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Tue, 3 Mar 2026 13:02:11 +0000 (GMT) From: Hari Bathini To: linuxppc-dev Cc: bpf@vger.kernel.org, Madhavan Srinivasan , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Saket Kumar Bhaskar , Abhishek Dubey , Venkat Rao Bagalkote , stable@vger.kernel.org Subject: [PATCH v3 1/6] powerpc64/bpf: do not increment tailcall count when prog is NULL Date: Tue, 3 Mar 2026 18:32:03 +0530 Message-ID: <20260303130208.325249-2-hbathini@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260303130208.325249-1-hbathini@linux.ibm.com> References: <20260303130208.325249-1-hbathini@linux.ibm.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=Rp/I7SmK c=1 sm=1 tr=0 ts=69a6dbda cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=Yq5XynenixoA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=Soa85jDk8zDDq4EPMLkA:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzAzMDA5OSBTYWx0ZWRfX2KfiV8FFZDFB RWI7HsZ1pF9qNe1ntBX4xLY1V2bC7va2orKLiWbWQsSHH33FmSUvAt5WwbLaW+8Ox9E5P+JCwFy 4rYs4NPL0LH++MjMBCk0Tq3CmTS4QUb7SW3tSHJSSS4KDq6e/K85r3hC4Sy1FCwBZ1gSI35o3oQ xIEsKmA1sqBjJdu9+0R4Czru6cEGsJu849j0qyjaJpLVXuu/6CUH/WWwPJN5Xx7iDqLR2li7UjA bp4P6iltxpYv9peMEO5l4FFtt8xY095/avltdhKD/2jXDXmEs0btfCivUgCS5knZOZYGB9Tnjqw ZEkW2M5lb9+H9hAzQYPLSoAClCMQteiD6KgZEjeEaXI94XFeoKP6wwHgeDKHSPa9hyZVhYJ0hZY /eGWXaYg8zCyFEUxZpzFB5z9pE40/K+PNPFN4k7tKd9FkkhCYfcuB6+1R79kCJytSXT5aj8x7wu RN67JUwV/H9gTQSCChQ== X-Proofpoint-GUID: NCGe2Ymsuz-r8PXr2WvRNTLIfHiXvMpS X-Proofpoint-ORIG-GUID: NCGe2Ymsuz-r8PXr2WvRNTLIfHiXvMpS X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-03-02_05,2026-03-03_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 priorityscore=1501 spamscore=0 phishscore=0 adultscore=0 bulkscore=0 clxscore=1015 impostorscore=0 malwarescore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2602130000 definitions=main-2603030099 Do not increment tailcall count, if tailcall did not succeed due to missing BPF program. Fixes: ce0761419fae ("powerpc/bpf: Implement support for tail calls") Cc: stable@vger.kernel.org Tested-by: Venkat Rao Bagalkote Signed-off-by: Hari Bathini --- Changes in v3: - Added Tested-by tag from Venkat. arch/powerpc/net/bpf_jit_comp64.c | 39 +++++++++++++++++-------------- 1 file changed, 21 insertions(+), 18 deletions(-) diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index b1a3945ccc9f..44ce8a8783f9 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -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); -- 2.53.0