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Subject[PATCH v4 2/4] Register exception handler to trace IDT
This patch registers exception handlers for tracing to a trace IDT.

To implemented it in set_intr_gate(), this patch does followings.
- Register the exception handlers to
the trace IDT by prepending "trace_" to the handler's names.
- Also, newly introduce trace_page_fault() to add tracepoints
in a subsequent patch.

Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
---
arch/x86/include/asm/desc.h | 28 +++++++++++++++++++++++-----
arch/x86/include/asm/hw_irq.h | 3 +++
arch/x86/include/asm/segment.h | 3 +++
arch/x86/include/asm/traps.h | 20 ++++++++++++++++++++
arch/x86/kernel/entry_32.S | 10 ++++++++++
arch/x86/kernel/entry_64.S | 13 ++++++++++++-
arch/x86/kernel/head64.c | 2 +-
arch/x86/kernel/kvm.c | 2 +-
arch/x86/kernel/traps.c | 28 ++++++++++++++--------------
arch/x86/mm/fault.c | 10 ++++++++++
10 files changed, 97 insertions(+), 22 deletions(-)

diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
index d939567..3d73437 100644
--- a/arch/x86/include/asm/desc.h
+++ b/arch/x86/include/asm/desc.h
@@ -327,10 +327,25 @@ static inline void write_trace_idt_entry(int entry, const gate_desc *gate)
{
write_idt_entry(trace_idt_table, entry, gate);
}
+
+static inline void _trace_set_gate(int gate, unsigned type, void *addr,
+ unsigned dpl, unsigned ist, unsigned seg)
+{
+ gate_desc s;
+
+ pack_gate(&s, type, (unsigned long)addr, dpl, ist, seg);
+ /*
+ * does not need to be atomic because it is only done once at
+ * setup time
+ */
+ write_trace_idt_entry(gate, &s);
+}
#else
static inline void write_trace_idt_entry(int entry, const gate_desc *gate)
{
}
+
+#define _trace_set_gate(gate, type, addr, dpl, ist, seg)
#endif

static inline void _set_gate(int gate, unsigned type, void *addr,
@@ -353,11 +368,14 @@ static inline void _set_gate(int gate, unsigned type, void *addr,
* Pentium F0 0F bugfix can have resulted in the mapped
* IDT being write-protected.
*/
-static inline void set_intr_gate(unsigned int n, void *addr)
-{
- BUG_ON((unsigned)n > 0xFF);
- _set_gate(n, GATE_INTERRUPT, addr, 0, 0, __KERNEL_CS);
-}
+#define set_intr_gate(n, addr) \
+ do { \
+ BUG_ON((unsigned)n > 0xFF); \
+ _set_gate(n, GATE_INTERRUPT, (void *)addr, 0, 0, \
+ __KERNEL_CS); \
+ _trace_set_gate(n, GATE_INTERRUPT, (void *)trace_##addr,\
+ 0, 0, __KERNEL_CS); \
+ } while (0)

extern int first_system_vector;
/* used_vectors is BITMAP for irq is not managed by percpu vector_irq */
diff --git a/arch/x86/include/asm/hw_irq.h b/arch/x86/include/asm/hw_irq.h
index 92b3bae..cba45d9 100644
--- a/arch/x86/include/asm/hw_irq.h
+++ b/arch/x86/include/asm/hw_irq.h
@@ -187,6 +187,9 @@ extern __visible void smp_invalidate_interrupt(struct pt_regs *);
#endif

extern void (*__initconst interrupt[NR_VECTORS-FIRST_EXTERNAL_VECTOR])(void);
+#ifdef CONFIG_TRACING
+#define trace_interrupt interrupt
+#endif

typedef int vector_irq_t[NR_VECTORS];
DECLARE_PER_CPU(vector_irq_t, vector_irq);
diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h
index c48a950..6f1c3a8 100644
--- a/arch/x86/include/asm/segment.h
+++ b/arch/x86/include/asm/segment.h
@@ -214,6 +214,9 @@
#ifdef __KERNEL__
#ifndef __ASSEMBLY__
extern const char early_idt_handlers[NUM_EXCEPTION_VECTORS][2+2+5];
+#ifdef CONFIG_TRACING
+#define trace_early_idt_handlers early_idt_handlers
+#endif

/*
* Load a segment. Fall back on loading the zero
diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h
index 7036cb6..58d66fe 100644
--- a/arch/x86/include/asm/traps.h
+++ b/arch/x86/include/asm/traps.h
@@ -37,6 +37,23 @@ asmlinkage void machine_check(void);
#endif /* CONFIG_X86_MCE */
asmlinkage void simd_coprocessor_error(void);

+#ifdef CONFIG_TRACING
+asmlinkage void trace_page_fault(void);
+#define trace_divide_error divide_error
+#define trace_bounds bounds
+#define trace_invalid_op invalid_op
+#define trace_device_not_available device_not_available
+#define trace_coprocessor_segment_overrun coprocessor_segment_overrun
+#define trace_invalid_TSS invalid_TSS
+#define trace_segment_not_present segment_not_present
+#define trace_general_protection general_protection
+#define trace_spurious_interrupt_bug spurious_interrupt_bug
+#define trace_coprocessor_error coprocessor_error
+#define trace_alignment_check alignment_check
+#define trace_simd_coprocessor_error simd_coprocessor_error
+#define trace_async_page_fault async_page_fault
+#endif
+
dotraplinkage void do_divide_error(struct pt_regs *, long);
dotraplinkage void do_debug(struct pt_regs *, long);
dotraplinkage void do_nmi(struct pt_regs *, long);
@@ -55,6 +72,9 @@ asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *);
#endif
dotraplinkage void do_general_protection(struct pt_regs *, long);
dotraplinkage void do_page_fault(struct pt_regs *, unsigned long);
+#ifdef CONFIG_TRACING
+dotraplinkage void trace_do_page_fault(struct pt_regs *, unsigned long);
+#endif
dotraplinkage void do_spurious_interrupt_bug(struct pt_regs *, long);
dotraplinkage void do_coprocessor_error(struct pt_regs *, long);
dotraplinkage void do_alignment_check(struct pt_regs *, long);
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index f0dcb0c..0661abe 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1247,6 +1247,16 @@ return_to_handler:
*/
.pushsection .kprobes.text, "ax"

+#ifdef CONFIG_TRACING
+ENTRY(trace_page_fault)
+ RING0_EC_FRAME
+ ASM_CLAC
+ pushl_cfi $trace_do_page_fault
+ jmp error_code
+ CFI_ENDPROC
+END(trace_page_fault)
+#endif
+
ENTRY(page_fault)
RING0_EC_FRAME
ASM_CLAC
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index b077f4c..8b7b169 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -1280,6 +1280,17 @@ ENTRY(\sym)
END(\sym)
.endm

+#ifdef CONFIG_TRACING
+.macro trace_errorentry sym do_sym
+errorentry trace(\sym) trace(\do_sym)
+errorentry \sym \do_sym
+.endm
+#else
+.macro trace_errorentry sym do_sym
+errorentry \sym \do_sym
+.endm
+#endif
+
/* error code is on the stack already */
.macro paranoiderrorentry sym do_sym
ENTRY(\sym)
@@ -1482,7 +1493,7 @@ zeroentry xen_int3 do_int3
errorentry xen_stack_segment do_stack_segment
#endif
errorentry general_protection do_general_protection
-errorentry page_fault do_page_fault
+trace_errorentry page_fault do_page_fault
#ifdef CONFIG_KVM_GUEST
errorentry async_page_fault do_async_page_fault
#endif
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 1be8e43..85126cc 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -162,7 +162,7 @@ asmlinkage void __init x86_64_start_kernel(char * real_mode_data)
clear_bss();

for (i = 0; i < NUM_EXCEPTION_VECTORS; i++)
- set_intr_gate(i, &early_idt_handlers[i]);
+ set_intr_gate(i, early_idt_handlers[i]);
load_idt((const struct desc_ptr *)&idt_descr);

copy_bootdata(__va(real_mode_data));
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index a0e2a8a..028d7a4 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -464,7 +464,7 @@ static struct notifier_block kvm_cpu_notifier = {

