WIP FPC-III support

[linux/fpc-iii.git] / arch / powerpc / kernel / rtas.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *
 * Procedures for interfacing to the RTAS on CHRP machines.
 *
 * Peter Bergner, IBM   March 2001.
 * Copyright (C) 2001 IBM.
 */

#include <stdarg.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/export.h>
#include <linux/init.h>
#include <linux/capability.h>
#include <linux/delay.h>
#include <linux/cpu.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/completion.h>
#include <linux/cpumask.h>
#include <linux/memblock.h>
#include <linux/slab.h>
#include <linux/reboot.h>
#include <linux/syscalls.h>

#include <asm/prom.h>
#include <asm/rtas.h>
#include <asm/hvcall.h>
#include <asm/machdep.h>
#include <asm/firmware.h>
#include <asm/page.h>
#include <asm/param.h>
#include <asm/delay.h>
#include <linux/uaccess.h>
#include <asm/udbg.h>
#include <asm/syscalls.h>
#include <asm/smp.h>
#include <linux/atomic.h>
#include <asm/time.h>
#include <asm/mmu.h>
#include <asm/topology.h>
#include <asm/paca.h>

/* This is here deliberately so it's only used in this file */
void enter_rtas(unsigned long);

struct rtas_t rtas = {
        .lock = __ARCH_SPIN_LOCK_UNLOCKED
};
EXPORT_SYMBOL(rtas);

DEFINE_SPINLOCK(rtas_data_buf_lock);
EXPORT_SYMBOL(rtas_data_buf_lock);

char rtas_data_buf[RTAS_DATA_BUF_SIZE] __cacheline_aligned;
EXPORT_SYMBOL(rtas_data_buf);

unsigned long rtas_rmo_buf;

/*
 * If non-NULL, this gets called when the kernel terminates.
 * This is done like this so rtas_flash can be a module.
 */
void (*rtas_flash_term_hook)(int);
EXPORT_SYMBOL(rtas_flash_term_hook);

/* RTAS use home made raw locking instead of spin_lock_irqsave
 * because those can be called from within really nasty contexts
 * such as having the timebase stopped which would lockup with
 * normal locks and spinlock debugging enabled
 */
static unsigned long lock_rtas(void)
{
        unsigned long flags;

        local_irq_save(flags);
        preempt_disable();
        arch_spin_lock(&rtas.lock);
        return flags;
}

static void unlock_rtas(unsigned long flags)
{
        arch_spin_unlock(&rtas.lock);
        local_irq_restore(flags);
        preempt_enable();
}

/*
 * call_rtas_display_status and call_rtas_display_status_delay
 * are designed only for very early low-level debugging, which
 * is why the token is hard-coded to 10.
 */
static void call_rtas_display_status(unsigned char c)
{
        unsigned long s;

        if (!rtas.base)
                return;

        s = lock_rtas();
        rtas_call_unlocked(&rtas.args, 10, 1, 1, NULL, c);
        unlock_rtas(s);
}

static void call_rtas_display_status_delay(char c)
{
        static int pending_newline = 0;  /* did last write end with unprinted newline? */
        static int width = 16;

        if (c == '\n') {        
                while (width-- > 0)
                        call_rtas_display_status(' ');
                width = 16;
                mdelay(500);
                pending_newline = 1;
        } else {
                if (pending_newline) {
                        call_rtas_display_status('\r');
                        call_rtas_display_status('\n');
                } 
                pending_newline = 0;
                if (width--) {
                        call_rtas_display_status(c);
                        udelay(10000);
                }
        }
}

void __init udbg_init_rtas_panel(void)
{
        udbg_putc = call_rtas_display_status_delay;
}

#ifdef CONFIG_UDBG_RTAS_CONSOLE

/* If you think you're dying before early_init_dt_scan_rtas() does its
 * work, you can hard code the token values for your firmware here and
 * hardcode rtas.base/entry etc.
 */
static unsigned int rtas_putchar_token = RTAS_UNKNOWN_SERVICE;
static unsigned int rtas_getchar_token = RTAS_UNKNOWN_SERVICE;

static void udbg_rtascon_putc(char c)
{
        int tries;

        if (!rtas.base)
                return;

        /* Add CRs before LFs */
        if (c == '\n')
                udbg_rtascon_putc('\r');

        /* if there is more than one character to be displayed, wait a bit */
        for (tries = 0; tries < 16; tries++) {
                if (rtas_call(rtas_putchar_token, 1, 1, NULL, c) == 0)
                        break;
                udelay(1000);
        }
}

static int udbg_rtascon_getc_poll(void)
{
        int c;

        if (!rtas.base)
                return -1;

        if (rtas_call(rtas_getchar_token, 0, 2, &c))
                return -1;

        return c;
}

static int udbg_rtascon_getc(void)
{
        int c;

        while ((c = udbg_rtascon_getc_poll()) == -1)
                ;

        return c;
}


void __init udbg_init_rtas_console(void)
{
        udbg_putc = udbg_rtascon_putc;
        udbg_getc = udbg_rtascon_getc;
        udbg_getc_poll = udbg_rtascon_getc_poll;
}
#endif /* CONFIG_UDBG_RTAS_CONSOLE */

