diff options
| -rw-r--r-- | arch/x86/include/asm/uaccess.h | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index d710a25..5ee2687 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -148,9 +148,16 @@ __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) * * Returns zero on success, or -EFAULT on error. * On error, the variable @x is set to zero. - * + */ +/* * 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 + * 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. */ #define get_user(x, ptr) \ ({ \ |