From: Jan Beulich <JBeulich@suse.com>
Date: Thu, 28 May 2015 08:16:45 +0000 (+0100)
Subject: x86/asm/entry/32: Really make user_mode() work correctly for VM86 mode
X-Git-Tag: firefly_0821_release~176^2~1686^2~3
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=7ba554b5ac69e5f3edac9ce3233beb5acd480878;p=firefly-linux-kernel-4.4.55.git

x86/asm/entry/32: Really make user_mode() work correctly for VM86 mode

While commit efa7045103 ("x86/asm/entry: Make user_mode() work
correctly if regs came from VM86 mode") claims that "user_mode()
is now identical to user_mode_vm()", this wasn't actually the
case - no prior commit made it so.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/5566EB0D020000780007E655@mail.emea.novell.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 19507ffa5d28..5fabf1362942 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -107,7 +107,7 @@ static inline unsigned long regs_return_value(struct pt_regs *regs)
 static inline int user_mode(struct pt_regs *regs)
 {
 #ifdef CONFIG_X86_32
-	return (regs->cs & SEGMENT_RPL_MASK) == USER_RPL;
+	return ((regs->cs & SEGMENT_RPL_MASK) | (regs->flags & X86_VM_MASK)) >= USER_RPL;
 #else
 	return !!(regs->cs & 3);
 #endif