tracing: Propagate is_signed to expression

During expression parsing, a new expression field is created which
should inherit the properties of the operands, such as size and
is_signed.

is_signed propagation was missing, causing spurious errors with signed
operands.  Add it in parse_expr() and parse_unary() to fix the problem.

Link: https://lkml.kernel.org/r/f4dac08742fd7a0920bf80a73c6c44042f5eaa40.1643319703.git.zanussi@kernel.org

Cc: stable@vger.kernel.org
Fixes: 100719d ("tracing: Add simple expression support to hist triggers")
Reported-by: Yordan Karadzhov <ykaradzhov@vmware.com>
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=215513
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Author: Tom Zanussi

kernel/trace/trace_events_hist.c

@@ -2503,6 +2503,8 @@ static struct hist_field *parse_unary(struct hist_trigger_data *hist_data,
 		(HIST_FIELD_FL_TIMESTAMP | HIST_FIELD_FL_TIMESTAMP_USECS);
 	expr->fn = hist_field_unary_minus;
 	expr->operands[0] = operand1;
+	expr->size = operand1->size;
+	expr->is_signed = operand1->is_signed;
 	expr->operator = FIELD_OP_UNARY_MINUS;
 	expr->name = expr_str(expr, 0);
 	expr->type = kstrdup_const(operand1->type, GFP_KERNEL);
@@ -2719,6 +2721,7 @@ static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
 
 		/* The operand sizes should be the same, so just pick one */
 		expr->size = operand1->size;
+		expr->is_signed = operand1->is_signed;
 
 		expr->operator = field_op;
 		expr->type = kstrdup_const(operand1->type, GFP_KERNEL);