[src/trunk]: src/sys/arch/amd64/amd64 Don't depend on #ifdef USER_LDT in cpu_...

[maxv <maxv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/c8fefe1342b0
branches:  trunk
changeset: 964895:c8fefe1342b0
user:      maxv <maxv%NetBSD.org@localhost>
date:      Wed Aug 21 12:33:12 2019 +0000

description:
Don't depend on #ifdef USER_LDT in cpu_mcontext32_validate(), but rather on
whether the proc uses a user-set LDT. Same as check_sigcontext32().

diffstat:

 sys/arch/amd64/amd64/netbsd32_machdep.c |  62 +++++++++++++++-----------------
 1 files changed, 29 insertions(+), 33 deletions(-)

diffs (117 lines):

diff -r a1d5bb265bf0 -r c8fefe1342b0 sys/arch/amd64/amd64/netbsd32_machdep.c
--- a/sys/arch/amd64/amd64/netbsd32_machdep.c   Wed Aug 21 12:16:07 2019 +0000
+++ b/sys/arch/amd64/amd64/netbsd32_machdep.c   Wed Aug 21 12:33:12 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: netbsd32_machdep.c,v 1.125 2019/07/20 18:25:11 christos Exp $  */
+/*     $NetBSD: netbsd32_machdep.c,v 1.126 2019/08/21 12:33:12 maxv Exp $      */
 
 /*
  * Copyright (c) 2001 Wasabi Systems, Inc.
@@ -36,7 +36,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: netbsd32_machdep.c,v 1.125 2019/07/20 18:25:11 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: netbsd32_machdep.c,v 1.126 2019/08/21 12:33:12 maxv Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_compat_netbsd.h"
@@ -903,12 +903,6 @@
        userret(l);
 }
 
-/*
- * For various reasons, the amd64 port can't do what the i386 port does,
- * and relies on catching invalid user contexts on exit from the kernel.
- * These functions perform the needed checks.
- */
-
 int
 check_sigcontext32(struct lwp *l, const struct netbsd32_sigcontext *scp)
 {
@@ -923,21 +917,22 @@
                return EINVAL;
 
        if (__predict_false(pmap->pm_ldt != NULL)) {
-               /* Only when the LDT is user-set (with USER_LDT) */
+               /* Allow unfamiliar segment register values (USER_LDT). */
                if (!USERMODE(scp->sc_cs))
                        return EINVAL;
        } else {
                if (!VALID_USER_CSEL32(scp->sc_cs))
                        return EINVAL;
                if (scp->sc_fs != 0 && !VALID_USER_DSEL32(scp->sc_fs) &&
-                       !(VALID_USER_FSEL32(scp->sc_fs) && pcb->pcb_fs != 0))
+                   !(VALID_USER_FSEL32(scp->sc_fs) && pcb->pcb_fs != 0))
                        return EINVAL;
                if (scp->sc_gs != 0 && !VALID_USER_DSEL32(scp->sc_gs) &&
-                       !(VALID_USER_GSEL32(scp->sc_gs) && pcb->pcb_gs != 0))
+                   !(VALID_USER_GSEL32(scp->sc_gs) && pcb->pcb_gs != 0))
                        return EINVAL;
                if (scp->sc_es != 0 && !VALID_USER_DSEL32(scp->sc_es))
                        return EINVAL;
-               if (!VALID_USER_DSEL32(scp->sc_ds) || !VALID_USER_DSEL32(scp->sc_ss))
+               if (!VALID_USER_DSEL32(scp->sc_ds) ||
+                   !VALID_USER_DSEL32(scp->sc_ss))
                        return EINVAL;
        }
 
@@ -950,36 +945,37 @@
 int
 cpu_mcontext32_validate(struct lwp *l, const mcontext32_t *mcp)
 {
+       struct pmap *pmap = l->l_proc->p_vmspace->vm_map.pmap;
        const __greg32_t *gr;
        struct trapframe *tf;
+       struct pcb *pcb;
 
        gr = mcp->__gregs;
        tf = l->l_md.md_regs;
+       pcb = lwp_getpcb(l);
 
        if (((gr[_REG32_EFL] ^ tf->tf_rflags) & PSL_USERSTATIC) != 0)
                return EINVAL;
 
-#ifdef USER_LDT
-       /* Userland is allowed to have unfamiliar segment register values */
-       if (!USERMODE(gr[_REG32_CS]))
-               return EINVAL;
-#else
-       struct pcb *pcb = lwp_getpcb(l);
-
-       if (!VALID_USER_CSEL32(gr[_REG32_CS]))
-               return EINVAL;
-       if (gr[_REG32_FS] != 0 && !VALID_USER_DSEL32(gr[_REG32_FS]) &&
-           !(VALID_USER_FSEL32(gr[_REG32_FS]) && pcb->pcb_fs != 0))
-               return EINVAL;
-       if (gr[_REG32_GS] != 0 && !VALID_USER_DSEL32(gr[_REG32_GS]) &&
-           !(VALID_USER_GSEL32(gr[_REG32_GS]) && pcb->pcb_gs != 0))
-               return EINVAL;
-       if (gr[_REG32_ES] != 0 && !VALID_USER_DSEL32(gr[_REG32_ES]))
-               return EINVAL;
-       if (!VALID_USER_DSEL32(gr[_REG32_DS]) ||
-           !VALID_USER_DSEL32(gr[_REG32_SS]))
-               return EINVAL;
-#endif
+       if (__predict_false(pmap->pm_ldt != NULL)) {
+               /* Allow unfamiliar segment register values (USER_LDT). */
+               if (!USERMODE(gr[_REG32_CS]))
+                       return EINVAL;
+       } else {
+               if (!VALID_USER_CSEL32(gr[_REG32_CS]))
+                       return EINVAL;
+               if (gr[_REG32_FS] != 0 && !VALID_USER_DSEL32(gr[_REG32_FS]) &&
+                   !(VALID_USER_FSEL32(gr[_REG32_FS]) && pcb->pcb_fs != 0))
+                       return EINVAL;
+               if (gr[_REG32_GS] != 0 && !VALID_USER_DSEL32(gr[_REG32_GS]) &&
+                   !(VALID_USER_GSEL32(gr[_REG32_GS]) && pcb->pcb_gs != 0))
+                       return EINVAL;
+               if (gr[_REG32_ES] != 0 && !VALID_USER_DSEL32(gr[_REG32_ES]))
+                       return EINVAL;
+               if (!VALID_USER_DSEL32(gr[_REG32_DS]) ||
+                   !VALID_USER_DSEL32(gr[_REG32_SS]))
+                       return EINVAL;
+       }
 
        if (gr[_REG32_EIP] >= VM_MAXUSER_ADDRESS32)
                return EINVAL;