From: Peter Zijlstra <peterz@infradead.org>
To: tglx@linutronix.de, luto@amacapital.net, peterz@infradead.org
Cc: linux-kernel@vger.kernel.org, x86@kernel.org
Subject: [RFC][PATCH 1/4] x86/entry: Introduce local_db_{rave,restore}()
Date: Fri, 22 May 2020 22:47:39 +0200 [thread overview]
Message-ID: <20200522204943.236748823@infradead.org> (raw)
In-Reply-To: 20200522204738.645043059@infradead.org
In order to allow other exceptions than #DB to disable breakpoints,
provide a common helper.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/include/asm/debugreg.h | 23 +++++++++++++++++++++++
arch/x86/kernel/traps.c | 18 ++----------------
2 files changed, 25 insertions(+), 16 deletions(-)
--- a/arch/x86/include/asm/debugreg.h
+++ b/arch/x86/include/asm/debugreg.h
@@ -113,6 +113,29 @@ static inline void debug_stack_usage_inc
static inline void debug_stack_usage_dec(void) { }
#endif /* X86_64 */
+static __always_inline void local_db_save(unsigned long *dr7)
+{
+ get_debugreg(*dr7, 7);
+ set_debugreg(0, 7);
+ /*
+ * Ensure the compiler doesn't lower the above statements into
+ * the critical section; disabling breakpoints late would not
+ * be good.
+ */
+ barrier();
+}
+
+static __always_inline void local_db_restore(unsigned long dr7)
+{
+ /*
+ * Ensure the compiler doesn't raise this statement into
+ * the critical section; enabling breakpoints early would
+ * not be good.
+ */
+ barrier();
+ set_debugreg(dr7, 7);
+}
+
#ifdef CONFIG_CPU_SUP_AMD
extern void set_dr_addr_mask(unsigned long mask, int dr);
#else
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -727,15 +727,7 @@ static __always_inline void debug_enter(
* Entry text is excluded for HW_BP_X and cpu_entry_area, which
* includes the entry stack is excluded for everything.
*/
- get_debugreg(*dr7, 7);
- set_debugreg(0, 7);
-
- /*
- * Ensure the compiler doesn't lower the above statements into
- * the critical section; disabling breakpoints late would not
- * be good.
- */
- barrier();
+ local_db_save(dr7);
/*
* The Intel SDM says:
@@ -756,13 +748,7 @@ static __always_inline void debug_enter(
static __always_inline void debug_exit(unsigned long dr7)
{
- /*
- * Ensure the compiler doesn't raise this statement into
- * the critical section; enabling breakpoints early would
- * not be good.
- */
- barrier();
- set_debugreg(dr7, 7);
+ local_db_restore(dr7);
}
/*
next prev parent reply other threads:[~2020-05-22 20:50 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-22 20:47 [RFC][PATCH 0/4] x86/entry: disallow #DB more Peter Zijlstra
2020-05-22 20:47 ` Peter Zijlstra [this message]
2020-05-22 20:47 ` [RFC][PATCH 2/4] x86/entry, nmi: Disable #DB Peter Zijlstra
2020-05-22 20:47 ` [RFC][PATCH 3/4] x86/entry: Remove debug IST frobbing Peter Zijlstra
2020-05-22 20:47 ` [RFC][PATCH 4/4] x86/entry, mce: Disallow #DB during #MC Peter Zijlstra
2020-05-22 22:13 ` [RFC][PATCH 0/4] x86/entry: disallow #DB more Andy Lutomirski
2020-05-22 22:20 ` Sean Christopherson
2020-05-22 22:43 ` Andy Lutomirski
2020-05-23 12:59 ` Peter Zijlstra
2020-05-23 21:32 ` Peter Zijlstra
2020-05-25 10:02 ` Rasmus Villemoes
2020-05-25 10:40 ` Peter Zijlstra
2020-05-25 11:01 ` Peter Zijlstra
2020-05-25 17:19 ` Andy Lutomirski
2020-05-25 18:08 ` Peter Zijlstra
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