On 1/23/23 02:53, Peter Maydell wrote:
On Fri, 6 Jan 2023 at 19:45, Richard Henderson
<richard.hender...@linaro.org> wrote:
Do not encode the pointer as a constant in the opcode stream.
This pointer is specific to the cpu that first generated the
translation, which runs into problems with both hot-pluggable
cpus and user-only threads, as cpus are removed.
Perform the lookup in either helper_access_check_cp_reg,
or a new helper_lookup_cp_reg.
As well as the use-after-free, this is also a correctness
bug, isn't it? If we hardwire in the cpregs pointer for
CPU 0 into the TB, and then CPU 1 with a slightly different
config executes the TB, it will get the cpregs of CPU 0,
not its own, so it might see a register it should not or
vice-versa.
Existing assumption was that each cpu configuration would have its own cluster_index,
which gets encoded into cpu->tcg_cflags, which is part of the comparison used when hashing
TBs.
But including this patch allows relaxation of what constitutes a "cpu
configuration".
r~
