From: Alper Nebi Yasak <alpernebiyasak@gmail.com>
To: linux-kernel@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: chrome-platform@lists.linux.dev,
Patrick Georgi <pgeorgi@chromium.org>,
Julius Werner <jwerner@chromium.org>,
Tzung-Bi Shih <tzungbi@kernel.org>,
Samuel Holland <samuel@sholland.org>,
coreboot@coreboot.org, Brian Norris <briannorris@chromium.org>,
Alper Nebi Yasak <alpernebiyasak@gmail.com>
Subject: [PATCH] firmware: coreboot: framebuffer: Avoid invalid zero physical address
Date: Wed, 8 Nov 2023 21:25:13 +0300 [thread overview]
Message-ID: <20231108182625.46563-1-alpernebiyasak@gmail.com> (raw)
On ARM64 systems coreboot defers framebuffer allocation to its payload,
to be done by a libpayload function call. In this case, coreboot tables
still include a framebuffer entry with display format details, but the
physical address field is set to zero (as in [1], for example).
Unfortunately, this field is not automatically updated when the
framebuffer is initialized through libpayload, citing that doing so
would invalidate checksums over the entire coreboot table [2].
This can be observed on ARM64 Chromebooks with stock firmware. On a
Google Kevin (RK3399), trying to use coreboot framebuffer driver as
built-in to the kernel results in a benign error. But on Google Hana
(MT8173) and Google Cozmo (MT8183) it causes a hang.
When the framebuffer physical address field in the coreboot table is
zero, we have no idea where coreboot initialized a framebuffer, or even
if it did. Instead of trying to set up a framebuffer located at zero,
return ENODEV to indicate that there isn't one.
[1] https://review.coreboot.org/c/coreboot/+/17109
[2] https://review.coreboot.org/c/coreboot/+/8797
Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
---
(I was previously told on #coreboot IRC that I could add coreboot
mailing list to CC for kernel patches related to coreboot.)
drivers/firmware/google/framebuffer-coreboot.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/firmware/google/framebuffer-coreboot.c b/drivers/firmware/google/framebuffer-coreboot.c
index c323a818805c..5c84bbebfef8 100644
--- a/drivers/firmware/google/framebuffer-coreboot.c
+++ b/drivers/firmware/google/framebuffer-coreboot.c
@@ -36,6 +36,9 @@ static int framebuffer_probe(struct coreboot_device *dev)
.format = NULL,
};
+ if (!fb->physical_address)
+ return -ENODEV;
+
for (i = 0; i < ARRAY_SIZE(formats); ++i) {
if (fb->bits_per_pixel == formats[i].bits_per_pixel &&
fb->red_mask_pos == formats[i].red.offset &&
base-commit: 2220f68f4504aa1ccce0fac721ccdb301e9da32f
--
2.42.0
next reply other threads:[~2023-11-08 18:26 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-08 18:25 Alper Nebi Yasak [this message]
2023-11-08 23:53 ` [PATCH] firmware: coreboot: framebuffer: Avoid invalid zero physical address Julius Werner
2023-12-28 3:17 ` Tzung-Bi Shih
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