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Tue, 5 Aug 2025 06:28:17 GMT Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5698920043; Tue, 5 Aug 2025 06:28:17 +0000 (GMT) Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 63A8320040; Tue, 5 Aug 2025 06:28:10 +0000 (GMT) Received: from li-621bac4c-27c7-11b2-a85c-c2bf7c4b3c07.ibm.com.com (unknown [9.43.39.141]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 5 Aug 2025 06:28:10 +0000 (GMT) From: Saket Kumar Bhaskar To: bpf@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Cc: hbathini@linux.ibm.com, sachinpb@linux.ibm.com, venkat88@linux.ibm.com, andrii@kernel.org, eddyz87@gmail.com, mykolal@fb.com, ast@kernel.org, daniel@iogearbox.net, martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, christophe.leroy@csgroup.eu, naveen@kernel.org, maddy@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, memxor@gmail.com, iii@linux.ibm.com, shuah@kernel.org Subject: [bpf-next 2/6] bpf,powerpc: Implement PROBE_MEM32 pseudo instructions Date: Tue, 5 Aug 2025 11:57:43 +0530 Message-ID: <20250805062747.3479221-3-skb99@linux.ibm.com> X-Mailer: git-send-email 2.43.5 In-Reply-To: <20250805062747.3479221-1-skb99@linux.ibm.com> References: <20250805062747.3479221-1-skb99@linux.ibm.com> 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-Proofpoint-GUID: 5GZma-dZGgal9zCf26Gy1vfz1S5_bwv3 X-Proofpoint-ORIG-GUID: Te_J4uSLL7WmQIYhyQWLAeX1HJUOmFeh X-Authority-Analysis: v=2.4 cv=GNoIEvNK c=1 sm=1 tr=0 ts=6891a487 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=2OwXVqhp2XgA:10 a=VnNF1IyMAAAA:8 a=ZFvp2un6vmrCkh9nRUAA:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwODA1MDA0NSBTYWx0ZWRfX9sfsT883v+S1 9/epqTWQdufx/qfvhczBMr+Uylx0mKHdzY5/xQMoBY9NaAjHciLSDn4gGOdKC/k28Ljxd5DRk5B i1jiBYxcFCPqXt5AmhJHnhab/7oLy2EljNQSLO+J5/uvJ9q1khnjmACZVb7xtG0S9MZgz4YhetO JAmB3bhhYpeY5U8b2Yrrph+46TlI8wzNU3/6CfINAKGSPe8Jb4COZrJcLWi1u29UIetr4lYeoGM fjdVZrmTtLpwGyjHEpMfsiQsZ2C/QBawVt7MpmrsEk7eqWC70xYMg/cboy/bGdKTG0pJ5q4CWQg HlX/HCKXKiZ+j8psAHsIrf4nt7tiyDaL8T+JE5Yo1FV4YKeApWOttYHqj94dBxxgCz6+kgVs89X WkmI9gQ8a+H+ABSiJ9PtniXm/kvorYlNCWYuCjYjBua5pHlx9z5hdskcJThWkBuHD6J/pbJA X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-08-05_01,2025-08-04_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 phishscore=0 adultscore=0 spamscore=0 bulkscore=0 mlxscore=0 mlxlogscore=899 impostorscore=0 priorityscore=1501 suspectscore=0 lowpriorityscore=0 clxscore=1015 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505280000 definitions=main-2508050045 Add support for [LDX | STX | ST], PROBE_MEM32, [B | H | W | DW] instructions. They are similar to PROBE_MEM instructions with the following differences: - PROBE_MEM32 supports store. - PROBE_MEM32 relies on the verifier to clear upper 32-bit of the src/dst register - PROBE_MEM32 adds 64-bit kern_vm_start address (which is stored in _R26 in the