STACK(9) BSD Kernel Developer's Manual STACK(9)NAME
stack — kernel thread stack tracing routines
In the kernel configuration file:
struct stack *
stack_destroy(struct stack *st);
stack_put(struct stack *st, vm_offset_t pc);
stack_copy(struct stack *src, struct stack dst);
stack_zero(struct stack *st);
stack_print(struct stack *st);
stack_print_ddb(struct stack *st);
stack_print_short(struct stack *st);
stack_print_short_ddb(struct stack *st);
stack_sbuf_print(struct sbuf sb*, struct stack *st);
stack_sbuf_print_ddb(struct sbuf sb*, struct stack *st);
stack_save(struct stack *st);
The stack KPI allows querying of kernel stack trace information and the
automated generation of kernel stack trace strings for the purposes of
debugging and tracing. To use the KPI, at least one of options DDB and
options STACK must be compiled into the kernel.
Each stack trace is described by a struct stack. Before a trace may be
created or otherwise manipulated, storage for the trace must be allocated
with stack_create(), which may sleep. Memory associated with a trace is
freed by calling stack_destroy().
A trace of the current kernel thread's call stack may be captured using
stack_print() and stack_print_short() may be used to print a stack trace
using the kernel printf(9), and may sleep as a result of acquiring sx(9)
locks in the kernel linker while looking up symbol names. In locking-
sensitive environments, the unsynchronized stack_print_ddb() and
stack_print_short_ddb() variants may be invoked. This function bypasses
kernel linker locking, making it usable in ddb(4), but not in a live sys‐
tem where linker data structures may change.
stack_sbuf_print() may be used to construct a human-readable string,
including conversion (where possible) from a simple kernel instruction
pointer to a named symbol and offset. The argument sb must be an ini‐
tialized struct sbuf as described in sbuf(9). This function may sleep if
an auto-extending struct sbuf is used, or due to kernel linker locking.
In locking-sensitive environments, such as ddb(4), the unsynchronized
stack_sbuf_print_ddb() variant may be invoked to avoid kernel linker
locking; it should be used with a fixed-length sbuf.
The utility functions stack_zero, stack_copy, and stack_put may be used
to manipulate stack data structures directly.
SEE ALSOddb(4), printf(9), sbuf(9), sx(9)AUTHORS
The stack(9) function suite was created by Antoine Brodin. stack(9) was
extended by Robert Watson for general-purpose use outside of ddb(4).
BSD June 24, 2009 BSD