void rtas_progress(char *s, unsigned short hex)
{
        struct device_node *root;
        int width;
        const __be32 *p;
        char *os;
        static int display_character, set_indicator;
        static int display_width, display_lines, form_feed;
        static const int *row_width;
        static DEFINE_SPINLOCK(progress_lock);
        static int current_line;
        static int pending_newline = 0;  /* did last write end with unprinted newline? */

        if (!rtas.base)
                return;

        if (display_width == 0) {
                display_width = 0x10;
                if ((root = of_find_node_by_path("/rtas"))) {
                        if ((p = of_get_property(root,
                                        "ibm,display-line-length", NULL)))
                                display_width = be32_to_cpu(*p);
                        if ((p = of_get_property(root,
                                        "ibm,form-feed", NULL)))
                                form_feed = be32_to_cpu(*p);
                        if ((p = of_get_property(root,
                                        "ibm,display-number-of-lines", NULL)))
                                display_lines = be32_to_cpu(*p);
                        row_width = of_get_property(root,
                                        "ibm,display-truncation-length", NULL);
                        of_node_put(root);
                }
                display_character = rtas_token("display-character");
                set_indicator = rtas_token("set-indicator");
        }

        if (display_character == RTAS_UNKNOWN_SERVICE) {
                /* use hex display if available */
                if (set_indicator != RTAS_UNKNOWN_SERVICE)
                        rtas_call(set_indicator, 3, 1, NULL, 6, 0, hex);
                return;
        }

        spin_lock(&progress_lock);

        /*
         * Last write ended with newline, but we didn't print it since
         * it would just clear the bottom line of output. Print it now
         * instead.
         *
         * If no newline is pending and form feed is supported, clear the
         * display with a form feed; otherwise, print a CR to start output
         * at the beginning of the line.
         */
        if (pending_newline) {
                rtas_call(display_character, 1, 1, NULL, '\r');
                rtas_call(display_character, 1, 1, NULL, '\n');
                pending_newline = 0;
        } else {
                current_line = 0;
                if (form_feed)
                        rtas_call(display_character, 1, 1, NULL,
                                  (char)form_feed);
                else
                        rtas_call(display_character, 1, 1, NULL, '\r');
        }
 
        if (row_width)
                width = row_width[current_line];
        else
                width = display_width;
        os = s;
        while (*os) {
                if (*os == '\n' || *os == '\r') {
                        /* If newline is the last character, save it
                         * until next call to avoid bumping up the
                         * display output.
                         */
                        if (*os == '\n' && !os[1]) {
                                pending_newline = 1;
                                current_line++;
                                if (current_line > display_lines-1)
                                        current_line = display_lines-1;
                                spin_unlock(&progress_lock);
                                return;
                        }
 
                        /* RTAS wants CR-LF, not just LF */
 
                        if (*os == '\n') {
                                rtas_call(display_character, 1, 1, NULL, '\r');
                                rtas_call(display_character, 1, 1, NULL, '\n');
                        } else {
                                /* CR might be used to re-draw a line, so we'll
                                 * leave it alone and not add LF.
                                 */
                                rtas_call(display_character, 1, 1, NULL, *os);
                        }
 
                        if (row_width)
                                width = row_width[current_line];
                        else
                                width = display_width;
                } else {
                        width--;
                        rtas_call(display_character, 1, 1, NULL, *os);
                }
 
                os++;
 
                /* if we overwrite the screen length */
                if (width <= 0)
                        while ((*os != 0) && (*os != '\n') && (*os != '\r'))
                                os++;
        }
 
        spin_unlock(&progress_lock);
}
EXPORT_SYMBOL(rtas_progress);           /* needed by rtas_flash module */

int rtas_token(const char *service)
{
        const __be32 *tokp;
        if (rtas.dev == NULL)
                return RTAS_UNKNOWN_SERVICE;
        tokp = of_get_property(rtas.dev, service, NULL);
        return tokp ? be32_to_cpu(*tokp) : RTAS_UNKNOWN_SERVICE;
}
EXPORT_SYMBOL(rtas_token);

int rtas_service_present(const char *service)
{
        return rtas_token(service) != RTAS_UNKNOWN_SERVICE;
}
EXPORT_SYMBOL(rtas_service_present);

#ifdef CONFIG_RTAS_ERROR_LOGGING
/*
 * Return the firmware-specified size of the error log buffer
 *  for all rtas calls that require an error buffer argument.
 *  This includes 'check-exception' and 'rtas-last-error'.
 */
int rtas_get_error_log_max(void)
{
        static int rtas_error_log_max;
        if (rtas_error_log_max)
                return rtas_error_log_max;

        rtas_error_log_max = rtas_token ("rtas-error-log-max");
        if ((rtas_error_log_max == RTAS_UNKNOWN_SERVICE) ||
            (rtas_error_log_max > RTAS_ERROR_LOG_MAX)) {
                printk (KERN_WARNING "RTAS: bad log buffer size %d\n",
                        rtas_error_log_max);
                rtas_error_log_max = RTAS_ERROR_LOG_MAX;
        }
        return rtas_error_log_max;
}
EXPORT_SYMBOL(rtas_get_error_log_max);


static char rtas_err_buf[RTAS_ERROR_LOG_MAX];
static int rtas_last_error_token;

