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Mon, 31 Aug 2026 07:16:32 +0000 (GMT) Received: from li-1cb9f04c-2ae1-11b2-a85c-a8a0a83790a8.ibm.com.com (unknown [9.67.146.121]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTP; Mon, 31 Aug 2026 07:16:32 +0000 (GMT) From: Saket Kumar Bhaskar To: bpf@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Cc: hbathini@linux.ibm.com, maddy@linux.ibm.com, ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, shuah@kernel.org, linux-kselftest@vger.kernel.org, stable@vger.kernel.org, venkat88@linux.ibm.com, yeswanth@linux.ibm.com, skb99@linux.ibm.com Subject: [PATCH v13 4/8] powerpc/bpf: fix alignment of long branch trampoline address Date: Mon, 31 Aug 2026 12:46:01 +0530 Message-ID: <0700c866205c8fa2f861e4b8d64fdf7469cba021.1788154635.git.skb99@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kselftest@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=bc1bluPB c=1 sm=1 tr=0 ts=6a952a5b cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=VwQbUJbxAAAA:8 a=Nr3H1HfpCltNh7mjoGcA:9 X-Proofpoint-Spam-Info: AW1haW4tMjYwODMxMDA1OSBTYWx0ZWRfX7jxckV4HhazB MAaCyQj3EfxOPgQGkKrklx4FTYGXAVOusG/4TWSdChWO0VzeR/uoLR6Au+AEzw9/m8j2Cab1/c+ WhZBUR27Y7NKLJkJigR+3VNG9giJgQM= X-Proofpoint-ORIG-GUID: rSFIU79rFB8UodCy58HPhc7cGgRFUcBs X-Proofpoint-GUID: rSFIU79rFB8UodCy58HPhc7cGgRFUcBs X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODMxMDA1OSBTYWx0ZWRfX1hdczVfHR8Li 3Ls9GWxlnbTgbErvU57naZlt9+gnpDWcc8FX8vOeSZyAysxia+sgsotrh0/Fj/eqEH6xa3gQVPL RLMIrTSX3YpPm/4Q25WOOqRF2opJcVN3ZBlH2g0Pbu7dFUiCDDZytoehINDpQLTs681uPBzAybv fgHvKhxkCSUXFZOcvwV6fTXao4nhrlI99zftwerUxP+dJcy6amHQWDw/EHskDLeqlOlci4DQC4Z 11SD4YmAiRaFxOLpEWrvxVAz+tgRsWXSHNgD3XmiMPWYm2aXv9KLh+ZfpbtpWo/tvD0TPjt9utC ZwfdzXQhXDTgzVN5PBi3ogOWoHYg/HK3Fs33/iqQXsR+cLxCtZN5RsN1UlqF9w1kl/W14YEbQNi J06p5lg9HazBh3JA6oLbqOGO0HCcq0lV00FcR/X9MfrBI8fbVm6uEOvMiSr46Ksg/lg6dCAFGt8 lhiaB7y3CLruwCbW1Jw== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-31_02,2026-08-27_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 suspectscore=0 adultscore=0 malwarescore=0 spamscore=0 lowpriorityscore=0 phishscore=0 clxscore=1015 priorityscore=1501 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608310059 From: Abhishek Dubey Ensure the dummy trampoline address field present between the OOL stub and the long branch stub is 4/8-byte aligned, for memory compatibility when content loaded to a register. Reported-by: Hari Bathini Fixes: d243b62b7bd3 ("powerpc64/bpf: Add support for bpf trampolines") Cc: stable@vger.kernel.org Signed-off-by: Abhishek Dubey Signed-off-by: Saket Kumar Bhaskar Tested-by: Yeswanth Krishna Tellakula --- arch/powerpc/net/bpf_jit.h | 7 +++--- arch/powerpc/net/bpf_jit_comp.c | 38 ++++++++++++++++++++++++++----- arch/powerpc/net/bpf_jit_comp32.c | 7 +++--- arch/powerpc/net/bpf_jit_comp64.c | 7 +++--- 4 files changed, 44 insertions(+), 15 deletions(-) diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h index 6d58df361648..4da8bde92e1e 100644 --- a/arch/powerpc/net/bpf_jit.h +++ b/arch/powerpc/net/bpf_jit.h @@ -227,10 +227,11 @@ int bpf_jit_emit_func_call_rel(u32 *image, u32 *fimage, struct codegen_context * int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct codegen_context *ctx, u32 *addrs, int pass, bool extra_pass); void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx); -void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx); -void bpf_jit_build_fentry_stubs(u32 *image, struct codegen_context *ctx); +void bpf_jit_build_epilogue(u32 *image, u32 *fimage, struct codegen_context *ctx); +void bpf_jit_build_fentry_stubs(u32 *image, u32 *fimage, struct codegen_context *ctx); void bpf_jit_realloc_regs(struct codegen_context *ctx); -int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, long exit_addr); +int bpf_jit_emit_exit_insn(u32 *image, u32 *fimage, struct codegen_context *ctx, int tmp_reg, + long exit_addr); void prepare_for_fsession_fentry(u32 *image, struct codegen_context *ctx, int cookie_cnt, int cookie_off, int retval_off); void store_func_meta(u32 *image, struct codegen_context *ctx, u64 func_meta, int func_meta_off); diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c index 11981d2270a9..8ca36a933c7a 100644 --- a/arch/powerpc/net/bpf_jit_comp.c +++ b/arch/powerpc/net/bpf_jit_comp.c @@ -49,11 +49,35 @@ asm ( " .popsection ;" ); -void bpf_jit_build_fentry_stubs(u32 *image, struct codegen_context *ctx) +void bpf_jit_build_fentry_stubs(u32 *image, u32 *fimage, struct codegen_context *ctx) { int ool_stub_idx, long_branch_stub_idx; + int ool_stub_sz; /* + * Align the mis-aligned dummy_tramp_addr field in the fimage. + * The alignment NOP must appear before OOL stub, to