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Commit 4234653e authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Thomas Gleixner
Browse files

x86/entry/64: Update comments and sanity tests for create_gap 



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

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: default avatarAndy Lutomirski <luto@kernel.org>
Cc: bp@alien8.de
Cc: torvalds@linux-foundation.org
Cc: hpa@zytor.com
Cc: dave.hansen@linux.intel.com
Cc: jgross@suse.com
Cc: zhe.he@windriver.com
Cc: joel@joelfernandes.org
Cc: devel@etsukata.com
Link: https://lkml.kernel.org/r/20190711114336.059780563@infradead.org
parent 2fd37912

arch/x86/entry/entry_64.S

+11 −6
Original line number Diff line number Diff line
@@ -922,6 +922,7 @@ apicinterrupt IRQ_WORK_VECTOR irq_work_interrupt smp_irq_work_interrupt 
 *			decrement the IST stack so that nested entries get a

 *			fresh stack.  (This is for #DB, which has a nasty habit

 *			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