GENWiki

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

NAME

     getunwind - copy the unwind data to caller's buffer

SYNOPSIS

     #include <syscall.h>
     #include <linux/unwind.h>

     long getunwind(void *buf, size_t buf_size);

     Note: There is no glibc wrapper for this system call; see NOTES.

DESCRIPTION

     Note: this function is obsolete.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.

VERSIONS

     This system call is available since Linux 2.4.

CONFORMING TO

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

NOTES

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

     Glibc does not provide a wrapper for this system call; in the  unlikely
     event that you want to call it, use syscall(2).