From patchwork Mon Jul 12 00:34:57 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tony Ambardar X-Patchwork-Id: 473376 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 566F9C07E9C for ; Mon, 12 Jul 2021 00:35:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3293B6100B for ; Mon, 12 Jul 2021 00:35:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232193AbhGLAik (ORCPT ); Sun, 11 Jul 2021 20:38:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33336 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232481AbhGLAi3 (ORCPT ); Sun, 11 Jul 2021 20:38:29 -0400 Received: from mail-pl1-x62b.google.com (mail-pl1-x62b.google.com [IPv6:2607:f8b0:4864:20::62b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A0C24C0613DD; Sun, 11 Jul 2021 17:35:40 -0700 (PDT) Received: by mail-pl1-x62b.google.com with SMTP id b12so5330364plh.10; Sun, 11 Jul 2021 17:35:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=KSSnFa9Hba5QV32S9y4LHnmrZP8UVxAeAaR27+inUSM=; b=Ssu9T6fLq8r4m4Fy+2FVBAvkExM1Z1VeJwKLbMc8v9uEPn/sc8K2ZrPisRbDGpGaLN IG8hy2WGNAu3dP6LDAnSlcK9Ig9mRhSdq5HSSkbi9iceSehx5EQsMO5/qXPMiCLV0/rJ LddkQzmOQTc+U2AWGth/s9rPfa3pIJio7wS07OSBvLmL6iFJIg3CgF5YJ7idT2QbziO2 Ixilw0lEX7L+Xnl91k/jZaZ8ihdfW68QALd0+x5okBhieILBmvM9xXy7SpT9tcP/nZ/j XV69kVML3zHV6QpS69FL2GBUY4jXwaJVtIhEouwZC+hSjrJWBZnONT1hMV8whqog1dKJ K7Fw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=KSSnFa9Hba5QV32S9y4LHnmrZP8UVxAeAaR27+inUSM=; b=NbCwDsncHJfDmrrOH61KEVtve6Jr2Vvl8gbo4NYCH0s3ji80SBYDpxEvQ4FG9Hk1// eJQHmWhDDIOwA6WTUe9NDljsfOqjKJWVZGkgTnr5Tz/IMbL/c+U4WJmyiRIUfMcZppMD YRTLrbkDL9eosARE9oM1UhcNq7NxqoALtQ+loNscAkY+7roTWNu+0Z0b1sMBa+vco2Vr qD3Llr1S8IND1hIEbjmSBMmMI2zkNBv4wzzml0SF/7Z1oIjIWkYfXnfUejtuFuEb7Zg/ yhgsx/5g3Y066WcDU76RbkgkZUlZsODtMCmiyE2EWBHYu2SItQl1GOS23ZRRnfOaw8x6 wEyQ== X-Gm-Message-State: AOAM532Gd+4bRAj0l+Ht9/0i4O+6JLENYQyr3R5qtGl5Cczpy3ddRGYX 2sVnM78HNyI7fGgjZMKYomM= X-Google-Smtp-Source: ABdhPJw60yhe1XaEjsysLZFJsBdJRKQhJO5K81x760kEop+PzkOEEGPwcMg4ZoDy3qURtExe6FRV9g== X-Received: by 2002:a17:902:b409:b029:129:a9a6:fc76 with SMTP id x9-20020a170902b409b0290129a9a6fc76mr27307168plr.68.1626050139813; Sun, 11 Jul 2021 17:35:39 -0700 (PDT) Received: from localhost.localdomain ([2001:470:e92d:10:4039:6c0e:1168:cc74]) by smtp.gmail.com with ESMTPSA id c24sm15588447pgj.11.2021.07.11.17.35.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 11 Jul 2021 17:35:39 -0700 (PDT) From: Tony Ambardar X-Google-Original-From: Tony Ambardar To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Thomas Bogendoerfer , Paul Burton Cc: Tony Ambardar , netdev@vger.kernel.org, bpf@vger.kernel.org, linux-mips@vger.kernel.org, Johan Almbladh , Hassan Naveed , David Daney , Luke Nelson , Serge Semin , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh Subject: [RFC PATCH bpf-next v1 11/14] MIPS: eBPF: add core support for 32/64-bit systems Date: Sun, 11 Jul 2021 17:34:57 -0700 Message-Id: <9a6e1b11fdc1f6a4c1b81cfb1b361d4628cc14c6.1625970384.git.Tony.Ambardar@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Update register definitions and flags for both 32/64-bit operation. Add a common register lookup table and modify ebpf_to_mips_reg() to