Author: jhb
Date: Fri Oct 14 20:01:07 2016
New Revision: 307332
URL: https://svnweb.freebsd.org/changeset/base/307332

Log:
  Drop support for using mmap() with /dev/kmem.
  
  Using the device pager with /dev/kmem is not stable since KVA mappings
  are transient, but the device pager caches the PA associated with a
  given offset forever.  Interestingly, mips' implementation of
  memmap() already refused requests for /dev/kmem.
  
  Note that kvm_read/kvm_write do not use mmap, but use read and write on
  /dev/kmem, so this should not affect libkvm users.
  
  Reviewed by:  kib
  MFC after:    2 months

Modified:
  head/sys/amd64/amd64/mem.c
  head/sys/arm/arm/mem.c
  head/sys/arm64/arm64/mem.c
  head/sys/i386/i386/mem.c
  head/sys/powerpc/powerpc/mem.c

Modified: head/sys/amd64/amd64/mem.c
==============================================================================
--- head/sys/amd64/amd64/mem.c  Fri Oct 14 18:43:17 2016        (r307331)
+++ head/sys/amd64/amd64/mem.c  Fri Oct 14 20:01:07 2016        (r307332)
@@ -172,10 +172,9 @@ memmmap(struct cdev *dev, vm_ooffset_t o
                if (offset >= (1ULL << cpu_maxphyaddr))
                        return (-1);
                *paddr = offset;
-       } else if (dev2unit(dev) == CDEV_MINOR_KMEM)
-               *paddr = vtophys(offset);
-       /* else panic! */
-       return (0);
+               return (0);
+       }
+       return (-1);
 }
 
 /*

Modified: head/sys/arm/arm/mem.c
==============================================================================
--- head/sys/arm/arm/mem.c      Fri Oct 14 18:43:17 2016        (r307331)
+++ head/sys/arm/arm/mem.c      Fri Oct 14 20:01:07 2016        (r307332)
@@ -161,10 +161,9 @@ int
 memmmap(struct cdev *dev, vm_ooffset_t offset, vm_paddr_t *paddr,
     int prot __unused, vm_memattr_t *memattr __unused)
 {
-       if (dev2unit(dev) == CDEV_MINOR_MEM)
+       if (dev2unit(dev) == CDEV_MINOR_MEM) {
                *paddr = offset;
-       else if (dev2unit(dev) == CDEV_MINOR_KMEM)
-               *paddr = vtophys(offset);
-       /* else panic! */
-       return (0);
+               return (0);
+       }
+       return (-1);
 }

Modified: head/sys/arm64/arm64/mem.c
==============================================================================
--- head/sys/arm64/arm64/mem.c  Fri Oct 14 18:43:17 2016        (r307331)
+++ head/sys/arm64/arm64/mem.c  Fri Oct 14 20:01:07 2016        (r307332)
@@ -123,10 +123,9 @@ int
 memmmap(struct cdev *dev, vm_ooffset_t offset, vm_paddr_t *paddr,
     int prot __unused, vm_memattr_t *memattr __unused)
 {
-       if (dev2unit(dev) == CDEV_MINOR_MEM)
+       if (dev2unit(dev) == CDEV_MINOR_MEM) {
                *paddr = offset;
-       else if (dev2unit(dev) == CDEV_MINOR_KMEM)
-               *paddr = vtophys(offset);
-       /* else panic! */
-       return (0);
+               return (0);
+       }
+       return (-1);
 }

Modified: head/sys/i386/i386/mem.c
==============================================================================
--- head/sys/i386/i386/mem.c    Fri Oct 14 18:43:17 2016        (r307331)
+++ head/sys/i386/i386/mem.c    Fri Oct 14 20:01:07 2016        (r307332)
@@ -161,12 +161,11 @@ int
 memmmap(struct cdev *dev, vm_ooffset_t offset, vm_paddr_t *paddr,
     int prot __unused, vm_memattr_t *memattr __unused)
 {
-       if (dev2unit(dev) == CDEV_MINOR_MEM)
+       if (dev2unit(dev) == CDEV_MINOR_MEM) {
                *paddr = offset;
-       else if (dev2unit(dev) == CDEV_MINOR_KMEM)
-               *paddr = vtophys(offset);
-       /* else panic! */
-       return (0);
+               return (0);
+       }
+       return (-1);
 }
 
 /*

Modified: head/sys/powerpc/powerpc/mem.c
==============================================================================
--- head/sys/powerpc/powerpc/mem.c      Fri Oct 14 18:43:17 2016        
(r307331)
+++ head/sys/powerpc/powerpc/mem.c      Fri Oct 14 20:01:07 2016        
(r307332)
@@ -179,8 +179,6 @@ memmmap(struct cdev *dev, vm_ooffset_t o
 
        if (dev2unit(dev) == CDEV_MINOR_MEM)
                *paddr = offset;
-       else if (dev2unit(dev) == CDEV_MINOR_KMEM)
-               *paddr = vtophys(offset);
        else
                return (EFAULT);
 
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