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authorPeter Zijlstra <peterz@infradead.org>2019-07-11 13:40:58 +0200
committerThomas Gleixner <tglx@linutronix.de>2019-07-17 23:17:38 +0200
commit4234653e882740cbf6625eeee294e388b3176583 (patch)
treeb04d86e8188d81b531f1cb031f00137a19df49e1 /arch/x86/entry
parent2fd37912cfb019228bf246215938e6f7619516a2 (diff)
x86/entry/64: Update comments and sanity tests for create_gap
Commit 2700fefdb2d9 ("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
Diffstat (limited to 'arch/x86/entry')
-rw-r--r--arch/x86/entry/entry_64.S17
1 files changed, 11 insertions, 6 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 3db5fede743b..95ae05f0edf2 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -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