On Mon, Jul 05, 2021 at 02:18:47PM +0200, Stephan Gerhold wrote: > According to arch/arm/lib/crt0_64.S, the BSS section is "UNAVAILABLE" > and uninitialized before relocation. Also, it overlaps with the > appended DTB before relocation, so writing data into a variable > in the BSS section might corrupt the appended DTB. > > Unfortunately, pinctrl-apq8016.c and pinctrl-apq8096.c do place the > "pin_name" variable in the BSS section (since it's uninitialized). > It's also used before relocation, when setting up the pinctrl for > the serial driver. > > On DB410c this causes "GPIO_5" to be written into some part of an > appended DTB, e.g.: > > 80111820: edfe0dd0 9f100000 38000000 c00e0000 ...........8.... > 80111830: 28000000 11000000 10000000 00000000 ...(............ > 80111840: 4f495047 8800355f 00000000 00000000 GPIO_5.......... > 80111850: 00000000 00000000 01000000 00000000 ................ > 80111860: 03000000 04000000 00000000 02000000 ................ > 80111870: 03000000 04000000 0f000000 02000000 ................ > 80111880: 03000000 2d000000 1b000000 6c617551 .......-....Qual > 80111890: 6d6d6f63 63655420 6c6f6e68 6569676f comm Technologie > > Depending on the part of the DTB that is corrupted this might not > cause any problems, but it can also result in strange reboots > without any serial output. > > Fortunately, in practice this does not cause issues on DB410c yet > because board_fdt_blob_setup() in dragonboard410c.c currently > overrides the appended DTB with the one passed by the previous > bootloader (LK) (which does not get corrupted). > > DB820c does not have board_fdt_blob_setup() so I would expect it to > be affected by this problem. Perhaps everyone was just fortunate to > not compile an U-Boot configuration where the pin_name corrupts an > important part of the DTB. > > Make sure "pin_name" is explicitly placed in the .data section > instead of .bss to fix this. > > Cc: Ramon Fried <rfried....@gmail.com> > Signed-off-by: Stephan Gerhold <step...@gerhold.net> > Reviewed-by: Ramon Fried <rfried....@gmail.com>
Applied to u-boot/master, thanks! -- Tom
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