On Thu, Feb 28, 2019 at 10:07:52AM -0500, Sasha Levin wrote: > From: Will Deacon <will.deacon@xxxxxxx> > > [ Upstream commit d23c808c6fc6132e812690648e14c0d6b0cbe273 ] > > When 52-bit virtual addressing is enabled for userspace > (CONFIG_ARM64_USER_VA_BITS_52=y), the kernel continues to utilise 48-bit > virtual addressing in TTBR1. Consequently, PTRS_PER_PGD reflects the > larger page table size for userspace and the pgd pointer for kernel page > tables is offset before being written to TTBR1. > > This means that we can't use PTRS_PER_PGD to iterate over kernel page > tables unless we apply the same offset, which is fiddly to get right and > leads to some non-idiomatic walking code. Instead, just follow the usual > pattern when walking page tables by using a while loop driven by > pXd_offset() and pXd_addr_end(). > > Reported-by: Qian Cai <cai@xxxxxx> > Tested-by: Qian Cai <cai@xxxxxx> > Acked-by: Steve Capper <steve.capper@xxxxxxx> > Tested-by: Steve Capper <steve.capper@xxxxxxx> > Signed-off-by: Will Deacon <will.deacon@xxxxxxx> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> > --- > arch/arm64/mm/dump.c | 59 ++++++++++++++++++++++---------------------- > 1 file changed, 29 insertions(+), 30 deletions(-) 4.20 doesn't support 52-bit VAs, so this isn't needed there afaict (and is why I didn't tag the commit for stable in the first place). Will
