Commit-ID: b2f680380ddf2f003882e59e00acd6c1952f91fc
Gitweb: http://git.kernel.org/tip/b2f680380ddf2f003882e59e00acd6c1952f91fc
Author: Benjamin LaHaise <bcrl@xxxxxxxxx>
AuthorDate: Wed, 9 Mar 2016 15:05:56 -0500
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 13 Apr 2016 13:01:03 +0200
x86/mm/32: Add support for 64-bit __get_user() on 32-bit kernels
The existing __get_user() implementation does not support fetching
64-bit values on 32-bit x86. Implement this in a way that does not
generate any incorrect warnings as cautioned by Russell King.
Test code available at:
http://www.kvack.org/~bcrl/x86_32-get_user.tar .
Signed-off-by: Benjamin LaHaise <bcrl@xxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/include/asm/uaccess.h | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index a969ae6..8b3fb76 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -333,7 +333,26 @@ do { \
} while (0)
#ifdef CONFIG_X86_32
-#define __get_user_asm_u64(x, ptr, retval, errret) (x) = __get_user_bad()
+#define __get_user_asm_u64(x, ptr, retval, errret) \
+({ \
+ __typeof__(ptr) __ptr = (ptr); \
+ asm volatile(ASM_STAC "\n" \
+ "1: movl %2,%%eax\n" \
+ "2: movl %3,%%edx\n" \
+ "3: " ASM_CLAC "\n" \
+ ".section .fixup,\"ax\"\n" \
+ "4: mov %4,%0\n" \
+ " xorl %%eax,%%eax\n" \
+ " xorl %%edx,%%edx\n" \
+ " jmp 3b\n" \
+ ".previous\n" \
+ _ASM_EXTABLE(1b, 4b) \
+ _ASM_EXTABLE(2b, 4b) \
+ : "=r" (retval), "=A"(x) \
+ : "m" (__m(__ptr)), "m" __m(((u32 *)(__ptr)) + 1), \
+ "i" (errret), "0" (retval)); \
+})
+
#define __get_user_asm_ex_u64(x, ptr) (x) = __get_user_bad()
#else
#define __get_user_asm_u64(x, ptr, retval, errret) \
@@ -420,7 +439,7 @@ do { \
#define __get_user_nocheck(x, ptr, size) \
({ \
int __gu_err; \
- unsigned long __gu_val; \
+ __inttype(*(ptr)) __gu_val; \
__uaccess_begin(); \
__get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT); \
__uaccess_end(); \
--
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