linux/arch
Michael Neuling 96dc89d526 powerpc/tm: Avoid possible userspace r1 corruption on reclaim
Current we store the userspace r1 to PACATMSCRATCH before finally
saving it to the thread struct.

In theory an exception could be taken here (like a machine check or
SLB miss) that could write PACATMSCRATCH and hence corrupt the
userspace r1. The SLB fault currently doesn't touch PACATMSCRATCH, but
others do.

We've never actually seen this happen but it's theoretically
possible. Either way, the code is fragile as it is.

This patch saves r1 to the kernel stack (which can't fault) before we
turn MSR[RI] back on. PACATMSCRATCH is still used but only with
MSR[RI] off. We then copy r1 from the kernel stack to the thread
struct once we have MSR[RI] back on.

Suggested-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2018-09-25 22:51:32 +10:00
..
alpha
arc
arm Fixes for KVM/ARM for Linux v4.19 v2: 2018-09-07 18:38:25 +02:00
arm64 KVM fixes for 4.19-rc3 2018-09-08 15:52:45 -07:00
c6x
h8300
hexagon
ia64
m68k
microblaze
mips KVM fixes for 4.19-rc3 2018-09-08 15:52:45 -07:00
nds32
nios2
openrisc
parisc
powerpc powerpc/tm: Avoid possible userspace r1 corruption on reclaim 2018-09-25 22:51:32 +10:00
riscv
s390
sh
sparc
um
unicore32
x86 Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-09-09 07:05:15 -07:00
xtensa
.gitignore
Kconfig