static void __init kvm_apf_trap_init(void)
{
- set_intr_gate(14, &async_page_fault);
+ set_intr_gate(14, async_page_fault);
}

void __init kvm_guest_init(void)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 8c8093b..1c9d0ad 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -713,7 +713,7 @@ void __init early_trap_init(void)
/* int3 can be called from all */
set_system_intr_gate_ist(X86_TRAP_BP, &int3, DEBUG_STACK);
#ifdef CONFIG_X86_32
- set_intr_gate(X86_TRAP_PF, &page_fault);
+ set_intr_gate(X86_TRAP_PF, page_fault);
#endif
load_idt(&idt_descr);
}
@@ -721,7 +721,7 @@ void __init early_trap_init(void)
void __init early_trap_pf_init(void)
{
#ifdef CONFIG_X86_64
- set_intr_gate(X86_TRAP_PF, &page_fault);
+ set_intr_gate(X86_TRAP_PF, page_fault);
#endif
}

@@ -737,30 +737,30 @@ void __init trap_init(void)
early_iounmap(p, 4);
#endif

- set_intr_gate(X86_TRAP_DE, &divide_error);
+ set_intr_gate(X86_TRAP_DE, divide_error);
set_intr_gate_ist(X86_TRAP_NMI, &nmi, NMI_STACK);
/* int4 can be called from all */
set_system_intr_gate(X86_TRAP_OF, &overflow);
- set_intr_gate(X86_TRAP_BR, &bounds);
- set_intr_gate(X86_TRAP_UD, &invalid_op);
- set_intr_gate(X86_TRAP_NM, &device_not_available);
+ set_intr_gate(X86_TRAP_BR, bounds);
+ set_intr_gate(X86_TRAP_UD, invalid_op);
+ set_intr_gate(X86_TRAP_NM, device_not_available);
#ifdef CONFIG_X86_32
set_task_gate(X86_TRAP_DF, GDT_ENTRY_DOUBLEFAULT_TSS);
#else
set_intr_gate_ist(X86_TRAP_DF, &double_fault, DOUBLEFAULT_STACK);
#endif
- set_intr_gate(X86_TRAP_OLD_MF, &coprocessor_segment_overrun);
- set_intr_gate(X86_TRAP_TS, &invalid_TSS);
- set_intr_gate(X86_TRAP_NP, &segment_not_present);
+ set_intr_gate(X86_TRAP_OLD_MF, coprocessor_segment_overrun);
+ set_intr_gate(X86_TRAP_TS, invalid_TSS);
+ set_intr_gate(X86_TRAP_NP, segment_not_present);
set_intr_gate_ist(X86_TRAP_SS, &stack_segment, STACKFAULT_STACK);
- set_intr_gate(X86_TRAP_GP, &general_protection);
- set_intr_gate(X86_TRAP_SPURIOUS, &spurious_interrupt_bug);
- set_intr_gate(X86_TRAP_MF, &coprocessor_error);
- set_intr_gate(X86_TRAP_AC, &alignment_check);
+ set_intr_gate(X86_TRAP_GP, general_protection);
+ set_intr_gate(X86_TRAP_SPURIOUS, spurious_interrupt_bug);
+ set_intr_gate(X86_TRAP_MF, coprocessor_error);
+ set_intr_gate(X86_TRAP_AC, alignment_check);
#ifdef CONFIG_X86_MCE
set_intr_gate_ist(X86_TRAP_MC, &machine_check, MCE_STACK);
#endif
- set_intr_gate(X86_TRAP_XF, &simd_coprocessor_error);
+ set_intr_gate(X86_TRAP_XF, simd_coprocessor_error);

/* Reserve all the builtin and the syscall vector: */
for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 3aaeffc..fd3e281 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1231,3 +1231,13 @@ do_page_fault(struct pt_regs *regs, unsigned long error_code)
__do_page_fault(regs, error_code);
exception_exit(prev_state);
}
+
+dotraplinkage void __kprobes
+trace_do_page_fault(struct pt_regs *regs, unsigned long error_code)
+{
+ enum ctx_state prev_state;
+
+ prev_state = exception_enter();
+ __do_page_fault(regs, error_code);
+ exception_exit(prev_state);
+}
--
1.8.3.1



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