[RFC PATCH V2 1/7] x86/hw_breakpoint: add within_area() to check data breakpoints

Lai Jiangshan
2020-05-26T01:42:52Z

within_area() is added for checking if the data breakpoints overlap
with cpu_entry_area, and will be used for checking if the data
breakpoints overlap with GDT, IDT, or TSS in places other than
cpu_entry_area next patches.

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86@kernel.org
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
arch/x86/kernel/hw_breakpoint.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
index 9ddf441ccaa8..c149c7b29ac3 100644
--- a/arch/x86/kernel/hw_breakpoint.c
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -227,14 +227,23 @@ int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw)
return (va >= TASK_SIZE_MAX) || ((va + len - 1) >= TASK_SIZE_MAX);
}

+/*
+ * Checks whether the range [addr, end], overlaps the area [base, base + size).
+ */
+static inline bool within_area(unsigned long addr, unsigned long end,
+ unsigned long base, unsigned long size)
+{
+ return end >= base && addr < (base + size);
+}
+
/*
* Checks whether the range from addr to end, inclusive, overlaps the CPU
* entry area range.
*/
static inline bool within_cpu_entry_area(unsigned long addr, unsigned long end)
{
- return end >= CPU_ENTRY_AREA_BASE &&
- addr < (CPU_ENTRY_AREA_BASE + CPU_ENTRY_AREA_TOTAL_SIZE);
+ return within_area(addr, end, CPU_ENTRY_AREA_BASE,
+ CPU_ENTRY_AREA_TOTAL_SIZE);
}

static int arch_build_bp_info(struct perf_event *bp,
--
2.20.1