use this, and add is64bit() and isbigend() common helper functions. On MIPS32, BPF registers are held in register pairs defined by the base register. Word-size and endian-aware helper macros select 32-bit registers from a pair and generate 32-bit word memory storage offsets. The BPF TCC is stored to the stack due to register pressure. Modify build_int_prologue() and build_int_epilogue() to handle MIPS32 registers and any adjustments needed during program entry/exit/transfer if transitioning between the native N64/O32 ABI and the BPF 64-bit ABI. Also ensure ABI-consistent stack alignment and use verifier-provided stack depth during setup. Update emit_const_to_reg() to work across MIPS64 and MIPS32 systems and optimize gen_imm_to_reg() to only set the lower halfword if needed. Rework emit_bpf_tail_call() to also support MIPS32 usage and add common helpers, emit_bpf_call() and emit_push_args(), handling TCC and ABI variations on MIPS32/MIPS64. Add tail_call_present() and update tailcall handling to support mixing BPF2BPF subprograms and tailcalls. Add sign and zero-extension helpers usable with verifier zext insertion, gen_zext_insn() and gen_sext_insn(). Add common functions emit_caller_save() and emit_caller_restore(), which push and pop all caller-saved BPF registers to the stack, for use with JIT-internal kernel calls such as those needed for BPF insns unsupported by native system ISA opcodes. Since these calls would be hidden from any BPF C compiler, which would normally spill needed registers during a call, the JIT must handle save/restore itself. Adopt a dedicated BPF FP (in MIPS_R_S8), and relax FP usage within insns. This reduces ad-hoc code doing $sp manipulation with temp registers, and allows wider usage of BPF FP for comparison and arithmetic. For example, the following tests from test_verifier are now jited but not previously: 939/p store PTR_TO_STACK in R10 to array map using BPF_B 981/p unpriv: cmp pointer with pointer 984/p unpriv: indirectly pass pointer on stack to helper function 985/p unpriv: mangle pointer on stack 1 986/p unpriv: mangle pointer on stack 2 1001/p unpriv: partial copy of pointer 1097/p xadd/w check whether src/dst got mangled, 1 1098/p xadd/w check whether src/dst got mangled, 2 Signed-off-by: Tony Ambardar --- arch/mips/net/ebpf_jit.c | 750 +++++++++++++++++++++++++++++---------- 1 file changed, 563 insertions(+), 187 deletions(-) diff --git a/arch/mips/net/ebpf_jit.c b/arch/mips/net/ebpf_jit.c index 61d7894051aa..525f1df8db21 100644 --- a/arch/mips/net/ebpf_jit.c +++ b/arch/mips/net/ebpf_jit.c @@ -1,11 +1,13 @@ // SPDX-License-Identifier: GPL-2.0-only /* - * Just-In-Time compiler for eBPF filters on MIPS - * - * Copyright (c) 2017 Cavium, Inc. + * Just-In-Time compiler for eBPF filters on MIPS32/MIPS64 + * Copyright (c) 2021 Tony Ambardar * * Based on code from: * + * Copyright (c) 2017 Cavium, Inc. + * Author: David Daney + * * Copyright (c) 2014 Imagination Technologies Ltd. * Author: Markos Chandras */ @@ -22,31 +24,42 @@ #include #include -/* Registers used by JIT */ +/* Registers used by JIT: (MIPS32) (MIPS64) */ #define MIPS_R_ZERO 0 #define MIPS_R_AT 1 -#define