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[src/trunk]: src/sys/arch Remove the osyscall call gate on i386, and emulate ...
details: https://anonhg.NetBSD.org/src/rev/40e323728803
branches: trunk
changeset: 825141:40e323728803
user: maxv <maxv%NetBSD.org@localhost>
date: Sat Jul 01 10:44:42 2017 +0000
description:
Remove the osyscall call gate on i386, and emulate it. There is a one-
instruction race in it that could panic the kernel.
diffstat:
sys/arch/amd64/amd64/locore.S | 3 +--
sys/arch/i386/i386/locore.S | 22 ++--------------------
sys/arch/i386/i386/machdep.c | 10 ++--------
sys/arch/i386/i386/trap.c | 35 ++++++++++++++++++++++++-----------
4 files changed, 29 insertions(+), 41 deletions(-)
diffs (185 lines):
diff -r affc49eeb92b -r 40e323728803 sys/arch/amd64/amd64/locore.S
--- a/sys/arch/amd64/amd64/locore.S Sat Jul 01 09:26:51 2017 +0000
+++ b/sys/arch/amd64/amd64/locore.S Sat Jul 01 10:44:42 2017 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: locore.S,v 1.123 2017/03/25 15:07:21 maxv Exp $ */
+/* $NetBSD: locore.S,v 1.124 2017/07/01 10:44:42 maxv Exp $ */
/*
* Copyright-o-rama!
@@ -1409,7 +1409,6 @@
addq $0x10,%rsp
#endif
pushq $2 /* size of instruction for restart */
-osyscall1:
pushq $T_ASTFLT /* trap # for doing ASTs */
INTRENTRY
STI(si)
diff -r affc49eeb92b -r 40e323728803 sys/arch/i386/i386/locore.S
--- a/sys/arch/i386/i386/locore.S Sat Jul 01 09:26:51 2017 +0000
+++ b/sys/arch/i386/i386/locore.S Sat Jul 01 10:44:42 2017 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: locore.S,v 1.145 2017/02/02 19:12:09 maxv Exp $ */
+/* $NetBSD: locore.S,v 1.146 2017/07/01 10:44:42 maxv Exp $ */
/*
* Copyright-o-rama!
@@ -128,7 +128,7 @@
*/
#include <machine/asm.h>
-__KERNEL_RCSID(0, "$NetBSD: locore.S,v 1.145 2017/02/02 19:12:09 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: locore.S,v 1.146 2017/07/01 10:44:42 maxv Exp $");
#include "opt_compat_oldboot.h"
#include "opt_copy_symtab.h"
@@ -1239,30 +1239,12 @@
END(savectx)
/*
- * osyscall()
- *
- * Old call gate entry for syscall
- */
-IDTVEC(osyscall)
-#ifndef XEN
- /* XXX we are in trouble! interrupts be off here. */
- cli /* must be first instruction */
-#endif
- pushfl /* set eflags in trap frame */
- popl 8(%esp)
- orl $PSL_I,8(%esp) /* re-enable ints on return to user */
- pushl $7 /* size of instruction for restart */
- jmp syscall1
-IDTVEC_END(osyscall)
-
-/*
* syscall()
*
* Trap gate entry for syscall
*/
IDTVEC(syscall)
pushl $2 /* size of instruction for restart */
-syscall1:
pushl $T_ASTFLT /* trap # for doing ASTs */
INTRENTRY
STI(%eax)
diff -r affc49eeb92b -r 40e323728803 sys/arch/i386/i386/machdep.c
--- a/sys/arch/i386/i386/machdep.c Sat Jul 01 09:26:51 2017 +0000
+++ b/sys/arch/i386/i386/machdep.c Sat Jul 01 10:44:42 2017 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: machdep.c,v 1.782 2017/03/24 17:09:36 maxv Exp $ */
+/* $NetBSD: machdep.c,v 1.783 2017/07/01 10:44:42 maxv Exp $ */
/*-
* Copyright (c) 1996, 1997, 1998, 2000, 2004, 2006, 2008, 2009
