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PowerNV: add buffer for OPAL console

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Avoid the lock in vtophys() by providing a static direct-mapped
spinlock- protected output buffer to use when the console driver
cannot acquire locks for some reason. This allows the idle thread
to use printf() (e.g. the SMP startup messages) without crashing
the kernel.

Created by:            Nathan Whitehorn <nwhitehorn@freebsd.org>
Submitted by:          Wojciech Macek <wma@freebsd.org>
Sponsored by:          FreeBSD Foundation
This commit is contained in:
Wojciech Macek 2018-01-11 09:42:24 +00:00
parent c024897601
commit fc1689021f
1 changed files with 54 additions and 10 deletions
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64
sys/powerpc/powernv/opal_console.c
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@ -34,6 +34,7 @@ __FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <sys/conf.h>
#include <sys/cons.h>
#include <sys/proc.h>
#include <sys/tty.h>
#include <vm/vm.h>
@ -72,6 +73,7 @@ struct uart_opal_softc {
};
static struct uart_opal_softc *console_sc = NULL;
#if defined(KDB)
static int alt_break_state;
#endif
@ -127,6 +129,48 @@ static struct ttydevsw uart_opal_tty_class = {
.tsw_outwakeup = uart_opal_ttyoutwakeup,
};
static struct {
char tmpbuf[16];
uint64_t size;
struct mtx mtx;
} escapehatch;
static void
uart_opal_real_map_outbuffer(uint64_t *bufferp, uint64_t *lenp)
{
if (!mtx_initialized(&escapehatch.mtx))
mtx_init(&escapehatch.mtx, "uart_opal", NULL, MTX_SPIN | MTX_QUIET |
MTX_NOWITNESS);
if (!pmap_bootstrapped)
return;
if (TD_IS_IDLETHREAD(curthread)) {
escapehatch.size = *(uint64_t *)(*lenp) =
min(sizeof(escapehatch.tmpbuf), *(uint64_t *)(*lenp));
mtx_lock_spin(&escapehatch.mtx);
memcpy(escapehatch.tmpbuf, (void *)(*bufferp), *(uint64_t *)(*lenp));
*bufferp = (uint64_t)escapehatch.tmpbuf;
*lenp = (uint64_t)&escapehatch.size;
}
*bufferp = vtophys(*bufferp);
*lenp = vtophys(*lenp);
}
static void
uart_opal_real_unmap_outbuffer(uint64_t lenp, uint64_t *origlen)
{
if (!pmap_bootstrapped || !TD_IS_IDLETHREAD(curthread))
return;
mtx_assert(&escapehatch.mtx, MA_OWNED);
*origlen = escapehatch.size;
mtx_unlock_spin(&escapehatch.mtx);
}
static int
uart_opal_probe_node(struct uart_opal_softc *sc)
{
@ -231,6 +275,7 @@ uart_opal_attach(device_t dev)
MTX_SPIN | MTX_QUIET | MTX_NOWITNESS);
if (console_sc != NULL && console_sc->vtermid == sc->vtermid) {
device_printf(dev, "console\n");
sc->outseqno = console_sc->outseqno;
console_sc = sc;
sprintf(uart_opal_consdev.cn_name, "ttyu%r", unit);
@ -332,25 +377,20 @@ static int
uart_opal_put(struct uart_opal_softc *sc, void *buffer, size_t bufsize)
{
uint16_t seqno;
uint64_t len = bufsize;
uint64_t len;
char cbuf[16];
int err;
uint64_t olen = (uint64_t)&len;
uint64_t obuf = (uint64_t)cbuf;
if (pmap_bootstrapped)
olen = vtophys(&len);
if (sc->protocol == OPAL_RAW) {
if (pmap_bootstrapped)
obuf = vtophys(buffer);
else
obuf = (uint64_t)(buffer);
obuf = (uint64_t)buffer;
len = bufsize;
uart_opal_real_map_outbuffer(&obuf, &olen);
err = opal_call(OPAL_CONSOLE_WRITE, sc->vtermid, olen, obuf);
uart_opal_real_unmap_outbuffer(olen, &len);
} else {
if (pmap_bootstrapped)
obuf = vtophys(cbuf);
uart_lock(&sc->sc_mtx);
if (bufsize > 12)
bufsize = 12;
@ -361,7 +401,11 @@ uart_opal_put(struct uart_opal_softc *sc, void *buffer, size_t bufsize)
cbuf[3] = seqno & 0xff;
memcpy(&cbuf[4], buffer, bufsize);
len = 4 + bufsize;
uart_opal_real_map_outbuffer(&obuf, &olen);
err = opal_call(OPAL_CONSOLE_WRITE, sc->vtermid, olen, obuf);
uart_opal_real_unmap_outbuffer(olen, &len);
uart_unlock(&sc->sc_mtx);
len -= 4;