/** Return a copy of the detailed error text associated with the
 *  most recent failed call to rtas.  Because the error text
 *  might go stale if there are any other intervening rtas calls,
 *  this routine must be called atomically with whatever produced
 *  the error (i.e. with rtas.lock still held from the previous call).
 */
static char *__fetch_rtas_last_error(char *altbuf)
{
        struct rtas_args err_args, save_args;
        u32 bufsz;
        char *buf = NULL;

        if (rtas_last_error_token == -1)
                return NULL;

        bufsz = rtas_get_error_log_max();

        err_args.token = cpu_to_be32(rtas_last_error_token);
        err_args.nargs = cpu_to_be32(2);
        err_args.nret = cpu_to_be32(1);
        err_args.args[0] = cpu_to_be32(__pa(rtas_err_buf));
        err_args.args[1] = cpu_to_be32(bufsz);
        err_args.args[2] = 0;

        save_args = rtas.args;
        rtas.args = err_args;

        enter_rtas(__pa(&rtas.args));

        err_args = rtas.args;
        rtas.args = save_args;

        /* Log the error in the unlikely case that there was one. */
        if (unlikely(err_args.args[2] == 0)) {
                if (altbuf) {
                        buf = altbuf;
                } else {
                        buf = rtas_err_buf;
                        if (slab_is_available())
                                buf = kmalloc(RTAS_ERROR_LOG_MAX, GFP_ATOMIC);
                }
                if (buf)
                        memcpy(buf, rtas_err_buf, RTAS_ERROR_LOG_MAX);
        }

        return buf;
}

#define get_errorlog_buffer()   kmalloc(RTAS_ERROR_LOG_MAX, GFP_KERNEL)

#else /* CONFIG_RTAS_ERROR_LOGGING */
#define __fetch_rtas_last_error(x)      NULL
#define get_errorlog_buffer()           NULL
#endif


static void
va_rtas_call_unlocked(struct rtas_args *args, int token, int nargs, int nret,
                      va_list list)
{
        int i;

        args->token = cpu_to_be32(token);
        args->nargs = cpu_to_be32(nargs);
        args->nret  = cpu_to_be32(nret);
        args->rets  = &(args->args[nargs]);

        for (i = 0; i < nargs; ++i)
                args->args[i] = cpu_to_be32(va_arg(list, __u32));

        for (i = 0; i < nret; ++i)
                args->rets[i] = 0;

        enter_rtas(__pa(args));
}

void rtas_call_unlocked(struct rtas_args *args, int token, int nargs, int nret, ...)
{
        va_list list;

        va_start(list, nret);
        va_rtas_call_unlocked(args, token, nargs, nret, list);
        va_end(list);
}

int rtas_call(int token, int nargs, int nret, int *outputs, ...)
{
        va_list list;
        int i;
        unsigned long s;
        struct rtas_args *rtas_args;
        char *buff_copy = NULL;
        int ret;

        if (!rtas.entry || token == RTAS_UNKNOWN_SERVICE)
                return -1;

        s = lock_rtas();

        /* We use the global rtas args buffer */
        rtas_args = &rtas.args;

        va_start(list, outputs);
        va_rtas_call_unlocked(rtas_args, token, nargs, nret, list);
        va_end(list);

        /* A -1 return code indicates that the last command couldn't
           be completed due to a hardware error. */
        if (be32_to_cpu(rtas_args->rets[0]) == -1)
                buff_copy = __fetch_rtas_last_error(NULL);

        if (nret > 1 && outputs != NULL)
                for (i = 0; i < nret-1; ++i)
                        outputs[i] = be32_to_cpu(rtas_args->rets[i+1]);
        ret = (nret > 0)? be32_to_cpu(rtas_args->rets[0]): 0;

        unlock_rtas(s);

        if (buff_copy) {
                log_error(buff_copy, ERR_TYPE_RTAS_LOG, 0);
                if (slab_is_available())
                        kfree(buff_copy);
        }
        return ret;
}
EXPORT_SYMBOL(rtas_call);

/* For RTAS_BUSY (-2), delay for 1 millisecond.  For an extended busy status
 * code of 990n, perform the hinted delay of 10^n (last digit) milliseconds.
 */
unsigned int rtas_busy_delay_time(int status)
{
        int order;
        unsigned int ms = 0;

        if (status == RTAS_BUSY) {
                ms = 1;
        } else if (status >= RTAS_EXTENDED_DELAY_MIN &&
                   status <= RTAS_EXTENDED_DELAY_MAX) {
                order = status - RTAS_EXTENDED_DELAY_MIN;
                for (ms = 1; order > 0; order--)
                        ms *= 10;
        }

        return ms;
}
EXPORT_SYMBOL(rtas_busy_delay_time);

