[PATCH bpf-next v1] bpf, x86: Fix objtool warning for timed may_goto

[Kumar Kartikeya Dwivedi <memxor@gmail.com>]

Kernel test robot reported "call without frame pointer save/setup"
warning in objtool. This will make stack traces unreliable on
CONFIG_UNWINDER_FRAME_POINTER=y, however it works on
CONFIG_UNWINDER_ORC=y. Fix this by creating a stack frame for the
function.

Fixes: 2cb0a5215274 ("bpf, x86: Add x86 JIT support for timed may_goto")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202503071350.QOhsHVaW-lkp@intel.com/
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
 arch/x86/net/bpf_timed_may_goto.S | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/arch/x86/net/bpf_timed_may_goto.S b/arch/x86/net/bpf_timed_may_goto.S
index 20de4a14dc4c..54c690cae190 100644
--- a/arch/x86/net/bpf_timed_may_goto.S
+++ b/arch/x86/net/bpf_timed_may_goto.S
@@ -11,6 +11,16 @@
 SYM_FUNC_START(arch_bpf_timed_may_goto)
 	ANNOTATE_NOENDBR

+	/*
+	 * r10 passes us stack depth, load the pointer to count and timestamp
+	 * into r10 by adding it to BPF frame pointer.
+	 */
+	leaq (%rbp, %r10, 1), %r10
+
+	/* Setup frame. */
+	pushq %rbp
+	movq %rsp, %rbp
+
 	/* Save r0-r5. */
 	pushq %rax
 	pushq %rdi
@@ -20,10 +30,10 @@ SYM_FUNC_START(arch_bpf_timed_may_goto)
 	pushq %r8

 	/*
-	 * r10 passes us stack depth, load the pointer to count and timestamp as
-	 * first argument to the call below.
+	 * r10 has the pointer to count and timestamp, pass it as first
+	 * argument.
 	 */
-	leaq (%rbp, %r10, 1), %rdi
+	movq %r10, %rdi

 	/* Emit call depth accounting for call below. */
 	CALL_DEPTH_ACCOUNT
@@ -40,5 +50,6 @@ SYM_FUNC_START(arch_bpf_timed_may_goto)
 	popq %rdi
 	popq %rax

+	leave
 	RET
 SYM_FUNC_END(arch_bpf_timed_may_goto)
--
2.47.1