Author: kib
Date: Wed Nov  1 10:32:44 2017
New Revision: 325270
URL: https://svnweb.freebsd.org/changeset/base/325270

Log:
  Consistently ensure that we do not load MXCSR with reserved bits set.
  
  Some callers of fpusetregs()/npxsetregs(), most importantly
  set_fpcontext(), clear reserved bits.  But some did not.  Do the
  clearing in fpusetregs() and remove now redundand operation from
  set_fpcontext().
  
  Reported by:  Maxime Villard <[email protected]>
  Sponsored by: The FreeBSD Foundation
  MFC after:    1 week

Modified:
  head/sys/amd64/amd64/fpu.c
  head/sys/amd64/amd64/machdep.c
  head/sys/i386/i386/machdep.c
  head/sys/i386/isa/npx.c

Modified: head/sys/amd64/amd64/fpu.c
==============================================================================
--- head/sys/amd64/amd64/fpu.c  Wed Nov  1 09:18:41 2017        (r325269)
+++ head/sys/amd64/amd64/fpu.c  Wed Nov  1 10:32:44 2017        (r325270)
@@ -806,6 +806,7 @@ fpusetregs(struct thread *td, struct savefpu *addr, ch
        struct pcb *pcb;
        int error;
 
+       addr->sv_env.en_mxcsr &= cpu_mxcsr_mask;
        pcb = td->td_pcb;
        critical_enter();
        if (td == PCPU_GET(fpcurthread) && PCB_USER_FPU(pcb)) {

Modified: head/sys/amd64/amd64/machdep.c
==============================================================================
--- head/sys/amd64/amd64/machdep.c      Wed Nov  1 09:18:41 2017        
(r325269)
+++ head/sys/amd64/amd64/machdep.c      Wed Nov  1 10:32:44 2017        
(r325270)
@@ -2238,7 +2238,6 @@ static int
 set_fpcontext(struct thread *td, mcontext_t *mcp, char *xfpustate,
     size_t xfpustate_len)
 {
-       struct savefpu *fpstate;
        int error;
 
        if (mcp->mc_fpformat == _MC_FPFMT_NODEV)
@@ -2251,9 +2250,8 @@ set_fpcontext(struct thread *td, mcontext_t *mcp, char
                error = 0;
        } else if (mcp->mc_ownedfp == _MC_FPOWNED_FPU ||
            mcp->mc_ownedfp == _MC_FPOWNED_PCB) {
-               fpstate = (struct savefpu *)&mcp->mc_fpstate;
-               fpstate->sv_env.en_mxcsr &= cpu_mxcsr_mask;
-               error = fpusetregs(td, fpstate, xfpustate, xfpustate_len);
+               error = fpusetregs(td, (struct savefpu *)&mcp->mc_fpstate,
+                   xfpustate, xfpustate_len);
        } else
                return (EINVAL);
        return (error);

Modified: head/sys/i386/i386/machdep.c
==============================================================================
--- head/sys/i386/i386/machdep.c        Wed Nov  1 09:18:41 2017        
(r325269)
+++ head/sys/i386/i386/machdep.c        Wed Nov  1 10:32:44 2017        
(r325270)
@@ -2851,7 +2851,6 @@ static int
 set_fpcontext(struct thread *td, mcontext_t *mcp, char *xfpustate,
     size_t xfpustate_len)
 {
-       union savefpu *fpstate;
        int error;
 
        if (mcp->mc_fpformat == _MC_FPFMT_NODEV)
@@ -2865,10 +2864,8 @@ set_fpcontext(struct thread *td, mcontext_t *mcp, char
                error = 0;
        } else if (mcp->mc_ownedfp == _MC_FPOWNED_FPU ||
            mcp->mc_ownedfp == _MC_FPOWNED_PCB) {
-               fpstate = (union savefpu *)&mcp->mc_fpstate;
-               if (cpu_fxsr)
-                       fpstate->sv_xmm.sv_env.en_mxcsr &= cpu_mxcsr_mask;
-               error = npxsetregs(td, fpstate, xfpustate, xfpustate_len);
+               error = npxsetregs(td, (union savefpu *)&mcp->mc_fpstate,
+                   xfpustate, xfpustate_len);
        } else
                return (EINVAL);
        return (error);

Modified: head/sys/i386/isa/npx.c
==============================================================================
--- head/sys/i386/isa/npx.c     Wed Nov  1 09:18:41 2017        (r325269)
+++ head/sys/i386/isa/npx.c     Wed Nov  1 10:32:44 2017        (r325270)
@@ -1045,6 +1045,8 @@ npxsetregs(struct thread *td, union savefpu *addr, cha
        if (!hw_float)
                return (ENXIO);
 
+       if (cpu_fxsr)
+               addr->sv_xmm.sv_env.en_mxcsr &= cpu_mxcsr_mask;
        pcb = td->td_pcb;
        critical_enter();
        if (td == PCPU_GET(fpcurthread) && PCB_USER_FPU(pcb)) {
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