/* For an RTAS busy status code, perform the hinted delay. */
unsigned int rtas_busy_delay(int status)
{
        unsigned int ms;

        might_sleep();
        ms = rtas_busy_delay_time(status);
        if (ms && need_resched())
                msleep(ms);

        return ms;
}
EXPORT_SYMBOL(rtas_busy_delay);

static int rtas_error_rc(int rtas_rc)
{
        int rc;

        switch (rtas_rc) {
                case -1:                /* Hardware Error */
                        rc = -EIO;
                        break;
                case -3:                /* Bad indicator/domain/etc */
                        rc = -EINVAL;
                        break;
                case -9000:             /* Isolation error */
                        rc = -EFAULT;
                        break;
                case -9001:             /* Outstanding TCE/PTE */
                        rc = -EEXIST;
                        break;
                case -9002:             /* No usable slot */
                        rc = -ENODEV;
                        break;
                default:
                        printk(KERN_ERR "%s: unexpected RTAS error %d\n",
                                        __func__, rtas_rc);
                        rc = -ERANGE;
                        break;
        }
        return rc;
}

int rtas_get_power_level(int powerdomain, int *level)
{
        int token = rtas_token("get-power-level");
        int rc;

        if (token == RTAS_UNKNOWN_SERVICE)
                return -ENOENT;

        while ((rc = rtas_call(token, 1, 2, level, powerdomain)) == RTAS_BUSY)
                udelay(1);

        if (rc < 0)
                return rtas_error_rc(rc);
        return rc;
}
EXPORT_SYMBOL(rtas_get_power_level);

int rtas_set_power_level(int powerdomain, int level, int *setlevel)
{
        int token = rtas_token("set-power-level");
        int rc;

        if (token == RTAS_UNKNOWN_SERVICE)
                return -ENOENT;

        do {
                rc = rtas_call(token, 2, 2, setlevel, powerdomain, level);
        } while (rtas_busy_delay(rc));

        if (rc < 0)
                return rtas_error_rc(rc);
        return rc;
}
EXPORT_SYMBOL(rtas_set_power_level);

int rtas_get_sensor(int sensor, int index, int *state)
{
        int token = rtas_token("get-sensor-state");
        int rc;

        if (token == RTAS_UNKNOWN_SERVICE)
                return -ENOENT;

        do {
                rc = rtas_call(token, 2, 2, state, sensor, index);
        } while (rtas_busy_delay(rc));

        if (rc < 0)
                return rtas_error_rc(rc);
        return rc;
}
EXPORT_SYMBOL(rtas_get_sensor);

int rtas_get_sensor_fast(int sensor, int index, int *state)
{
        int token = rtas_token("get-sensor-state");
        int rc;

        if (token == RTAS_UNKNOWN_SERVICE)
                return -ENOENT;

        rc = rtas_call(token, 2, 2, state, sensor, index);
        WARN_ON(rc == RTAS_BUSY || (rc >= RTAS_EXTENDED_DELAY_MIN &&
                                    rc <= RTAS_EXTENDED_DELAY_MAX));

        if (rc < 0)
                return rtas_error_rc(rc);
        return rc;
}

bool rtas_indicator_present(int token, int *maxindex)
{
        int proplen, count, i;
        const struct indicator_elem {
                __be32 token;
                __be32 maxindex;
        } *indicators;

        indicators = of_get_property(rtas.dev, "rtas-indicators", &proplen);
        if (!indicators)
                return false;

        count = proplen / sizeof(struct indicator_elem);

        for (i = 0; i < count; i++) {
                if (__be32_to_cpu(indicators[i].token) != token)
                        continue;
                if (maxindex)
                        *maxindex = __be32_to_cpu(indicators[i].maxindex);
                return true;
        }

        return false;
}
EXPORT_SYMBOL(rtas_indicator_present);

int rtas_set_indicator(int indicator, int index, int new_value)
{
        int token = rtas_token("set-indicator");
        int rc;

        if (token == RTAS_UNKNOWN_SERVICE)
                return -ENOENT;

        do {
                rc = rtas_call(token, 3, 1, NULL, indicator, index, new_value);
        } while (rtas_busy_delay(rc));

        if (rc < 0)
                return rtas_error_rc(rc);
        return rc;
}
EXPORT_SYMBOL(rtas_set_indicator);

/*
 * Ignoring RTAS extended delay
 */
int rtas_set_indicator_fast(int indicator, int index, int new_value)
{
        int rc;
        int token = rtas_token("set-indicator");

        if (token == RTAS_UNKNOWN_SERVICE)
                return -ENOENT;

        rc = rtas_call(token, 3, 1, NULL, indicator, index, new_value);

