getunwind(2)                                            System Calls Manual                                            getunwind(2)

       getunwind - copy the unwind data to caller's buffer

       Standard C library (libc, -lc)

       #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);

       Note: this system call is obsolete.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 par‐
       ticular 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.

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

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

       This system call is available since Linux 2.4.

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

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


Linux man-pages 6.03                                         2022-11-10                                                getunwind(2)