prologue). Due to bpf_arena constructions such _R26 + reg + off16 access is guaranteed to be within arena virtual range, so no address check at run-time. - PROBE_MEM32 allows STX and ST. If they fault the store is a nop. When LDX faults the destination register is zeroed. To support these on powerpc, we do tmp1 = _R26 + src/dst reg and then use tmp1 as the new src/dst register. This allows us to reuse most of the code for normal [LDX | STX | ST]. Signed-off-by: Saket Kumar Bhaskar --- arch/powerpc/net/bpf_jit.h | 5 +- arch/powerpc/net/bpf_jit_comp.c | 10 ++- arch/powerpc/net/bpf_jit_comp32.c | 2 +- arch/powerpc/net/bpf_jit_comp64.c | 108 ++++++++++++++++++++++++++++-- 4 files changed, 114 insertions(+), 11 deletions(-) diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h index 4c26912c2e3c..2d095a873305 100644 --- a/arch/powerpc/net/bpf_jit.h +++ b/arch/powerpc/net/bpf_jit.h @@ -161,9 +161,10 @@ struct codegen_context { unsigned int seen; unsigned int idx; unsigned int stack_size; - int b2p[MAX_BPF_JIT_REG + 2]; + int b2p[MAX_BPF_JIT_REG + 3]; unsigned int exentry_idx; unsigned int alt_exit_addr; + u64 arena_vm_start; }; #define bpf_to_ppc(r) (ctx->b2p[r]) @@ -201,7 +202,7 @@ int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, u32 *fimage, int pass, struct codegen_context *ctx, int insn_idx, - int jmp_off, int dst_reg); + int jmp_off, int dst_reg, u32 code); #endif diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c index c0684733e9d6..35bfdf4d8785 100644 --- a/arch/powerpc/net/bpf_jit_comp.c +++ b/arch/powerpc/net/bpf_jit_comp.c @@ -204,6 +204,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) /* Make sure that the stack is quadword aligned. */ cgctx.stack_size = round_up(fp->aux->stack_depth, 16); + cgctx.arena_vm_start = bpf_arena_get_kern_vm_start(fp->aux->arena); /* Scouting faux-generate pass 0 */ if (bpf_jit_build_body(fp, NULL, NULL, &cgctx, addrs, 0, false)) { @@ -326,7 +327,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) */ int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, u32 *fimage, int pass, struct codegen_context *ctx, int insn_idx, int jmp_off, - int dst_reg) + int dst_reg, u32 code) { off_t offset; unsigned long pc; @@ -354,7 +355,12 @@ int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, u32 *fimage, int pass (fp->aux->num_exentries * BPF_FIXUP_LEN * 4) + (ctx->exentry_idx * BPF_FIXUP_LEN * 4); - fixup[0] = PPC_RAW_LI(dst_reg, 0); + if ((BPF_CLASS(code) == BPF_LDX && BPF_MODE(code) == BPF_PROBE_MEM32) || + (BPF_CLASS(code) == BPF_LDX && BPF_MODE(code) == BPF_PROBE_MEM)) + fixup[0] = PPC_RAW_LI(dst_reg, 0); + else if (BPF_CLASS(code) == BPF_ST || BPF_CLASS(code) == BPF_STX) + fixup[0] = PPC_RAW_NOP(); + if (IS_ENABLED(CONFIG_PPC32)) fixup[1] = PPC_RAW_LI(dst_reg - 1, 0); /* clear higher 32-bit register too */ diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c