12272 loader: bc_add can not use any other probes than ah=0x4b

Reviewed by: Alexander Eremin <a.eremin@nexenta.com>
Reviewed by: Matthias Scheler <mscheler@tintri.com>
Approved by: Dan McDonald <danmcd@joyent.com>

2 files changed, 98 insertions, 52 deletions

diff --git a/usr/src/boot/Makefile.version b/usr/src/boot/Makefile.version
index f11337041e..b4fb4691f4 100644
--- a/usr/src/boot/Makefile.version
+++ b/usr/src/boot/Makefile.version
@@ -33,4 +33,4 @@ LOADER_VERSION = 1.1
 # Use date like formatting here, YYYY.MM.DD.XX, without leading zeroes.
 # The version is processed from left to right, the version number can only
 # be increased.
-BOOT_VERSION = $(LOADER_VERSION)-2020.01.17.1
+BOOT_VERSION = $(LOADER_VERSION)-2020.02.02.1
diff --git a/usr/src/boot/sys/boot/i386/libi386/biosdisk.c b/usr/src/boot/sys/boot/i386/libi386/biosdisk.c
index 3d1ab645d5..343b8b0df9 100644
--- a/usr/src/boot/sys/boot/i386/libi386/biosdisk.c
+++ b/usr/src/boot/sys/boot/i386/libi386/biosdisk.c
@@ -97,7 +97,8 @@ struct specification_packet {
 	uint16_t	sp_sectorcount;
 	uint16_t	sp_cylsec;
 	uint8_t		sp_head;
-};
+	uint8_t		sp_dummy[16];	/* Avoid memory corruption */
+} __packed;
 
 /*
  * List of BIOS devices, translation from disk unit number to
@@ -367,54 +368,92 @@ cd_init(void)
 	return (0);
 }
 
-int
-bc_add(int biosdev)
+/*
+ * Information from bootable CD-ROM.
+ */
+static int
+bd_get_diskinfo_cd(struct bdinfo *bd)
 {
-	bdinfo_t *bd;
 	struct specification_packet bc_sp;
-	int nbcinfo = 0;
+	int ret = -1;
 
-	if (!STAILQ_EMPTY(&cdinfo))
-		return (-1);
+	(void) memset(&bc_sp, 0, sizeof (bc_sp));
+	/* Set sp_size as per specification. */
+	bc_sp.sp_size = sizeof (bc_sp) - sizeof (bc_sp.sp_dummy);
 
 	v86.ctl = V86_FLAGS;
 	v86.addr = DISK_BIOS;
 	v86.eax = CMD_CD_GET_STATUS;
-	v86.edx = biosdev;
+	v86.edx = bd->bd_unit;
 	v86.ds = VTOPSEG(&bc_sp);
 	v86.esi = VTOPOFF(&bc_sp);
 	v86int();
-	if ((v86.eax & 0xff00) != 0)
-		return (-1);
 
-	if ((bd = calloc(1, sizeof (*bd))) == NULL)
-		return (-1);
+	if ((v86.eax & 0xff00) == 0 &&
+	    bc_sp.sp_drive == bd->bd_unit) {
+		bd->bd_cyl = ((bc_sp.sp_cylsec & 0xc0) << 2) +
+		    ((bc_sp.sp_cylsec & 0xff00) >> 8) + 1;
+		bd->bd_sec = bc_sp.sp_cylsec & 0x3f;
+		bd->bd_hds = bc_sp.sp_head + 1;
+		bd->bd_sectors = (uint64_t)bd->bd_cyl * bd->bd_hds * bd->bd_sec;
 
-	bd->bd_flags = BD_CDROM;
-	bd->bd_unit = biosdev;
-	bd->bd_sectorsize = 2048;
+		if (bc_sp.sp_bootmedia & 0x0F) {
+			/* Floppy or hard-disk emulation */
+			bd->bd_sectorsize = BIOSDISK_SECSIZE;
+			return (-1);
+		} else {
+			bd->bd_sectorsize = 2048;
+			bd->bd_flags = BD_MODEEDD | BD_CDROM;
+			ret = 0;
+		}
+	}
 
 	/*
-	 * Ignore result from bd_int13probe(), we will use local
-	 * workaround below.
+	 * If this is the boot_drive, default to non-emulation bootable CD-ROM.
 	 */
-	(void) bd_int13probe(bd);
-
-	if (bd->bd_cyl == 0) {
-		bd->bd_cyl = ((bc_sp.sp_cylsec & 0xc0) << 2) +
-		    ((bc_sp.sp_cylsec & 0xff00) >> 8) + 1;
+	if (ret != 0 && bd->bd_unit >= 0x88) {
+		bd->bd_cyl = 0;
+		bd->bd_hds = 1;
+		bd->bd_sec = 15;
+		bd->bd_sectorsize = 2048;
+		bd->bd_flags = BD_MODEEDD | BD_CDROM;
+		bd->bd_sectors = 0;
+		ret = 0;
 	}
-	if (bd->bd_hds == 0)
-		bd->bd_hds = bc_sp.sp_head + 1;
-	if (bd->bd_sec == 0)
-		bd->bd_sec = bc_sp.sp_cylsec & 0x3f;
-	if (bd->bd_sectors == 0)
-		bd->bd_sectors = (uint64_t)bd->bd_cyl * bd->bd_hds * bd->bd_sec;
 
