Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/li…

…nux/kernel/git/tip/tip * 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (39 commits) perf tools: Fix compile error on x86_64 Ubuntu perf report: Fix --stdio output alignment when --showcpuutilization used perf annotate: Get rid of field_sep check perf annotate: Fix usage string perf kmem: Fix a memory leak perf kmem: Add missing closedir() calls perf top: Add error message for EMFILE perf test: Change type of '-v' option to INCR perf script: Add missing closedir() calls tracing: Fix compile error when static ftrace is enabled recordmcount: Fix handling of elf64 big-endian objects. perf tools: Add const.h to MANIFEST to make perf-tar-src-pkg work again perf tools: Add support for guest/host-only profiling perf kvm: Do guest-only counting by default perf top: Don't update total_period on process_sample perf hists: Stop using 'self' for struct hist_entry perf hists: Rename total_session to total_period x86: Add counter when debug stack is used with interrupts enabled x86: Allow NMIs to hit breakpoints in i386 x86: Keep current stack in NMI breakpoints ...
mrcsosa · Jan 15, 2012 · 83c2f91 · 83c2f91
2 parents f0ed5b9 + 172d1b0
commit 83c2f91
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Showing 29 changed files with 1,262 additions and 468 deletions.
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
@@ -2475,6 +2475,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 	stacktrace	[FTRACE]
 			Enabled the stack tracer on boot up.
 
+	stacktrace_filter=[function-list]
+			[FTRACE] Limit the functions that the stack tracer
+			will trace at boot up. function-list is a comma separated
+			list of functions. This list can be changed at run
+			time by the stack_trace_filter file in the debugfs
+			tracing directory. Note, this enables stack tracing
+			and the stacktrace above is not needed.
+
 	sti=		[PARISC,HW]
 			Format: <num>
 			Set the STI (builtin display/keyboard on the HP-PARISC

diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h
@@ -101,6 +101,28 @@ extern void aout_dump_debugregs(struct user *dump);
 
 extern void hw_breakpoint_restore(void);
 
+#ifdef CONFIG_X86_64
+DECLARE_PER_CPU(int, debug_stack_usage);
+static inline void debug_stack_usage_inc(void)
+{
+	__get_cpu_var(debug_stack_usage)++;
+}
+static inline void debug_stack_usage_dec(void)
+{
+	__get_cpu_var(debug_stack_usage)--;
+}
+int is_debug_stack(unsigned long addr);
+void debug_stack_set_zero(void);
+void debug_stack_reset(void);
+#else /* !X86_64 */
+static inline int is_debug_stack(unsigned long addr) { return 0; }
+static inline void debug_stack_set_zero(void) { }
+static inline void debug_stack_reset(void) { }
+static inline void debug_stack_usage_inc(void) { }
+static inline void debug_stack_usage_dec(void) { }
+#endif /* X86_64 */
+
+
 #endif	/* __KERNEL__ */
 
 #endif /* _ASM_X86_DEBUGREG_H */
diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
@@ -35,6 +35,8 @@ 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[];
 
 struct gdt_page {
 	struct desc_struct gdt[GDT_ENTRIES];
@@ -307,6 +309,16 @@ static inline void set_desc_limit(struct desc_struct *desc, unsigned long limit)
 	desc->limit = (limit >> 16) & 0xf;
 }
 
+#ifdef CONFIG_X86_64
+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);
+}
+#endif
+
 static inline void _set_gate(int gate, unsigned type, void *addr,
 			     unsigned dpl, unsigned ist, unsigned seg)
 {

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
@@ -1021,6 +1021,8 @@ __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 };
 
 DEFINE_PER_CPU_FIRST(union irq_stack_union,
 		     irq_stack_union) __aligned(PAGE_SIZE);
@@ -1085,6 +1087,26 @@ unsigned long kernel_eflags;
  */
 DEFINE_PER_CPU(struct orig_ist, orig_ist);
 
+static DEFINE_PER_CPU(unsigned long, debug_stack_addr);
+DEFINE_PER_CPU(int, debug_stack_usage);
+
+int is_debug_stack(unsigned long addr)
+{
+	return __get_cpu_var(debug_stack_usage) ||
+		(addr <= __get_cpu_var(debug_stack_addr) &&
+		 addr > (__get_cpu_var(debug_stack_addr) - DEBUG_STKSZ));
+}
+
+void debug_stack_set_zero(void)
+{
+	load_idt((const struct desc_ptr *)&nmi_idt_descr);
+}
+
+void debug_stack_reset(void)
+{
+	load_idt((const struct desc_ptr *)&idt_descr);
+}
+
 #else	/* CONFIG_X86_64 */
 
 DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task;
@@ -1212,6 +1234,8 @@ void __cpuinit cpu_init(void)
 			estacks += exception_stack_sizes[v];
 			oist->ist[v] = t->x86_tss.ist[v] =
 					(unsigned long)estacks;
+			if (v == DEBUG_STACK-1)
+				per_cpu(debug_stack_addr, cpu) = (unsigned long)estacks;
 		}
 	}
 

