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authorPeter Zijlstra <peterz@infradead.org>2020-05-29 23:27:33 +0200
committerThomas Gleixner <tglx@linutronix.de>2020-06-11 15:15:21 +0200
commite1de11d4d1a64ac1b90b9833f1a3629dae18facb (patch)
tree0018983a29a3b2b285805eefe8151a9ca335698c /arch/x86/include
parentfdef24dfccb7be06e6ebe11d6c6c56987421870f (diff)
downloadlinux-e1de11d4d1a64ac1b90b9833f1a3629dae18facb.tar.gz
x86/entry: Introduce local_db_{save,restore}()
In order to allow other exceptions than #DB to disable breakpoints, provide common helpers. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20200529213321.012060983@infradead.org
Diffstat (limited to 'arch/x86/include')
-rw-r--r--arch/x86/include/asm/debugreg.h30
1 files changed, 30 insertions, 0 deletions
diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h
index 1a8609a15856..4ef8690be8a7 100644
--- 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(void) { }
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