From 2a6e3cf63f58e289802a11faad5fb495e2d04e97 Mon Sep 17 00:00:00 2001
From: vboxsync <vboxsync@cfe28804-0f27-0410-a406-dd0f0b0b656f>
Date: Wed, 9 Dec 2020 18:59:04 +0000
Subject: [PATCH] Runtime/memobj-r0drv-linux.c: Changes to support the upcoming
 5.10 kernel, bugref:9879

Upstream-Status: Backport

git-svn-id: http://www.virtualbox.org/svn/vbox@87074 cfe28804-0f27-0410-a406-dd0f0b0b656f

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
---
 .../Runtime/r0drv/linux/memobj-r0drv-linux.c  | 68 ++++++++++++++++++-
 1 file changed, 67 insertions(+), 1 deletion(-)

--- a/src/VBox/Runtime/r0drv/linux/memobj-r0drv-linux.c
+++ b/src/VBox/Runtime/r0drv/linux/memobj-r0drv-linux.c
@@ -56,9 +56,19 @@
  * Whether we use alloc_vm_area (3.2+) for executable memory.
  * This is a must for 5.8+, but we enable it all the way back to 3.2.x for
  * better W^R compliance (fExecutable flag). */
-#if RTLNX_VER_MIN(3,2,0) || defined(DOXYGEN_RUNNING)
+#if RTLNX_VER_RANGE(3,2,0, 5,10,0) || defined(DOXYGEN_RUNNING)
 # define IPRT_USE_ALLOC_VM_AREA_FOR_EXEC
 #endif
+/** @def IPRT_USE_APPLY_TO_PAGE_RANGE_FOR_EXEC
+ * alloc_vm_area was removed with 5.10 so we have to resort to a different way
+ * to allocate executable memory.
+ * It would be possible to remove IPRT_USE_ALLOC_VM_AREA_FOR_EXEC and use
+ * this path execlusively for 3.2+ but no time to test it really works on every
+ * supported kernel, so better play safe for now.
+ */
+#if RTLNX_VER_MIN(5,10,0) || defined(DOXYGEN_RUNNING)
+# define IPRT_USE_APPLY_TO_PAGE_RANGE_FOR_EXEC
+#endif
 
 /*
  * 2.6.29+ kernels don't work with remap_pfn_range() anymore because
@@ -502,6 +512,46 @@ static void rtR0MemObjLinuxFreePages(PRT
 }
 
 
+#ifdef IPRT_USE_APPLY_TO_PAGE_RANGE_FOR_EXEC
+/**
+ * User data passed to the apply_to_page_range() callback.
+ */
+typedef struct LNXAPPLYPGRANGE
+{
+    /** Pointer to the memory object. */
+    PRTR0MEMOBJLNX pMemLnx;
+    /** The page protection flags to apply. */
+    pgprot_t       fPg;
+} LNXAPPLYPGRANGE;
+/** Pointer to the user data. */
+typedef LNXAPPLYPGRANGE *PLNXAPPLYPGRANGE;
+/** Pointer to the const user data. */
+typedef const LNXAPPLYPGRANGE *PCLNXAPPLYPGRANGE;
+
+/**
+ * Callback called in apply_to_page_range().
+ *
+ * @returns Linux status code.
+ * @param   pPte                Pointer to the page table entry for the given address.
+ * @param   uAddr               The address to apply the new protection to.
+ * @param   pvUser              The opaque user data.
+ */
+#ifdef __i386__
+static int rtR0MemObjLinuxApplyPageRange(pte_t *pPte, unsigned long uAddr, void *pvUser)
+#else
+static DECLCALLBACK(int) rtR0MemObjLinuxApplyPageRange(pte_t *pPte, unsigned long uAddr, void *pvUser)
+#endif
+{
+    PCLNXAPPLYPGRANGE pArgs = (PCLNXAPPLYPGRANGE)pvUser;
+    PRTR0MEMOBJLNX pMemLnx = pArgs->pMemLnx;
+    size_t idxPg = (uAddr - (unsigned long)pMemLnx->Core.pv) >> PAGE_SHIFT;
+
+    set_pte(pPte, mk_pte(pMemLnx->apPages[idxPg], pArgs->fPg));
+    return 0;
+}
+#endif
+
+
 /**
  * Maps the allocation into ring-0.
  *
@@ -584,6 +634,11 @@ static int rtR0MemObjLinuxVMap(PRTR0MEMO
         else
 # endif
         {
+#  if defined(IPRT_USE_APPLY_TO_PAGE_RANGE_FOR_EXEC)
+            if (fExecutable)
+                pgprot_val(fPg) |= _PAGE_NX; /* Uses RTR0MemObjProtect to clear NX when memory ready, W^X fashion. */
+#  endif
+
 # ifdef VM_MAP
             pMemLnx->Core.pv = vmap(&pMemLnx->apPages[0], pMemLnx->cPages, VM_MAP, fPg);
 # else
@@ -1851,6 +1906,21 @@ DECLHIDDEN(int) rtR0MemObjNativeProtect(
         preempt_enable();
         return VINF_SUCCESS;
     }
+# elif defined(IPRT_USE_APPLY_TO_PAGE_RANGE_FOR_EXEC)
+    PRTR0MEMOBJLNX pMemLnx = (PRTR0MEMOBJLNX)pMem;
+    if (   pMemLnx->fExecutable
+        && pMemLnx->fMappedToRing0)
+    {
+        LNXAPPLYPGRANGE Args;
+        Args.pMemLnx = pMemLnx;
+        Args.fPg = rtR0MemObjLinuxConvertProt(fProt, true /*fKernel*/);
+        int rcLnx = apply_to_page_range(current->active_mm, (unsigned long)pMemLnx->Core.pv + offSub, cbSub,
+                                        rtR0MemObjLinuxApplyPageRange, (void *)&Args);
+        if (rcLnx)
+            return VERR_NOT_SUPPORTED;
+
+        return VINF_SUCCESS;
+    }
 # endif
 
     NOREF(pMem);