On 10/2/18 11:35 AM, Peter Maydell wrote: > Add the v8M stack checks for: > * LDRD (immediate) > * STRD (immediate) > > Loads and stores are more complicated than ADD/SUB/MOV, because we > must ensure that memory accesses below the stack limit are not > performed, so we can't simply do the check when we actually update > SP. > > For these instructions, if the stack limit check triggers > we must not: > * perform any memory access below the SP limit > * update PC, SP or the load/store base register > but it is IMPDEF whether we: > * perform any accesses above or equal to the SP limit > * update destination registers for loads > > For QEMU we choose to always check the limit before doing any other > part of the load or store, so we won't update any registers or > perform any memory accesses. > > It is UNKNOWN whether the limit check triggers for a load or store > where the initial SP value is below the limit and one of the stores > would be below the limit, but the writeback moves SP to above the > limit. For QEMU we choose to trigger the check in this situation. > > Note that limit checks happen only for loads and stores which update > SP via writeback; they do not happen for loads and stores which > simply use SP as a base register. > > Signed-off-by: Peter Maydell <peter.mayd...@linaro.org> > --- > target/arm/translate.c | 27 +++++++++++++++++++++++++-- > 1 file changed, 25 insertions(+), 2 deletions(-)
Reviewed-by: Richard Henderson <richard.hender...@linaro.org> r~