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
@@ -1480,62 +1480,214 @@ ENTRY(error_exit)
 	CFI_ENDPROC
 END(error_exit)
 
+/*
+ * Test if a given stack is an NMI stack or not.
+ */
+	.macro test_in_nmi reg stack nmi_ret normal_ret
+	cmpq %\reg, \stack
+	ja \normal_ret
+	subq $EXCEPTION_STKSZ, %\reg
+	cmpq %\reg, \stack
+	jb \normal_ret
+	jmp \nmi_ret
+	.endm
 
 	/* runs on exception stack */
 ENTRY(nmi)
 	INTR_FRAME
 	PARAVIRT_ADJUST_EXCEPTION_FRAME
-	pushq_cfi $-1
+	/*
+	 * We allow breakpoints in NMIs. If a breakpoint occurs, then
+	 * the iretq it performs will take us out of NMI context.
+	 * This means that we can have nested NMIs where the next
+	 * NMI is using the top of the stack of the previous NMI. We
+	 * can't let it execute because the nested NMI will corrupt the
+	 * stack of the previous NMI. NMI handlers are not re-entrant
+	 * anyway.
+	 *
+	 * To handle this case we do the following:
+	 *  Check the a special location on the stack that contains
+	 *  a variable that is set when NMIs are executing.
+	 *  The interrupted task's stack is also checked to see if it
+	 *  is an NMI stack.
+	 *  If the variable is not set and the stack is not the NMI
+	 *  stack then:
+	 *    o Set the special variable on the stack
+	 *    o Copy the interrupt frame into a "saved" location on the stack
+	 *    o Copy the interrupt frame into a "copy" location on the stack
+	 *    o Continue processing the NMI
+	 *  If the variable is set or the previous stack is the NMI stack:
+	 *    o Modify the "copy" location to jump to the repeate_nmi
+	 *    o return back to the first NMI
+	 *
+	 * Now on exit of the first NMI, we first clear the stack variable
+	 * The NMI stack will tell any nested NMIs at that point that it is
+	 * nested. Then we pop the stack normally with iret, and if there was
+	 * a nested NMI that updated the copy interrupt stack frame, a
+	 * jump will be made to the repeat_nmi code that will handle the second
+	 * NMI.
+	 */
+
+	/* Use %rdx as out temp variable throughout */
+	pushq_cfi %rdx
+
+	/*
+	 * Check the special variable on the stack to see if NMIs are
+	 * executing.
+	 */
+	cmp $1, -8(%rsp)
+	je nested_nmi
+
+	/*
+	 * Now test if the previous stack was an NMI stack.
+	 * We need the double check. We check the NMI stack to satisfy the
+	 * race when the first NMI clears the variable before returning.
+	 * We check the variable because the first NMI could be in a
+	 * breakpoint routine using a breakpoint stack.
+	 */
+	lea 6*8(%rsp), %rdx
+	test_in_nmi rdx, 4*8(%rsp), nested_nmi, first_nmi
+
+nested_nmi:
+	/*
+	 * Do nothing if we interrupted the fixup in repeat_nmi.
+	 * It's about to repeat the NMI handler, so we are fine
+	 * with ignoring this one.
+	 */
+	movq $repeat_nmi, %rdx
+	cmpq 8(%rsp), %rdx
+	ja 1f
+	movq $end_repeat_nmi, %rdx
+	cmpq 8(%rsp), %rdx
+	ja nested_nmi_out
+
+1:
+	/* Set up the interrupted NMIs stack to jump to repeat_nmi */
+	leaq -6*8(%rsp), %rdx
+	movq %rdx, %rsp
+	CFI_ADJUST_CFA_OFFSET 6*8
+	pushq_cfi $__KERNEL_DS
+	pushq_cfi %rdx
+	pushfq_cfi
+	pushq_cfi $__KERNEL_CS
+	pushq_cfi $repeat_nmi
+
+	/* Put stack back */
+	addq $(11*8), %rsp
+	CFI_ADJUST_CFA_OFFSET -11*8
+
+nested_nmi_out:
+	popq_cfi %rdx
+
+	/* No need to check faults here */
+	INTERRUPT_RETURN
+
+first_nmi:
+	/*
+	 * Because nested NMIs will use the pushed location that we
+	 * stored in rdx, we must keep that space available.
+	 * Here's what our stack frame will look like:
+	 * +-------------------------+
+	 * | original SS             |
+	 * | original Return RSP     |
+	 * | original RFLAGS         |
+	 * | original CS             |
+	 * | original RIP            |
+	 * +-------------------------+
+	 * | temp storage for rdx    |
+	 * +-------------------------+
+	 * | NMI executing variable  |
