From 475fe593d238f6b1c8edd78d2d819be7e79d6305 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@linux.intel.com>
Date: Fri, 25 Jun 2010 13:56:19 -0700
Subject: [PATCH] chain.c32: correctly set the length of the GPT handover
 structure

We need to make sure the entire GPT handover structure is mapped
correctly by the shuffler.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
---
 com32/modules/chain.c | 107 +++++++++++++++++++++++++++-----------------------
 1 file changed, 57 insertions(+), 50 deletions(-)

diff --git a/com32/modules/chain.c b/com32/modules/chain.c
index 6f3729f..b4fe3ef 100644
--- a/com32/modules/chain.c
+++ b/com32/modules/chain.c
@@ -1419,60 +1419,67 @@ int main(int argc, char *argv[])
 	ndata++;
     }
 
-    /* Do GPT hand-over, if applicable (as per syslinux/doc/gpt.txt) */
-    if (cur_part && (cur_part->next == next_gpt_part)) {
-	struct part_entry *record;
-	/* Look at the GPT partition */
-	const struct gpt_part *gp = (const struct gpt_part *)
+    if (cur_part) {
+	if (cur_part->next == next_gpt_part) {
+	    /* Do GPT hand-over, if applicable (as per syslinux/doc/gpt.txt) */
+	    struct part_entry *record;
+	    /* Look at the GPT partition */
+	    const struct gpt_part *gp = (const struct gpt_part *)
 	    (cur_part->block +
 	     (cur_part->private.gpt.size * cur_part->private.gpt.index));
-	/* Note the partition length */
-	uint64_t lba_count = gp->lba_last - gp->lba_first + 1;
-	/* The length of the hand-over */
-	int synth_size =
-	    sizeof(struct part_entry) + sizeof(uint32_t) +
-	    cur_part->private.gpt.size;
-	/* Will point to the partition record length in the hand-over */
-	uint32_t *plen;
-
-	/* Allocate the hand-over record */
-	record = malloc(synth_size);
-	if (!record) {
-	    error("Could not build GPT hand-over record!\n");
-	    goto bail;
-	}
-	/* Synthesize the record */
-	memset(record, 0, synth_size);
-	record->active_flag = 0x80;
-	record->ostype = 0xED;
-	/* All bits set by default */
-	record->start_lba = ~(uint32_t) 0;
-	record->length = ~(uint32_t) 0;
-	/* If these fit the precision, pass them on */
-	if (cur_part->lba_data < record->start_lba)
-	    record->start_lba = cur_part->lba_data;
-	if (lba_count < record->length)
-	    record->length = lba_count;
-	/* Next comes the GPT partition record length */
-	plen = (uint32_t *) (record + 1);
-	plen[0] = cur_part->private.gpt.size;
-	/* Next comes the GPT partition record copy */
-	memcpy(plen + 1, gp, plen[0]);
-	cur_part->record = record;
-	regs.eax.l = 0x54504721;	/* '!GPT' */
+	    /* Note the partition length */
+	    uint64_t lba_count = gp->lba_last - gp->lba_first + 1;
+	    /* The length of the hand-over */
+	    int synth_size =
+		sizeof(struct part_entry) + sizeof(uint32_t) +
+		cur_part->private.gpt.size;
+	    /* Will point to the partition record length in the hand-over */
+	    uint32_t *plen;
+
+	    /* Allocate the hand-over record */
+	    record = malloc(synth_size);
+	    if (!record) {
+		error("Could not build GPT hand-over record!\n");
+		goto bail;
+	    }
+	    /* Synthesize the record */
+	    memset(record, 0, synth_size);
+	    record->active_flag = 0x80;
+	    record->ostype = 0xED;
+	    /* All bits set by default */
+	    record->start_lba = ~(uint32_t) 0;
+	    record->length = ~(uint32_t) 0;
+	    /* If these fit the precision, pass them on */
+	    if (cur_part->lba_data < record->start_lba)
+		record->start_lba = cur_part->lba_data;
+	    if (lba_count < record->length)
+		record->length = lba_count;
+	    /* Next comes the GPT partition record length */
+	    plen = (uint32_t *) (record + 1);
+	    plen[0] = cur_part->private.gpt.size;
+	    /* Next comes the GPT partition record copy */
+	    memcpy(plen + 1, gp, plen[0]);
+	    cur_part->record = record;
+
+	    regs.eax.l = 0x54504721;	/* '!GPT' */
+	    data[ndata].base = 0x7be;
+	    data[ndata].size = synth_size;
+	    data[ndata].data = (void *)record;
+	    ndata++;
+	    regs.esi.w[0] = 0x7be;
 #if DEBUG
-	mbr_part_dump(record);
-	gpt_part_dump((struct gpt_part *)(plen + 1));
+	    mbr_part_dump(record);
+	    gpt_part_dump((struct gpt_part *)(plen + 1));
 #endif
-    }
-
-    if (cur_part && cur_part->record) {
-	/* 0x7BE is the canonical place for the first partition entry. */
-	data[ndata].data = (void *)cur_part->record;
-	data[ndata].base = 0x7be;
-	data[ndata].size = sizeof(*cur_part->record);
-	ndata++;
-	regs.esi.w[0] = 0x7be;
+	} else if (cur_part->record) {
+	    /* MBR handover protocol */
+
+	    data[ndata].base = 0x7be;
+	    data[ndata].size = sizeof(*cur_part->record);
+	    data[ndata].data = (void *)cur_part->record;
+	    ndata++;
+	    regs.esi.w[0] = 0x7be;
+	}
     }
 
     do_boot(data, ndata, &regs);
-- 
2.7.4