make + * ool_stub_idx & long_branch_stub_idx constant from end. + * + * The fimage can be non 8-byte aligned, so final alignment depends + * on start of fimage and the stub's instruction count offset. The + * OOL stub size is 4 instructions (with CONFIG_PPC_FTRACE_OUT_OF_LINE) + * or 3 instructions (without) before dummy_tramp_addr. + * + * Emit a NOP here if address is not SZL aligned. + * + * In pass=0 when image==NULL, conservatively account for space + * required to accommodate alignment NOP. In case final pass skips + * emitting alignment NOP, the image buffer have 4 spare bytes and + * jited_len signifies correct program size. + */ + + ool_stub_sz = IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE) ? 16 : 12; + if (!image || !IS_ALIGNED((unsigned long)fimage + ctx->idx*4 + ool_stub_sz, SZL)) + EMIT(PPC_RAW_NOP()); + + /* + * nop // optional, for alignment of dummy_tramp_addr * Out-of-line stub: * mflr r0 * [b|bl] tramp @@ -70,7 +94,7 @@ void bpf_jit_build_fentry_stubs(u32 *image, struct codegen_context *ctx) /* * Long branch stub: - * .long + * .long // 8-byte aligned * mflr r11 * bcl 20,31,$+4 * mflr r12 @@ -81,6 +105,7 @@ void bpf_jit_build_fentry_stubs(u32 *image, struct codegen_context *ctx) */ if (image) *((unsigned long *)&image[ctx->idx]) = (unsigned long)dummy_tramp; + ctx->idx += SZL / 4; long_branch_stub_idx = ctx->idx; EMIT(PPC_RAW_MFLR(_R11)); @@ -97,7 +122,8 @@ void bpf_jit_build_fentry_stubs(u32 *image, struct codegen_context *ctx) } } -int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, long exit_addr) +int bpf_jit_emit_exit_insn(u32 *image, u32 *fimage, struct codegen_context *ctx, + int tmp_reg, long exit_addr) { if (exit_addr && is_offset_in_branch_range(exit_addr - (long)(ctx->idx * 4))) { PPC_JMP(exit_addr); @@ -106,7 +132,7 @@ int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, PPC_JMP(ctx->alt_exit_addr); } else { ctx->alt_exit_addr = ctx->idx * 4; - bpf_jit_build_epilogue(image, ctx); + bpf_jit_build_epilogue(image, fimage, ctx); } return 0; @@ -286,7 +312,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_verifier_env *env, struct bpf_pr */ bpf_jit_build_prologue(NULL, &cgctx); addrs[fp->len] = cgctx.idx * 4; - bpf_jit_build_epilogue(NULL, &cgctx); + bpf_jit_build_epilogue(NULL, NULL, &cgctx); fixup_len = fp->aux->num_exentries * BPF_FIXUP_LEN * 4; extable_len = fp->aux->num_exentries * sizeof(struct exception_table_entry); @@ -322,7 +348,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_verifier_env *env, struct bpf_pr goto out_err; } addrs[fp->len] = cgctx.idx * 4; - bpf_jit_build_epilogue(code_base, &cgctx); + bpf_jit_build_epilogue(code_base, fcode_base, &cgctx); proglen = cgctx.idx * 4; diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c index bfdc50740da8..f5b9441cf46a 100644 --- a/arch/powerpc/net/bpf_jit_comp32.c +++ b/arch/powerpc/net/bpf_jit_comp32.c @@ -229,7 +229,7 @@ static void bpf_jit_emit_common_epilogue(u32 *image, struct codegen_context *ctx } -void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx) +void bpf_jit_build_epilogue(u32 *image, u32 *fimage, struct codegen_context *ctx) { EMIT(PPC_RAW_MR(_R3, bpf_to_ppc(BPF_REG_0))); @@ -237,7 +237,7 @@ void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx) EMIT(PPC_RAW_BLR()); - bpf_jit_build_fentry_stubs(image, ctx); + bpf_jit_build_fentry_stubs(image, fimage, ctx); } /* Relative offset needs to be calculated based on final image location */ @@ -1149,7 +1149,8 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code * we'll just fall through to the epilogue. */ if (i != flen - 1) { - ret = bpf_jit_emit_exit_insn(image, ctx, _R0, exit_addr); + ret = bpf_jit_emit_exit_insn(image, fimage, + ctx, _R0, exit_addr); if (ret) return ret; } diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 59302cabc466..e80312171aa7 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -398,7 +398,7 @@ static void bpf_jit_emit_common_epilogue(u32 *image, struct codegen_context *ctx } } -void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx) +void bpf_jit_build_epilogue(u32 *image, u32 *fimage, struct codegen_context *ctx) { bpf_jit_emit_common_epilogue(image, ctx); @@ -407,7 +407,7 @@ void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx) EMIT(PPC_RAW_BLR()); - bpf_jit_build_fentry_stubs(image, ctx); + bpf_jit_build_fentry_stubs(image, fimage, ctx); } /* @@ -1737,7 +1737,8 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code * we'll just fall through to the epilogue. */ if (i != flen - 1) { - ret = bpf_jit_emit_exit_insn(image, ctx, tmp1_reg, exit_addr); + ret = bpf_jit_emit_exit_insn(image, fimage, ctx, + tmp1_reg, exit_addr); if (ret) return ret; } -- 2.55.0