Kernel/linux-next
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git synced 2025-01-11 00:08:50 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

x86-32: Add support for 64bit get_user()

Browse Source 
Implement __get_user_8() for x86-32. It will return the
64-bit result in edx:eax register pair, and ecx is used
to pass in the address and return the error value.

For consistency, change the register assignment for all
other __get_user_x() variants, so that address is passed in
ecx/rcx, the error value is returned in ecx/rcx, and eax/rax
contains the actual value.

[ hpa: I modified the patch so that it does NOT change the calling
  conventions for the existing callsites, this also means that the code
  is completely unchanged for 64 bits.

  Instead, continue to use eax for address input/error output and use
  the ecx:edx register pair for the output. ]

This is a partial refresh of a patch [1] by Jamie Lokier from
2004. Only the minimal changes to implement 64bit get_user()
were picked from the original patch.

[1] http://article.gmane.org/gmane.linux.kernel/198823

Originally-by: Jamie Lokier <jamie@shareable.org>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link:
http://lkml.kernel.org/r/1355312043-11467-1-git-send-email-ville.syrjala@linux.intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Ville Syrjälä 2012-12-12 13:34:03 +02:00 committed by H. Peter Anvin
parent 07f4207a30
commit 96477b4cd7
3 changed files with 48 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
arch/x86/include/asm/uaccess.h
View File

@ -151,8 +151,15 @@ extern int __get_user_bad(void);
* On error, the variable @x is set to zero.
*/
#ifdef CONFIG_X86_32
#define __get_user_8(__ret_gu, __val_gu, ptr) \
__get_user_x(X, __ret_gu, __val_gu, ptr)
#define __get_user_8(ret, x, ptr) \
do { \
register unsigned long long __xx asm("%edx"); \
asm volatile("call __get_user_8" \
: "=a" (ret), "=r" (__xx) \
: "0" (ptr)); \
(x) = __xx; \
} while (0)
#else
#define __get_user_8(__ret_gu, __val_gu, ptr) \
__get_user_x(8, __ret_gu, __val_gu, ptr)
@ -162,6 +169,7 @@ extern int __get_user_bad(void);
({ \
int __ret_gu; \
unsigned long __val_gu; \
unsigned long long __val_gu8; \
__chk_user_ptr(ptr); \
might_fault(); \
switch (sizeof(*(ptr))) { \
@ -175,13 +183,16 @@ extern int __get_user_bad(void);
__get_user_x(4, __ret_gu, __val_gu, ptr); \
break; \
case 8: \
__get_user_8(__ret_gu, __val_gu, ptr); \
__get_user_8(__ret_gu, __val_gu8, ptr); \
break; \
default: \
__get_user_x(X, __ret_gu, __val_gu, ptr); \
break; \
} \
(x) = (__typeof__(*(ptr)))__val_gu; \
if (sizeof(*(ptr)) == 8) \
(x) = (__typeof__(*(ptr)))__val_gu8; \
else \
(x) = (__typeof__(*(ptr)))__val_gu; \
__ret_gu; \
})

1
arch/x86/kernel/i386_ksyms_32.c
View File

@ -26,6 +26,7 @@ EXPORT_SYMBOL(csum_partial_copy_generic);
EXPORT_SYMBOL(__get_user_1);
EXPORT_SYMBOL(__get_user_2);
EXPORT_SYMBOL(__get_user_4);
EXPORT_SYMBOL(__get_user_8);
EXPORT_SYMBOL(__put_user_1);
EXPORT_SYMBOL(__put_user_2);

37
arch/x86/lib/getuser.S
View File

@ -15,11 +15,10 @@
* __get_user_X
*
* Inputs: %[r|e]ax contains the address.
* The register is modified, but all changes are undone
* before returning because the C code doesn't know about it.
*
* Outputs: %[r|e]ax is error code (0 or -EFAULT)
* %[r|e]dx contains zero-extended value
* %ecx contains the high half for 32-bit __get_user_8
*
*
* These functions should not modify any other registers,
@ -79,22 +78,35 @@ ENTRY(__get_user_4)
CFI_ENDPROC
ENDPROC(__get_user_4)
#ifdef CONFIG_X86_64
ENTRY(__get_user_8)
CFI_STARTPROC
#ifdef CONFIG_X86_64
add $7,%_ASM_AX
jc bad_get_user
GET_THREAD_INFO(%_ASM_DX)
cmp TI_addr_limit(%_ASM_DX),%_ASM_AX
jae bad_get_user
jae bad_get_user
ASM_STAC
4: movq -7(%_ASM_AX),%_ASM_DX
xor %eax,%eax
ASM_CLAC
ret
#else
add $7,%_ASM_AX
jc bad_get_user_8
GET_THREAD_INFO(%_ASM_DX)
cmp TI_addr_limit(%_ASM_DX),%_ASM_AX
jae bad_get_user_8
ASM_STAC
4: mov -7(%_ASM_AX),%edx
5: mov -3(%_ASM_AX),%ecx
xor %eax,%eax
ASM_CLAC
ret
#endif
CFI_ENDPROC
ENDPROC(__get_user_8)
#endif
bad_get_user:
CFI_STARTPROC
@ -105,9 +117,24 @@ bad_get_user:
CFI_ENDPROC
END(bad_get_user)
#ifdef CONFIG_X86_32
bad_get_user_8:
CFI_STARTPROC
xor %edx,%edx
xor %ecx,%ecx
mov $(-EFAULT),%_ASM_AX
ASM_CLAC
ret
CFI_ENDPROC
END(bad_get_user_8)
#endif
_ASM_EXTABLE(1b,bad_get_user)
_ASM_EXTABLE(2b,bad_get_user)
_ASM_EXTABLE(3b,bad_get_user)
#ifdef CONFIG_X86_64
_ASM_EXTABLE(4b,bad_get_user)
#else
_ASM_EXTABLE(4b,bad_get_user_8)
_ASM_EXTABLE(5b,bad_get_user_8)
#endif