linux-kernel - [PATCH] ix86: really make user_mode() work correctly for VM86 mode

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Message-Id: <5566EB0D020000780007E655@mail.emea.novell.com>
Date:	Thu, 28 May 2015 09:16:45 +0100
From:	"Jan Beulich" <JBeulich@...e.com>
To:	<mingo@...e.hu>, <tglx@...utronix.de>, <hpa@...or.com>
Cc:	<luto@...nel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] ix86: 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@...e.com>
Cc: Andy Lutomirski <luto@...nel.org>
---
 arch/x86/include/asm/ptrace.h |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- 4.1-rc5/arch/x86/include/asm/ptrace.h
+++ 4.1-rc5-ix86-user_mode/arch/x86/include/asm/ptrace.h
@@ -107,7 +107,8 @@ static inline unsigned long regs_return_
 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



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