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Message-ID: <51C0AE2D.9000109@hds.com>
Date: Tue, 18 Jun 2013 14:59:57 -0400
From: Seiji Aguchi <seiji.aguchi@....com>
To: linux-kernel@...r.kernel.org, hpa@...or.com, rostedt@...dmis.org
CC: tglx@...utronix.de, mingo@...e.hu, bp@...en8.de,
linux-edac@...r.kernel.org, tony.luck@...el.com,
tomoki.sekiyama@....com, dle-develop@...ts.sourceforge.net
Subject: [PATCH v16 3/4] x86: Rename variables for debugging
Rename variables for debugging to describe meaning of them precisely.
Also, introduce a generic way to switch IDT by checking a current state,
debug on/off.
Signed-off-by: Seiji Aguchi <seiji.aguchi@....com>
---
arch/x86/include/asm/desc.h | 47 +++++++++++++++++++++++++++++++++++++++--
arch/x86/kernel/cpu/common.c | 16 +++++++-------
arch/x86/kernel/head_64.S | 2 +-
arch/x86/kernel/traps.c | 2 +-
4 files changed, 54 insertions(+), 13 deletions(-)
diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
index 8bf1c06..af290b8 100644
--- a/arch/x86/include/asm/desc.h
+++ b/arch/x86/include/asm/desc.h
@@ -36,8 +36,8 @@ static inline void fill_ldt(struct desc_struct *desc, const struct user_desc *in
extern struct desc_ptr idt_descr;
extern gate_desc idt_table[];
-extern struct desc_ptr nmi_idt_descr;
-extern gate_desc nmi_idt_table[];
+extern struct desc_ptr debug_idt_descr;
+extern gate_desc debug_idt_table[];
struct gdt_page {
struct desc_struct gdt[GDT_ENTRIES];
@@ -316,7 +316,7 @@ static inline void set_nmi_gate(int gate, void *addr)
gate_desc s;
pack_gate(&s, GATE_INTERRUPT, (unsigned long)addr, 0, 0, __KERNEL_CS);
- write_idt_entry(nmi_idt_table, gate, &s);
+ write_idt_entry(debug_idt_table, gate, &s);
}
#endif
@@ -405,4 +405,45 @@ static inline void set_system_intr_gate_ist(int n, void *addr, unsigned ist)
_set_gate(n, GATE_INTERRUPT, addr, 0x3, ist, __KERNEL_CS);
}
+#ifdef CONFIG_X86_64
+DECLARE_PER_CPU(u32, debug_idt_ctr);
+static inline bool is_debug_idt_enabled(void)
+{
+ if (this_cpu_read(debug_idt_ctr))
+ return true;
+
+ return false;
+}
+
+static inline void load_debug_idt(void)
+{
+ load_idt((const struct desc_ptr *)&debug_idt_descr);
+}
+#else
+static inline bool is_debug_idt_enabled(void)
+{
+ return false;
+}
+
+static inline void load_debug_idt(void)
+{
+}
+#endif
+
+/*
+ * the load_current_idt() is called with interrupt disabled by local_irq_save()
+ * to avoid races. That way the IDT will always be set back to the expected
+ * descriptor.
+ */
+static inline void load_current_idt(void)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ if (is_debug_idt_enabled())
+ load_debug_idt();
+ else
+ load_idt((const struct desc_ptr *)&idt_descr);
+ local_irq_restore(flags);
+}
#endif /* _ASM_X86_DESC_H */
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 22018f7..8f6a0f9 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1071,8 +1071,8 @@ __setup("clearcpuid=", setup_disablecpuid);
#ifdef CONFIG_X86_64
struct desc_ptr idt_descr = { NR_VECTORS * 16 - 1, (unsigned long) idt_table };
-struct desc_ptr nmi_idt_descr = { NR_VECTORS * 16 - 1,
- (unsigned long) nmi_idt_table };
+struct desc_ptr debug_idt_descr = { NR_VECTORS * 16 - 1,
+ (unsigned long) debug_idt_table };
DEFINE_PER_CPU_FIRST(union irq_stack_union,
irq_stack_union) __aligned(PAGE_SIZE);
@@ -1148,20 +1148,20 @@ int is_debug_stack(unsigned long addr)
addr > (__get_cpu_var(debug_stack_addr) - DEBUG_STKSZ));
}
-static DEFINE_PER_CPU(u32, debug_stack_use_ctr);
+DEFINE_PER_CPU(u32, debug_idt_ctr);
void debug_stack_set_zero(void)
{
- this_cpu_inc(debug_stack_use_ctr);
- load_idt((const struct desc_ptr *)&nmi_idt_descr);
+ this_cpu_inc(debug_idt_ctr);
+ load_current_idt();
}
void debug_stack_reset(void)
{
- if (WARN_ON(!this_cpu_read(debug_stack_use_ctr)))
+ if (WARN_ON(!this_cpu_read(debug_idt_ctr)))
return;
- if (this_cpu_dec_return(debug_stack_use_ctr) == 0)
- load_idt((const struct desc_ptr *)&idt_descr);
+ if (this_cpu_dec_return(debug_idt_ctr) == 0)
+ load_current_idt();
}
#else /* CONFIG_X86_64 */
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 321d65e..84fb779 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -518,7 +518,7 @@ ENTRY(idt_table)
.skip IDT_ENTRIES * 16
.align L1_CACHE_BYTES
-ENTRY(nmi_idt_table)
+ENTRY(debug_idt_table)
.skip IDT_ENTRIES * 16
__PAGE_ALIGNED_BSS
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 772e2a8..d27182d 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -785,7 +785,7 @@ void __init trap_init(void)
x86_init.irqs.trap_init();
#ifdef CONFIG_X86_64
- memcpy(&nmi_idt_table, &idt_table, IDT_ENTRIES * 16);
+ memcpy(&debug_idt_table, &idt_table, IDT_ENTRIES * 16);
set_nmi_gate(X86_TRAP_DB, &debug);
set_nmi_gate(X86_TRAP_BP, &int3);
#endif
--
1.7.1
--
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