From 840fa0f86d6de5c7b45c37a69ae86e07795b2f2a Mon Sep 17 00:00:00 2001
From: Toomas Soome <tsoome@FreeBSD.org>
Date: Tue, 17 Sep 2019 13:50:25 +0000
Subject: [PATCH] loader.efi: efipart needs to use ioalign

UEFI specification 2.7A, EFI_BLOCK_IO_PROTOCOL, page 566.

The ioalign property does define the alignment of data buffer.

If the alignment is required and our buffer is not aligned, or if
the data buffer is not multiple of Blocksize, we need to use bounce buffer
to perform the block IO. This is much like with BIOS version, except
there the INT13 needs buffer to be located in low memory.

Additionally, we need to handle disk writes properly.
---
 stand/efi/libefi/efipart.c | 137 ++++++++++++++++++++++++++++++-------
 1 file changed, 113 insertions(+), 24 deletions(-)

diff --git a/stand/efi/libefi/efipart.c b/stand/efi/libefi/efipart.c
index 973ad8f7722f..2affab1c4274 100644
--- a/stand/efi/libefi/efipart.c
+++ b/stand/efi/libefi/efipart.c
@@ -64,6 +64,9 @@ static int efipart_printhd(int);
 #define	PNP0700	0x700
 #define	PNP0701	0x701
 
+/* Bounce buffer max size */
+#define	BIO_BUFFER_SIZE	0x4000
+
 struct devsw efipart_fddev = {
 	.dv_name = "fd",
 	.dv_type = DEVT_FD,
@@ -266,6 +269,12 @@ efipart_inithandles(void)
 			continue;
 		}
 
+		/* Allowed values are 0, 1 and power of 2. */
+		if (blkio->Media->IoAlign > 1 &&
+		    !powerof2(blkio->Media->IoAlign)) {
+			continue;
+		}
+
 		/* This is bad. */
 		if ((pd = calloc(1, sizeof(*pd))) == NULL) {
 			printf("efipart_inithandles: Out of memory.\n");
@@ -979,8 +988,10 @@ efipart_realstrategy(void *devdata, int rw, daddr_t blk, size_t size,
 	EFI_BLOCK_IO *blkio;
 	uint64_t off, disk_blocks, d_offset = 0;
 	char *blkbuf;
-	size_t blkoff, blksz;
-	int error;
+	size_t blkoff, blksz, bio_size;
+	unsigned ioalign;
+	bool need_buf;
+	int rc;
 	uint64_t diskend, readstart;
 
 	if (dev == NULL || blk < 0)
@@ -1028,40 +1039,118 @@ efipart_realstrategy(void *devdata, int rw, daddr_t blk, size_t size,
 		size = size * blkio->Media->BlockSize;
 	}
 
-	if (rsize != NULL)
-		*rsize = size;
-
+	need_buf = true;
+	/* Do we need bounce buffer? */
 	if ((size % blkio->Media->BlockSize == 0) &&
 	    (off % blkio->Media->BlockSize == 0))
-		return (efipart_readwrite(blkio, rw,
-		    off / blkio->Media->BlockSize,
-		    size / blkio->Media->BlockSize, buf));
+		need_buf = false;
+
+	/* Do we have IO alignment requirement? */
+	ioalign = blkio->Media->IoAlign;
+	if (ioalign == 0)
+		ioalign++;
+
+	if (ioalign > 1 && (uintptr_t)buf != roundup2((uintptr_t)buf, ioalign))
+		need_buf = true;
+
+	if (need_buf) {
+		for (bio_size = BIO_BUFFER_SIZE; bio_size > 0;
+		    bio_size -= blkio->Media->BlockSize) {
+			blkbuf = memalign(ioalign, bio_size);
+			if (blkbuf != NULL)
+				break;
+		}
+	} else {
+		blkbuf = buf;
+		bio_size = size;
+	}
 
-	/*
-	 * The buffer size is not a multiple of the media block size.
-	 */
-	blkbuf = malloc(blkio->Media->BlockSize);
 	if (blkbuf == NULL)
 		return (ENOMEM);
 
-	error = 0;
+	if (rsize != NULL)
+		*rsize = size;
+
+	rc = 0;
 	blk = off / blkio->Media->BlockSize;
 	blkoff = off % blkio->Media->BlockSize;
-	blksz = blkio->Media->BlockSize - blkoff;
+
 	while (size > 0) {
-		error = efipart_readwrite(blkio, rw, blk, 1, blkbuf);
-		if (error)
+		size_t x = min(size, bio_size);
+
+		if (x < blkio->Media->BlockSize)
+			x = 1;
+		else
+			x /= blkio->Media->BlockSize;
+
+		switch (rw & F_MASK) {
+		case F_READ:
+			blksz = blkio->Media->BlockSize * x - blkoff;
+			if (size < blksz)
+				blksz = size;
+
+			rc = efipart_readwrite(blkio, rw, blk, x, blkbuf);
+			if (rc != 0)
+				goto error;
+
+			if (need_buf)
+				bcopy(blkbuf + blkoff, buf, blksz);
 			break;
-		if (size < blksz)
-			blksz = size;
-		bcopy(blkbuf + blkoff, buf, blksz);
+		case F_WRITE:
+			rc = 0;
+			if (blkoff != 0) {
+				/*
+				 * We got offset to sector, read 1 sector to
+				 * blkbuf.
+				 */
+				x = 1;
+				blksz = blkio->Media->BlockSize - blkoff;
+				blksz = min(blksz, size);
+				rc = efipart_readwrite(blkio, F_READ, blk, x,
+				    blkbuf);
+			} else if (size < blkio->Media->BlockSize) {
+				/*
+				 * The remaining block is not full
+				 * sector. Read 1 sector to blkbuf.
+				 */
+				x = 1;
+				blksz = size;
+				rc = efipart_readwrite(blkio, F_READ, blk, x,
+				    blkbuf);
+			} else {
+				/* We can write full sector(s). */
+				blksz = blkio->Media->BlockSize * x;
+			}
+
+			if (rc != 0)
+				goto error;
+			/*
+			 * Put your Data In, Put your Data out,
+			 * Put your Data In, and shake it all about
+			 */
+			if (need_buf)
+				bcopy(buf, blkbuf + blkoff, blksz);
+			rc = efipart_readwrite(blkio, F_WRITE, blk, x, blkbuf);
+			if (rc != 0)
+				goto error;
+			break;
+		default:
+			/* DO NOTHING */
+			rc = EROFS;
+			goto error;
+		}
+
+		blkoff = 0;
 		buf += blksz;
 		size -= blksz;
-		blk++;
-		blkoff = 0;
-		blksz = blkio->Media->BlockSize;
+		blk += x;
 	}
 
-	free(blkbuf);
-	return (error);
+error:
+	if (rsize != NULL)
+		*rsize -= size;
+
+	if (need_buf)
+		free(blkbuf);
+	return (rc);
 }