mirror of https://github.com/mkerrisk/man-pages
92 lines
3.0 KiB
Groff
92 lines
3.0 KiB
Groff
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.\" Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
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.\" Written by Marcela Maslanova <mmaslano@redhat.com>
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\"
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.TH GETUNWIND 2 "29 August 2006" Linux "Linux System Calls"
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.SH NAME
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getunwind \- copy the unwind data to caller's buffer
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.SH SYNOPSIS
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.nf
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.B #include <syscall.h>
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.B #include <linux/unwind.h>
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.sp
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.BI "long getunwind (void " *buf ", size_t " buf_size );
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.fi
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.SH DESCRIPTION
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The
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.B sys_getunwind
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function returns size of unwind table, which describes gate page (kernel code that
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is mapped into user space).
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The unwind data is copied to the buffer \fIbuf\fR, which has size \fIbuf_size\fR.
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The data is copied
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only if \fIbuf_size\fR is greater than or equal to the size of the
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unwind data and \fIbuf\fR is not NULL.
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The system call returns the size of the unwind data in both cases.
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The first part of the unwind data contains an unwind table.
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The rest contains the associated unwind info in random order.
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The unwind table contains a table looking like:
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.nf
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u64 start; (64-bit address of start of function)
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u64 end; (64-bit address of start of function)
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u64 info; (BUF-relative offset to unwind info)
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.fi
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An entry with a START address of zero is the end of table.
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For more information about the format you can see the IA-64
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Software Conventions and Runtime Architecture.
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.SH "RETURN VALUE"
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The
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.B sys_getunwind
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function returns size of unwind table.
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.SH ERRORS
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The
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.B sys_getunwind
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function fails with
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.B EFAULT
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if the unwind info can't be stored in the space specified by
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the
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.I buf
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argument.
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.SH AVAILABILITY
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This system call is available only on the IA-64 architecture.
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.SH APPLICATION USAGE
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This system call has been deprecated. It's highly recommended to get at the kernel's
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unwind info by the gate DSO. The address of the ELF header for this DSO
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is passed to user level via AT_SYSINFO_EHDR.
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The system call is not available to application programs as a function;
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it can be called using the
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.BR syscall (2)
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function.
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.SH "SEE ALSO"
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.BR syscall(2),
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