linux-user: i386/signal: support FXSAVE fpstate on 32-bit emulation

Linux can use FXSAVE to save/restore XMM registers even on 32-bit
systems.  This requires some care in order to keep the FXSAVE area
aligned to 16 bytes; for this reason, get_sigframe is changed to
pass the offset into the FXSAVE area rather than the full frame
size.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 file changed