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Date: Tue, 26 May 2020 01:42:20 +0000 From: Lai Jiangshan <laijs@...ux.alibaba.com> To: linux-kernel@...r.kernel.org Cc: Lai Jiangshan <laijs@...ux.alibaba.com>, Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>, Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, "H. Peter Anvin" <hpa@...or.com>, Alexandre Chartre <alexandre.chartre@...cle.com>, Changbin Du <changbin.du@...el.com>, Martin Molnar <martin.molnar.programming@...il.com> Subject: [RFC PATCH V2 6/7] x86/entry: is_debug_stack() don't check of DB1 stack IST-shift code is removed from entry code, #DB will not at DB1 stack. So we remove the check of DB1 stack in is_debug_stack(). Cc: Andy Lutomirski <luto@...nel.org> Cc: Peter Zijlstra (Intel) <peterz@...radead.org> Cc: Thomas Gleixner <tglx@...utronix.de> Cc: x86@...nel.org Signed-off-by: Lai Jiangshan <laijs@...ux.alibaba.com> --- arch/x86/kernel/nmi.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c index 1c58454ac5fb..2f463f5880c6 100644 --- a/arch/x86/kernel/nmi.c +++ b/arch/x86/kernel/nmi.c @@ -500,15 +500,10 @@ static noinstr bool is_debug_stack(unsigned long addr) { struct cea_exception_stacks *cs = __this_cpu_read(cea_exception_stacks); unsigned long top = CEA_ESTACK_TOP(cs, DB); - unsigned long bot = CEA_ESTACK_BOT(cs, DB1); + unsigned long bot = CEA_ESTACK_BOT(cs, DB); if (__this_cpu_read(debug_stack_usage)) return true; - /* - * Note, this covers the guard page between DB and DB1 as well to - * avoid two checks. But by all means @addr can never point into - * the guard page. - */ return addr >= bot && addr < top; } #endif -- 2.20.1
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