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Commit b538ed27 authored by Jan Beulich's avatar Jan Beulich Committed by Linus Torvalds
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[PATCH] x86_64: reliable stack trace support (x86-64) 



These are the x86_64-specific pieces to enable reliable stack traces. The
only restriction with this is that it currently cannot unwind across the
interrupt->normal stack boundary, as that transition is lacking proper
annotation.

Signed-off-by: default avatarJan Beulich <jbeulich@novell.com>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 4552d5dc

arch/x86_64/kernel/entry.S

+33 −0
Original line number Diff line number Diff line
@@ -1089,3 +1089,36 @@ ENTRY(call_softirq) 
	ret

	CFI_ENDPROC

ENDPROC(call_softirq)



#ifdef CONFIG_STACK_UNWIND

ENTRY(arch_unwind_init_running)

	CFI_STARTPROC

	movq	%r15, R15(%rdi)

	movq	%r14, R14(%rdi)

	xchgq	%rsi, %rdx

	movq	%r13, R13(%rdi)

	movq	%r12, R12(%rdi)

	xorl	%eax, %eax

	movq	%rbp, RBP(%rdi)

	movq	%rbx, RBX(%rdi)

	movq	(%rsp), %rcx

	movq	%rax, R11(%rdi)

	movq	%rax, R10(%rdi)

	movq	%rax, R9(%rdi)

	movq	%rax, R8(%rdi)

	movq	%rax, RAX(%rdi)

	movq	%rax, RCX(%rdi)

	movq	%rax, RDX(%rdi)

	movq	%rax, RSI(%rdi)

	movq	%rax, RDI(%rdi)

	movq	%rax, ORIG_RAX(%rdi)

	movq	%rcx, RIP(%rdi)

	leaq	8(%rsp), %rcx

	movq	$__KERNEL_CS, CS(%rdi)

	movq	%rax, EFLAGS(%rdi)

	movq	%rcx, RSP(%rdi)

	movq	$__KERNEL_DS, SS(%rdi)

	jmpq	*%rdx

	CFI_ENDPROC

ENDPROC(arch_unwind_init_running)

#endif

arch/x86_64/kernel/process.c

+1 −1
Original line number Diff line number Diff line
@@ -334,7 +334,7 @@ void show_regs(struct pt_regs *regs) 
{

	printk("CPU %d:", smp_processor_id());

	__show_regs(regs);

	show_trace(&regs->rsp);

	show_trace(NULL, regs, (void *)(regs + 1));

}



/*

arch/x86_64/kernel/traps.c

+48 −6
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ 
#include <linux/nmi.h>

#include <linux/kprobes.h>

#include <linux/kexec.h>

#include <linux/unwind.h>



#include <asm/system.h>

#include <asm/uaccess.h>
@@ -39,7 +40,7 @@ 
#include <asm/i387.h>

#include <asm/kdebug.h>

#include <asm/processor.h>



#include <asm/unwind.h>

#include <asm/smp.h>

#include <asm/pgalloc.h>

#include <asm/pda.h>
@@ -189,6 +190,23 @@ static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack, 
	return NULL;

}



static void show_trace_unwind(struct unwind_frame_info *info, void *context)

{

	int i = 11;



	while (unwind(info) == 0 && UNW_PC(info)) {

		if (i > 50) {

			printk("\n       ");

			i = 7;

		} else

			i += printk(" ");

		i += printk_address(UNW_PC(info));

		if (arch_unw_user_mode(info))

			break;

	}

	printk("\n");

}



/*

 * x86-64 can have upto three kernel stacks: 

 * process stack
@@ -196,15 +214,34 @@ static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack, 
 * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack

 */



void show_trace(unsigned long *stack)

void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * stack)

{

	const unsigned cpu = safe_smp_processor_id();

	unsigned long *irqstack_end = (unsigned long *)cpu_pda(cpu)->irqstackptr;

	int i;

	unsigned used = 0;

	struct unwind_frame_info info;



	printk("\nCall Trace:");



	if (!tsk)

		tsk = current;



	if (regs) {

		if (unwind_init_frame_info(&info, tsk, regs) == 0) {

			show_trace_unwind(&info, NULL);

			return;

		}

	} else if (tsk == current) {

		if (unwind_init_running(&info, show_trace_unwind, NULL) == 0)

			return;

	} else {

		if (unwind_init_blocked(&info, tsk) == 0) {

			show_trace_unwind(&info, NULL);

			return;

		}

	}



#define HANDLE_STACK(cond) \

	do while (cond) { \

		unsigned long addr = *stack++; \
@@ -262,7 +299,7 @@ void show_trace(unsigned long *stack) 
	printk("\n");

}



void show_stack(struct task_struct *tsk, unsigned long * rsp)

static void _show_stack(struct task_struct *tsk, struct pt_regs *regs, unsigned long * rsp)

{

	unsigned long *stack;

	int i;
@@ -296,7 +333,12 @@ void show_stack(struct task_struct *tsk, unsigned long * rsp) 
		printk("%016lx ", *stack++);

		touch_nmi_watchdog();

	}

	show_trace((unsigned long *)rsp);

	show_trace(tsk, regs, rsp);

}



void show_stack(struct task_struct *tsk, unsigned long * rsp)

{

	_show_stack(tsk, NULL, rsp);

}



/*
@@ -305,7 +347,7 @@ void show_stack(struct task_struct *tsk, unsigned long * rsp) 
void dump_stack(void)

{

	unsigned long dummy;

	show_trace(&dummy);

	show_trace(NULL, NULL, &dummy);

}



EXPORT_SYMBOL(dump_stack);
@@ -332,7 +374,7 @@ void show_registers(struct pt_regs *regs) 
	if (in_kernel) {



		printk("Stack: ");

		show_stack(NULL, (unsigned long*)rsp);

		_show_stack(NULL, regs, (unsigned long*)rsp);



		printk("\nCode: ");

		if (regs->rip < PAGE_OFFSET)

arch/x86_64/kernel/vmlinux.lds.S

+9 −0
Original line number Diff line number Diff line
@@ -45,6 +45,15 @@ SECTIONS 


  RODATA



#ifdef CONFIG_STACK_UNWIND

  . = ALIGN(8);

  .eh_frame : AT(ADDR(.eh_frame) - LOAD_OFFSET) {

	__start_unwind = .;

  	*(.eh_frame)

	__end_unwind = .;

  }

#endif



				/* Data */

  .data : AT(ADDR(.data) - LOAD_OFFSET) {

	*(.data)

include/asm-x86_64/proto.h

+1 −1
Original line number Diff line number Diff line
@@ -75,7 +75,7 @@ extern void main_timer_handler(struct pt_regs *regs); 


extern unsigned long end_pfn_map; 



extern void show_trace(unsigned long * rsp);

extern void show_trace(struct task_struct *, struct pt_regs *, unsigned long * rsp);

extern void show_registers(struct pt_regs *regs);



extern void exception_table_check(void);