diff options
| author | H. Peter Anvin | 2013-08-29 13:34:50 -0700 |
|---|---|---|
| committer | H. Peter Anvin | 2013-08-29 13:34:50 -0700 |
| commit | f69fa9a91f60fff6f2d8b658b7d84d235d9d89b7 (patch) | |
| tree | 5fb0d2b09deda3299e2e303924ec8b3466840ffa /arch/x86 | |
| parent | bdfc017eead9bc17cd23317ff42eb7297cb9468a (diff) | |
x86, doc: Update uaccess.h comment to reflect clang changes
Update comment in uaccess.h to reflect the changes for clang support:
gcc only cares about the base register (most architectures don't
encode the size of the operation in the operands like x86 does, and so
it is treated effectively like a register number), whereas clang tries
to enforce the size -- but not for register pairs.
Link: http://lkml.kernel.org/r/1377803585-5913-3-git-send-email-dl9pf@gmx.de
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Jan-Simon Möller <dl9pf@gmx.de>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/include/asm/uaccess.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index f715fee40821..5838fa911aa0 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -153,11 +153,14 @@ __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) * Careful: we have to cast the result to the type of the pointer * for sign reasons. * - * The use of %edx as the register specifier is a bit of a + * The use of _ASM_DX as the register specifier is a bit of a * simplification, as gcc only cares about it as the starting point * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits * (%ecx being the next register in gcc's x86 register sequence), and * %rdx on 64 bits. + * + * Clang/LLVM cares about the size of the register, but still wants + * the base register for something that ends up being a pair. */ #define get_user(x, ptr) \ ({ \ |