        WARN_ON(rc == RTAS_BUSY || (rc >= RTAS_EXTENDED_DELAY_MIN &&
                                    rc <= RTAS_EXTENDED_DELAY_MAX));

        if (rc < 0)
                return rtas_error_rc(rc);

        return rc;
}

/**
 * rtas_ibm_suspend_me() - Call ibm,suspend-me to suspend the LPAR.
 *
 * @fw_status: RTAS call status will be placed here if not NULL.
 *
 * rtas_ibm_suspend_me() should be called only on a CPU which has
 * received H_CONTINUE from the H_JOIN hcall. All other active CPUs
 * should be waiting to return from H_JOIN.
 *
 * rtas_ibm_suspend_me() may suspend execution of the OS
 * indefinitely. Callers should take appropriate measures upon return, such as
 * resetting watchdog facilities.
 *
 * Callers may choose to retry this call if @fw_status is
 * %RTAS_THREADS_ACTIVE.
 *
 * Return:
 * 0          - The partition has resumed from suspend, possibly after
 *              migration to a different host.
 * -ECANCELED - The operation was aborted.
 * -EAGAIN    - There were other CPUs not in H_JOIN at the time of the call.
 * -EBUSY     - Some other condition prevented the suspend from succeeding.
 * -EIO       - Hardware/platform error.
 */
int rtas_ibm_suspend_me(int *fw_status)
{
        int fwrc;
        int ret;

        fwrc = rtas_call(rtas_token("ibm,suspend-me"), 0, 1, NULL);

        switch (fwrc) {
        case 0:
                ret = 0;
                break;
        case RTAS_SUSPEND_ABORTED:
                ret = -ECANCELED;
                break;
        case RTAS_THREADS_ACTIVE:
                ret = -EAGAIN;
                break;
        case RTAS_NOT_SUSPENDABLE:
        case RTAS_OUTSTANDING_COPROC:
                ret = -EBUSY;
                break;
        case -1:
        default:
                ret = -EIO;
                break;
        }

        if (fw_status)
                *fw_status = fwrc;

        return ret;
}

void __noreturn rtas_restart(char *cmd)
{
        if (rtas_flash_term_hook)
                rtas_flash_term_hook(SYS_RESTART);
        printk("RTAS system-reboot returned %d\n",
               rtas_call(rtas_token("system-reboot"), 0, 1, NULL));
        for (;;);
}

void rtas_power_off(void)
{
        if (rtas_flash_term_hook)
                rtas_flash_term_hook(SYS_POWER_OFF);
        /* allow power on only with power button press */
        printk("RTAS power-off returned %d\n",
               rtas_call(rtas_token("power-off"), 2, 1, NULL, -1, -1));
        for (;;);
}

void __noreturn rtas_halt(void)
{
        if (rtas_flash_term_hook)
                rtas_flash_term_hook(SYS_HALT);
        /* allow power on only with power button press */
        printk("RTAS power-off returned %d\n",
               rtas_call(rtas_token("power-off"), 2, 1, NULL, -1, -1));
        for (;;);
}

/* Must be in the RMO region, so we place it here */
static char rtas_os_term_buf[2048];

void rtas_os_term(char *str)
{
        int status;

        /*
         * Firmware with the ibm,extended-os-term property is guaranteed
         * to always return from an ibm,os-term call. Earlier versions without
         * this property may terminate the partition which we want to avoid
         * since it interferes with panic_timeout.
         */
        if (RTAS_UNKNOWN_SERVICE == rtas_token("ibm,os-term") ||
            RTAS_UNKNOWN_SERVICE == rtas_token("ibm,extended-os-term"))
                return;

        snprintf(rtas_os_term_buf, 2048, "OS panic: %s", str);

        do {
                status = rtas_call(rtas_token("ibm,os-term"), 1, 1, NULL,
                                   __pa(rtas_os_term_buf));
        } while (rtas_busy_delay(status));

        if (status != 0)
                printk(KERN_EMERG "ibm,os-term call failed %d\n", status);
}

/**
 * rtas_activate_firmware() - Activate a new version of firmware.
 *
 * Activate a new version of partition firmware. The OS must call this
 * after resuming from a partition hibernation or migration in order
 * to maintain the ability to perform live firmware updates. It's not
 * catastrophic for this method to be absent or to fail; just log the
 * condition in that case.
 *
 * Context: This function may sleep.
 */
void rtas_activate_firmware(void)
{
        int token;
        int fwrc;

        token = rtas_token("ibm,activate-firmware");
        if (token == RTAS_UNKNOWN_SERVICE) {
                pr_notice("ibm,activate-firmware method unavailable\n");
                return;
        }

        do {
                fwrc = rtas_call(token, 0, 1, NULL);
        } while (rtas_busy_delay(fwrc));

        if (fwrc)
                pr_err("ibm,activate-firmware failed (%i)\n", fwrc);
}

static int ibm_suspend_me_token = RTAS_UNKNOWN_SERVICE;
#ifdef CONFIG_PPC_PSERIES
/**
 * rtas_call_reentrant() - Used for reentrant rtas calls
 * @token:      Token for desired reentrant RTAS call
 * @nargs:      Number of Input Parameters
 * @nret:       Number of Output Parameters
 * @outputs:    Array of outputs
 * @...:        Inputs for desired RTAS call
 *
 * According to LoPAR documentation, only "ibm,int-on", "ibm,int-off",
 * "ibm,get-xive" and "ibm,set-xive" are currently reentrant.
 * Reentrant calls need their own rtas_args buffer, so not using rtas.args, but
 * PACA one instead.
 *
 * Return:      -1 on error,
 *              First output value of RTAS call if (nret > 0),
 *              0 otherwise,
 */
int rtas_call_reentrant(int token, int nargs, int nret, int *outputs, ...)
{
        va_list list;
        struct rtas_args *args;
        unsigned long flags;
        int i, ret = 0;

        if (!rtas.entry || token == RTAS_UNKNOWN_SERVICE)
                return -1;

        local_irq_save(flags);
        preempt_disable();

