extended event log version 6 or later.
     79	 * No need to check event log version.
     80	 */
     81	if (unlikely(rtas_error_type(elog) != RTAS_TYPE_IO)) {
     82		printk_once(KERN_WARNING"io_event_irq: Unexpected event type %d",
     83			    rtas_error_type(elog));
     84		return NULL;
     85	}
     86
     87	sect = get_pseries_errorlog(elog, PSERIES_ELOG_SECT_ID_IO_EVENT);
     88	if (unlikely(!sect)) {
     89		printk_once(KERN_WARNING "io_event_irq: RTAS extended event "
     90			    "log does not contain an IO Event section. "
     91			    "Could be a bug in system firmware!\n");
     92		return NULL;
     93	}
     94	return (struct pseries_io_event *) &sect->data;
     95}
     96
     97/*
     98 * PAPR:
     99 * - check-exception returns the first found error or event and clear that
    100 *   error or event so it is reported once.
    101 * - Each interrupt returns one event. If a plateform chooses to report
    102 *   multiple events through a single interrupt, it must ensure that the
    103 *   interrupt remains asserted until check-exception has been used to
    104 *   process all out-standing events for that interrupt.
    105 *
    106 * Implementation notes:
    107 * - Events must be processed in the order they are returned. Hence,
    108 *   sequential in nature.
    109 * - The owner of an event is determined by combinations of scope,
    110 *   event type, and sub-type. There is no easy way to pre-sort clients
    111 *   by scope or event type alone. For example, Torrent ISR route change
    112 *   event is reported with scope 0x00 (Not Applicable) rather than
    113 *   0x3B (Torrent-hub). It is better to let the clients to identify
    114 *   who owns the event.
    115 */
    116
    117static irqreturn_t ioei_interrupt(int irq, void *dev_id)
    118{
    119	struct pseries_io_event *event;
    120	int rtas_rc;
    121
    122	for (;;) {
    123		rtas_rc = rtas_call(ioei_check_exception_token, 6, 1, NULL,
    124				    RTAS_VECTOR_EXTERNAL_INTERRUPT,
    125				    virq_to_hw(irq),
    126				    RTAS_IO_EVENTS, 1 /* Time Critical */,
    127				    __pa(ioei_rtas_buf),
    128				    RTAS_DATA_BUF_SIZE);
    129		if (rtas_rc != 0)
    130			break;
    131
    132		event = ioei_find_event((struct rtas_error_log *)ioei_rtas_buf);
    133		if (!event)
    134			continue;
    135
    136		atomic_notifier_call_chain(&pseries_ioei_notifier_list,
    137					   0, event);
    138	}
    139	return IRQ_HANDLED;
    140}
    141
    142static int __init ioei_init(void)
    143{
    144	struct device_node *np;
    145
    146	ioei_check_exception_token = rtas_token("check-exception");
    147	if (ioei_check_exception_token == RTAS_UNKNOWN_SERVICE)
    148		return -ENODEV;
    149
    150	np = of_find_node_by_path("/event-sources/ibm,io-events");
    151	if (np) {
    152		request_event_sources_irqs(np, ioei_interrupt, "IO_EVENT");
    153		pr_info("IBM I/O event interrupts enabled\n");
    154		of_node_put(np);
    155	} else {
    156		return -ENODEV;
    157	}
    158	return 0;
    159}
    160machine_subsys_initcall(pseries, ioei_init);
    161