[coreboot-gerrit] Change in coreboot[master]: libpayload/corebootfb: Fix character buffer relocation

[Nico Huber (Code Review)]

Hello Julius Werner,

I'd like you to do a code review. Please visit

https://review.coreboot.org/c/coreboot/+/38536

to review the following change.

Change subject: libpayload/corebootfb: Fix character buffer relocation
......................................................................

libpayload/corebootfb: Fix character buffer relocation

The `chars` pointer references the heap which is part of the payload
and relocated along with it. So calling phys_to_virt() on it was
always wrong; and the virt_to_phys() at its initialization was a
no-op anyway, when the console was brought up before relocation.

While we are at it, add a null-pointer check.

Change-Id: Ic03150f0bcd14a6ec6bf514dffe2b9153d5a6d2a
Signed-off-by: Nico Huber 
---
M payloads/libpayload/drivers/video/corebootfb.c
1 file changed, 6 insertions(+), 5 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/36/38536/1

diff --git a/payloads/libpayload/drivers/video/corebootfb.c b/payloads/libpayload/drivers/video/corebootfb.c
index b5ad1a5..11397ba 100644
--- a/payloads/libpayload/drivers/video/corebootfb.c
+++ b/payloads/libpayload/drivers/video/corebootfb.c
@@ -64,11 +64,11 @@
 /* Addresses for the various components */
 static unsigned long fbinfo;
 static unsigned long fbaddr;
-static unsigned long chars;
+static unsigned short *chars;

#define FI ((struct cb_framebuffer *) phys_to_virt(fbinfo))
 #define FB ((unsigned char *) phys_to_virt(fbaddr))
-#define CHARS ((unsigned short *) phys_to_virt(chars))
+#define CHARS (chars)

static void corebootfb_scroll_up(void)
 {
@@ -243,9 +243,10 @@
    coreboot_video_console.columns = FI->x_resolution / font_width;
    coreboot_video_console.rows = FI->y_resolution / font_height;

-	/* See setting of fbinfo above. */
-	chars = virt_to_phys(malloc(coreboot_video_console.rows *
-				    coreboot_video_console.columns * 2));
+	chars = malloc(coreboot_video_console.rows *
+		       coreboot_video_console.columns * 2);
+	if (!chars)
+		return -1;

// clear boot splash screen if there is one.
    corebootfb_clear();