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Commit 9164b4ce authored by David Herrmann's avatar David Herrmann Committed by Ingo Molnar
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x86/sysfb: Add support for 64bit EFI lfb_base 



The screen_info object was extended to support 64-bit lfb_base addresses
in:

  ae2ee627 ("efifb: Add support for 64-bit frame buffer addresses")

However, the x86 simple-framebuffer setup code never made use of it. Fix
it to properly assemble and verify the lfb_base before advertising
simple-framebuffer devices.

In particular, this means if VIDEO_CAPABILITY_64BIT_BASE is set, the
screen_info->ext_lfb_base field will contain the upper 32bit of the
actual lfb_base. Make sure the address is not 0 (i.e., unset), as well as
does not overflow the physical address type.

Signed-off-by: default avatarDavid Herrmann <dh.herrmann@gmail.com>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tom Gundersen <teg@jklm.no>
Link: http://lkml.kernel.org/r/20161115120158.15388-2-dh.herrmann@gmail.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 81bcfe5e

arch/x86/kernel/sysfb_simplefb.c

+16 −2
Original line number Diff line number Diff line
@@ -67,6 +67,20 @@ __init int create_simplefb(const struct screen_info *si, 
	struct platform_device *pd;

	struct resource res;

	unsigned long len;

	u64 base;



	/*

	 * If the 64BIT_BASE capability is set, ext_lfb_base will contain the

	 * upper half of the base address. Assemble the address, then make sure

	 * it is valid and we can actually access it.

	 */

	base = si->lfb_base;

	if (si->capabilities & VIDEO_CAPABILITY_64BIT_BASE)

		base |= (u64)si->ext_lfb_base << 32;

	if (!base || (u64)(resource_size_t)base != base) {

		printk(KERN_DEBUG "sysfb: inaccessible VRAM base\n");

		return -EINVAL;

	}



	/* don't use lfb_size as it may contain the whole VMEM instead of only

	 * the part that is occupied by the framebuffer */
@@ -81,8 +95,8 @@ __init int create_simplefb(const struct screen_info *si, 
	memset(&res, 0, sizeof(res));

	res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;

	res.name = simplefb_resname;

	res.start = si->lfb_base;

	res.end = si->lfb_base + len - 1;

	res.start = base;

	res.end = res.start + len - 1;

	if (res.end <= res.start)

		return -EINVAL;