| diff -up linux-3.10.0-327.sdl7.x86_64/arch/x86/include/asm/ptrace.h.addmissing linux-3.10.0-327.sdl7.x86_64/arch/x86/include/asm/ptrace.h |
| |
| |
| @@ -109,6 +109,23 @@ static inline int user_mode_vm(struct pt |
| #endif |
| } |
| |
| +/* |
| + * This is the fastest way to check whether regs come from user space. |
| + * It is unsafe if regs might come from vm86 mode, though -- in vm86 |
| + * mode, all bits of CS and SS are completely under the user's control. |
| + * The CPU considers vm86 mode to be CPL 3 regardless of CS and SS. |
| + * |
| + * Do NOT use this function unless you have already ruled out the |
| + * possibility that regs came from vm86 mode. |
| + * |
| + * We check for RPL != 0 instead of RPL == 3 because we don't use rings |
| + * 1 or 2 and this is more efficient. |
| + */ |
| +static inline int user_mode_ignore_vm86(struct pt_regs *regs) |
| +{ |
| + return (regs->cs & SEGMENT_RPL_MASK) != 0; |
| +} |
| + |
| static inline int v8086_mode(struct pt_regs *regs) |
| { |
| #ifdef CONFIG_X86_32 |