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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [linux-2.6.18-xen] fix hypercall fallback code for very old hypervisors
# HG changeset patch
# User Jan Beulich <jbeulich@xxxxxxxx>
# Date 1350464319 -7200
# Node ID c5d77641c7380dfe628491656d8a2001d08cd390
# Parent 9db2ee23611eb88e3f29fc177ded2fca2bcb89b9
fix hypercall fallback code for very old hypervisors
While copying the argument structures in HYPERVISOR_event_channel_op()
and HYPERVISOR_physdev_op() into the local variable is sufficiently
safe even if the actual structure is smaller than the container one,
copying back eventual output values the same way isn't: This may
collide with on-stack variables (particularly "rc") which may change
between the first and second memcpy() (i.e. the second memcpy() could
discard that change).
Move the fallback code into out-of-line functions, and handle all of
the operations known by this old a hypervisor individually: Some don't
require copying back anything at all, and for the rest use the
individual argument structures' sizes rather than the container's.
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
diff -r 9db2ee23611e -r c5d77641c738 drivers/pci/msi-xen.c
--- a/drivers/pci/msi-xen.c Wed Oct 17 10:41:46 2012 +0200
+++ b/drivers/pci/msi-xen.c Wed Oct 17 10:58:39 2012 +0200
@@ -15,6 +15,7 @@
#include <linux/pci.h>
#include <linux/proc_fs.h>
+#include <xen/interface/physdev.h>
#include <xen/evtchn.h>
#include <asm/errno.h>
diff -r 9db2ee23611e -r c5d77641c738 drivers/xen/core/Makefile
--- a/drivers/xen/core/Makefile Wed Oct 17 10:41:46 2012 +0200
+++ b/drivers/xen/core/Makefile Wed Oct 17 10:58:39 2012 +0200
@@ -2,7 +2,7 @@
# Makefile for the linux kernel.
#
-obj-y := evtchn.o gnttab.o features.o reboot.o machine_reboot.o
+obj-y := evtchn.o gnttab.o features.o reboot.o machine_reboot.o fallback.o
obj-$(CONFIG_PCI) += pci.o
obj-$(CONFIG_XEN_PRIVILEGED_GUEST) += firmware.o
diff -r 9db2ee23611e -r c5d77641c738 drivers/xen/core/fallback.c
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/drivers/xen/core/fallback.c Wed Oct 17 10:58:39 2012 +0200
@@ -0,0 +1,84 @@
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <asm/bug.h>
+#include <asm/hypervisor.h>
+
+#if CONFIG_XEN_COMPAT <= 0x030002
+
+#include <xen/interface/event_channel.h>
+#include <xen/interface/physdev.h>
+
+int HYPERVISOR_event_channel_op_compat(int cmd, void *arg)
+{
+ struct evtchn_op op;
+ int rc;
+
+ op.cmd = cmd;
+ memcpy(&op.u, arg, sizeof(op.u));
+ rc = _hypercall1(int, event_channel_op_compat, &op);
+
+ switch (cmd) {
+ case EVTCHNOP_close:
+ case EVTCHNOP_send:
+ case EVTCHNOP_bind_vcpu:
+ case EVTCHNOP_unmask:
+ /* no output */
+ break;
+
+#define COPY_BACK(eop) \
+ case EVTCHNOP_##eop: \
+ memcpy(arg, &op.u.eop, sizeof(op.u.eop)); \
+ break
+
+ COPY_BACK(bind_interdomain);
+ COPY_BACK(bind_virq);
+ COPY_BACK(bind_pirq);
+ COPY_BACK(status);
+ COPY_BACK(alloc_unbound);
