[PATCH] netbsd32 swapctl, round 4

[Emmanuel Dreyfus <manu%netbsd.org@localhost>]

Latest revision of the netbsd32 swapctl patch

I noted david@ suggestion to rework uvm_swap_stats() to add a callback,
but I am not sure it is worth it. This is just the emulation path for
a rarely used code path. I can work on it if the consensus is that it
is the way to go, though.

Index: sys/compat/netbsd32/netbsd32_netbsd.c
===================================================================
RCS file: /cvsroot/src/sys/compat/netbsd32/netbsd32_netbsd.c,v
retrieving revision 1.179
diff -U 4 -r1.179 netbsd32_netbsd.c
--- sys/compat/netbsd32/netbsd32_netbsd.c       1 Feb 2012 05:43:54 -0000       
1.179
+++ sys/compat/netbsd32/netbsd32_netbsd.c       2 Feb 2014 04:31:02 -0000
@@ -55,8 +55,9 @@
 #include <sys/sockio.h>
 #include <sys/socketvar.h>
 #include <sys/mbuf.h>
 #include <sys/stat.h>
+#include <sys/swap.h>
 #include <sys/time.h>
 #include <sys/signalvar.h>
 #include <sys/ptrace.h>
 #include <sys/ktrace.h>
@@ -72,8 +73,9 @@
 #include <sys/kauth.h>
 #include <sys/vfs_syscalls.h>
 
 #include <uvm/uvm_extern.h>
+#include <uvm/uvm_swap.h>
 
 #include <sys/sa.h>
 #include <sys/savar.h>
 #include <sys/syscallargs.h>
@@ -1727,8 +1729,48 @@
        NETBSD32TOP_UAP(to, const char);
        return (sys___posix_rename(l, &ua, retval));
 }
 
+static int
+netbsd32_swapctl_stats(struct lwp *l, struct sys_swapctl_args *uap, register_t 
*retval)
+{
+       struct swapent *sep;
+       struct netbsd32_swapent *sep32;
+       int count = SCARG(uap, misc);
+       int i, error = 0;
+
+       /* Make sure userland cannot exhaust kernel memory */
+       if ((size_t)count > (size_t)uvmexp.nswapdev)
+               count = uvmexp.nswapdev;
+
+       sep = kmem_alloc(sizeof(*sep) * count, KM_SLEEP);
+       sep32 = kmem_alloc(sizeof(*sep32) * count, KM_SLEEP);
+
+       uvm_swap_stats(SWAP_STATS, sep, count, retval);
+       count = *retval;
+
+       if (count < 1)
+               goto out;
+
+       for (i = 0; i < count; i++) {
+               sep32[i].se_dev = sep[i].se_dev;
+               sep32[i].se_flags = sep[i].se_flags;
+               sep32[i].se_nblks = sep[i].se_nblks;
+               sep32[i].se_inuse = sep[i].se_inuse;
+               sep32[i].se_priority = sep[i].se_priority;
+               memcpy(sep32[i].se_path, sep[i].se_path,
+                       sizeof(sep32[i].se_path));
+       }
+
+       error = copyout(sep32, SCARG(uap, arg), sizeof(*sep32) * count);
+       
+out:
+       kmem_free(sep, sizeof(*sep));
+       kmem_free(sep32, sizeof(*sep32));
+
+       return error;
+}
+
 int
 netbsd32_swapctl(struct lwp *l, const struct netbsd32_swapctl_args *uap, 
register_t *retval)
 {
        /* {
@@ -1740,8 +1782,13 @@
 
        NETBSD32TO64_UAP(cmd);
        NETBSD32TOP_UAP(arg, void);
        NETBSD32TO64_UAP(misc);
+
+       /* SWAP_STATS50 and SWAP_STATS13 structures need no translation */
+       if (SCARG(&ua, cmd) == SWAP_STATS)
+               return netbsd32_swapctl_stats(l, &ua, retval);
+       
        return (sys_swapctl(l, &ua, retval));
 }
 
 int
Index: sys/uvm/uvm_swap.c
===================================================================
RCS file: /cvsroot/src/sys/uvm/uvm_swap.c,v
retrieving revision 1.161
diff -U 4 -r1.161 uvm_swap.c
--- sys/uvm/uvm_swap.c  5 Feb 2012 16:08:28 -0000       1.161
+++ sys/uvm/uvm_swap.c  2 Feb 2014 04:31:02 -0000
@@ -236,10 +236,8 @@
 
 static int swap_on(struct lwp *, struct swapdev *);
 static int swap_off(struct lwp *, struct swapdev *);
 
-static void uvm_swap_stats(int, struct swapent *, int, register_t *);
-
 static void sw_reg_strategy(struct swapdev *, struct buf *, int);
 static void sw_reg_biodone(struct buf *);
 static void sw_reg_iodone(struct work *wk, void *dummy);
 static void sw_reg_start(struct swapdev *);
@@ -733,9 +731,9 @@
  * copying the swapent array to the stackgap, and this array's size
  * is not known at build time. Hence it would not be possible to
  * ensure it would fit in the stackgap in any case.
  */
-static void
+void
 uvm_swap_stats(int cmd, struct swapent *sep, int sec, register_t *retval)
 {
        struct swappri *spp;
        struct swapdev *sdp;
Index: sys/uvm/uvm_swap.h
===================================================================
RCS file: /cvsroot/src/sys/uvm/uvm_swap.h,v
retrieving revision 1.18
diff -U 4 -r1.18 uvm_swap.h
--- sys/uvm/uvm_swap.h  27 Apr 2011 00:35:52 -0000      1.18
+++ sys/uvm/uvm_swap.h  2 Feb 2014 04:31:02 -0000
@@ -46,10 +46,12 @@
 int    uvm_swap_alloc(int *, bool);
 void   uvm_swap_free(int, int);
 void   uvm_swap_markbad(int, int);
 bool   uvm_swapisfull(void);
+void    uvm_swap_stats(int, struct swapent *, int, register_t *);
 #else /* defined(VMSWAP) */
 #define        uvm_swapisfull()        true
+#define uvm_swap_stats(c, sep, count, retval) { *retval = 0; }
 #endif /* defined(VMSWAP) */
 
 #endif /* _KERNEL */
 
-- 
Emmanuel Dreyfus
manu%netbsd.org@localhost