Messages in this thread Patch in this message |  | | From | Lai Jiangshan <> | Subject | [PATCH 2/2] x86/hw_breakpoint: Prevent data breakpoints on cpu_dr7 | Date | Thu, 4 Feb 2021 23:27:07 +0800 |
| |
From: Lai Jiangshan <laijs@linux.alibaba.com>
When in guest (X86_FEATURE_HYPERVISOR), local_db_save() will read per-cpu cpu_dr7 before clear dr7 register.
local_db_save() is called at the start of exc_debug_kernel(). To avoid recursive #DB, we have to disallow data breakpoints on cpu_dr7.
Fixes: 84b6a3491567a("x86/entry: Optimize local_db_save() for virt") Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com> --- arch/x86/kernel/hw_breakpoint.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c index bc7493a0736f..de34dd49d317 100644 --- a/arch/x86/kernel/hw_breakpoint.c +++ b/arch/x86/kernel/hw_breakpoint.c @@ -307,6 +307,14 @@ static inline bool within_cpu_entry(unsigned long addr, unsigned long end) (unsigned long)&per_cpu(cpu_tlbstate, cpu), sizeof(struct tlb_state))) return true; + + /* + * When in guest (X86_FEATURE_HYPERVISOR), local_db_save() + * will read per-cpu cpu_dr7 before clear dr7 register. + */ + if (within_area(addr, end, (unsigned long)&per_cpu(cpu_dr7, cpu), + sizeof(cpu_dr7))) + return true; } return false; -- 2.19.1.6.gb485710b
|  |