SFI: Fixed MMAP search routine

BZ: 114933

Needs to search for MMAP via SYST table
Added SFI table verification
Optimized table search:
  * Search for SYST on 16-byte boundary
  * Table signature match via magic number rather than strcmp

Change-Id: Ic1e32eb7622ac1839ceb22e1315df50709df485a
Signed-off-by: Mark F. Brown <mark.f.brown@intel.com>
Reviewed-by: Jim A. Pelner <jim.a.pelner@intel.com>
Reviewed-on: http://android.intel.com:8080/112532
Reviewed-by: Fourdan, Olivier <olivier.fourdan@intel.com>
Tested-by: Fourdan, Olivier <olivier.fourdan@intel.com>
Reviewed-by: Fert, Laurent <laurent.fert@intel.com>
Reviewed-by: cactus <cactus@intel.com>
Tested-by: cactus <cactus@intel.com>

2 files changed, 71 insertions, 12 deletions

diff --git a/sfi.c b/sfi.c
index f5e5656..1f88d71 100644
--- a/sfi.c
+++ b/sfi.c
@@ -25,19 +25,67 @@
 
 #define SFI_BASE_ADDR		0x000E0000
 #define SFI_LENGTH		0x00020000
+#define SFI_TABLE_LENGTH	16
 
-static unsigned long sfi_search_mmap(unsigned long start, int len)
+static int sfi_table_check(struct sfi_table_header *sbh)
 {
-	unsigned long i = 0;
-	char *pchar = (char *)start;
-
-	for (i = 0; i < len; i++, pchar++) {
-		if (pchar[0] == 'M'
-			&& pchar[1] == 'M'
-			&& pchar[2] == 'A'
-			&& pchar[3] == 'P')
-			return start + i;
+	char chksum = 0;
+	char *pos = (char *)sbh;
+	int i;
+
+	if (sbh->length < SFI_TABLE_LENGTH)
+		return -1;
+
+	if (sbh->length > SFI_LENGTH)
+		return -1;
+
+	for (i = 0; i < sbh->length; i++)
+		chksum += *pos++;
+
+	if (chksum)
+		bs_printk("sfi: Invalid checksum\n");
+
+	/* checksum is ok if zero */
+	return chksum;
+}
+
+static unsigned long sfi_search_mmap(void)
+{
+	u32 i = 0;
+	u32 *pos = (u32 *)SFI_BASE_ADDR;
+	u32 *end = (u32 *)(SFI_BASE_ADDR + SFI_LENGTH);
+	struct sfi_table_header *sbh;
+	struct sfi_table *sb;
+	u32 sys_entry_cnt = 0;
+
+	/* Find SYST table */
+	for (; pos < end; pos += 4) {
+		if (*pos == SFI_SYST_MAGIC) {
+			if (!sfi_table_check((struct sfi_table_header *)pos))
+				break;
+		}
+	}
+
+	if (pos >= end) {
+		bs_printk("Bootstub: failed to locate SFI SYST table\n");
+		return 0;
 	}
+
+	/* map table pointers */
+	sb = (struct sfi_table *)pos;
+	sbh = (struct sfi_table_header *)sb;
+
+	sys_entry_cnt = (sbh->length - sizeof(struct sfi_table_header)) >> 3;
+
+	/* Search through each SYST entry for MMAP table */
+	for (i = 0; i < sys_entry_cnt; i++) {
+		sbh = (struct sfi_table_header *)sb->entry[i].low;
+		if (*(u32 *)sbh->signature == SFI_MMAP_MAGIC) {
+			if (!sfi_table_check((struct sfi_table_header *)sbh))
+				return (unsigned long) sbh;
+		}
+	}
+
 	return 0;
 }
 
@@ -52,7 +100,7 @@ void sfi_setup_e820(struct boot_params *bp)
 	total = 0;
 
 	/* search for sfi mmap table */
-	sb = (struct sfi_table *)sfi_search_mmap(SFI_BASE_ADDR, SFI_LENGTH);
+	sb = (struct sfi_table *)sfi_search_mmap();
 	if (!sb) {
 		bs_printk("Bootstub: failed to locate SFI MMAP table\n");
 		return;
diff --git a/sfi.h b/sfi.h
index 019cc96..21e5d1a 100644
--- a/sfi.h
+++ b/sfi.h
@@ -37,9 +37,17 @@ struct sfi_table_header {
 	char oem_table_id[8];
 }__attribute__((packed));
 
+struct __sfi_quad_word {
+	u32 low;
+	u32 high;
+};
+
 struct sfi_table {
 	struct sfi_table_header header;
-	u64 pentry[1];
+	union {
+		u64 pentry[1];
+		struct __sfi_quad_word entry[1];
+	};
 }__attribute__((packed));
 
 #define SFI_TBL_HEADER_LEN      24
@@ -54,5 +62,8 @@ struct sfi_table {
 #define E820_NVS	4
 #define E820_UNUSABLE	5
 
+#define SFI_SYST_MAGIC	0x54535953 /* SYST */
+#define SFI_MMAP_MAGIC	0x50414d4d /* MMAP */
+
 extern void sfi_setup_e820(struct boot_params *bp);
 #endif /* _SFI_H */