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[54.240.197.231]) by smtp.gmail.com with ESMTPSA id g4-20020a05600c310400b0041462294fe3sm8754094wmo.42.2024.03.25.08.54.42 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 25 Mar 2024 08:54:42 -0700 (PDT) From: Puranjay Mohan To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , =?utf-8?b?QmrDtnJuIFTDtnBlbA==?= , Luke Nelson , Xi Wang , Paul Walmsley , Palmer Dabbelt , Albert Ou , bpf@vger.kernel.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Pu Lehui Cc: puranjay12@gmail.com Subject: [PATCH bpf-next v2 1/2] bpf,riscv: Implement PROBE_MEM32 pseudo instructions Date: Mon, 25 Mar 2024 15:54:33 +0000 Message-Id: <20240325155434.65589-2-puranjay12@gmail.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20240325155434.65589-1-puranjay12@gmail.com> References: <20240325155434.65589-1-puranjay12@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net 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 S7 in the prologue). Due to bpf_arena constructions such S7 + reg + off16 access is guaranteed to be within arena virtual range, so no address check at run-time. - S7 is a free callee-saved register, so it is used to store kern_vm_start - 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 riscv, we do tmp = S7 + src/dst reg and then use tmp2 as the new src/dst register. This allows us to reuse most of the code for normal [LDX | STX | ST]. Signed-off-by: Puranjay Mohan --- arch/riscv/net/bpf_jit.h | 1 + arch/riscv/net/bpf_jit_comp64.c | 193 +++++++++++++++++++++++++++++++- arch/riscv/net/bpf_jit_core.c | 1 + 3 files changed, 192 insertions(+), 3 deletions(-) diff --git a/arch/riscv/net/bpf_jit.h b/arch/riscv/net/bpf_jit.h index f4b6b3b9edda..8a47da08dd9c 100644 --- a/arch/riscv/net/bpf_jit.h +++ b/arch/riscv/net/bpf_jit.h @@ -81,6 +81,7 @@ struct rv_jit_context { int nexentries; unsigned long flags; int stack_size; + u64 arena_vm_start; }; /* Convert from ninsns to bytes. */ diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c index 1adf2f39ce59..0c0588e327af 100644 --- a/arch/riscv/net/bpf_jit_comp64.c +++ b/arch/riscv/net/bpf_jit_comp64.c @@ -255,6 +255,10 @@ static void __build_epilogue(bool is_tail_call, struct rv_jit_context *ctx) emit_ld(RV_REG_S6, store_offset, RV_REG_SP, ctx); store_offset -= 8; } + if (ctx->arena_vm_start) { + emit_ld(RV_REG_S7, store_offset, RV_REG_SP, ctx); + store_offset -= 8; + } emit_addi(RV_REG_SP, RV_REG_SP, stack_adjust, ctx); /* Set return value. */ @@ -548,6 +552,7 @@ static void emit_atomic(u8 rd, u8 rs, s16 off, s32 imm, bool is64, #define BPF_FIXUP_OFFSET_MASK GENMASK(26, 0) #define BPF_FIXUP_REG_MASK GENMASK(31, 27) +#define DONT_CLEAR 17 /* RV_REG_A7 unused in pt_regmap */ bool ex_handler_bpf(const struct exception_table_entry *ex, struct pt_regs *regs) @@ -555,7 +560,8 @@ bool ex_handler_bpf(const struct exception_table_entry *ex, off_t offset = FIELD_GET(BPF_FIXUP_OFFSET_MASK, ex->fixup); int regs_offset = FIELD_GET(BPF_FIXUP_REG_MASK, ex->fixup); - *(unsigned long *)((void *)regs + pt_regmap[regs_offset]) = 0; + if (regs_offset != DONT_CLEAR) + *(unsigned long *)((void *)regs + pt_regmap[regs_offset]) = 0; regs->epc = (unsigned long)&ex->fixup - offset; return true; @@ -572,7 +578,8 @@ static int add_exception_handler(const struct bpf_insn *insn, off_t fixup_offset; if (!ctx->insns || !ctx->ro_insns || !ctx->prog->aux->extable || - (BPF_MODE(insn->code) != BPF_PROBE_MEM && BPF_MODE(insn->code) != BPF_PROBE_MEMSX)) + (BPF_MODE(insn->code) != BPF_PROBE_MEM && BPF_MODE(insn->code) != BPF_PROBE_MEMSX && + BPF_MODE(insn->code) != BPF_PROBE_MEM32)) return 0; if (WARN_ON_ONCE(ctx->nexentries >= ctx->prog->aux->num_exentries)) @@ -622,6 +629,9 @@ static int add_exception_handler(const struct bpf_insn *insn, ex->insn = ins_offset; + if (BPF_CLASS(insn->code) != BPF_LDX) + dst_reg = DONT_CLEAR; + ex->fixup = FIELD_PREP(BPF_FIXUP_OFFSET_MASK, fixup_offset) | FIELD_PREP(BPF_FIXUP_REG_MASK, dst_reg); ex->type = EX_TYPE_BPF; @@ -1063,7 +1073,7 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, BPF_CLASS(insn->code) == BPF_JMP; int s, e, rvoff, ret, i = insn - ctx->prog->insnsi; struct bpf_prog_aux *aux = ctx->prog->aux; - u8 rd = -1, rs = -1, code = insn->code; + u8 rd = -1, rs = -1, code = insn->code, reg_arena_vm_start = RV_REG_S7; s16 off = insn->off; s32 imm = insn->imm; @@ -1539,6 +1549,11 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, case BPF_LDX | BPF_PROBE_MEMSX | BPF_B: case BPF_LDX | BPF_PROBE_MEMSX | BPF_H: case BPF_LDX | BPF_PROBE_MEMSX | BPF_W: + /* LDX | PROBE_MEM32: dst = *(unsigned size *)(src + S7 + 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: { int insn_len, insns_start; bool sign_ext; @@ -1546,6 +1561,11 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, sign_ext = BPF_MODE(insn->code) == BPF_MEMSX || BPF_MODE(insn->code) == BPF_PROBE_MEMSX; + if (BPF_MODE(insn->code) == BPF_PROBE_MEM32) { + emit_add(RV_REG_T2, rs, reg_arena_vm_start, ctx); + rs = RV_REG_T2; + } + switch (BPF_SIZE(code)) { case BPF_B: if (is_12b_int(off)) { @@ -1682,6 +1702,87 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, emit_sd(RV_REG_T2, 0, RV_REG_T1, ctx); 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: + { + int insn_len, insns_start; + + emit_add(RV_REG_T3, rd, reg_arena_vm_start, ctx); + rd = RV_REG_T3; + + /* Load imm to a register then store it */ + emit_imm(RV_REG_T1, imm, ctx); + + switch (BPF_SIZE(code)) { + case BPF_B: + if (is_12b_int(off)) { + insns_start = ctx->ninsns; + emit(rv_sb(rd, off, RV_REG_T1), ctx); + insn_len = ctx->ninsns - insns_start; + break; + } + + emit_imm(RV_REG_T2, off, ctx); + emit_add(RV_REG_T2, RV_REG_T2, rd, ctx); + insns_start = ctx->ninsns; + emit(rv_sb(RV_REG_T2, 0, RV_REG_T1), ctx); + insn_len = ctx->ninsns - insns_start; + + break; + + case BPF_H: + if (is_12b_int(off)) { + insns_start = ctx->ninsns; + emit(rv_sh(rd, off, RV_REG_T1), ctx); + insn_len = ctx->ninsns - insns_start; + break; + } + + emit_imm(RV_REG_T2, off, ctx); + emit_add(RV_REG_T2, RV_REG_T2, rd, ctx); + insns_start = ctx->ninsns; + emit(rv_sh(RV_REG_T2, 0, RV_REG_T1), ctx); + insn_len = ctx->ninsns - insns_start; + break; + case BPF_W: + if (is_12b_int(off)) { + insns_start = ctx->ninsns; + emit_sw(rd, off, RV_REG_T1, ctx); + insn_len = ctx->ninsns - insns_start; + break; + } + + emit_imm(RV_REG_T2, off, ctx); + emit_add(RV_REG_T2, RV_REG_T2, rd, ctx); + insns_start = ctx->ninsns; + emit_sw(RV_REG_T2, 0, RV_REG_T1, ctx); + insn_len = ctx->ninsns - insns_start; + break; + case BPF_DW: + if (is_12b_int(off)) { + insns_start = ctx->ninsns; + emit_sd(rd, off, RV_REG_T1, ctx); + insn_len = ctx->ninsns - insns_start; + break; + } + + emit_imm(RV_REG_T2, off, ctx); + emit_add(RV_REG_T2, RV_REG_T2, rd, ctx); + insns_start = ctx->ninsns; + emit_sd(RV_REG_T2, 0, RV_REG_T1, ctx); + insn_len = ctx->ninsns - insns_start; + break; + } + + ret = add_exception_handler(insn, ctx, rd, insn_len); + if (ret) + return ret; + + break; + } + /* STX: *(size *)(dst + off) = src */ case BPF_STX | BPF_MEM | BPF_B: if (is_12b_int(off)) { @@ -1728,6 +1829,83 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, emit_atomic(rd, rs, off, imm, BPF_SIZE(code) == BPF_DW, ctx); 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: + { + int insn_len, insns_start; + + emit_add(RV_REG_T2, rd, reg_arena_vm_start, ctx); + rd = RV_REG_T2; + + switch (BPF_SIZE(code)) { + case BPF_B: + if (is_12b_int(off)) { + insns_start = ctx->ninsns; + emit(rv_sb(rd, off, rs), ctx); + insn_len = ctx->ninsns - insns_start; + break; + } + + emit_imm(RV_REG_T1, off, ctx); + emit_add(RV_REG_T1, RV_REG_T1, rd, ctx); + insns_start = ctx->ninsns; + emit(rv_sb(RV_REG_T1, 0, rs), ctx); + insn_len = ctx->ninsns - insns_start; + break; + case BPF_H: + if (is_12b_int(off)) { + insns_start = ctx->ninsns; + emit(rv_sh(rd, off, rs), ctx); + insn_len = ctx->ninsns - insns_start; + break; + } + + emit_imm(RV_REG_T1, off, ctx); + emit_add(RV_REG_T1, RV_REG_T1, rd, ctx); + insns_start = ctx->ninsns; + emit(rv_sh(RV_REG_T1, 0, rs), ctx); + insn_len = ctx->ninsns - insns_start; + break; + case BPF_W: + if (is_12b_int(off)) { + insns_start = ctx->ninsns; + emit_sw(rd, off, rs, ctx); + insn_len = ctx->ninsns - insns_start; + break; + } + + emit_imm(RV_REG_T1, off, ctx); + emit_add(RV_REG_T1, RV_REG_T1, rd, ctx); + insns_start = ctx->ninsns; + emit_sw(RV_REG_T1, 0, rs, ctx); + insn_len = ctx->ninsns - insns_start; + break; + case BPF_DW: + if (is_12b_int(off)) { + insns_start = ctx->ninsns; + emit_sd(rd, off, rs, ctx); + insn_len = ctx->ninsns - insns_start; + break; + } + + emit_imm(RV_REG_T1, off, ctx); + emit_add(RV_REG_T1, RV_REG_T1, rd, ctx); + insns_start = ctx->ninsns; + emit_sd(RV_REG_T1, 0, rs, ctx); + insn_len = ctx->ninsns - insns_start; + break; + } + + ret = add_exception_handler(insn, ctx, rd, insn_len); + if (ret) + return ret; + + break; + } + default: pr_err("bpf-jit: unknown opcode %02x\n", code); return -EINVAL; @@ -1759,6 +1937,8 @@ void bpf_jit_build_prologue(struct rv_jit_context *ctx, bool is_subprog) stack_adjust += 8; if (seen_reg(RV_REG_S6, ctx)) stack_adjust += 8; + if (ctx->arena_vm_start) + stack_adjust += 8; stack_adjust = round_up(stack_adjust, 16); stack_adjust += bpf_stack_adjust; @@ -1810,6 +1990,10 @@ void bpf_jit_build_prologue(struct rv_jit_context *ctx, bool is_subprog) emit_sd(RV_REG_SP, store_offset, RV_REG_S6, ctx); store_offset -= 8; } + if (ctx->arena_vm_start) { + emit_sd(RV_REG_SP, store_offset, RV_REG_S7, ctx); + store_offset -= 8; + } emit_addi(RV_REG_FP, RV_REG_SP, stack_adjust, ctx); @@ -1823,6 +2007,9 @@ void bpf_jit_build_prologue(struct rv_jit_context *ctx, bool is_subprog) emit_mv(RV_REG_TCC_SAVED, RV_REG_TCC, ctx); ctx->stack_size = stack_adjust; + + if (ctx->arena_vm_start) + emit_imm(RV_REG_S7, ctx->arena_vm_start, ctx); } void bpf_jit_build_epilogue(struct rv_jit_context *ctx) diff --git a/arch/riscv/net/bpf_jit_core.c b/arch/riscv/net/bpf_jit_core.c index 6b3acac30c06..9ab739b9f9a2 100644 --- a/arch/riscv/net/bpf_jit_core.c +++ b/arch/riscv/net/bpf_jit_core.c @@ -80,6 +80,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) goto skip_init_ctx; } + ctx->arena_vm_start = bpf_arena_get_kern_vm_start(prog->aux->arena); ctx->prog = prog; ctx->offset = kcalloc(prog->len, sizeof(int), GFP_KERNEL); if (!ctx->offset) {