Commit 37c7ba1b authored by Menglong Dong's avatar Menglong Dong Committed by Alexei Starovoitov
Browse files

bpf,x86: introduce emit_store_stack_imm64() for trampoline 



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: default avatarMenglong Dong <dongml2@chinatelecom.cn>
Link: https://lore.kernel.org/r/20260124062008.8657-7-dongml2@chinatelecom.cn


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent eeee4239

arch/x86/net/bpf_jit_comp.c

+14 −12
Original line number Diff line number Diff line
@@ -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);