linux-kernel - [PATCH 01/14] x86/hw_breakpoint: Add within

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Message-ID: <20200529213320.784524504@infradead.org>
Date:   Fri, 29 May 2020 23:27:29 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     tglx@...utronix.de, luto@...capital.net, peterz@...radead.org
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        Lai Jiangshan <laijs@...ux.alibaba.com>,
        sean.j.christopherson@...el.com, andrew.cooper3@...rix.com,
        daniel.thompson@...aro.org, a.darwish@...utronix.de,
        rostedt@...dmis.org, bigeasy@...utronix.de
Subject: [PATCH 01/14] x86/hw_breakpoint: Add within_area() to check data breakpoints

From: Lai Jiangshan <laijs@...ux.alibaba.com>

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.

Signed-off-by: Lai Jiangshan <laijs@...ux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lkml.kernel.org/r/20200526014221.2119-2-laijs@linux.alibaba.com
---
 arch/x86/kernel/hw_breakpoint.c |   13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

--- a/arch/x86/kernel/hw_breakpoint.c
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -228,13 +228,22 @@ int arch_check_bp_in_kernelspace(struct
 }
 
 /*
+ * 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,