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Subject: Re: [PATCH 16/21] x86/entry/64: Use a per-CPU trampoline stack for
 IDT entries
To: Andy Lutomirski <luto@kernel.org>
References: <20171127104529.12435-1-mingo@kernel.org>
 <20171127104529.12435-17-mingo@kernel.org>
 <305ed448-6f8e-eecd-d120-546efc185443@linux.intel.com>
 <CALCETrUnaRZd1t-XX-Ax4n_hqj+o81OXO3DRG4OBY2g=qo4gHg@mail.gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        "H . Peter Anvin" <hpa@zytor.com>,
        Peter Zijlstra <peterz@infradead.org>, Borislav Petkov <bp@alien8.de>,
        Linus Torvalds <torvalds@linux-foundation.org>
From: Dave Hansen <dave.hansen@linux.intel.com>
Message-ID: <5b74d67c-8253-8585-c8c0-9e61e3f119b2@linux.intel.com>
Date: Fri, 1 Dec 2017 13:21:50 -0800
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>>> [   30.811750] CR2: fffffffffdeb2f98 CR3: 0000000423fae001 CR4: 00000000001607e0
>>> [   30.819712] Call Trace:
>>> [   30.822442]  <SYSENTER>
>>> [   30.825170]  trace_hardirqs_on_thunk+0x1c/0x1c
>> ...
>>> [   31.000571] R13: 0000000000000050 R14: 0000000000000076 R15: 00007f59f76f2d60
>>> [   31.008533]  </SYSENTER>
>>
>> Should we change that string to something more descriptive?
> 
> I suppose we could rename it to "ENTRY_TRAMPOLINE" or something like that.

The attached patch does just that.  Any objections?

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From: Dave Hansen <dave.hansen@linux.intel.com>

The "SYSENTER" stack is used for a lot more than SYSENTER now.
Give it a better string to display in stack dumps.

We should probably cleanse the 64-bit code of the remaining
"SYSENTER" nomenclature too at some point.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
---

 b/arch//x86/kernel/dumpstack_64.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff -puN arch//x86/kernel/dumpstack_64.c~SYSENTER-rename arch//x86/kernel/dumpstack_64.c
--- a/arch//x86/kernel/dumpstack_64.c~SYSENTER-rename	2017-12-01 12:43:16.768707737 -0800
+++ b/arch//x86/kernel/dumpstack_64.c	2017-12-01 13:19:21.741702337 -0800
@@ -37,8 +37,14 @@ const char *stack_type_name(enum stack_t
 	if (type == STACK_TYPE_IRQ)
 		return "IRQ";
 
-	if (type == STACK_TYPE_SYSENTER)
-		return "SYSENTER";
+	if (type == STACK_TYPE_SYSENTER) {
+		/*
+		 * On 64-bit, we have a generic entry stack that we
+		 * use for all the kernel try points, including
+		 * SYSENTER.
+		 */
+		return "ENTRY_TRAMPOLINE";
+	}
 
 	if (type >= STACK_TYPE_EXCEPTION && type <= STACK_TYPE_EXCEPTION_LAST)
 		return exception_stack_names[type - STACK_TYPE_EXCEPTION];
_

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