On Thu, May 20, 2021 at 01:23:50PM +0200, Marek Behún wrote: > There is a serious bug in regmap_read() and regmap_write() functions > where an uint pointer is cast to (void *) which is then cast to (u8 *), > (u16 *), (u32 *) or (u64 *), depending on register width of the map. > > For example given a regmap with 16-bit register width the code > int val = 0x12340000; > regmap_read(map, 0, &val); > only changes the lower 16 bits of val on little-endian machines. > The upper 16 bits will remain 0x1234. > > Nobody noticed this probably because this bug can be triggered with > regmap_write() only on big-endian architectures (which are not used by > many people anymore), and on little endian this bug has consequences > only if register width is 8 or 16 bits and also the memory place to > which regmap_read() should store it's result has non-zero upper bits, > which it seems doesn't happen anywhere in U-Boot normally. CI managed to > trigger this bug in unit test of dm_test_devm_regmap_field when compiled > for sandbox_defconfig using LTO. > > Fix this by utilizing an union { u8; u16; u32; u64; } and reading data > into this union / writing data from this union. > > Signed-off-by: Marek Behún <marek.be...@nic.cz> > Cc: Simon Glass <s...@chromium.org> > Cc: Heiko Schocher <h...@denx.de> > Cc: Bin Meng <bmeng...@gmail.com> > Cc: Pratyush Yadav <p.ya...@ti.com>
Applied to u-boot/master, thanks! -- Tom
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