Hi Rob, On 24 October 2014 22:51, Rob Herring <[email protected]> wrote: > On Sat, Oct 25, 2014 at 1:56 AM, Simon Glass <[email protected]> wrote: >> +Tom >> >> Hi Rob, >> >> On 15 October 2014 03:21, Rob Herring <[email protected]> wrote: >>> From: Rob Herring <[email protected]> >>> >>> Commit f18295d3837c282f (fdt_support: fix an endian bug of >>> fdt_fixup_memory_banks) changed fdt_fixup_memory_banks cell writing from a >>> byte at a time to casting the buffer pointer to a 64-bit pointer. This can >>> result in unaligned accesses when there is a mixture of cell sizes of 1 >>> and 2. >> >> Should that be 739a01ed8e0? > > Uhh, yes. > >> >>> >>> Cc: Masahiro Yamada <[email protected]> >>> Signed-off-by: Rob Herring <[email protected]> >>> --- >>> common/fdt_support.c | 11 +++++++---- >>> 1 file changed, 7 insertions(+), 4 deletions(-) >>> >>> diff --git a/common/fdt_support.c b/common/fdt_support.c >>> index 3f64156..9c41f3a 100644 >>> --- a/common/fdt_support.c >>> +++ b/common/fdt_support.c >>> @@ -388,19 +388,22 @@ static int fdt_pack_reg(const void *fdt, void *buf, >>> uint64_t *address, >>> int i; >>> int address_len = get_cells_len(fdt, "#address-cells"); >>> int size_len = get_cells_len(fdt, "#size-cells"); >>> + u64 cell; >>> char *p = buf; >>> >>> for (i = 0; i < n; i++) { >>> if (address_len == 8) >>> - *(fdt64_t *)p = cpu_to_fdt64(address[i]); >>> + cell = cpu_to_fdt64(address[i]); >>> else >>> - *(fdt32_t *)p = cpu_to_fdt32(address[i]); >>> + cell = cpu_to_fdt32(address[i]); >>> + memcpy(p, &cell, address_len); >>> p += address_len; >>> >>> if (size_len == 8) >>> - *(fdt64_t *)p = cpu_to_fdt64(size[i]); >>> + cell = cpu_to_fdt64(size[i]); >>> else >>> - *(fdt32_t *)p = cpu_to_fdt32(size[i]); >>> + cell = cpu_to_fdt32(size[i]); >>> + memcpy(p, &cell, size_len); >> >> What will this do with 32-bit values? Aren't use assuming that the >> first 32-bit word of 'cell' will contain the least significant 32 >> bits? Is that always true? I'm not quite sure. > > We've already done the endian conversion, so we're just copying a > string of bytes only changing the alignment potentially.
Yes I think you are right. Then I suggest adding a comment here, as memcpy() from a native type is unusual. > >> >> Also I really thing this needs a test. It's a pretty simple function >> so a unit test would be easy to write. > > I'll look into that. See test/command_ut.c for one way to do this with sandbox by adding a new command. Regards, Simon _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
