getunwind(2) — Linux manual page


GETUNWIND(2)            Linux Programmer's Manual           GETUNWIND(2)

NAME         top

       getunwind - copy the unwind data to caller's buffer

SYNOPSIS         top

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

       long syscall(SYS_getunwind, void *buf, size_t buf_size);

       Note: glibc provides no wrapper for getunwind(), necessitating
       the use of syscall(2).

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       Note: this system call is obsolete.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 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         top

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

VERSIONS         top

       This system call is available since Linux 2.4.

CONFORMING TO         top

       This system call is Linux-specific, and is available only on the
       IA-64 architecture.

NOTES         top

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

SEE ALSO         top


COLOPHON         top

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       and the latest version of this page, can be found at

Linux                          2021-03-22                   GETUNWIND(2)

Pages that refer to this page: syscalls(2)