Commit-ID: 4234653e882740cbf6625eeee294e388b3176583
Gitweb: https://git.kernel.org/tip/4234653e882740cbf6625eeee294e388b3176583
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Thu, 11 Jul 2019 13:40:58 +0200
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Wed, 17 Jul 2019 23:17:38 +0200
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@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Acked-by: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: bp@xxxxxxxxx
Cc: torvalds@xxxxxxxxxxxxxxxxxxxx
Cc: hpa@xxxxxxxxx
Cc: dave.hansen@xxxxxxxxxxxxxxx
Cc: jgross@xxxxxxxx
Cc: zhe.he@xxxxxxxxxxxxx
Cc: joel@xxxxxxxxxxxxxxxxx
Cc: devel@xxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20190711114336.059780563@xxxxxxxxxxxxx
---
arch/x86/entry/entry_64.S | 17 +++++++++++------
1 file 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
|