linux-kernel - [tip:efi/urgent] efi/libstub: Skip GOP with PIXEL_BLT

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Date:   Wed, 5 Apr 2017 00:57:55 -0700
From:   "tip-bot for Cohen, Eugene" <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     ard.biesheuvel@...aro.org, peterz@...radead.org, mingo@...nel.org,
        torvalds@...ux-foundation.org, eugene@...com, hpa@...or.com,
        linux-kernel@...r.kernel.org, tglx@...utronix.de,
        matt@...eblueprint.co.uk
Subject: [tip:efi/urgent] efi/libstub: Skip GOP with PIXEL_BLT_ONLY format

Commit-ID:  540f4c0e894f7e46a66dfa424b16424cbdc12c38
Gitweb:     http://git.kernel.org/tip/540f4c0e894f7e46a66dfa424b16424cbdc12c38
Author:     Cohen, Eugene <eugene@...com>
AuthorDate: Tue, 4 Apr 2017 16:27:43 +0100
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 5 Apr 2017 09:20:18 +0200

efi/libstub: Skip GOP with PIXEL_BLT_ONLY format

The UEFI Specification permits Graphics Output Protocol (GOP) instances
without direct framebuffer access. This is indicated in the Mode structure
with a PixelFormat enumeration value of PIXEL_BLT_ONLY. Given that the
kernel does not know how to drive a Blt() only framebuffer (which is only
permitted before ExitBootServices() anyway), we should disregard such
framebuffers when looking for a GOP instance that is suitable for use as
the boot console.

So modify the EFI GOP initialization to not use a PIXEL_BLT_ONLY instance,
preventing attempts later in boot to use an invalid screen_info.lfb_base
address.

Signed-off-by: Eugene Cohen <eugene@...com>
[ Moved the Blt() only check into the loop and clarified that Blt() only GOPs are unusable by the kernel. ]
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc: <stable@...r.kernel.org> # v4.7+
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Matt Fleming <matt@...eblueprint.co.uk>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: leif.lindholm@...aro.org
Cc: linux-efi@...r.kernel.org
Cc: lorenzo.pieralisi@....com
Fixes: 9822504c1fa5 ("efifb: Enable the efi-framebuffer platform driver ...")
Link: http://lkml.kernel.org/r/20170404152744.26687-2-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 drivers/firmware/efi/libstub/gop.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/efi/libstub/gop.c b/drivers/firmware/efi/libstub/gop.c
index 932742e..24c461d 100644
--- a/drivers/firmware/efi/libstub/gop.c
+++ b/drivers/firmware/efi/libstub/gop.c
@@ -149,7 +149,8 @@ setup_gop32(efi_system_table_t *sys_table_arg, struct screen_info *si,
 
 		status = __gop_query32(sys_table_arg, gop32, &info, &size,
 				       &current_fb_base);
-		if (status == EFI_SUCCESS && (!first_gop || conout_found)) {
+		if (status == EFI_SUCCESS && (!first_gop || conout_found) &&
+		    info->pixel_format != PIXEL_BLT_ONLY) {
 			/*
 			 * Systems that use the UEFI Console Splitter may
 			 * provide multiple GOP devices, not all of which are
@@ -266,7 +267,8 @@ setup_gop64(efi_system_table_t *sys_table_arg, struct screen_info *si,
 
 		status = __gop_query64(sys_table_arg, gop64, &info, &size,
 				       &current_fb_base);
-		if (status == EFI_SUCCESS && (!first_gop || conout_found)) {
+		if (status == EFI_SUCCESS && (!first_gop || conout_found) &&
+		    info->pixel_format != PIXEL_BLT_ONLY) {
 			/*
 			 * Systems that use the UEFI Console Splitter may
 			 * provide multiple GOP devices, not all of which are