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150 lines
3.5 KiB
Groff
150 lines
3.5 KiB
Groff
'\" t
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.\" Manual page created with latex2man on Tue Mar 30 23:28:14 PST 2004
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.\" NOTE: This file is generated, DO NOT EDIT.
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.de Vb
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.ft CW
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.nf
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..
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.de Ve
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.ft R
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.fi
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..
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.TH "UNW\\_RESUME" "3" "30 March 2004" "Programming Library " "Programming Library "
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.SH NAME
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unw_resume
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\-\- resume execution in a particular stack frame
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.PP
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.SH SYNOPSIS
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.PP
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#include <libunwind.h>
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.br
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.PP
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int
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unw_resume(unw_cursor_t *cp);
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.br
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.PP
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.SH DESCRIPTION
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.PP
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The unw_resume()
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routine resumes execution at the stack frame
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identified by cp\&.
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The behavior of this routine differs
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slightly for local and remote unwinding.
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.PP
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For local unwinding, unw_resume()
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restores the machine state
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and then directly resumes execution in the target stack frame. Thus
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unw_resume()
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does not return in this case. Restoring the
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machine state normally involves restoring the ``preserved\&''
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(callee\-saved) registers. However, if execution in any of the stack
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frames younger (more deeply nested) than the one identified by
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cp
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was interrupted by a signal, then unw_resume()
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will
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restore all registers as well as the signal mask. Attempting to call
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unw_resume()
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on a cursor which identifies the stack frame of
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another thread results in undefined behavior (e.g., the program may
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crash).
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.PP
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For remote unwinding, unw_resume()
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installs the machine state
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identified by the cursor by calling the access_reg
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and
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access_fpreg
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accessor callbacks as needed. Once that is
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accomplished, the resume
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accessor callback is invoked. The
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unw_resume
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routine then returns normally (that is, unlikely
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for local unwinding, unw_resume
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will always return for remote
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unwinding).
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.PP
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Most platforms reserve some registers to pass arguments to exception
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handlers (e.g., IA\-64 uses r15\-r18
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for this
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purpose). These registers are normally treated like ``scratch\&''
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registers. However, if libunwind
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is used to set an exception
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argument register to a particular value (e.g., via
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unw_set_reg()),
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then unw_resume()
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will install this
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value as the contents of the register. In other words, the exception
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handling arguments are installed even in cases where normally only the
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``preserved\&'' registers are restored.
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.PP
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Note that unw_resume()
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does \fInot\fP
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invoke any unwind
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handlers (aka, ``personality routines\&''). If a program needs this, it
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will have to do so on its own by obtaining the unw_proc_info_t
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of each unwound frame and appropriately processing its unwind handler
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and language\-specific data area (lsda). These steps are generally
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dependent on the target\-platform and are regulated by the
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processor\-specific ABI (application\-binary interface).
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.PP
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.SH RETURN VALUE
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.PP
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For local unwinding, unw_resume()
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does not return on success.
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For remote unwinding, it returns 0 on success. On failure, the
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negative value of one of the errors below is returned.
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.PP
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.SH THREAD AND SIGNAL SAFETY
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.PP
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unw_resume()
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is thread\-safe. If cursor cp
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is in the
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local address\-space, this routine is also safe to use from a signal
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handler.
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.PP
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.SH ERRORS
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.PP
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.TP
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UNW_EUNSPEC
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An unspecified error occurred.
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.TP
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UNW_EBADREG
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A register needed by unw_resume()
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wasn\&'t
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accessible.
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.TP
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UNW_EINVALIDIP
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The instruction pointer identified by
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cp
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is not valid.
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.TP
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UNW_BADFRAME
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The stack frame identified by
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cp
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is not valid.
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.PP
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.SH SEE ALSO
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.PP
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libunwind(3),
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unw_set_reg(3),
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sigprocmask(2)
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.PP
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.SH AUTHOR
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.PP
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David Mosberger\-Tang
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.br
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Hewlett\-Packard Labs
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.br
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Palo\-Alto, CA 94304
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.br
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Email: \fBdavidm@hpl.hp.com\fP
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.br
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WWW: \fBhttp://www.hpl.hp.com/research/linux/libunwind/\fP\&.
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.\" NOTE: This file is generated, DO NOT EDIT.
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