Observed Issue
==============
When using the event notification capture feature to capture a context
field, e.g. '$ctx.cpu_id', the captured value is often observed in
reverse byte order.
Cause
=====
Within the bytecode interpreter, context_get_index() leaves the "rev_bo"
field uninitialized in the top of stack.
This only affects the event notification capture bytecode because the
BYTECODE_OP_GET_SYMBOL bytecode instruction (as of lttng-tools 2.13)
is only generated for capture bytecode in lttng-tools. Therefore, only
capture bytecode targeting contexts are affected by this issue. The
reason why lttng-tools uses the "legacy" bytecode instruction to get
context (BYTECODE_OP_GET_CONTEXT_REF) for the filter bytecode is to
preserve backward compatibility of filtering when interacting with
applications linked against LTTng-UST 2.12.
Solution
========
Initialize the rev_bo field based on the context field type
reserve_byte_order field.
Known drawbacks
===============
None.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I1483642b0b8f6bc28d5b68be170a04fb419fd9b3
ptr->u.u64 = v.u.s64; /* Cast. */
ptr->ptr = &ptr->u.u64;
}
+ ptr->rev_bo = lttng_kernel_get_type_integer(field->type)->reverse_byte_order;
break;
case lttng_kernel_type_enum:
{
ptr->u.u64 = v.u.s64; /* Cast. */
ptr->ptr = &ptr->u.u64;
}
+ ptr->rev_bo = integer_type->reverse_byte_order;
break;
}
case lttng_kernel_type_array: