vmmon: fix indirect call with retpoline build

Build against kernel with retpoline support issues warning

  objtool: Task_Switch()+0x425: indirect call found in RETPOLINE build

This is because an indirect call in TaskSwitchToMonitor() is encoded using
inline assembler so that it bypasses retpoline generation. For this
purpose, macro CALL_NOSPEC exists since v4.15-rc8 (and has been backported
into some distribution kernels with the rest of retpoline support). Use the
macro if available and fallback to the original code if not.

INSTALL

@@ -150,7 +150,7 @@ test build).
 When using a downloaded tarball, simply run
 
   tar -cf vmmon.tar vmmon-only
-  tar -cf vmnet.tar vmnet-only
+  tar -cf vmnet.tar vmmon-only
 
 to create the tarballs. In this case, there is no protection against
 unwanted local changes.

vmmon-only/Makefile

@@ -107,7 +107,7 @@ prebuild:: ;
 postbuild:: ;
 
 $(DRIVER_KO): prebuild
-	$(MAKE) -C $(BUILD_DIR) M=$$PWD SRCROOT=$$PWD/$(SRCROOT) \
+	$(MAKE) -C $(BUILD_DIR) SUBDIRS=$$PWD SRCROOT=$$PWD/$(SRCROOT) \
 	  MODULEBUILDDIR=$(MODULEBUILDDIR) modules
 	$(MAKE) -C $$PWD SRCROOT=$$PWD/$(SRCROOT) \
 	  MODULEBUILDDIR=$(MODULEBUILDDIR) postbuild

vmmon-only/include/compat_poll.h

@@ -1,30 +0,0 @@
-#ifndef __COMPAT_POLL_H__
-#define __COMPAT_POLL_H__
-
-#include <linux/poll.h>
-
-#if (LINUX_VERSION_CODE < KERNEL_VERSION(4, 18, 0))
-
-#ifndef __poll_t
-typedef unsigned int __poll_t;
-#endif
-
-static inline __poll_t compat_vfs_poll(struct file *file,
-				       struct poll_table_struct *pt)
-{
-	if (unlikely(!file->f_op->poll))
-		return DEFAULT_POLLMASK;
-	return file->f_op->poll(file, pt);
-}
-
-#else
-
-static inline __poll_t compat_vfs_poll(struct file *file,
-				       struct poll_table_struct *pt)
-{
-	return vfs_poll(file, pt);
-}
-
-#endif
-
-#endif /* __COMPAT_POLL_H__ */

vmmon-only/include/hashFunc.h

@@ -251,7 +251,6 @@ static INLINE ub8 hash2(register const ub8 *k, /* the key */
   {
     /* c is reserved for the length */
   case  2: b+=k[1];
-	   /* fall through */
   case  1: a+=k[0];
     /* case 0: nothing left to add */
   }

vmmon-only/linux/driver.c

@@ -73,9 +73,6 @@ static Bool LinuxDriverCheckPadding(void);
 
 struct VMXLinuxState linuxState;
 
-#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 17, 0)
-typedef int vm_fault_t;
-#endif
 
 /*
  *----------------------------------------------------------------------
@@ -100,9 +97,9 @@ long LinuxDriver_Ioctl(struct file *filp, u_int iocmd,
 
 static int LinuxDriver_Close(struct inode *inode, struct file *filp);
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 11, 0)
-static vm_fault_t LinuxDriverFault(struct vm_fault *fault);
+static int LinuxDriverFault(struct vm_fault *fault);
 #else
-static vm_fault_t LinuxDriverFault(struct vm_area_struct *vma, struct vm_fault *fault);
+static int LinuxDriverFault(struct vm_area_struct *vma, struct vm_fault *fault);
 #endif
 static int LinuxDriverMmap(struct file *filp, struct vm_area_struct *vma);
 
@@ -597,7 +594,7 @@ LinuxDriver_Close(struct inode *inode, // IN
  *-----------------------------------------------------------------------------
  */
 
-static vm_fault_t
+static int
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 11, 0)
 LinuxDriverFault(struct vm_fault *fault)     //IN/OUT
 #else

vmmon-only/linux/hostif.c

@@ -74,7 +74,6 @@
 
 #include "pgtbl.h"
 #include "versioned_atomic.h"
-#include "compat_poll.h"
 
 #if !defined(CONFIG_HIGH_RES_TIMERS)
 #error CONFIG_HIGH_RES_TIMERS required for acceptable performance
@@ -181,32 +180,6 @@ static struct {
 uint8 monitorIPIVector;
 uint8 hvIPIVector;
 
-static unsigned long compat_totalram_pages(void)
-{
-#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 0, 0)
-	return totalram_pages;
-#else
-	return totalram_pages();
-#endif
-}
-
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 0, 0)
-static void do_gettimeofday(struct timeval *tv)
-{
-	struct timespec64 now;
-
-	ktime_get_real_ts64(&now);
-	tv->tv_sec = now.tv_sec;
-	tv->tv_usec = now.tv_nsec / 1000;
-}
-#endif
-
-#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 0, 0) && defined(VERIFY_WRITE)
-	#define write_access_ok(addr, size) access_ok(VERIFY_WRITE, addr, size)
-#else
-	#define write_access_ok(addr, size) access_ok(addr, size)
-#endif
-
 /*
  *-----------------------------------------------------------------------------
  *
@@ -1521,7 +1494,14 @@ unsigned int
 HostIF_EstimateLockedPageLimit(const VMDriver* vm,                // IN
                                unsigned int currentlyLockedPages) // IN
 {
-   unsigned int totalPhysicalPages = compat_totalram_pages();
+   /*
+    * This variable is available and exported to modules,
+    * since at least 2.6.0.
+    */
+
+   extern unsigned long totalram_pages;
+
+   unsigned int totalPhysicalPages = totalram_pages;
 
    /*
     * Use the memory information linux exports as of late for a more
@@ -2184,7 +2164,7 @@ isVAReadable(VA r)  // IN:
    int ret;
 
    old_fs = get_fs();
-   set_fs(KERNEL_DS);
+   set_fs(get_ds());
    r = APICR_TO_ADDR(r, APICR_VERSION);
    ret = HostIF_CopyFromUser(&dummy, r, sizeof dummy);
    set_fs(old_fs);
@@ -2385,7 +2365,7 @@ HostIF_SemaphoreWait(VMDriver *vm,   // IN:
    }
 
    old_fs = get_fs();
-   set_fs(KERNEL_DS);
+   set_fs(get_ds());
 
    {
       struct poll_wqueues table;
@@ -2393,7 +2373,7 @@ HostIF_SemaphoreWait(VMDriver *vm,   // IN:
 
       poll_initwait(&table);
       current->state = TASK_INTERRUPTIBLE;
-      mask = compat_vfs_poll(file, &table.pt);
+      mask = file->f_op->poll(file, &table.pt);
       if (!(mask & (POLLIN | POLLERR | POLLHUP))) {
          vm->vmhost->vcpuSemaTask[vcpuid] = current;
          schedule_timeout(timeoutms * HZ / 1000);  // convert to Hz
@@ -2514,7 +2494,7 @@ HostIF_SemaphoreSignal(uint64 *args)  // IN:
    }
 
    old_fs = get_fs();
-   set_fs(KERNEL_DS);
+   set_fs(get_ds());
 
    /*
     * Always write sizeof(uint64) bytes. This works fine for eventfd and
@@ -3174,7 +3154,7 @@ HostIF_SetFastClockRate(unsigned int rate) // IN: Frequency in Hz.
       }
    } else {
       if (linuxState.fastClockThread) {
-         send_sig(SIGKILL, linuxState.fastClockThread, 1);
+         force_sig(SIGKILL, linuxState.fastClockThread);
          kthread_stop(linuxState.fastClockThread);
 
          linuxState.fastClockThread = NULL;
@@ -3220,7 +3200,7 @@ HostIF_MapUserMem(VA addr,                  // IN: User memory virtual address
 
    ASSERT(handle);
 
-   if (!write_access_ok(p, size)) {
+   if (!access_ok(VERIFY_WRITE, p, size)) {
       printk(KERN_ERR "%s: Couldn't verify write to uva 0x%p with size %"
              FMTSZ"u\n", __func__, p, size);
 

vmnet-only/Makefile

@@ -107,7 +107,7 @@ prebuild:: ;
 postbuild:: ;
 
