system76-coreboot/payloads/libpayload/drivers/cbmem_console.c

/*
 *
 * Copyright (c) 2012 Google Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <libpayload.h>
#include <stdint.h>

struct cbmem_console {
	uint32_t size;
	uint32_t cursor;
	uint8_t body[];
} __packed;

#define CURSOR_MASK ((1 << 28) - 1)
#define OVERFLOW (1 << 31)

static uintptr_t cbmem_console_p;

static struct console_output_driver cbmem_console_driver =
{
	.write = &cbmem_console_write,
};

static void do_write(const void *buffer, size_t count)
{
	struct cbmem_console *const cbmem_cons = phys_to_virt(cbmem_console_p);

	memcpy(cbmem_cons->body + (cbmem_cons->cursor & CURSOR_MASK), buffer, count);
	cbmem_cons->cursor += count;
}

void cbmem_console_init(void)
{
	const struct cbmem_console *const cbmem_cons = phys_to_virt(lib_sysinfo.cbmem_cons);

	cbmem_console_p = lib_sysinfo.cbmem_cons;

	if (cbmem_console_p && cbmem_cons->size)
		console_add_output_driver(&cbmem_console_driver);
}

void cbmem_console_write(const void *buffer, size_t count)
{
	struct cbmem_console *const cbmem_cons = phys_to_virt(cbmem_console_p);

	while ((cbmem_cons->cursor & CURSOR_MASK) + count >=
	       cbmem_cons->size) {
		size_t still_fits = cbmem_cons->size - (cbmem_cons->cursor & CURSOR_MASK);
		do_write(buffer, still_fits);
		cbmem_cons->cursor &= ~CURSOR_MASK;
		cbmem_cons->cursor |= OVERFLOW;
		buffer += still_fits;
		count -= still_fits;
	}

	do_write(buffer, count);
}

static void snapshot_putc(char *console, uint32_t *cursor, char c)
{
	/* This is BIOS_LOG_IS_MARKER() from coreboot. Due to stupid
	   licensing restrictions, we can't use it directly. */
	if (c >= 0x10 && c <= 0x18)
		return;

	/* Slight memory corruption may occur between reboots and give us a few
	   unprintable characters like '\0'. Replace them with '?' on output. */
	if (!isprint(c) && !isspace(c))
		console[*cursor] = '?';
	else
		console[*cursor] = c;

	*cursor += 1;
}

char *cbmem_console_snapshot(void)
{
	const struct cbmem_console *const console_p = phys_to_virt(cbmem_console_p);
	char *console_c;
	uint32_t size, cursor, overflow, newc, oldc;

	if (!console_p) {
		printf("ERROR: No cbmem console found in coreboot table\n");
		return NULL;
	}

	cursor = console_p->cursor & CURSOR_MASK;
	overflow = console_p->cursor & OVERFLOW;
	if (!overflow && cursor < console_p->size)
		size = cursor;
	else
		size = console_p->size;

	console_c = malloc(size + 1);
	if (!console_c) {
		printf("ERROR: Not enough memory for console (size = %u)\n",
		       size);
		return NULL;
	}

	newc = 0;
	if (overflow) {
		if (cursor >= size) {
			printf("ERROR: CBMEM console struct is corrupted\n");
			return NULL;
		}
		for (oldc = cursor; oldc < size; oldc++)
			snapshot_putc(console_c, &newc, console_p->body[oldc]);
	}
	for (oldc = 0; oldc < size && oldc < cursor; oldc++)
		snapshot_putc(console_c, &newc, console_p->body[oldc]);
	console_c[newc] = '\0';

	return console_c;
}