        /* We use the per-cpu (PACA) rtas args buffer */
        args = local_paca->rtas_args_reentrant;

        va_start(list, outputs);
        va_rtas_call_unlocked(args, token, nargs, nret, list);
        va_end(list);

        if (nret > 1 && outputs)
                for (i = 0; i < nret - 1; ++i)
                        outputs[i] = be32_to_cpu(args->rets[i + 1]);

        if (nret > 0)
                ret = be32_to_cpu(args->rets[0]);

        local_irq_restore(flags);
        preempt_enable();

        return ret;
}

#endif /* CONFIG_PPC_PSERIES */

/**
 * Find a specific pseries error log in an RTAS extended event log.
 * @log: RTAS error/event log
 * @section_id: two character section identifier
 *
 * Returns a pointer to the specified errorlog or NULL if not found.
 */
struct pseries_errorlog *get_pseries_errorlog(struct rtas_error_log *log,
                                              uint16_t section_id)
{
        struct rtas_ext_event_log_v6 *ext_log =
                (struct rtas_ext_event_log_v6 *)log->buffer;
        struct pseries_errorlog *sect;
        unsigned char *p, *log_end;
        uint32_t ext_log_length = rtas_error_extended_log_length(log);
        uint8_t log_format = rtas_ext_event_log_format(ext_log);
        uint32_t company_id = rtas_ext_event_company_id(ext_log);

        /* Check that we understand the format */
        if (ext_log_length < sizeof(struct rtas_ext_event_log_v6) ||
            log_format != RTAS_V6EXT_LOG_FORMAT_EVENT_LOG ||
            company_id != RTAS_V6EXT_COMPANY_ID_IBM)
                return NULL;

        log_end = log->buffer + ext_log_length;
        p = ext_log->vendor_log;

        while (p < log_end) {
                sect = (struct pseries_errorlog *)p;
                if (pseries_errorlog_id(sect) == section_id)
                        return sect;
                p += pseries_errorlog_length(sect);
        }

        return NULL;
}

#ifdef CONFIG_PPC_RTAS_FILTER

/*
 * The sys_rtas syscall, as originally designed, allows root to pass
 * arbitrary physical addresses to RTAS calls. A number of RTAS calls
 * can be abused to write to arbitrary memory and do other things that
 * are potentially harmful to system integrity, and thus should only
 * be used inside the kernel and not exposed to userspace.
 *
 * All known legitimate users of the sys_rtas syscall will only ever
 * pass addresses that fall within the RMO buffer, and use a known
 * subset of RTAS calls.
 *
 * Accordingly, we filter RTAS requests to check that the call is
 * permitted, and that provided pointers fall within the RMO buffer.
 * The rtas_filters list contains an entry for each permitted call,
 * with the indexes of the parameters which are expected to contain
 * addresses and sizes of buffers allocated inside the RMO buffer.
 */
struct rtas_filter {
        const char *name;
        int token;
        /* Indexes into the args buffer, -1 if not used */
        int buf_idx1;
        int size_idx1;
        int buf_idx2;
        int size_idx2;

        int fixed_size;
};

static struct rtas_filter rtas_filters[] __ro_after_init = {
        { "ibm,activate-firmware", -1, -1, -1, -1, -1 },
        { "ibm,configure-connector", -1, 0, -1, 1, -1, 4096 },  /* Special cased */
        { "display-character", -1, -1, -1, -1, -1 },
        { "ibm,display-message", -1, 0, -1, -1, -1 },
        { "ibm,errinjct", -1, 2, -1, -1, -1, 1024 },
        { "ibm,close-errinjct", -1, -1, -1, -1, -1 },
        { "ibm,open-errinjct", -1, -1, -1, -1, -1 },
        { "ibm,get-config-addr-info2", -1, -1, -1, -1, -1 },
        { "ibm,get-dynamic-sensor-state", -1, 1, -1, -1, -1 },
        { "ibm,get-indices", -1, 2, 3, -1, -1 },
        { "get-power-level", -1, -1, -1, -1, -1 },
        { "get-sensor-state", -1, -1, -1, -1, -1 },
        { "ibm,get-system-parameter", -1, 1, 2, -1, -1 },
        { "get-time-of-day", -1, -1, -1, -1, -1 },
        { "ibm,get-vpd", -1, 0, -1, 1, 2 },
        { "ibm,lpar-perftools", -1, 2, 3, -1, -1 },
        { "ibm,platform-dump", -1, 4, 5, -1, -1 },
        { "ibm,read-slot-reset-state", -1, -1, -1, -1, -1 },
        { "ibm,scan-log-dump", -1, 0, 1, -1, -1 },
        { "ibm,set-dynamic-indicator", -1, 2, -1, -1, -1 },
        { "ibm,set-eeh-option", -1, -1, -1, -1, -1 },
        { "set-indicator", -1, -1, -1, -1, -1 },
        { "set-power-level", -1, -1, -1, -1, -1 },
        { "set-time-for-power-on", -1, -1, -1, -1, -1 },
        { "ibm,set-system-parameter", -1, 1, -1, -1, -1 },
        { "set-time-of-day", -1, -1, -1, -1, -1 },
#ifdef CONFIG_CPU_BIG_ENDIAN
        { "ibm,suspend-me", -1, -1, -1, -1, -1 },
        { "ibm,update-nodes", -1, 0, -1, -1, -1, 4096 },
        { "ibm,update-properties", -1, 0, -1, -1, -1, 4096 },
#endif
        { "ibm,physical-attestation", -1, 0, 1, -1, -1 },
};

