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Tue, 24 Feb 2026 20:36:20 +0000 Received: from smtpav02.fra02v.mail.ibm.com (smtpav02.fra02v.mail.ibm.com [10.20.54.101]) by smtprelay02.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 61OKaG3G33947998 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 24 Feb 2026 20:36:16 GMT Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 67EC820043; Tue, 24 Feb 2026 20:36:16 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id DD2C620040; Tue, 24 Feb 2026 20:36:14 +0000 (GMT) Received: from ltcrain4-lp15.ltc.tadn.ibm.com (unknown [9.5.7.39]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 24 Feb 2026 20:36:14 +0000 (GMT) From: adubey@linux.ibm.com To: linuxppc-dev@lists.ozlabs.org Cc: bpf@vger.kernel.org, hbathini@linux.ibm.com, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, maddy@linux.ibm.com, Abhishek Dubey Subject: [PATCH 2/4] selftest/bpf: Fixing powerpc JIT disassembly failure Date: Tue, 24 Feb 2026 20:36:25 -0500 Message-ID: <20260225013627.22098-3-adubey@linux.ibm.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260225013627.22098-1-adubey@linux.ibm.com> References: <20260225013627.22098-1-adubey@linux.ibm.com> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: TiAGzuz9J_GhPCyqqkrvlNFWaRqtnr8g X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMjI0MDE3MyBTYWx0ZWRfX3EWqtKwZNcnK gMw7BWe1i+1y1Ob6zUVkpn6sr04Yn9yJSLqzPWo9xP7enAO8UDa11ApHS5abIpNJvIlIku36CyI uflwHhTJ3m88/tglUB4DSp8NxzbvHYmCTHBd+h+zr8zQEXD02jEyjuDVXZ9AG9Jn62HQK/aPtkZ bUOGsNQlRuwjD+F5g0hCgFwRZg79XAA2HDz2Wldvb5Dq/1ARHkTLnzf2Ef2GTYUXgMgiEau8tgr A4Cx+5Ii7DG+ZHpz9y0s0Pv530oO3lXl/Qr2/VUmuT0z9/4t75Yn074v8wwkJK+ysFq68JgN36A eHsUvc76Ycw59JQ5OZwMnUy3EBBgtp7CgISFNhIB4Ml8I3DDYVJkDK2OebsZtOLGaRfbLZ0spgi 7zpwSpDY6S8WfhrRh0zXQ8PBcElXFaPpuHrL4VmHNHVSz+yJdHlUJhWUoQQDRr3ZgZyfqRyxiKS DjYW480JVOSNKYRwgxw== X-Authority-Analysis: v=2.4 cv=R7wO2NRX c=1 sm=1 tr=0 ts=699e0bc5 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=HzLeVaNsDn8A:10 a=VkNPw1HP01LnGYTKEx00:22 a=Mpw57Om8IfrbqaoTuvik:22 a=GgsMoib0sEa3-_RKJdDe:22 a=VnNF1IyMAAAA:8 a=kVjrMc9Is9WrAmO39HcA:9 X-Proofpoint-GUID: TiAGzuz9J_GhPCyqqkrvlNFWaRqtnr8g 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=2026-02-24_02,2026-02-23_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 clxscore=1015 impostorscore=0 phishscore=0 spamscore=0 suspectscore=0 malwarescore=0 bulkscore=0 adultscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2601150000 definitions=main-2602240173 From: Abhishek Dubey Ensure that the trampoline stubs JITed at the tail of the epilogue do not expose the dummy trampoline address stored in the last 8 bytes (for both 64-bit and 32-bit PowerPC) to the disassembly flow. Prevent the disassembler from ingesting this memory address, as it may occasionally decode into a seemingly valid but incorrect instruction. Fix this issue by truncating the last 8 bytes from JITed buffers before supplying them for disassembly. Signed-off-by: Abhishek Dubey --- tools/testing/selftests/bpf/jit_disasm_helpers.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/jit_disasm_helpers.c b/tools/testing/selftests/bpf/jit_disasm_helpers.c index febd6b12e372..cadddeaa6ed7 100644 --- a/tools/testing/selftests/bpf/jit_disasm_helpers.c +++ b/tools/testing/selftests/bpf/jit_disasm_helpers.c @@ -170,9 +170,11 @@ int get_jited_program_text(int fd, char *text, size_t text_sz) struct bpf_prog_info info = {}; __u32 info_len = sizeof(info); __u32 jited_funcs, len, pc; + __u32 trunc_len = 0; __u32 *func_lens = NULL; FILE *text_out = NULL; uint8_t *image = NULL; + char *triple = NULL; int i, err = 0; if (!llvm_initialized) { @@ -216,9 +218,18 @@ int get_jited_program_text(int fd, char *text, size_t text_sz) if (!ASSERT_OK(err, "bpf_prog_get_info_by_fd #2")) goto out; + /* + * last 8 bytes contains dummy_trampoline address in JIT + * output for 64-bit and 32-bit powerpc, which can't + * disassemble a to valid instruction. + */ + triple = LLVMGetDefaultTargetTriple(); + if (strstr(triple, "powerpc")) + trunc_len = 8; + for (pc = 0, i = 0; i < jited_funcs; ++i) { fprintf(text_out, "func #%d:\n", i); - disasm_one_func(text_out, image + pc, func_lens[i]); + disasm_one_func(text_out, image + pc, func_lens[i] - trunc_len); fprintf(text_out, "\n"); pc += func_lens[i]; } -- 2.52.0