getunwind(2)

1GETUNWIND(2)                  Linux System Calls                  GETUNWIND(2)
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NAME

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

10       #include <syscall.h>
11       #include <linux/unwind.h>
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13       long getunwind (void *buf, size_t buf_size);
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DESCRIPTION

16       The   sys_getunwind  function  returns  size  of  unwind  table,  which
17       describes gate page (kernel code that is mapped into user space).
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19       The unwind data is copied to the buffer buf, which has  size  buf_size.
20       The  data  is  copied  only if buf_size is greater than or equal to the
21       size of the unwind data and buf is not NULL.  The system  call  returns
22       the size of the unwind data in both cases.
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24       The  first  part of the unwind data contains an unwind table.  The rest
25       contains the associated unwind info in random order.  The unwind  table
26       contains a table looking like:
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28            u64 start;      (64-bit address of start of function)
29            u64 end;        (64-bit address of start of function)
30            u64 info;       (BUF-relative offset to unwind info)
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32       An  entry  with  a START address of zero is the end of table.  For more
33       information about the format you can see the IA-64 Software Conventions
34       and Runtime Architecture.
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RETURN VALUE

38       The sys_getunwind function returns size of unwind table.
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ERRORS

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

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

51       This system call has been deprecated. It's highly recommended to get at
52       the kernel's unwind info by the gate DSO. The address of the ELF header
53       for this DSO is passed to user level via AT_SYSINFO_EHDR.
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55       The system call is not available to application programs as a function;
56       it can be called using the syscall(2) function.
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