 $(DRIVER_KO): prebuild
-	$(MAKE) -C $(BUILD_DIR) M=$$PWD SRCROOT=$$PWD/$(SRCROOT) \
+	$(MAKE) -C $(BUILD_DIR) SUBDIRS=$$PWD SRCROOT=$$PWD/$(SRCROOT) \
 	  MODULEBUILDDIR=$(MODULEBUILDDIR) modules
 	$(MAKE) -C $$PWD SRCROOT=$$PWD/$(SRCROOT) \
 	  MODULEBUILDDIR=$(MODULEBUILDDIR) postbuild

vmnet-only/userif.c

@@ -78,37 +78,11 @@ static int  VNetUserIfSetUplinkState(VNetPort *port, uint8 linkUp);
 extern unsigned int  vnet_max_qlen;
 
 #if COMPAT_LINUX_VERSION_CHECK_LT(3, 2, 0)
-#   define compat_kmap_frag(frag) kmap((frag)->page)
-#   define compat_kunmap_frag(page) kunmap((frag)->page)
+#   define compat_kmap(page) kmap(page)
+#   define compat_kunmap(page) kunmap(page)
 #else
-#   define compat_kmap_frag(frag) kmap(skb_frag_page(frag))
-#   define compat_kunmap_frag(frag) kunmap(skb_frag_page(frag))
-#endif
-
-static unsigned int compat_skb_frag_size(const skb_frag_t *frag)
-{
-#if COMPAT_LINUX_VERSION_CHECK_LT(3, 2, 0)
-	return frag->size;
-#else
-	return skb_frag_size(frag);
-#endif
-}
-
-static unsigned int compat_skb_frag_off(const skb_frag_t *frag)
-{
-#if COMPAT_LINUX_VERSION_CHECK_LT(5, 4, 0) && \
-	!(defined(CONFIG_SUSE_VERSION) && CONFIG_SUSE_VERSION == 15 && \
-	  defined(CONFIG_SUSE_PATCHLEVEL) && CONFIG_SUSE_PATCHLEVEL >= 2)
-	return frag->page_offset;
-#else
-	return skb_frag_off(frag);
-#endif
-}
-
-#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 0, 0) && defined(VERIFY_WRITE)
-	#define write_access_ok(addr, size) access_ok(VERIFY_WRITE, addr, size)
-#else
-	#define write_access_ok(addr, size) access_ok(addr, size)
+#   define compat_kmap(page) kmap((page).p)
+#   define compat_kunmap(page) kunmap((page).p)
 #endif
 
 /*
@@ -168,7 +142,7 @@ VNetUserIfMapPtr(VA uAddr,        // IN: pointer to user memory
                  struct page **p, // OUT: locked page
                  void **ptr)      // OUT: kernel mapped pointer
 {
-   if (!write_access_ok((void *)uAddr, size) ||
+   if (!access_ok(VERIFY_WRITE, (void *)uAddr, size) ||
        (((uAddr + size - 1) & ~(PAGE_SIZE - 1)) !=
         (uAddr & ~(PAGE_SIZE - 1)))) {
       return -EINVAL;
@@ -585,21 +559,20 @@ VNetCsumCopyDatagram(const struct sk_buff *skb,	// IN: skb to copy
    for (frag = skb_shinfo(skb)->frags;
 	frag != skb_shinfo(skb)->frags + skb_shinfo(skb)->nr_frags;
 	frag++) {
-      if (compat_skb_frag_size(frag) > 0) {
+      if (frag->size > 0) {
 	 unsigned int tmpCsum;
 	 const void *vaddr;
 
-	 vaddr = compat_kmap_frag(frag);
-	 tmpCsum = csum_and_copy_to_user(vaddr + compat_skb_frag_off(frag),
-					 curr, compat_skb_frag_size(frag), 0,
-					 &err);
-	 compat_kunmap_frag(frag);
+	 vaddr = compat_kmap(frag->page);
+	 tmpCsum = csum_and_copy_to_user(vaddr + frag->page_offset,
+					 curr, frag->size, 0, &err);
+	 compat_kunmap(frag->page);
 
 	 if (err) {
 	    return err;
 	 }
 	 csum = csum_block_add(csum, tmpCsum, curr - buf);
-	 curr += compat_skb_frag_size(frag);
+	 curr += frag->size;
       }
    }