getunwind(2) System Calls Manual getunwind(2)
NAME
getunwind - copy the unwind data to caller's buffer
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#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);
DESCRIPTION
Note: this system call is obsolete.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 un-
wind 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 un-
wind data.
The first part of the unwind data contains an unwind table. The rest
contains the associated unwind information, in no particular 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.
RETURN VALUE
On success, getunwind() returns the size of the unwind data. On error,
-1 is returned and errno is set to indicate the error.
ERRORS
getunwind() fails with the error EFAULT if the unwind info can't be
stored in the space specified by buf.
STANDARDS
Linux on IA-64.
HISTORY
Linux 2.4.
This system call has been deprecated. The modern way to obtain the
kernel's unwind data is via the vdso(7).
SEE ALSO
getauxval(3)
Linux man-pages 6.7 2023-10-31 getunwind(2)
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