+	 * +-------------------------+
+	 * | Saved SS                |
+	 * | Saved Return RSP        |
+	 * | Saved RFLAGS            |
+	 * | Saved CS                |
+	 * | Saved RIP               |
+	 * +-------------------------+
+	 * | copied SS               |
+	 * | copied Return RSP       |
+	 * | copied RFLAGS           |
+	 * | copied CS               |
+	 * | copied RIP              |
+	 * +-------------------------+
+	 * | pt_regs                 |
+	 * +-------------------------+
+	 *
+	 * The saved RIP is used to fix up the copied RIP that a nested
+	 * NMI may zero out. The original stack frame and the temp storage
+	 * is also used by nested NMIs and can not be trusted on exit.
+	 */
+	/* Set the NMI executing variable on the stack. */
+	pushq_cfi $1
+
+	/* Copy the stack frame to the Saved frame */
+	.rept 5
+	pushq_cfi 6*8(%rsp)
+	.endr
+
+	/* Make another copy, this one may be modified by nested NMIs */
+	.rept 5
+	pushq_cfi 4*8(%rsp)
+	.endr
+
+	/* Do not pop rdx, nested NMIs will corrupt it */
+	movq 11*8(%rsp), %rdx
+
+	/*
+	 * Everything below this point can be preempted by a nested
+	 * NMI if the first NMI took an exception. Repeated NMIs
+	 * caused by an exception and nested NMI will start here, and
+	 * can still be preempted by another NMI.
+	 */
+restart_nmi:
+	pushq_cfi $-1		/* ORIG_RAX: no syscall to restart */
 	subq $ORIG_RAX-R15, %rsp
 	CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
+	/*
+	 * Use save_paranoid to handle SWAPGS, but no need to use paranoid_exit
+	 * as we should not be calling schedule in NMI context.
+	 * Even with normal interrupts enabled. An NMI should not be
+	 * setting NEED_RESCHED or anything that normal interrupts and
+	 * exceptions might do.
+	 */
 	call save_paranoid
 	DEFAULT_FRAME 0
 	/* paranoidentry do_nmi, 0; without TRACE_IRQS_OFF */
 	movq %rsp,%rdi
 	movq $-1,%rsi
 	call do_nmi
-#ifdef CONFIG_TRACE_IRQFLAGS
-	/* paranoidexit; without TRACE_IRQS_OFF */
-	/* ebx:	no swapgs flag */
-	DISABLE_INTERRUPTS(CLBR_NONE)
 	testl %ebx,%ebx				/* swapgs needed? */
 	jnz nmi_restore
-	testl $3,CS(%rsp)
-	jnz nmi_userspace
 nmi_swapgs:
 	SWAPGS_UNSAFE_STACK
 nmi_restore:
 	RESTORE_ALL 8
+	/* Clear the NMI executing stack variable */
+	movq $0, 10*8(%rsp)
 	jmp irq_return
-nmi_userspace:
-	GET_THREAD_INFO(%rcx)
-	movl TI_flags(%rcx),%ebx
-	andl $_TIF_WORK_MASK,%ebx
-	jz nmi_swapgs
-	movq %rsp,%rdi			/* &pt_regs */
-	call sync_regs
-	movq %rax,%rsp			/* switch stack for scheduling */
-	testl $_TIF_NEED_RESCHED,%ebx
-	jnz nmi_schedule
-	movl %ebx,%edx			/* arg3: thread flags */
-	ENABLE_INTERRUPTS(CLBR_NONE)
-	xorl %esi,%esi 			/* arg2: oldset */
-	movq %rsp,%rdi 			/* arg1: &pt_regs */
-	call do_notify_resume
-	DISABLE_INTERRUPTS(CLBR_NONE)
-	jmp nmi_userspace
-nmi_schedule:
-	ENABLE_INTERRUPTS(CLBR_ANY)
-	call schedule
-	DISABLE_INTERRUPTS(CLBR_ANY)
-	jmp nmi_userspace
-	CFI_ENDPROC
-#else
-	jmp paranoid_exit
 	CFI_ENDPROC
-#endif
 END(nmi)
 
+	/*
+	 * If an NMI hit an iret because of an exception or breakpoint,
+	 * it can lose its NMI context, and a nested NMI may come in.
+	 * In that case, the nested NMI will change the preempted NMI's
+	 * stack to jump to here when it does the final iret.
+	 */
+repeat_nmi:
+	INTR_FRAME
+	/* Update the stack variable to say we are still in NMI */
+	movq $1, 5*8(%rsp)
+
+	/* copy the saved stack back to copy stack */
+	.rept 5
+	pushq_cfi 4*8(%rsp)
+	.endr
+
+	jmp restart_nmi
+	CFI_ENDPROC
+end_repeat_nmi:
+
 ENTRY(ignore_sysret)
 	CFI_STARTPROC
 	mov $-ENOSYS,%eax

diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
@@ -417,6 +417,10 @@ ENTRY(phys_base)
 ENTRY(idt_table)
 	.skip IDT_ENTRIES * 16
 
+	.align L1_CACHE_BYTES
+ENTRY(nmi_idt_table)
+	.skip IDT_ENTRIES * 16
+
 	__PAGE_ALIGNED_BSS
 	.align PAGE_SIZE
 ENTRY(empty_zero_page)