X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=include%2Fasm-i386%2Fptrace.h;h=7e0f2945d17d48587dadf5a6b6b5d027b9869b0a;hb=24c83d45d76303db8325b8553a05c69c838ef370;hp=05532875e39e2846a7d757f242617990d039d279;hpb=96fad28a781069eb40156f78b8f50c349805b652;p=linux-2.6

diff --git a/include/asm-i386/ptrace.h b/include/asm-i386/ptrace.h
index 05532875e3..7e0f2945d1 100644
--- a/include/asm-i386/ptrace.h
+++ b/include/asm-i386/ptrace.h
@@ -61,6 +61,13 @@ struct pt_regs {
 struct task_struct;
 extern void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code);
 
+/*
+ * user_mode_vm(regs) determines whether a register set came from user mode.
+ * This is true if V8086 mode was enabled OR if the register set was from
+ * protected mode with RPL-3 CS value.  This tricky test checks that with
+ * one comparison.  Many places in the kernel can bypass this full check
+ * if they have already ruled out V8086 mode, so user_mode(regs) can be used.
+ */
 static inline int user_mode(struct pt_regs *regs)
 {
 	return (regs->xcs & 3) != 0;