1GETUNWIND(2)               Linux Programmer's Manual              GETUNWIND(2)
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NAME

6       getunwind - copy the unwind data to caller's buffer
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SYNOPSIS

9       #include <linux/unwind.h>
10       #include <sys/syscall.h>      /* Definition of SYS_* constants */
11       #include <unistd.h>
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13       long syscall(SYS_getunwind, void *buf, size_t buf_size);
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15       Note:  glibc provides no wrapper for getunwind(), necessitating the use
16       of syscall(2).
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DESCRIPTION

19       Note: this system call is obsolete.
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21       The IA-64-specific getunwind() system call  copies  the  kernel's  call
22       frame  unwind  data  into  the buffer pointed to by buf and returns the
23       size of the unwind data; this data describes the gate page (kernel code
24       that is mapped into user space).
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26       The  size  of  the  buffer  buf  is specified in buf_size.  The data is
27       copied only if buf_size is greater than or equal to the size of the un‐
28       wind  data  and  buf is not NULL; otherwise, no data is copied, and the
29       call succeeds, returning the size that would be needed to store the un‐
30       wind data.
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32       The  first  part of the unwind data contains an unwind table.  The rest
33       contains the associated unwind information,  in  no  particular  order.
34       The unwind table contains entries of the following form:
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36           u64 start;      (64-bit address of start of function)
37           u64 end;        (64-bit address of end of function)
38           u64 info;       (BUF-relative offset to unwind info)
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40       An entry whose start value is zero indicates the end of the table.  For
41       more information about the format, see the IA-64  Software  Conventions
42       and Runtime Architecture manual.
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RETURN VALUE

45       On success, getunwind() returns the size of the unwind data.  On error,
46       -1 is returned and errno is set to indicate the error.
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ERRORS

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

53       This system call is available since Linux 2.4.
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CONFORMING TO

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

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

64       getauxval(3)
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COLOPHON

67       This  page  is  part of release 5.12 of the Linux man-pages project.  A
68       description of the project, information about reporting bugs,  and  the
69       latest     version     of     this    page,    can    be    found    at
70       https://www.kernel.org/doc/man-pages/.
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74Linux                             2021-03-22                      GETUNWIND(2)
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