Commit f9fe0b89 authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Thomas Gleixner
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x86/hw_breakpoint: Prevent data breakpoints on per_cpu cpu_tss_rw 



cpu_tss_rw is not directly referenced by hardware, but cpu_tss_rw is
accessed in CPU entry code, especially when #DB shifts its stacks.

If a data breakpoint would be set on cpu_tss_rw.x86_tss.ist[IST_INDEX_DB],
it would cause recursive #DB ending up in a double fault.

Add it to the list of protected items.

Signed-off-by: default avatarLai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200526014221.2119-4-laijs@linux.alibaba.com
Link: https://lkml.kernel.org/r/20200529213320.897976479@infradead.org
parent 97417cb9

arch/x86/kernel/hw_breakpoint.c

+9 −0
Original line number Diff line number Diff line
@@ -255,6 +255,15 @@ static inline bool within_cpu_entry(unsigned long addr, unsigned long end) 
		if (within_area(addr, end, (unsigned long)get_cpu_gdt_rw(cpu),

				GDT_SIZE))

			return true;



		/*

		 * cpu_tss_rw is not directly referenced by hardware, but

		 * cpu_tss_rw is also used in CPU entry code,

		 */

		if (within_area(addr, end,

				(unsigned long)&per_cpu(cpu_tss_rw, cpu),

				sizeof(struct tss_struct)))

			return true;

	}



	return false;