@@ -67,7 +67,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: machdep.c,v 1.782 2017/03/24 17:09:36 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: machdep.c,v 1.783 2017/07/01 10:44:42 maxv Exp $");
#include "opt_beep.h"
#include "opt_compat_ibcs2.h"
@@ -933,7 +933,6 @@
#define IDTVEC(name) __CONCAT(X, name)
typedef void (vector)(void);
extern vector IDTVEC(syscall);
-extern vector IDTVEC(osyscall);
extern vector *IDTVEC(exceptions)[];
extern vector IDTVEC(svr4_fasttrap);
void (*svr4_fasttrap_vec)(void) = (void (*)(void))nullop;
@@ -1290,14 +1289,9 @@
#endif /* XEN */
/* make ldt gates and memory segments */
- setgate(&ldtstore[LSYS5CALLS_SEL].gd, &IDTVEC(osyscall), 1,
- SDT_SYS386CGT, SEL_UPL, GSEL(GCODE_SEL, SEL_KPL));
-
ldtstore[LUCODE_SEL] = gdtstore[GUCODE_SEL];
ldtstore[LUCODEBIG_SEL] = gdtstore[GUCODEBIG_SEL];
ldtstore[LUDATA_SEL] = gdtstore[GUDATA_SEL];
- ldtstore[LSOL26CALLS_SEL] = ldtstore[LBSDICALLS_SEL] =
- ldtstore[LSYS5CALLS_SEL];
#ifndef XEN
/* exceptions */
diff -r affc49eeb92b -r 40e323728803 sys/arch/i386/i386/trap.c
--- a/sys/arch/i386/i386/trap.c Sat Jul 01 09:26:51 2017 +0000
+++ b/sys/arch/i386/i386/trap.c Sat Jul 01 10:44:42 2017 +0000
@@ -1,5 +1,5 @@
-/* $NetBSD: trap.c,v 1.287 2017/03/18 13:39:23 maxv Exp $ */
+/* $NetBSD: trap.c,v 1.288 2017/07/01 10:44:42 maxv Exp $ */
/*-
* Copyright (c) 1998, 2000, 2005, 2006, 2007, 2008 The NetBSD Foundation, Inc.
@@ -69,7 +69,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: trap.c,v 1.287 2017/03/18 13:39:23 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: trap.c,v 1.288 2017/07/01 10:44:42 maxv Exp $");
#include "opt_ddb.h"
#include "opt_kgdb.h"
@@ -78,6 +78,7 @@
#include "opt_vm86.h"
#include "opt_xen.h"
#include "opt_dtrace.h"
+#include "opt_compat_netbsd.h"
#include <sys/param.h>
#include <sys/systm.h>
@@ -250,8 +251,7 @@
struct lwp *l = curlwp;
struct proc *p;
struct pcb *pcb;
- extern char fusubail[], kcopy_fault[], return_address_fault[],
- IDTVEC(osyscall)[];
+ extern char fusubail[], kcopy_fault[], return_address_fault[];
struct trapframe *vframe;
ksiginfo_t ksi;
void *onfault;
@@ -418,6 +418,26 @@
/* NOTREACHED */
case T_PROTFLT|T_USER: /* protection fault */
+#if defined(COMPAT_10)
+ {
+ static const char lcall[7] = { 0x9a, 0, 0, 0, 0, 7, 0 };
+ const size_t sz = sizeof(lcall);
+ char tmp[sz];
+
+ /* Check for the osyscall lcall instruction. */
+ if (frame->tf_eip < VM_MAXUSER_ADDRESS - sz &&
+ copyin((void *)frame->tf_eip, tmp, sz) == 0 &&
+ memcmp(tmp, lcall, sz) == 0) {
+
+ /* Advance past the lcall. */
+ frame->tf_eip += sz;
+
+ /* Do the syscall. */
+ p->p_md.md_syscall(frame);
+ goto out;
+ }
+ }
+#endif
case T_TSSFLT|T_USER:
case T_SEGNPFLT|T_USER:
case T_STKFLT|T_USER:
@@ -710,13 +730,6 @@
if (x86_dbregs_user_trap())
break;
- /* Check whether they single-stepped into a lcall. */
- if (frame->tf_eip == (int)IDTVEC(osyscall))
- return;
- if (frame->tf_eip == (int)IDTVEC(osyscall) + 1) {
- frame->tf_eflags &= ~PSL_T;
- return;
- }
goto we_re_toast;
case T_BPTFLT|T_USER: /* bpt instruction fault */
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