static bool in_rmo_buf(u32 base, u32 end)
{
        return base >= rtas_rmo_buf &&
                base < (rtas_rmo_buf + RTAS_RMOBUF_MAX) &&
                base <= end &&
                end >= rtas_rmo_buf &&
                end < (rtas_rmo_buf + RTAS_RMOBUF_MAX);
}

static bool block_rtas_call(int token, int nargs,
                            struct rtas_args *args)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(rtas_filters); i++) {
                struct rtas_filter *f = &rtas_filters[i];
                u32 base, size, end;

                if (token != f->token)
                        continue;

                if (f->buf_idx1 != -1) {
                        base = be32_to_cpu(args->args[f->buf_idx1]);
                        if (f->size_idx1 != -1)
                                size = be32_to_cpu(args->args[f->size_idx1]);
                        else if (f->fixed_size)
                                size = f->fixed_size;
                        else
                                size = 1;

                        end = base + size - 1;
                        if (!in_rmo_buf(base, end))
                                goto err;
                }

                if (f->buf_idx2 != -1) {
                        base = be32_to_cpu(args->args[f->buf_idx2]);
                        if (f->size_idx2 != -1)
                                size = be32_to_cpu(args->args[f->size_idx2]);
                        else if (f->fixed_size)
                                size = f->fixed_size;
                        else
                                size = 1;
                        end = base + size - 1;

                        /*
                         * Special case for ibm,configure-connector where the
                         * address can be 0
                         */
                        if (!strcmp(f->name, "ibm,configure-connector") &&
                            base == 0)
                                return false;

                        if (!in_rmo_buf(base, end))
                                goto err;
                }

                return false;
        }

err:
        pr_err_ratelimited("sys_rtas: RTAS call blocked - exploit attempt?\n");
        pr_err_ratelimited("sys_rtas: token=0x%x, nargs=%d (called by %s)\n",
                           token, nargs, current->comm);
        return true;
}

#else

static bool block_rtas_call(int token, int nargs,
                            struct rtas_args *args)
{
        return false;
}

#endif /* CONFIG_PPC_RTAS_FILTER */

/* We assume to be passed big endian arguments */
SYSCALL_DEFINE1(rtas, struct rtas_args __user *, uargs)
{
        struct rtas_args args;
        unsigned long flags;
        char *buff_copy, *errbuf = NULL;
        int nargs, nret, token;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        if (!rtas.entry)
                return -EINVAL;

        if (copy_from_user(&args, uargs, 3 * sizeof(u32)) != 0)
                return -EFAULT;

        nargs = be32_to_cpu(args.nargs);
        nret  = be32_to_cpu(args.nret);
        token = be32_to_cpu(args.token);

        if (nargs >= ARRAY_SIZE(args.args)
            || nret > ARRAY_SIZE(args.args)
            || nargs + nret > ARRAY_SIZE(args.args))
                return -EINVAL;

        /* Copy in args. */
        if (copy_from_user(args.args, uargs->args,
                           nargs * sizeof(rtas_arg_t)) != 0)
                return -EFAULT;

        if (token == RTAS_UNKNOWN_SERVICE)
                return -EINVAL;

        args.rets = &args.args[nargs];
        memset(args.rets, 0, nret * sizeof(rtas_arg_t));

        if (block_rtas_call(token, nargs, &args))
                return -EINVAL;

        /* Need to handle ibm,suspend_me call specially */
        if (token == ibm_suspend_me_token) {

                /*
                 * rtas_ibm_suspend_me assumes the streamid handle is in cpu
                 * endian, or at least the hcall within it requires it.
                 */
                int rc = 0;
                u64 handle = ((u64)be32_to_cpu(args.args[0]) << 32)
                              | be32_to_cpu(args.args[1]);
                rc = rtas_syscall_dispatch_ibm_suspend_me(handle);
                if (rc == -EAGAIN)
                        args.rets[0] = cpu_to_be32(RTAS_NOT_SUSPENDABLE);
                else if (rc == -EIO)
                        args.rets[0] = cpu_to_be32(-1);
                else if (rc)
                        return rc;
                goto copy_return;
        }

        buff_copy = get_errorlog_buffer();

        flags = lock_rtas();

        rtas.args = args;
        enter_rtas(__pa(&rtas.args));
        args = rtas.args;

