Commit 521bd39d authored by Hari Bathini's avatar Hari Bathini Committed by Madhavan Srinivasan
Browse files

powerpc64/bpf: do not increment tailcall count when prog is NULL 



Do not increment tailcall count, if tailcall did not succeed due to
missing BPF program.

Fixes: ce076141 ("powerpc/bpf: Implement support for tail calls")
Cc: stable@vger.kernel.org
Tested-by: default avatarVenkat Rao Bagalkote <venkat88@linux.ibm.com>
Signed-off-by: default avatarHari Bathini <hbathini@linux.ibm.com>
Signed-off-by: default avatarMadhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260303181031.390073-2-hbathini@linux.ibm.com
parent db54c287

arch/powerpc/net/bpf_jit_comp64.c

+21 −18
Original line number Diff line number Diff line
@@ -522,9 +522,30 @@ static int bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 o 


	/*

	 * tail_call_info++; <- Actual value of tcc here

	 * Writeback this updated value only if tailcall succeeds.

	 */

	EMIT(PPC_RAW_ADDI(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), 1));



	/* prog = array->ptrs[index]; */

	EMIT(PPC_RAW_MULI(bpf_to_ppc(TMP_REG_2), b2p_index, 8));

	EMIT(PPC_RAW_ADD(bpf_to_ppc(TMP_REG_2), bpf_to_ppc(TMP_REG_2), b2p_bpf_array));

	EMIT(PPC_RAW_LD(bpf_to_ppc(TMP_REG_2), bpf_to_ppc(TMP_REG_2),

			offsetof(struct bpf_array, ptrs)));



	/*

	 * if (prog == NULL)

	 *   goto out;

	 */

	EMIT(PPC_RAW_CMPLDI(bpf_to_ppc(TMP_REG_2), 0));

	PPC_BCC_SHORT(COND_EQ, out);



	/* goto *(prog->bpf_func + prologue_size); */

	EMIT(PPC_RAW_LD(bpf_to_ppc(TMP_REG_2), bpf_to_ppc(TMP_REG_2),

			offsetof(struct bpf_prog, bpf_func)));

	EMIT(PPC_RAW_ADDI(bpf_to_ppc(TMP_REG_2), bpf_to_ppc(TMP_REG_2),

			  FUNCTION_DESCR_SIZE + bpf_tailcall_prologue_size));

	EMIT(PPC_RAW_MTCTR(bpf_to_ppc(TMP_REG_2)));



	/*

	 * Before writing updated tail_call_info, distinguish if current frame

	 * is storing a reference to tail_call_info or actual tcc value in
@@ -539,24 +560,6 @@ static int bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 o 
	/* Writeback updated value to tail_call_info */

	EMIT(PPC_RAW_STD(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_2), 0));



	/* prog = array->ptrs[index]; */

	EMIT(PPC_RAW_MULI(bpf_to_ppc(TMP_REG_1), b2p_index, 8));

	EMIT(PPC_RAW_ADD(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), b2p_bpf_array));

	EMIT(PPC_RAW_LD(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), offsetof(struct bpf_array, ptrs)));



	/*

	 * if (prog == NULL)

	 *   goto out;

	 */

	EMIT(PPC_RAW_CMPLDI(bpf_to_ppc(TMP_REG_1), 0));

	PPC_BCC_SHORT(COND_EQ, out);



	/* goto *(prog->bpf_func + prologue_size); */

	EMIT(PPC_RAW_LD(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), offsetof(struct bpf_prog, bpf_func)));

	EMIT(PPC_RAW_ADDI(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1),

			FUNCTION_DESCR_SIZE + bpf_tailcall_prologue_size));

	EMIT(PPC_RAW_MTCTR(bpf_to_ppc(TMP_REG_1)));



	/* tear down stack, restore NVRs, ... */

	bpf_jit_emit_common_epilogue(image, ctx);