Searched hist:"3943 abf2" (Results 1 – 1 of 1) sorted by relevance
| /openbmc/linux/arch/x86/kernel/ |
| H A D | hw_breakpoint.c | 3943abf2 Thu Feb 04 09:27:07 CST 2021 Lai Jiangshan <laijs@linux.alibaba.com> x86/debug: Prevent data breakpoints on cpu_dr7
local_db_save() is called at the start of exc_debug_kernel(), reads DR7 and
disables breakpoints to prevent recursion.
When running in a guest (X86_FEATURE_HYPERVISOR), local_db_save() reads the
per-cpu variable cpu_dr7 to check whether a breakpoint is active or not
before it accesses DR7.
A data breakpoint on cpu_dr7 therefore results in infinite #DB recursion.
Disallow data breakpoints on cpu_dr7 to prevent that.
Fixes: 84b6a3491567a("x86/entry: Optimize local_db_save() for virt")
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210204152708.21308-2-jiangshanlai@gmail.com
|