From aa3cc56ab20763eb1d8e04085ee6013636760606 Mon Sep 17 00:00:00 2001
From: Michael Brown
Date: Fri, 25 Apr 2025 10:52:26 +0100
Subject: [fbcon] Remove userptr_t from framebuffer console drivers

Simplify the framebuffer console drivers by assuming that the raw
framebuffer, character cell array, background picture, and glyph data
are all directly accessible via pointer dereferences.

In particular, this avoids the need to copy each glyph during drawing:
the VESA framebuffer driver can simply return a pointer to the glyph
data stored in the video ROM.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
---
 src/interface/efi/efi_fbcon.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

(limited to 'src/interface/efi/efi_fbcon.c')

diff --git a/src/interface/efi/efi_fbcon.c b/src/interface/efi/efi_fbcon.c
index 09cfde4c2..9c5d7063d 100644
--- a/src/interface/efi/efi_fbcon.c
+++ b/src/interface/efi/efi_fbcon.c
@@ -42,6 +42,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #include <ipxe/ansicol.h>
 #include <ipxe/fbcon.h>
 #include <ipxe/console.h>
+#include <ipxe/uaccess.h>
 #include <ipxe/umalloc.h>
 #include <ipxe/rotate.h>
 #include <config/console.h>
@@ -91,7 +92,7 @@ struct efifb {
 	/** Font definition */
 	struct fbcon_font font;
 	/** Character glyph cache */
-	userptr_t glyphs;
+	uint8_t *glyphs;
 	/** Dynamic characters in cache */
 	unsigned int dynamic[EFIFB_DYNAMIC];
 	/** Next dynamic character cache entry to evict */
@@ -117,14 +118,14 @@ static int efifb_draw ( unsigned int character, unsigned int index,
 	unsigned int height;
 	unsigned int x;
 	unsigned int y;
+	uint8_t *glyph;
 	uint8_t bitmask;
-	size_t offset;
 	EFI_STATUS efirc;
 	int rc;
 
 	/* Clear existing glyph */
-	offset = ( index * efifb.font.height );
-	memset ( ( efifb.glyphs + offset ), 0, efifb.font.height );
+	glyph = &efifb.glyphs[ index * efifb.font.height ];
+	memset ( glyph, 0, efifb.font.height );
 
 	/* Get glyph */
 	blt = NULL;
@@ -157,8 +158,7 @@ static int efifb_draw ( unsigned int character, unsigned int index,
 			pixel++;
 		}
 		bitmask ^= toggle;
-		copy_to_user ( efifb.glyphs, offset++, &bitmask,
-			       sizeof ( bitmask ) );
+		*(glyph++) = bitmask;
 	}
 
 	/* Free glyph */
@@ -223,11 +223,10 @@ static unsigned int efifb_dynamic ( unsigned int character ) {
  * Get character glyph
  *
  * @v character		Unicode character
- * @v glyph		Character glyph to fill in
+ * @ret glyph		Character glyph to fill in
  */
-static void efifb_glyph ( unsigned int character, uint8_t *glyph ) {
+static const uint8_t * efifb_glyph ( unsigned int character ) {
 	unsigned int index;
-	size_t offset;
 
 	/* Identify glyph */
 	if ( character < EFIFB_ASCII ) {
@@ -241,9 +240,8 @@ static void efifb_glyph ( unsigned int character, uint8_t *glyph ) {
 		index = efifb_dynamic ( character );
 	}
 
-	/* Copy cached glyph */
-	offset = ( index * efifb.font.height );
-	copy_from_user ( glyph, efifb.glyphs, offset, efifb.font.height );
+	/* Return cached glyph */
+	return &efifb.glyphs[ index * efifb.font.height ];
 }
 
 /**
-- 
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