From d390e6de89d30402bd06056c40cea72328aec9b1 Mon Sep 17 00:00:00 2001
From: Lai Jiangshan <laijs@linux.alibaba.com>
Date: Fri, 29 May 2020 23:27:29 +0200
Subject: [PATCH] x86/hw_breakpoint: Add within_area() to check data
breakpoints
Add a within_area() helper to checking whether the data breakpoints overlap
with cpu_entry_area.
It will be used to completely prevent data breakpoints on GDT, IDT, or TSS.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200526014221.2119-2-laijs@linux.alibaba.com
Link: https://lkml.kernel.org/r/20200529213320.784524504@infradead.org
---
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 9ddf441ccaa87..c149c7b29ac31 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,
--
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