[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: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S
index 9999d70..6c68bee 100644
--- a/arch/x86_64/kernel/entry.S
+++ b/arch/x86_64/kernel/entry.S
@@ -1089,3 +1089,36 @@
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
diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c
index dcb77b4..d6fa414 100644
--- a/arch/x86_64/kernel/process.c
+++ b/arch/x86_64/kernel/process.c
@@ -334,7 +334,7 @@
{
printk("CPU %d:", smp_processor_id());
__show_regs(regs);
- show_trace(®s->rsp);
+ show_trace(NULL, regs, (void *)(regs + 1));
}
/*
diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c
index 9f8f1ef..eb1534f 100644
--- a/arch/x86_64/kernel/traps.c
+++ b/arch/x86_64/kernel/traps.c
@@ -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 @@
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 @@
* 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 @@
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 @@
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 dump_stack(void)
{
unsigned long dummy;
- show_trace(&dummy);
+ show_trace(NULL, NULL, &dummy);
}
EXPORT_SYMBOL(dump_stack);
@@ -332,7 +374,7 @@
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)
diff --git a/arch/x86_64/kernel/vmlinux.lds.S b/arch/x86_64/kernel/vmlinux.lds.S
index 5968c24..1c6a5f3 100644
--- a/arch/x86_64/kernel/vmlinux.lds.S
+++ b/arch/x86_64/kernel/vmlinux.lds.S
@@ -45,6 +45,15 @@
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)