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authorH. Peter Anvin <hpa@zytor.com>2013-02-11 16:27:28 -0800
committerH. Peter Anvin <hpa@zytor.com>2013-02-11 17:26:51 -0800
commitb390784dc1649f6e6c5e66e5f53c21e715ccf39b (patch)
treed8c68a501fcb84f3b69820b0558d936a331c1aac /arch/x86/include
parent136867f517cbc3f8a91f035677911a6b503c3323 (diff)
x86, mm: Use a bitfield to mask nuisance get_user() warnings
Even though it is never executed, gcc wants to warn for casting from a large integer to a pointer. Furthermore, using a variable with __typeof__() doesn't work because __typeof__ retains storage specifiers (const, restrict, volatile). However, we can declare a bitfield using sizeof(), which is legal because sizeof() is a constant expression. This quiets the warning, although the code generated isn't 100% identical from the baseline before 96477b4 x86-32: Add support for 64bit get_user(): [x86-mb is baseline, x86-mm is this commit] text data bss filename 113716147 15858380 35037184 tip.x86-mb/o.i386-allconfig/vmlinux 113716145 15858380 35037184 tip.x86-mm/o.i386-allconfig/vmlinux 12989837 3597944 12255232 tip.x86-mb/o.i386-modconfig/vmlinux 12989831 3597944 12255232 tip.x86-mm/o.i386-modconfig/vmlinux 1462784 237608 1401988 tip.x86-mb/o.i386-noconfig/vmlinux 1462837 237608 1401964 tip.x86-mm/o.i386-noconfig/vmlinux 7938994 553688 7639040 tip.x86-mb/o.i386-pae/vmlinux 7943136 557784 7639040 tip.x86-mm/o.i386-pae/vmlinux 7186126 510572 6574080 tip.x86-mb/o.i386/vmlinux 7186124 510572 6574080 tip.x86-mm/o.i386/vmlinux 103747269 33578856 65888256 tip.x86-mb/o.x86_64-allconfig/vmlinux 103746949 33578856 65888256 tip.x86-mm/o.x86_64-allconfig/vmlinux 12116695 11035832 20160512 tip.x86-mb/o.x86_64-modconfig/vmlinux 12116567 11035832 20160512 tip.x86-mm/o.x86_64-modconfig/vmlinux 1700790 380524 511808 tip.x86-mb/o.x86_64-noconfig/vmlinux 1700790 380524 511808 tip.x86-mm/o.x86_64-noconfig/vmlinux 12413612 1133376 1101824 tip.x86-mb/o.x86_64/vmlinux 12413484 1133376 1101824 tip.x86-mm/o.x86_64/vmlinux Cc: Jamie Lokier <jamie@shareable.org> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Russell King <linux@arm.linux.org.uk> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20130209110031.GA17833@n2100.arm.linux.org.uk Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'arch/x86/include')
-rw-r--r--arch/x86/include/asm/uaccess.h20
1 files changed, 9 insertions, 11 deletions
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 1e963267d44e..a8d12653f304 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -168,31 +168,29 @@ do { \
#define get_user(x, ptr) \
({ \
int __ret_gu; \
- unsigned long __val_gu; \
- unsigned long long __val_gu8; \
+ struct { \
+ unsigned long long __val_n : 8*sizeof(*(ptr)); \
+ } __val_gu; \
__chk_user_ptr(ptr); \
might_fault(); \
switch (sizeof(*(ptr))) { \
case 1: \
- __get_user_x(1, __ret_gu, __val_gu, ptr); \
+ __get_user_x(1, __ret_gu, __val_gu.__val_n, ptr); \
break; \
case 2: \
- __get_user_x(2, __ret_gu, __val_gu, ptr); \
+ __get_user_x(2, __ret_gu, __val_gu.__val_n, ptr); \
break; \
case 4: \
- __get_user_x(4, __ret_gu, __val_gu, ptr); \
+ __get_user_x(4, __ret_gu, __val_gu.__val_n, ptr); \
break; \
case 8: \
- __get_user_8(__ret_gu, __val_gu8, ptr); \
+ __get_user_8(__ret_gu, __val_gu.__val_n, ptr); \
break; \
default: \
- __get_user_x(X, __ret_gu, __val_gu, ptr); \
+ __get_user_x(X, __ret_gu, __val_gu.__val_n, ptr); \
break; \
} \
- if (sizeof(*(ptr)) == 8) \
- (x) = (__typeof__(*(ptr)))__val_gu8; \
- else \
- (x) = (__typeof__(*(ptr)))__val_gu; \
+ (x) = (__typeof__(*(ptr)))__val_gu.__val_n; \
__ret_gu; \
})