samples: ftrace: Replace bti assembly with hint for older compiler

JIRA: https://issues.redhat.com/browse/RHEL-101598

commit e332938
Author: GONG, Ruiqi <gongruiqi1@huawei.com>
Date:   Sun Aug 20 19:15:09 2023 +0800

    samples: ftrace: Replace bti assembly with hint for older compiler

    When cross-building the arm64 kernel with allmodconfig using GCC 9.4,
    the following error occurs on multiple files under samples/ftrace/:

    /tmp/ccPC1ODs.s: Assembler messages:
    /tmp/ccPC1ODs.s:8: Error: selected processor does not support `bti c'

    Fix this issue by replacing `bti c` with `hint 34`, which is compatible
    for the older compiler.

    Link: https://lore.kernel.org/linux-trace-kernel/20230820111509.1470826-1-gongruiqi@huaweicloud.com

    Cc: Masami Hiramatsu <mhiramat@kernel.org>
    Cc: Mark Rutland <mark.rutland@arm.com>
    Cc: Florent Revest <revest@chromium.org>
    Fixes: 8c3526f ("arm64: ftrace: Add direct call trampoline samples support")
    Acked-by: Mark Rutland <mark.rutland@arm.com>
    Signed-off-by: GONG, Ruiqi <gongruiqi1@huawei.com>
    Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Signed-off-by: Jerome Marchand <jmarchan@redhat.com>

Author: jeromemarchand

samples/ftrace/ftrace-direct-modify.c

@@ -105,7 +105,7 @@ asm (
 "	.type		my_tramp1, @function\n"
 "	.globl		my_tramp1\n"
 "   my_tramp1:"
-"	bti	c\n"
+"	hint	34\n" // bti	c
 "	sub	sp, sp, #16\n"
 "	stp	x9, x30, [sp]\n"
 "	bl	my_direct_func1\n"
@@ -117,7 +117,7 @@ asm (
 "	.type		my_tramp2, @function\n"
 "	.globl		my_tramp2\n"
 "   my_tramp2:"
-"	bti	c\n"
+"	hint	34\n" // bti	c
 "	sub	sp, sp, #16\n"
 "	stp	x9, x30, [sp]\n"
 "	bl	my_direct_func2\n"

samples/ftrace/ftrace-direct-multi-modify.c

@@ -112,7 +112,7 @@ asm (
 "	.type		my_tramp1, @function\n"
 "	.globl		my_tramp1\n"
 "   my_tramp1:"
-"	bti	c\n"
+"	hint	34\n" // bti	c
 "	sub	sp, sp, #32\n"
 "	stp	x9, x30, [sp]\n"
 "	str	x0, [sp, #16]\n"
@@ -127,7 +127,7 @@ asm (
 "	.type		my_tramp2, @function\n"
 "	.globl		my_tramp2\n"
 "   my_tramp2:"
-"	bti	c\n"
+"	hint	34\n" // bti	c
 "	sub	sp, sp, #32\n"
 "	stp	x9, x30, [sp]\n"
 "	str	x0, [sp, #16]\n"

samples/ftrace/ftrace-direct-multi.c

@@ -75,7 +75,7 @@ asm (
 "	.type		my_tramp, @function\n"
 "	.globl		my_tramp\n"
 "   my_tramp:"
-"	bti	c\n"
+"	hint	34\n" // bti	c
 "	sub	sp, sp, #32\n"
 "	stp	x9, x30, [sp]\n"
 "	str	x0, [sp, #16]\n"

samples/ftrace/ftrace-direct-too.c

@@ -81,7 +81,7 @@ asm (
 "	.type		my_tramp, @function\n"
 "	.globl		my_tramp\n"
 "   my_tramp:"
-"	bti	c\n"
+"	hint	34\n" // bti	c
 "	sub	sp, sp, #48\n"
 "	stp	x9, x30, [sp]\n"
 "	stp	x0, x1, [sp, #16]\n"

samples/ftrace/ftrace-direct.c

@@ -72,7 +72,7 @@ asm (
 "	.type		my_tramp, @function\n"
 "	.globl		my_tramp\n"
 "   my_tramp:"
-"	bti	c\n"
+"	hint	34\n" // bti	c
 "	sub	sp, sp, #32\n"
 "	stp	x9, x30, [sp]\n"
 "	str	x0, [sp, #16]\n"