On Sun, Mar 7, 2021 at 12:26 PM Marek Behún <marek.be...@nic.cz> 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 simply by taking into account that regmap_raw_read() and > regmap_raw_write() behave as if the data given to these functions were > in little-endian format, i.e. use cpu_to_le32() / le32_to_cpu(). In > regmap_read() also zero out the space so that we don't get invalid > result if regmap_raw_read() does not fill the whole object. > > Signed-off-by: Marek Behún <marek.be...@nic.cz> > Reviewed-by: Simon Glass <s...@chromium.org> > Reviewed-by: Heiko Schocher <h...@denx.de> > --- > drivers/core/regmap.c | 13 ++++++++++++- > 1 file changed, 12 insertions(+), 1 deletion(-) >
Reviewed-by: Bin Meng <bmeng...@gmail.com> Maybe we can create a test case on QEMU PPC to cover the big endian targets? Regards, Bin