index 0aace304dfe1..3087e744fb25 100644 --- a/arch/powerpc/net/bpf_jit_comp32.c +++ b/arch/powerpc/net/bpf_jit_comp32.c @@ -1087,7 +1087,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code } ret = bpf_add_extable_entry(fp, image, fimage, pass, ctx, insn_idx, - jmp_off, dst_reg); + jmp_off, dst_reg, code); if (ret) return ret; } diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 489de21fe3d6..16e62766c757 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -44,6 +44,7 @@ /* BPF register usage */ #define TMP_REG_1 (MAX_BPF_JIT_REG + 0) #define TMP_REG_2 (MAX_BPF_JIT_REG + 1) +#define ARENA_VM_START (MAX_BPF_JIT_REG + 2) /* BPF to ppc register mappings */ void bpf_jit_init_reg_mapping(struct codegen_context *ctx) @@ -61,6 +62,8 @@ void bpf_jit_init_reg_mapping(struct codegen_context *ctx) ctx->b2p[BPF_REG_7] = _R28; ctx->b2p[BPF_REG_8] = _R29; ctx->b2p[BPF_REG_9] = _R30; + /* non volatile register for kern_vm_start address */ + ctx->b2p[ARENA_VM_START] = _R26; /* frame pointer aka BPF_REG_10 */ ctx->b2p[BPF_REG_FP] = _R31; /* eBPF jit internal registers */ @@ -69,8 +72,8 @@ void bpf_jit_init_reg_mapping(struct codegen_context *ctx) ctx->b2p[TMP_REG_2] = _R10; } -/* PPC NVR range -- update this if we ever use NVRs below r27 */ -#define BPF_PPC_NVR_MIN _R27 +/* PPC NVR range -- update this if we ever use NVRs below r26 */ +#define BPF_PPC_NVR_MIN _R26 static inline bool bpf_has_stack_frame(struct codegen_context *ctx) { @@ -170,10 +173,17 @@ void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx) if (bpf_is_seen_register(ctx, bpf_to_ppc(i))) EMIT(PPC_RAW_STD(bpf_to_ppc(i), _R1, bpf_jit_stack_offsetof(ctx, bpf_to_ppc(i)))); + if (ctx->arena_vm_start) + EMIT(PPC_RAW_STD(bpf_to_ppc(ARENA_VM_START), _R1, + bpf_jit_stack_offsetof(ctx, bpf_to_ppc(ARENA_VM_START)))); + /* Setup frame pointer to point to the bpf stack area */ if (bpf_is_seen_register(ctx, bpf_to_ppc(BPF_REG_FP))) EMIT(PPC_RAW_ADDI(bpf_to_ppc(BPF_REG_FP), _R1, STACK_FRAME_MIN_SIZE + ctx->stack_size)); + + if (ctx->arena_vm_start) + PPC_LI64(bpf_to_ppc(ARENA_VM_START), ctx->arena_vm_start); } static void bpf_jit_emit_common_epilogue(u32 *image, struct codegen_context *ctx) @@ -185,6 +195,10 @@ static void bpf_jit_emit_common_epilogue(u32 *image, struct codegen_context *ctx if (bpf_is_seen_register(ctx, bpf_to_ppc(i))) EMIT(PPC_RAW_LD(bpf_to_ppc(i), _R1, bpf_jit_stack_offsetof(ctx, bpf_to_ppc(i)))); + if (ctx->arena_vm_start) + EMIT(PPC_RAW_LD(bpf_to_ppc(ARENA_VM_START), _R1, + bpf_jit_stack_offsetof(ctx, bpf_to_ppc(ARENA_VM_START)))); + /* Tear down our stack frame */ if (bpf_has_stack_frame(ctx)) { EMIT(PPC_RAW_ADDI(_R1, _R1, BPF_PPC_STACKFRAME + ctx->stack_size)); @@ -990,6 +1004,50 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code } break; + case BPF_STX | BPF_PROBE_MEM32 | BPF_B: + case BPF_STX | BPF_PROBE_MEM32 | BPF_H: + case