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Date: Wed, 13 Sep 2017 17:14:09 +0800
From: "Du, Changbin" <changbin.du@...el.com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: "Du, Changbin" <changbin.du@...el.com>, peterz@...radead.org,
mingo@...hat.com, alexander.shishkin@...ux.intel.com,
linux-kernel@...r.kernel.org
Subject: Re: Does perf-annotate work correctly?
Here is another example which may be easy to analyse. I beleve that something wrong
in parsing objdump output.
The 'test %esi,%esi' is not of 'if (unlikely(error))', but 'if (!idtv_info_valid)'.
perf annotate of function vmx_complete_interrupts():
vmx_complete_interrupts /lib/modules/4.13.0+/kernel/arch/x86/kvm/kvm-intel.ko
Percent│ mov 0x4590(%rdi),%esi ▒
│ vmx_cancel_injection(): ▒
│ vmcs_read32(VM_ENTRY_INTR_INFO_FIELD), ▒
│ VM_ENTRY_INSTRUCTION_LEN, ▒
│ VM_ENTRY_EXCEPTION_ERROR_CODE); ▒
│ ▒
│ vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, 0); ▒
│ } ▒
│ movb $0x0,0x32c8(%rdi) ▒
│ __vmx_complete_interrupts(): ▒
│ movb $0x0,0x1a7c(%rdi) ▒
│ movb $0x0,0x1a88(%rdi) ▒
│ __vmcs_writel(): ▒
│ u8 error; ▒
│ ▒
│ asm volatile (__ex(ASM_VMX_VMWRITE_RAX_RDX) "; setna %0" ▒
│ : "=q"(error) : "a"(value), "d"(field) : "cc"); ▒
│ if (unlikely(error)) ▒
│ vmwrite_error(field, value); ▒
0.02 │ test %esi,%esi ▒
│ ↓ js 25 ▒
99.98 │ ← retq ▒
│25: push %rbp ▒
│ mov $0x440a,%ecx ▒
│ mov $0x440c,%edx ▒
│ vmx_complete_interrupts(): ◆
│ break; ▒
│ } ▒
│ } ▒
│ ▒
│ static void vmx_complete_interrupts(struct vcpu_vmx *vmx) ▒
│ { ▒
│ mov %rsp,%rbp ▒
│ → callq __vmx_complete_interrupts.part.64 ▒
│ __vmx_complete_interrupts(&vmx->vcpu, vmx->idt_vectoring_info, ▒
│ pop %rbp ▒
│ ← retq ▒
GDB disassable:
(gdb) disassemble /s vmx_complete_interrupts
Dump of assembler code for function vmx_complete_interrupts:
arch/x86/kvm/vmx.c:
8917 {
0x0000000000007110 <+0>: callq 0x7115 <vmx_complete_interrupts+5>
8918 __vmx_complete_interrupts(&vmx->vcpu, vmx->idt_vectoring_info,
0x0000000000007115 <+5>: mov 0x4590(%rdi),%esi
8873 vcpu->arch.nmi_injected = false;
0x000000000000711b <+11>: movb $0x0,0x32c8(%rdi)
arch/x86/kvm/x86.h:
14 vcpu->arch.exception.pending = false;
0x0000000000007122 <+18>: movb $0x0,0x1a7c(%rdi)
15 }
16
17 static inline void kvm_queue_interrupt(struct kvm_vcpu *vcpu, u8 vector,
18 bool soft)
19 {
20 vcpu->arch.interrupt.pending = true;
21 vcpu->arch.interrupt.soft = soft;
22 vcpu->arch.interrupt.nr = vector;
23 }
24
25 static inline void kvm_clear_interrupt_queue(struct kvm_vcpu *vcpu)
26 {
27 vcpu->arch.interrupt.pending = false;
0x0000000000007129 <+25>: movb $0x0,0x1a88(%rdi)
arch/x86/kvm/vmx.c:
8877 if (!idtv_info_valid)
0x0000000000007130 <+32>: test %esi,%esi
0x0000000000007132 <+34>: js 0x7135 <vmx_complete_interrupts+37>
8919 VM_EXIT_INSTRUCTION_LEN,
8920 IDT_VECTORING_ERROR_CODE);
8921 }
0x0000000000007134 <+36>: retq
8917 {
0x0000000000007135 <+37>: push %rbp
0x0000000000007136 <+38>: mov $0x440a,%ecx
0x000000000000713b <+43>: mov $0x440c,%edx
---Type <return> to continue, or q <return> to quit---
0x0000000000007140 <+48>: mov %rsp,%rbp
0x0000000000007143 <+51>: callq 0x7000 <__vmx_complete_interrupts>
8919 VM_EXIT_INSTRUCTION_LEN,
8920 IDT_VECTORING_ERROR_CODE);
8921 }
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