fbdev: Warn on incorrect framebuffer access

Test in framebuffer read, write and drawing helpers if FBINFO_VIRTFB
has been set correctly. Framebuffers in I/O memory should only be
accessed with the architecture's respective helpers. Framebuffers
in system memory should be accessed with the regular load and
store operations. Presumably not all drivers get this right, so we
now warn about it.

Signed-off-by: Thomas Zimmermann <[e-mail]>
Reviewed-by: Javier Martinez Canillas <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/video/fbdev/core/cfbcopyarea.c

···
 	if (p->state != FBINFO_STATE_RUNNING)
 		return;
 
+	if (p->flags & FBINFO_VIRTFB)
+		fb_warn_once(p, "Framebuffer is not in I/O address space.");
+
 	/* if the beginning of the target area might overlap with the end of
 	the source area, be have to copy the area reverse. */
 	if ((dy == sy && dx > sx) || (dy > sy)) {

drivers/video/fbdev/core/cfbfillrect.c

···
 	if (p->state != FBINFO_STATE_RUNNING)
 		return;
 
+	if (p->flags & FBINFO_VIRTFB)
+		fb_warn_once(p, "Framebuffer is not in I/O address space.");
+
 	if (p->fix.visual == FB_VISUAL_TRUECOLOR ||
 	    p->fix.visual == FB_VISUAL_DIRECTCOLOR )
 		fg = ((u32 *) (p->pseudo_palette))[rect->color];

drivers/video/fbdev/core/cfbimgblt.c

···
 	if (p->state != FBINFO_STATE_RUNNING)
 		return;
 
+	if (p->flags & FBINFO_VIRTFB)
+		fb_warn_once(p, "Framebuffer is not in I/O address space.");
+
 	bitstart = (dy * p->fix.line_length * 8) + (dx * bpp);
 	start_index = bitstart & (32 - 1);
 	pitch_index = (p->fix.line_length & (bpl - 1)) * 8;

drivers/video/fbdev/core/fb_io_fops.c

···
 	int c, cnt = 0, err = 0;
 	unsigned long total_size, trailing;
 
+	if (info->flags & FBINFO_VIRTFB)
+		fb_warn_once(info, "Framebuffer is not in I/O address space.");
+
 	if (!info->screen_base)
 		return -ENODEV;
 
···
 	u8 __iomem *dst;
 	int c, cnt = 0, err = 0;
 	unsigned long total_size, trailing;
+
+	if (info->flags & FBINFO_VIRTFB)
+		fb_warn_once(info, "Framebuffer is not in I/O address space.");
 
 	if (!info->screen_base)
 		return -ENODEV;
···
 	unsigned long start = info->fix.smem_start;
 	u32 len = info->fix.smem_len;
 	unsigned long mmio_pgoff = PAGE_ALIGN((start & ~PAGE_MASK) + len) >> PAGE_SHIFT;
+
+	if (info->flags & FBINFO_VIRTFB)
+		fb_warn_once(info, "Framebuffer is not in I/O address space.");
 
 	/*
 	 * This can be either the framebuffer mapping, or if pgoff points

drivers/video/fbdev/core/fb_sys_fops.c

···
 	unsigned long total_size, c;
 	ssize_t ret;
 
+	if (!(info->flags & FBINFO_VIRTFB))
+		fb_warn_once(info, "Framebuffer is not in virtual address space.");
+
 	if (!info->screen_buffer)
 		return -ENODEV;
 
···
 	int err = 0;
 	unsigned long total_size, c;
 	size_t ret;
+
+	if (!(info->flags & FBINFO_VIRTFB))
+		fb_warn_once(info, "Framebuffer is not in virtual address space.");
 
 	if (!info->screen_buffer)
 		return -ENODEV;

drivers/video/fbdev/core/syscopyarea.c

···
 	if (p->state != FBINFO_STATE_RUNNING)
 		return;
 
+	if (!(p->flags & FBINFO_VIRTFB))
+		fb_warn_once(p, "Framebuffer is not in virtual address space.");
+
 	/* if the beginning of the target area might overlap with the end of
 	the source area, be have to copy the area reverse. */
 	if ((dy == sy && dx > sx) || (dy > sy)) {

drivers/video/fbdev/core/sysfillrect.c

···
 	if (p->state != FBINFO_STATE_RUNNING)
 		return;
 
+	if (!(p->flags & FBINFO_VIRTFB))
+		fb_warn_once(p, "Framebuffer is not in virtual address space.");
+
 	if (p->fix.visual == FB_VISUAL_TRUECOLOR ||
 	    p->fix.visual == FB_VISUAL_DIRECTCOLOR )
 		fg = ((u32 *) (p->pseudo_palette))[rect->color];

drivers/video/fbdev/core/sysimgblt.c

···
 	if (p->state != FBINFO_STATE_RUNNING)
 		return;
 
+	if (!(p->flags & FBINFO_VIRTFB))
+		fb_warn_once(p, "Framebuffer is not in virtual address space.");
+
 	bitstart = (dy * p->fix.line_length * 8) + (dx * bpp);
 	start_index = bitstart & (32 - 1);
 	pitch_index = (p->fix.line_length & (bpl - 1)) * 8;

include/linux/fb.h

···
 }
 #endif
 
-/* Convenience logging macros */
+/*
+ * Convenience logging macros
+ */
+
 #define fb_err(fb_info, fmt, ...)					\
 	pr_err("fb%d: " fmt, (fb_info)->node, ##__VA_ARGS__)
 #define fb_notice(info, fmt, ...)					\
···
 	pr_info("fb%d: " fmt, (fb_info)->node, ##__VA_ARGS__)
 #define fb_dbg(fb_info, fmt, ...)					\
 	pr_debug("fb%d: " fmt, (fb_info)->node, ##__VA_ARGS__)
+
+#define fb_warn_once(fb_info, fmt, ...)					\
+	pr_warn_once("fb%d: " fmt, (fb_info)->node, ##__VA_ARGS__)
 
 #endif /* _LINUX_FB_H */