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GETUNWIND(2)                  Linux System Calls                  GETUNWIND(2)

       getunwind - copy the unwind data to caller's buffer

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

       long getunwind (void *buf, size_t buf_size);

       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.

       The sys_getunwind function returns size of unwind table.

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

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

       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)


Linux                           29 August 2006                    GETUNWIND(2)