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bpf,x86: introduce emit_store_stack_imm64() for trampoline

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Introduce the helper emit_store_stack_imm64(), which is used to store a
imm64 to the stack with the help of a register.

Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Link: https://lore.kernel.org/r/20260124062008.8657-7-dongml2@chinatelecom.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Menglong Dong 2026-01-24 14:20:01 +08:00 committed by Alexei Starovoitov
parent eeee4239db
commit 37c7ba1b39
1 changed files with 14 additions and 12 deletions
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26
arch/x86/net/bpf_jit_comp.c
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@ -1300,6 +1300,16 @@ 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_store_stack_imm64(u8 **pprog, int reg, int stack_off, u64 imm64)
{
/*
* mov reg, imm64
* mov QWORD PTR [rbp + stack_off], reg
*/
emit_mov_imm64(pprog, reg, imm64 >> 32, (u32) imm64);
emit_stx(pprog, BPF_DW, BPF_REG_FP, reg, stack_off);
}
static int emit_atomic_rmw(u8 **pprog, u32 atomic_op,
u32 dst_reg, u32 src_reg, s16 off, u8 bpf_size)
{
@ -3348,20 +3358,12 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
/* mov QWORD PTR [rbp - rbx_off], rbx */
emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_6, -rbx_off);
/* Store number of argument registers of the traced function:
* mov rax, nr_regs
* mov QWORD PTR [rbp - nregs_off], rax
*/
emit_mov_imm64(&prog, BPF_REG_0, 0, (u32) nr_regs);
emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -nregs_off);
/* Store number of argument registers of the traced function */
emit_store_stack_imm64(&prog, BPF_REG_0, -nregs_off, nr_regs);
if (flags & BPF_TRAMP_F_IP_ARG) {
/* Store IP address of the traced function:
* movabsq rax, func_addr
* mov QWORD PTR [rbp - ip_off], rax
*/
emit_mov_imm64(&prog, BPF_REG_0, (long) func_addr >> 32, (u32) (long) func_addr);
emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -ip_off);
/* Store IP address of the traced function */
emit_store_stack_imm64(&prog, BPF_REG_0, -ip_off, (long)func_addr);
}
save_args(m, &prog, regs_off, false, flags);