GETUNWIND(2)                                           Linux System Calls                                           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);

DESCRIPTION
       The  sys_getunwind function returns size of unwind table, which describes gate page (kernel code that is mapped into user
       space).

       The unwind data is copied to the buffer buf, which has size 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.  The system call returns the size of the unwind data in
       both cases.

       The first part of the unwind data contains an unwind table.  The rest contains  the  associated  unwind  info  in  random
       order.  The unwind table contains a table looking like:

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

       An  entry  with a START address of zero is the end of table.  For more information about the format you can see the IA-64
       Software Conventions and Runtime Architecture.


RETURN VALUE
       The sys_getunwind function returns size of unwind table.


ERRORS
       The sys_getunwind function fails with EFAULT if the unwind info can't be stored in the space specified by the  buf  argu-
       ment.


AVAILABILITY
       This system call is available only on the IA-64 architecture.


APPLICATION USAGE
       This  system  call  has  been deprecated. It's highly recommended to get at the kernel's unwind info by the gate DSO. The
       address of the ELF header for this DSO is passed to user level via AT_SYSINFO_EHDR.

       The system call is not available to application programs as a function; it can be called using the syscall(2) function.


SEE ALSO
       syscall(2),



Linux                                                    29 August 2006                                             GETUNWIND(2)