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,
Lai Jiangshan <laijs@linux.alibaba.com>,
sean.j.christopherson@intel.com, andrew.cooper3@citrix.com,
daniel.thompson@linaro.org, a.darwish@linutronix.de,
rostedt@goodmis.org, bigeasy@linutronix.de
Subject: [PATCH 05/14] x86/entry: Introduce local_db_{save,restore}()
Date: Fri, 29 May 2020 23:27:33 +0200 [thread overview]
Message-ID: <20200529213321.012060983@infradead.org> (raw)
In-Reply-To: 20200529212728.795169701@infradead.org
In order to allow other exceptions than #DB to disable breakpoints,
provide common helpers.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/include/asm/debugreg.h | 30 ++++++++++++++++++++++++++++++
arch/x86/kernel/traps.c | 18 ++----------------
2 files changed, 32 insertions(+), 16 deletions(-)
--- a/arch/x86/include/asm/debugreg.h
+++ b/arch/x86/include/asm/debugreg.h
@@ -113,6 +113,36 @@ static inline void debug_stack_usage_inc
static inline void debug_stack_usage_dec(void) { }
#endif /* X86_64 */
+static __always_inline unsigned long local_db_save(void)
+{
+ unsigned long dr7;
+
+ get_debugreg(dr7, 7);
+ dr7 &= ~0x400; /* architecturally set bit */
+ if (dr7)
+ 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();
+
+ return dr7;
+}
+
+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();
+ if (dr7)
+ 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();
+ *dr7 = local_db_save();
/*
* 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:[~2020-05-29 21:35 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-29 21:27 [PATCH 00/14] x86/entry: disallow #DB more and x86/entry lockdep/nmi Peter Zijlstra
2020-05-29 21:27 ` [PATCH 01/14] x86/hw_breakpoint: Add within_area() to check data breakpoints Peter Zijlstra
2020-05-29 21:27 ` [PATCH 02/14] x86/hw_breakpoint: Prevent data breakpoints on direct GDT Peter Zijlstra
2020-05-30 12:45 ` Andrew Cooper
2020-05-30 15:15 ` Lai Jiangshan
2020-05-29 21:27 ` [PATCH 03/14] x86/hw_breakpoint: Prevent data breakpoints on per_cpu cpu_tss_rw Peter Zijlstra
2020-05-29 21:27 ` [PATCH 04/14] x86/hw_breakpoint: Prevent data breakpoints on user_pcid_flush_mask Peter Zijlstra
2020-05-29 21:27 ` Peter Zijlstra [this message]
2020-05-30 9:57 ` [tip: x86/entry] x86/entry: Introduce local_db_{save,restore}() tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` [PATCH 06/14] x86/entry, nmi: Disable #DB Peter Zijlstra
2020-05-30 9:57 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` [PATCH 07/14] x86/entry, mce: Disallow #DB during #MC Peter Zijlstra
2020-05-30 9:57 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` [PATCH 08/14] x86/entry: Optimize local_db_save() for virt Peter Zijlstra
2020-05-30 9:57 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-06-03 1:17 ` [PATCH 08/14] " Sean Christopherson
2020-05-29 21:27 ` [PATCH 09/14] x86/entry: Remove debug IDT frobbing Peter Zijlstra
2020-05-30 9:57 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` [PATCH 10/14] x86/entry: Remove DBn stacks Peter Zijlstra
2020-05-30 9:57 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` [PATCH 11/14] x86/entry: Clarify irq_{enter,exit}_rcu() Peter Zijlstra
2020-05-30 9:57 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-06-02 14:42 ` [PATCH 11/14] " Qian Cai
2020-06-02 15:05 ` Peter Zijlstra
2020-06-02 18:47 ` Qian Cai
2020-06-03 17:50 ` [tip: x86/entry] x86/entry: Use __irq_exit_rcu() in irq_exit() tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` [PATCH 12/14] x86/entry: Rename trace_hardirqs_off_prepare() Peter Zijlstra
2020-05-30 9:57 ` [tip: x86/entry] " tip-bot2 for Peter Zijlstra
2020-05-29 21:27 ` [PATCH 13/14] lockdep: Prepare for NMI IRQ state tracking Peter Zijlstra
2020-05-29 22:14 ` Steven Rostedt
2020-05-29 22:25 ` Peter Zijlstra
2020-05-29 22:28 ` Steven Rostedt
2020-05-29 22:33 ` Peter Zijlstra
2020-06-02 20:00 ` Peter Zijlstra
2020-05-29 21:27 ` [PATCH 14/14] x86/entry: Fix NMI vs " Peter Zijlstra
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