On 2026/1/10 10:45, Alexei Starovoitov wrote:

On Wed, Jan 7, 2026 at 6:26 PM Menglong Dong [off-list ref] wrote:

quoted

Introduce the helper emit_st_r0_imm64(), which is used to store a imm64 to
the stack with the help of r0.

Signed-off-by: Menglong Dong <redacted>
---
 arch/x86/net/bpf_jit_comp.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index e3b1c4b1d550..a87304161d45 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c

@@ -1300,6 +1300,15 @@ static void emit_st_r12(u8 **pprog, u32 size, u32 dst_reg, int off, int imm)
        emit_st_index(pprog, size, dst_reg, X86_REG_R12, off, imm);
 }

+static void emit_st_r0_imm64(u8 **pprog, u64 value, int off)
+{
+       /* mov rax, value
+        * mov QWORD PTR [rbp - off], rax
+        */
+       emit_mov_imm64(pprog, BPF_REG_0, value >> 32, (u32) value);
+       emit_stx(pprog, BPF_DW, BPF_REG_FP, BPF_REG_0, -off);
+}

The name is cryptic.
How about emit_store_stack_imm64(pprog, stack_off, imm64) ?
or emit_mov_stack_imm64.

emit_store_stack_imm64() sounds fine. I'll use it in the next version.

Thanks!
Menglong Dong