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

Commit 2700fefdb2 ("x86_64: Add gap to int3 to allow for call
emulation") forgot to update the comment, do so now.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Andy 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
This commit is contained in:
Peter Zijlstra 2019-07-11 13:40:58 +02:00 committed by Thomas Gleixner
parent 2fd37912cf
commit 4234653e88
1 changed files with 11 additions and 6 deletions
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17
arch/x86/entry/entry_64.S
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@ -913,15 +913,16 @@ apicinterrupt IRQ_WORK_VECTOR irq_work_interrupt smp_irq_work_interrupt
/**
* 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