getunwind(2) — Linux manual page

getunwind(2)               System Calls Manual              getunwind(2)

NAME

       getunwind - copy the unwind data to caller's buffer

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

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

       [[deprecated]] long syscall(SYS_getunwind, void buf[.buf_size],
                                   size_t buf_size);

DESCRIPTION

       Note: this system call is obsolete.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 buf_size.  The data is
       copied only if buf_size 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

       On success, getunwind() returns the size of the unwind data.  On
       error, -1 is returned and errno is set to indicate the error.

ERRORS

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

STANDARDS

       Linux on IA-64.

HISTORY

       Linux 2.4.

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

SEE ALSO

       getauxval(3)

COLOPHON

       This page is part of the man-pages (Linux kernel and C library
       user-space interface documentation) project.  Information about
       the project can be found at 
       ⟨https://www.kernel.org/doc/man-pages/⟩.  If you have a bug report
       for this manual page, see
       ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
       This page was obtained from the tarball man-pages-6.9.1.tar.gz
       fetched from
       ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
       2024-06-26.  If you discover any rendering problems in this HTML
       version of the page, or you believe there is a better or more up-
       to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not
       part of the original manual page), send a mail to
       man-pages@man7.org

Linux man-pages 6.9.1          2024-05-02                   getunwind(2)

Pages that refer to this page: syscalls(2)

---