+ COPY_BACK(bind_ipi);
+#undef COPY_BACK
+
+ default:
+ WARN_ON(rc != -ENOSYS);
+ break;
+ }
+
+ return rc;
+}
+
+int HYPERVISOR_physdev_op_compat(int cmd, void *arg)
+{
+ struct physdev_op op;
+ int rc;
+
+ op.cmd = cmd;
+ memcpy(&op.u, arg, sizeof(op.u));
+ rc = _hypercall1(int, physdev_op_compat, &op);
+
+ switch (cmd) {
+ case PHYSDEVOP_IRQ_UNMASK_NOTIFY:
+ case PHYSDEVOP_set_iopl:
+ case PHYSDEVOP_set_iobitmap:
+ case PHYSDEVOP_apic_write:
+ /* no output */
+ break;
+
+#define COPY_BACK(pop, fld) \
+ case PHYSDEVOP_##pop: \
+ memcpy(arg, &op.u.fld, sizeof(op.u.fld)); \
+ break
+
+ COPY_BACK(irq_status_query, irq_status_query);
+ COPY_BACK(apic_read, apic_op);
+ COPY_BACK(ASSIGN_VECTOR, irq_op);
+#undef COPY_BACK
+
+ default:
+ WARN_ON(rc != -ENOSYS);
+ break;
+ }
+
+ return rc;
+}
+
+#endif /* CONFIG_XEN_COMPAT <= 0x030002 */
diff -r 9db2ee23611e -r c5d77641c738 include/asm-i386/mach-xen/asm/hypercall.h
--- a/include/asm-i386/mach-xen/asm/hypercall.h Wed Oct 17 10:41:46 2012 +0200
+++ b/include/asm-i386/mach-xen/asm/hypercall.h Wed Oct 17 10:58:39 2012 +0200
@@ -33,7 +33,6 @@
#ifndef __HYPERCALL_H__
#define __HYPERCALL_H__
-#include <linux/string.h> /* memcpy() */
#include <linux/stringify.h>
#ifndef __HYPERVISOR_H__
@@ -128,6 +127,11 @@
__res; \
})
+#if CONFIG_XEN_COMPAT <= 0x030002
+int __must_check HYPERVISOR_event_channel_op_compat(int, void *);
+int __must_check HYPERVISOR_physdev_op_compat(int, void *);
+#endif
+
static inline int __must_check
HYPERVISOR_set_trap_table(
const trap_info_t *table)
@@ -267,13 +271,8 @@ HYPERVISOR_event_channel_op(
int rc = _hypercall2(int, event_channel_op, cmd, arg);
#if CONFIG_XEN_COMPAT <= 0x030002
- if (unlikely(rc == -ENOSYS)) {
- struct evtchn_op op;
- op.cmd = cmd;
- memcpy(&op.u, arg, sizeof(op.u));
- rc = _hypercall1(int, event_channel_op_compat, &op);
- memcpy(arg, &op.u, sizeof(op.u));
- }
+ if (unlikely(rc == -ENOSYS))
+ rc = HYPERVISOR_event_channel_op_compat(cmd, arg);
#endif
return rc;
@@ -300,13 +299,8 @@ HYPERVISOR_physdev_op(
int rc = _hypercall2(int, physdev_op, cmd, arg);
#if CONFIG_XEN_COMPAT <= 0x030002
- if (unlikely(rc == -ENOSYS)) {
- struct physdev_op op;
- op.cmd = cmd;
- memcpy(&op.u, arg, sizeof(op.u));
- rc = _hypercall1(int, physdev_op_compat, &op);
- memcpy(arg, &op.u, sizeof(op.u));
- }
+ if (unlikely(rc == -ENOSYS))
+ rc = HYPERVISOR_physdev_op_compat(cmd, arg);
#endif
return rc;
diff -r 9db2ee23611e -r c5d77641c738 include/asm-i386/mach-xen/asm/hypervisor.h
--- a/include/asm-i386/mach-xen/asm/hypervisor.h Wed Oct 17 10:41:46
2012 +0200
+++ b/include/asm-i386/mach-xen/asm/hypervisor.h Wed Oct 17 10:58:39
2012 +0200
@@ -39,8 +39,6 @@
#include <linux/errno.h>
#include <xen/interface/xen.h>
#include <xen/interface/platform.h>
-#include <xen/interface/event_channel.h>
-#include <xen/interface/physdev.h>
#include <xen/interface/sched.h>
#include <xen/interface/nmi.h>
#include <xen/interface/tmem.h>
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