Quoting James Morse (2019-05-16 10:34:16) > Hi! > > On 16/05/2019 17:48, Hsin-Yi Wang wrote: > > On Thu, May 16, 2019 at 11:32 PM Rob Herring <robh+dt@xxxxxxxxxx> wrote: > >> Doesn't kexec operate on a copy because it already does modifications. > > It does! > > > This patch is to assist "[PATCH v3 3/3] fdt: add support for rng-seed" > > (https://lkml.org/lkml/2019/5/16/257). I thought that by default > > second kernel would use original fdt, so I write new seed back to > > original fdt. Might be wrong. > > > > ** "[PATCH v3 3/3] fdt: add support for rng-seed" is supposed to > > handle for adding new seed in kexec case, discussed in v2 > > (https://lkml.org/lkml/2019/5/13/425) > > > > By default (not considering user defines their own fdt), if second > > kernel uses copied fdt, when is it copied and can we modify that? > > Regular kexec's user-space already updates the dtb for the cmdline and maybe the initrd. > For KASLR, it generates its own seed with getrandom(): > > https://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git/tree/kexec/arch/arm64/kexec-arm64.c#n483 > > If user-space can do it, user-space should do it! > Doesn't it need to be done in two places? Userspace and also in the kernel when kexec_file_load() is used? At least, I see a bit of code that does kaslr seed updates to the copied dtb in setup_dtb() of arch/arm64/kernel/machine_kexec_file.c that probably needs to get an update for this new property too.
