[PATCH] Common compat_sys_sysinfo

I noticed that almost all architectures implemented exactly the same
sys32_sysinfo...  except parisc, where a bug was to be found in handling of
the uptime.  So let's remove a whole whack of code for fun and profit.
Cribbed compat_sys_sysinfo from x86_64's implementation, since I figured it
would be the best tested.

This patch incorporates Arnd's suggestion of not using set_fs/get_fs, but
instead extracting out the common code from sys_sysinfo.

Cc: Christoph Hellwig <hch@infradead.org>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 66 insertions, 0 deletions

diff --git a/kernel/compat.c b/kernel/compat.c
index 6952dd057300..cebb4c28c039 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -1016,3 +1016,69 @@ asmlinkage long compat_sys_migrate_pages(compat_pid_t pid,
         return sys_migrate_pages(pid, nr_bits + 1, old, new);
 }
 #endif
+
+struct compat_sysinfo {
+        s32 uptime;
+        u32 loads[3];
+        u32 totalram;
+        u32 freeram;
+        u32 sharedram;
+        u32 bufferram;
+        u32 totalswap;
+        u32 freeswap;
+        u16 procs;
+        u16 pad;
+        u32 totalhigh;
+        u32 freehigh;
+        u32 mem_unit;
+        char _f[20-2*sizeof(u32)-sizeof(int)];
+};
+
+asmlinkage long
+compat_sys_sysinfo(struct compat_sysinfo __user *info)
+{
+        struct sysinfo s;
+
+        do_sysinfo(&s);
+
+        /* Check to see if any memory value is too large for 32-bit and scale
+         *  down if needed
+         */
+        if ((s.totalram >> 32) || (s.totalswap >> 32)) {
+                int bitcount = 0;
+
+                while (s.mem_unit < PAGE_SIZE) {
+                        s.mem_unit <<= 1;
+                        bitcount++;
+                }
+
+                s.totalram >>= bitcount;
+                s.freeram >>= bitcount;
+                s.sharedram >>= bitcount;
+                s.bufferram >>= bitcount;
+                s.totalswap >>= bitcount;
+                s.freeswap >>= bitcount;
+                s.totalhigh >>= bitcount;
+                s.freehigh >>= bitcount;
+        }
+
+        if (!access_ok(VERIFY_WRITE, info, sizeof(struct compat_sysinfo)) ||
+            __put_user (s.uptime, &info->uptime) ||
+            __put_user (s.loads[0], &info->loads[0]) ||
+            __put_user (s.loads[1], &info->loads[1]) ||
+            __put_user (s.loads[2], &info->loads[2]) ||
+            __put_user (s.totalram, &info->totalram) ||
+            __put_user (s.freeram, &info->freeram) ||
+            __put_user (s.sharedram, &info->sharedram) ||
+            __put_user (s.bufferram, &info->bufferram) ||
+            __put_user (s.totalswap, &info->totalswap) ||
+            __put_user (s.freeswap, &info->freeswap) ||
+            __put_user (s.procs, &info->procs) ||
+            __put_user (s.totalhigh, &info->totalhigh) ||
+            __put_user (s.freehigh, &info->freehigh) ||
+            __put_user (s.mem_unit, &info->mem_unit))
+                return -EFAULT;
+
+        return 0;
+}
+