        /* A -1 return code indicates that the last command couldn't
           be completed due to a hardware error. */
        if (be32_to_cpu(args.rets[0]) == -1)
                errbuf = __fetch_rtas_last_error(buff_copy);

        unlock_rtas(flags);

        if (buff_copy) {
                if (errbuf)
                        log_error(errbuf, ERR_TYPE_RTAS_LOG, 0);
                kfree(buff_copy);
        }

 copy_return:
        /* Copy out args. */
        if (copy_to_user(uargs->args + nargs,
                         args.args + nargs,
                         nret * sizeof(rtas_arg_t)) != 0)
                return -EFAULT;

        return 0;
}

/*
 * Call early during boot, before mem init, to retrieve the RTAS
 * information from the device-tree and allocate the RMO buffer for userland
 * accesses.
 */
void __init rtas_initialize(void)
{
        unsigned long rtas_region = RTAS_INSTANTIATE_MAX;
        u32 base, size, entry;
        int no_base, no_size, no_entry;
#ifdef CONFIG_PPC_RTAS_FILTER
        int i;
#endif

        /* Get RTAS dev node and fill up our "rtas" structure with infos
         * about it.
         */
        rtas.dev = of_find_node_by_name(NULL, "rtas");
        if (!rtas.dev)
                return;

        no_base = of_property_read_u32(rtas.dev, "linux,rtas-base", &base);
        no_size = of_property_read_u32(rtas.dev, "rtas-size", &size);
        if (no_base || no_size) {
                of_node_put(rtas.dev);
                rtas.dev = NULL;
                return;
        }

        rtas.base = base;
        rtas.size = size;
        no_entry = of_property_read_u32(rtas.dev, "linux,rtas-entry", &entry);
        rtas.entry = no_entry ? rtas.base : entry;

        /* If RTAS was found, allocate the RMO buffer for it and look for
         * the stop-self token if any
         */
#ifdef CONFIG_PPC64
        if (firmware_has_feature(FW_FEATURE_LPAR)) {
                rtas_region = min(ppc64_rma_size, RTAS_INSTANTIATE_MAX);
                ibm_suspend_me_token = rtas_token("ibm,suspend-me");
        }
#endif
        rtas_rmo_buf = memblock_phys_alloc_range(RTAS_RMOBUF_MAX, PAGE_SIZE,
                                                 0, rtas_region);
        if (!rtas_rmo_buf)
                panic("ERROR: RTAS: Failed to allocate %lx bytes below %pa\n",
                      PAGE_SIZE, &rtas_region);

#ifdef CONFIG_RTAS_ERROR_LOGGING
        rtas_last_error_token = rtas_token("rtas-last-error");
#endif

#ifdef CONFIG_PPC_RTAS_FILTER
        for (i = 0; i < ARRAY_SIZE(rtas_filters); i++) {
                rtas_filters[i].token = rtas_token(rtas_filters[i].name);
        }
#endif
}

int __init early_init_dt_scan_rtas(unsigned long node,
                const char *uname, int depth, void *data)
{
        const u32 *basep, *entryp, *sizep;

        if (depth != 1 || strcmp(uname, "rtas") != 0)
                return 0;

        basep  = of_get_flat_dt_prop(node, "linux,rtas-base", NULL);
        entryp = of_get_flat_dt_prop(node, "linux,rtas-entry", NULL);
        sizep  = of_get_flat_dt_prop(node, "rtas-size", NULL);

        if (basep && entryp && sizep) {
                rtas.base = *basep;
                rtas.entry = *entryp;
                rtas.size = *sizep;
        }

#ifdef CONFIG_UDBG_RTAS_CONSOLE
        basep = of_get_flat_dt_prop(node, "put-term-char", NULL);
        if (basep)
                rtas_putchar_token = *basep;

        basep = of_get_flat_dt_prop(node, "get-term-char", NULL);
        if (basep)
                rtas_getchar_token = *basep;

        if (rtas_putchar_token != RTAS_UNKNOWN_SERVICE &&
            rtas_getchar_token != RTAS_UNKNOWN_SERVICE)
                udbg_init_rtas_console();

#endif

        /* break now */
        return 1;
}

static arch_spinlock_t timebase_lock;
static u64 timebase = 0;

void rtas_give_timebase(void)
{
        unsigned long flags;

        local_irq_save(flags);
        hard_irq_disable();
        arch_spin_lock(&timebase_lock);
        rtas_call(rtas_token("freeze-time-base"), 0, 1, NULL);
        timebase = get_tb();
        arch_spin_unlock(&timebase_lock);

        while (timebase)
                barrier();
        rtas_call(rtas_token("thaw-time-base"), 0, 1, NULL);
        local_irq_restore(flags);
}

void rtas_take_timebase(void)
{
        while (!timebase)
                barrier();
        arch_spin_lock(&timebase_lock);
        set_tb(timebase >> 32, timebase & 0xffffffff);
        timebase = 0;
        arch_spin_unlock(&timebase_lock);
}