[Xen-changelog] Ensure that 64-bit get_user/put_user only transfer to

[Xen patchbot -unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID 21d2b0144306720d5a2e33d435031672187656ab
# Parent  f6aa23148c193b5fe3f0886ac1b3fb026f73dac7
Ensure that 64-bit get_user/put_user only transfer to
a 64-bit local variable. Some gcc versions have bugs
if this restriction isn't observed.

Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>

diff -r f6aa23148c19 -r 21d2b0144306 xen/include/asm-x86/x86_32/uaccess.h
--- a/xen/include/asm-x86/x86_32/uaccess.h      Mon Aug 22 09:43:58 2005
+++ b/xen/include/asm-x86/x86_32/uaccess.h      Mon Aug 22 09:52:06 2005
@@ -22,7 +22,11 @@
 #define array_access_ok(addr,count,size) \
     (likely(count < (~0UL/size)) && access_ok(addr,count*size))
 
+/* Undefined function to catch size mismatches on 64-bit get_user/put_user. */
+extern void __uaccess_var_not_u64(void);
+
 #define __put_user_u64(x, addr, retval, errret)                        \
+       if (sizeof(x) != 8) __uaccess_var_not_u64();            \
        __asm__ __volatile__(                                   \
                "1:     movl %%eax,0(%2)\n"                     \
                "2:     movl %%edx,4(%2)\n"                     \
@@ -52,6 +56,7 @@
 } while (0)
 
 #define __get_user_u64(x, addr, retval, errret)                        \
+       if (sizeof(x) != 8) __uaccess_var_not_u64();            \
        __asm__ __volatile__(                                   \
                "1:     movl 0(%2),%%eax\n"                     \
                "2:     movl 4(%2),%%edx\n"                     \

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