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

[tip-bot for Jan Beulich]

Commit-ID:  7ba554b5ac69e5f3edac9ce3233beb5acd480878
Gitweb:     http://git.kernel.org/tip/7ba554b5ac69e5f3edac9ce3233beb5acd480878
Author:     Jan Beulich <JBeulich@xxxxxxxx>
AuthorDate: Thu, 28 May 2015 09:16:45 +0100
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 29 May 2015 09:46:40 +0200

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@xxxxxxxx>
Acked-by: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/5566EB0D020000780007E655@xxxxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/include/asm/ptrace.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 19507ff..5fabf13 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
--
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