getunwind(2) - Linux manual page (original) (raw)

getunwind(2) System Calls Manual getunwind(2)

NAME top

   getunwind - copy the unwind data to caller's buffer

LIBRARY top

   Standard C library (_libc_, _-lc_)

SYNOPSIS top

   **#include <linux/unwind.h>**
   **#include <sys/syscall.h>** /* Definition of **SYS_*** constants */
   **#include <unistd.h>**

   **[[deprecated]] long syscall(SYS_getunwind, void** _buf_**[.**_bufsize_**],**
                               **size_t** _bufsize_**);**

DESCRIPTION top

   _Note: this system call is obsolete._

   The IA-64-specific **getunwind**() system call copies the kernel's
   call frame unwind data into the buffer pointed to by _buf_ and
   returns the size of the unwind data; this data describes the gate
   page (kernel code that is mapped into user space).

   The size of the buffer _buf_ is specified in _bufsize_.  The data is
   copied only if _bufsize_ is greater than or equal to the size of
   the unwind data and _buf_ is not NULL; otherwise, no data is copied,
   and the call succeeds, returning the size that would be needed to
   store the unwind data.

   The first part of the unwind data contains an unwind table.  The
   rest contains the associated unwind information, in no particular
   order.  The unwind table contains entries of the following form:

       u64 start;      (64-bit address of start of function)
       u64 end;        (64-bit address of end of function)
       u64 info;       (BUF-relative offset to unwind info)

   An entry whose _start_ value is zero indicates the end of the table.
   For more information about the format, see the _IA-64 Software_
   _Conventions and Runtime Architecture_ manual.

RETURN VALUE top

   On success, **getunwind**() returns the size of the unwind data.  On
   error, -1 is returned and _[errno](../man3/errno.3.html)_ is set to indicate the error.

ERRORS top

   **getunwind**() fails with the error **EFAULT** if the unwind info can't
   be stored in the space specified by _buf_.

STANDARDS top

   Linux on IA-64.

HISTORY top

   Linux 2.4.

   This system call has been deprecated.  The modern way to obtain
   the kernel's unwind data is via the [vdso(7)](../man7/vdso.7.html).

SEE ALSO top

   [getauxval(3)](../man3/getauxval.3.html)

COLOPHON top

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Linux man-pages 6.10 2024-07-23 getunwind(2)

Pages that refer to this page:syscalls(2)