-	/* Still no size? use 7.961GB */
+	/*
+	 * Note we can not use bd_get_diskinfo_ext() nor bd_get_diskinfo_std()
+	 * here - some systems do get hung with those.
+	 */
+	/*
+	 * Still no size? use 7.961GB. The size does not really matter
+	 * as long as it is reasonably large to make our reads to pass
+	 * the sector count check.
+	 */
 	if (bd->bd_sectors == 0)
 		bd->bd_sectors = 4173824;
 
+	return (ret);
+}
+
+int
+bc_add(int biosdev)
+{
+	bdinfo_t *bd;
+	int nbcinfo = 0;
+
+	if (!STAILQ_EMPTY(&cdinfo))
+		return (-1);
+
+	if ((bd = calloc(1, sizeof (*bd))) == NULL)
+		return (-1);
+
+	bd->bd_unit = biosdev;
+	if (bd_get_diskinfo_cd(bd) < 0) {
+		free(bd);
+		return (-1);
+	}
+
 	STAILQ_INSERT_TAIL(&cdinfo, bd, bd_link);
 	printf("BIOS CD is cd%d\n", nbcinfo);
 	nbcinfo++;
@@ -494,22 +533,31 @@ bd_get_diskinfo_std(struct bdinfo *bd)
 
 /*
  * Read EDD info. Return 0 on success, error otherwise.
+ *
+ * Avoid stack corruption on some systems by adding extra bytes to
+ * params block.
  */
 static int
 bd_get_diskinfo_ext(struct bdinfo *bd)
 {
-	struct edd_params params;
+	struct disk_params {
+		struct edd_params head;
+		struct edd_device_path_v3 device_path;
+		uint8_t	dummy[16];
+	} __packed dparams;
+	struct edd_params *params;
 	uint64_t total;
 
+	params = &dparams.head;
 	/* Get disk params */
-	bzero(&params, sizeof (params));
-	params.len = sizeof (params);
+	bzero(&dparams, sizeof (dparams));
+	params->len = sizeof (struct edd_params_v3);
 	v86.ctl = V86_FLAGS;
 	v86.addr = DISK_BIOS;
 	v86.eax = CMD_EXT_PARAM;
 	v86.edx = bd->bd_unit;
-	v86.ds = VTOPSEG(&params);
-	v86.esi = VTOPOFF(&params);
+	v86.ds = VTOPSEG(&dparams);
+	v86.esi = VTOPOFF(&dparams);
 	v86int();
 
 	if (V86_CY(v86.efl) && ((v86.eax & 0xff00) != 0))
@@ -521,20 +569,20 @@ bd_get_diskinfo_ext(struct bdinfo *bd)
 	 * powerof2(params.sector_size).
 	 * 16K is largest read buffer we can use at this time.
 	 */
-	if (params.sector_size >= 512 &&
-	    params.sector_size <= 16384 &&
-	    (params.sector_size % BIOSDISK_SECSIZE) == 0)
-		bd->bd_sectorsize = params.sector_size;
+	if (params->sector_size >= 512 &&
+	    params->sector_size <= 16384 &&
+	    (params->sector_size % BIOSDISK_SECSIZE) == 0)
+		bd->bd_sectorsize = params->sector_size;
 
-	bd->bd_cyl = params.cylinders;
-	bd->bd_hds = params.heads;
-	bd->bd_sec = params.sectors_per_track;
+	bd->bd_cyl = params->cylinders;
+	bd->bd_hds = params->heads;
+	bd->bd_sec = params->sectors_per_track;
 
-	if (params.sectors != 0) {
-		total = params.sectors;
+	if (params->sectors != 0) {
+		total = params->sectors;
 	} else {
-		total = (uint64_t)params.cylinders *
-		    params.heads * params.sectors_per_track;
+		total = (uint64_t)params->cylinders *
+		    params->heads * params->sectors_per_track;
 	}
 	bd->bd_sectors = total;
 
@@ -551,6 +599,10 @@ bd_int13probe(bdinfo_t *bd)
 
 	bd->bd_flags &= ~BD_NO_MEDIA;
 
+	if ((bd->bd_flags & BD_CDROM) != 0) {
+		return (bd_get_diskinfo_cd(bd) == 0);
+	}
+
 	edd = bd_check_extensions(bd->bd_unit);
 	if (edd == 0)
 		bd->bd_flags |= BD_MODEINT13;
@@ -599,10 +651,6 @@ bd_int13probe(bdinfo_t *bd)
 	}
 
 	if (ret != 0) {
-		/* CD is special case, bc_add() has its own fallback. */
-		if ((bd->bd_flags & BD_CDROM) != 0)
-			return (true);
-
 		if (bd->bd_sectors != 0 && edd != 0) {
 			bd->bd_sec = 63;
 			bd->bd_hds = 255;
@@ -614,8 +662,6 @@ bd_int13probe(bdinfo_t *bd)
 
 			if ((bd->bd_flags & BD_FLOPPY) != 0)
 				dv_name = biosfd.dv_name;
-			else if ((bd->bd_flags & BD_CDROM) != 0)
-				dv_name = bioscd.dv_name;
 			else
 				dv_name = bioshd.dv_name;