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From: Peter Zijlstra <peterz@infradead.org>
To: tglx@linutronix.de, bp@alien8.de, mingo@kernel.org,
	rostedt@goodmis.org, luto@kernel.org,
	torvalds@linux-foundation.org
Cc: hpa@zytor.com, dave.hansen@linux.intel.com, jgross@suse.com,
	linux-kernel@vger.kernel.org, zhe.he@windriver.com,
	joel@joelfernandes.org, devel@etsukata.com, peterz@infradead.org
Subject: [PATCH v3 4/6] x86/entry/64: Update comments and sanity tests for create_gap
Date: Thu, 11 Jul 2019 13:40:58 +0200	[thread overview]
Message-ID: <20190711114336.059780563@infradead.org> (raw)
In-Reply-To: 20190711114054.406765395@infradead.org

Commit 2700fefdb2d9 ("x86_64: Add gap to int3 to allow for call
emulation") forgot to update the comment, do so now.

Acked-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 arch/x86/entry/entry_64.S |   17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -913,15 +913,16 @@ apicinterrupt IRQ_WORK_VECTOR			irq_work
 /**
  * idtentry - Generate an IDT entry stub
  * @sym:		Name of the generated entry point
- * @do_sym: 		C function to be called
- * @has_error_code: 	True if this IDT vector has an error code on the stack
- * @paranoid: 		non-zero means that this vector may be invoked from
+ * @do_sym:		C function to be called
+ * @has_error_code:	True if this IDT vector has an error code on the stack
+ * @paranoid:		non-zero means that this vector may be invoked from
  *			kernel mode with user GSBASE and/or user CR3.
  *			2 is special -- see below.
  * @shift_ist:		Set to an IST index if entries from kernel mode should
- *             		decrement the IST stack so that nested entries get a
+ *			decrement the IST stack so that nested entries get a
  *			fresh stack.  (This is for #DB, which has a nasty habit
- *             		of recursing.)
+ *			of recursing.)
+ * @create_gap:		create a 6-word stack gap when coming from kernel mode.
  *
  * idtentry generates an IDT stub that sets up a usable kernel context,
  * creates struct pt_regs, and calls @do_sym.  The stub has the following
@@ -951,10 +952,14 @@ ENTRY(\sym)
 	UNWIND_HINT_IRET_REGS offset=\has_error_code*8
 
 	/* Sanity check */
-	.if \shift_ist != -1 && \paranoid == 0
+	.if \shift_ist != -1 && \paranoid != 1
 	.error "using shift_ist requires paranoid=1"
 	.endif
 
+	.if \create_gap && \paranoid
+	.error "using create_gap requires paranoid=0"
+	.endif
+
 	ASM_CLAC
 
 	.if \has_error_code == 0



  parent reply	other threads:[~2019-07-11 11:52 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-11 11:40 [PATCH v3 0/6] Tracing vs CR2 Peter Zijlstra
2019-07-11 11:40 ` [PATCH v3 1/6] x86/paravirt: Make read_cr2() CALLEE_SAVE Peter Zijlstra
2019-07-17 21:22   ` [tip:x86/urgent] " tip-bot for Peter Zijlstra
2019-07-11 11:40 ` [PATCH v3 2/6] x86/entry/32: Simplify common_exception Peter Zijlstra
2019-07-17 21:23   ` [tip:x86/urgent] " tip-bot for Peter Zijlstra
2019-07-11 11:40 ` [PATCH v3 3/6] x86/entry/64: Simplify idtentry a little Peter Zijlstra
2019-07-17 21:24   ` [tip:x86/urgent] " tip-bot for Peter Zijlstra
2019-07-11 11:40 ` Peter Zijlstra [this message]
2019-07-17 21:25   ` [tip:x86/urgent] x86/entry/64: Update comments and sanity tests for create_gap tip-bot for Peter Zijlstra
2019-07-11 11:40 ` [PATCH v3 5/6] x86/mm, tracing: Fix CR2 corruption Peter Zijlstra
2019-07-17 21:25   ` [tip:x86/urgent] " tip-bot for Peter Zijlstra
2019-07-11 11:41 ` [PATCH v3 6/6] x86/entry/64: Remove TRACE_IRQS_*_DEBUG Peter Zijlstra
2019-07-11 14:45   ` Andy Lutomirski
2019-07-11 18:28     ` Peter Zijlstra
2019-07-16 19:33 ` [PATCH v3 0/6] Tracing vs CR2 Vegard Nossum
2019-07-16 21:51   ` Vegard Nossum
2019-07-17  1:02     ` Andy Lutomirski
2019-07-17  7:46       ` Vegard Nossum
2019-07-17  7:47       ` Peter Zijlstra
2019-07-17  9:37     ` Eiichi Tsukata
2019-07-18 20:27       ` Andy Lutomirski
2019-07-20  3:59         ` Eiichi Tsukata
2019-07-20 12:49           ` Andy Lutomirski
2019-07-20 14:23             ` Eiichi Tsukata
2019-07-17  8:07   ` Peter Zijlstra
2019-07-17  8:09     ` Vegard Nossum
2019-07-18  8:57       ` [PATCH] stacktrace: Force USER_DS for stack_trace_save_user() Peter Zijlstra
2019-07-18 13:21         ` Joel Fernandes
2019-07-18 14:52         ` [tip:core/urgent] " tip-bot for Peter Zijlstra

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