BPF_STX | BPF_PROBE_MEM32 | BPF_W: + case BPF_STX | BPF_PROBE_MEM32 | BPF_DW: + + EMIT(PPC_RAW_ADD(tmp1_reg, dst_reg, bpf_to_ppc(ARENA_VM_START))); + + ret = bpf_jit_emit_probe_mem_store(ctx, src_reg, off, code, image); + if (ret) + return ret; + + ret = bpf_add_extable_entry(fp, image, fimage, pass, ctx, + ctx->idx - 1, 4, -1, code); + if (ret) + return ret; + + break; + + case BPF_ST | BPF_PROBE_MEM32 | BPF_B: + case BPF_ST | BPF_PROBE_MEM32 | BPF_H: + case BPF_ST | BPF_PROBE_MEM32 | BPF_W: + case BPF_ST | BPF_PROBE_MEM32 | BPF_DW: + + EMIT(PPC_RAW_ADD(tmp1_reg, dst_reg, bpf_to_ppc(ARENA_VM_START))); + + if (BPF_SIZE(code) == BPF_W || BPF_SIZE(code) == BPF_DW) { + PPC_LI32(tmp2_reg, imm); + src_reg = tmp2_reg; + } else { + EMIT(PPC_RAW_LI(tmp2_reg, imm)); + src_reg = tmp2_reg; + } + + ret = bpf_jit_emit_probe_mem_store(ctx, src_reg, off, code, image); + if (ret) + return ret; + + ret = bpf_add_extable_entry(fp, image, fimage, pass, ctx, + ctx->idx - 1, 4, -1, code); + if (ret) + return ret; + + break; + /* * BPF_STX ATOMIC (atomic ops) */ @@ -1142,9 +1200,10 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code * Check if 'off' is word aligned for BPF_DW, because * we might generate two instructions. */ - if ((BPF_SIZE(code) == BPF_DW || - (BPF_SIZE(code) == BPF_B && BPF_MODE(code) == BPF_PROBE_MEMSX)) && - (off & 3)) + if ((BPF_SIZE(code) == BPF_DW && (off & 3)) || + (BPF_SIZE(code) == BPF_B && + BPF_MODE(code) == BPF_PROBE_MEMSX) || + (BPF_SIZE(code) == BPF_B && BPF_MODE(code) == BPF_MEMSX)) PPC_JMP((ctx->idx + 3) * 4); else PPC_JMP((ctx->idx + 2) * 4); @@ -1190,12 +1249,49 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code if (BPF_MODE(code) == BPF_PROBE_MEM) { ret = bpf_add_extable_entry(fp, image, fimage, pass, ctx, - ctx->idx - 1, 4, dst_reg); + ctx->idx - 1, 4, dst_reg, code); if (ret) return ret; } break; + /* dst = *(u64 *)(ul) (src + ARENA_VM_START + off) */ + case BPF_LDX | BPF_PROBE_MEM32 | BPF_B: + case BPF_LDX | BPF_PROBE_MEM32 | BPF_H: + case BPF_LDX | BPF_PROBE_MEM32 | BPF_W: + case BPF_LDX | BPF_PROBE_MEM32 | BPF_DW: + + EMIT(PPC_RAW_ADD(tmp1_reg, src_reg, bpf_to_ppc(ARENA_VM_START))); + + switch (size) { + case BPF_B: + EMIT(PPC_RAW_LBZ(dst_reg, tmp1_reg, off)); + break; + case BPF_H: + EMIT(PPC_RAW_LHZ(dst_reg, tmp1_reg, off)); + break; + case BPF_W: + EMIT(PPC_RAW_LWZ(dst_reg, tmp1_reg, off)); + break; + case BPF_DW: + if (off % 4) { + EMIT(PPC_RAW_LI(tmp2_reg, off)); + EMIT(PPC_RAW_LDX(dst_reg, tmp1_reg, tmp2_reg)); + } else { + EMIT(PPC_RAW_LD(dst_reg, tmp1_reg, off)); + } + break; + } + + if (size != BPF_DW && insn_is_zext(&insn[i + 1])) + addrs[++i] = ctx->idx * 4; + + ret = bpf_add_extable_entry(fp, image, fimage, pass, ctx, + ctx->idx - 1, 4, dst_reg, code); + if (ret) + return ret; + break; + /* * Doubleword load * 16 byte instruction that uses two 'struct bpf_insn' -- 2.43.5