From 66eac7d687219c71a9e3482f80b62de8b3693423 Mon Sep 17 00:00:00 2001 From: cinap_lenrek Date: Mon, 21 May 2018 19:23:54 +0200 Subject: pc64: fix fpu bug fpurestore() unconditionally changed fpstate to FPinactive when the kernel used the FPU. but in the FPinit case, the registers are not saved by mathemu(), resulting in all zero initialized registers being loaded once userspace uses the FPU so the process would have wrong MXCR value. the index overflow check was wrong with using shifted value. --- sys/src/9/pc64/main.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/sys/src/9/pc64/main.c b/sys/src/9/pc64/main.c index 175f809bc..7e1b8449a 100644 --- a/sys/src/9/pc64/main.c +++ b/sys/src/9/pc64/main.c @@ -535,7 +535,7 @@ mathemu(Ureg *ureg, void*) case FPinit: fpinit(); index = up->fpstate >> FPindexs; - if(index < 0 || index > FPindexm) + if(index < 0 || index > (FPindexm>>FPindexs)) panic("fpslot index overflow: %d", index); if(userureg(ureg)){ if(index != 0) @@ -684,7 +684,7 @@ procsave(Proc *p) * emulation fault to activate the FPU. */ fpsave(p->fpsave); - p->fpstate = FPinactive | (p->fpstate & (FPpush|FPnouser|FPkernel|FPindexm)); + p->fpstate = FPinactive | (p->fpstate & ~FPactive); break; } @@ -729,7 +729,8 @@ fpurestore(int ostate) if((astate & ~(FPnouser|FPkernel|FPindexm)) == FPactive) _stts(); up->fpsave = up->fpslot[ostate>>FPindexs]; - ostate = FPinactive | (ostate & (FPillegal|FPpush|FPnouser|FPkernel|FPindexm)); + if(ostate & FPactive) + ostate = FPinactive | (ostate & ~FPactive); } up->fpstate = ostate; } -- cgit v1.2.3