MIPS_R_V0 2 /* BPF_R0 */ -#define MIPS_R_V1 3 -#define MIPS_R_A0 4 /* BPF_R1 */ -#define MIPS_R_A1 5 /* BPF_R2 */ -#define MIPS_R_A2 6 /* BPF_R3 */ -#define MIPS_R_A3 7 /* BPF_R4 */ -#define MIPS_R_A4 8 /* BPF_R5 */ -#define MIPS_R_T4 12 /* BPF_AX */ -#define MIPS_R_T5 13 -#define MIPS_R_T6 14 -#define MIPS_R_T7 15 -#define MIPS_R_S0 16 /* BPF_R6 */ -#define MIPS_R_S1 17 /* BPF_R7 */ -#define MIPS_R_S2 18 /* BPF_R8 */ -#define MIPS_R_S3 19 /* BPF_R9 */ -#define MIPS_R_S4 20 /* BPF_TCC */ -#define MIPS_R_S5 21 -#define MIPS_R_S6 22 -#define MIPS_R_S7 23 -#define MIPS_R_T8 24 -#define MIPS_R_T9 25 +#define MIPS_R_V0 2 /* BPF_R0 BPF_R0 */ +#define MIPS_R_V1 3 /* BPF_R0 BPF_TCC */ +#define MIPS_R_A0 4 /* BPF_R1 BPF_R1 */ +#define MIPS_R_A1 5 /* BPF_R1 BPF_R2 */ +#define MIPS_R_A2 6 /* BPF_R2 BPF_R3 */ +#define MIPS_R_A3 7 /* BPF_R2 BPF_R4 */ + +/* MIPS64 replaces T0-T3 scratch regs with extra arguments A4-A7. */ +#ifdef CONFIG_64BIT +# define MIPS_R_A4 8 /* (n/a) BPF_R5 */ +#else +# define MIPS_R_T0 8 /* BPF_R3 (n/a) */ +# define MIPS_R_T1 9 /* BPF_R3 (n/a) */ +# define MIPS_R_T2 10 /* BPF_R4 (n/a) */ +# define MIPS_R_T3 11 /* BPF_R4 (n/a) */ +#endif + +#define MIPS_R_T4 12 /* BPF_R5 BPF_AX */ +#define MIPS_R_T5 13 /* BPF_R5 (free) */ +#define MIPS_R_T6 14 /* BPF_AX (used) */ +#define MIPS_R_T7 15 /* BPF_AX (free) */ +#define MIPS_R_S0 16 /* BPF_R6 BPF_R6 */ +#define MIPS_R_S1 17 /* BPF_R6 BPF_R7 */ +#define MIPS_R_S2 18 /* BPF_R7 BPF_R8 */ +#define MIPS_R_S3 19 /* BPF_R7 BPF_R9 */ +#define MIPS_R_S4 20 /* BPF_R8 BPF_TCC */ +#define MIPS_R_S5 21 /* BPF_R8 (free) */ +#define MIPS_R_S6 22 /* BPF_R9 (free) */ +#define MIPS_R_S7 23 /* BPF_R9 (free) */ +#define MIPS_R_T8 24 /* (used) (used) */ +#define MIPS_R_T9 25 /* (used) (used) */ #define MIPS_R_SP 29 +#define MIPS_R_S8 30 /* BPF_R10 BPF_R10 */ #define MIPS_R_RA 31 /* eBPF flags */ @@ -55,10 +68,117 @@ #define EBPF_SAVE_S2 BIT(2) #define EBPF_SAVE_S3 BIT(3) #define EBPF_SAVE_S4 BIT(4) -#define EBPF_SAVE_RA BIT(5) -#define EBPF_SEEN_FP BIT(6) -#define EBPF_SEEN_TC BIT(7) -#define EBPF_TCC_IN_V1 BIT(8) +#define EBPF_SAVE_S5 BIT(5) +#define EBPF_SAVE_S6 BIT(6) +#define EBPF_SAVE_S7 BIT(7) +#define EBPF_SAVE_S8 BIT(8) +#define EBPF_SAVE_RA BIT(9) +#define EBPF_SEEN_FP BIT(10) +#define EBPF_SEEN_TC BIT(11) +#define EBPF_TCC_IN_RUN BIT(12) + +/* + * Extra JIT registers dedicated to holding TCC during runtime or saving + * across calls. + */ +enum { + JIT_RUN_TCC = MAX_BPF_JIT_REG, + JIT_SAV_TCC +}; +/* Temporary register for passing TCC if nothing dedicated. */ +#define TEMP_PASS_TCC MIPS_R_T8 + +/* + * Word-size and endianness-aware helpers for building MIPS32 vs MIPS64 + * tables and selecting 32-bit subregisters from a register pair base. + * Simplify use by emulating MIPS_R_SP and MIPS_R_ZERO as register pairs + * and adding HI/LO word memory offsets. + */ +#ifdef CONFIG_64BIT +# define HI(reg) (reg) +# define LO(reg) (reg) +# define OFFHI(mem) (mem) +# define OFFLO(mem) (mem) +#else /* CONFIG_32BIT */ +# ifdef __BIG_ENDIAN +# define HI(reg) ((reg) == MIPS_R_SP ? MIPS_R_ZERO : \ + (reg) == MIPS_R_S8 ? MIPS_R_ZERO : \ + (reg)) +# define LO(reg) ((reg) == MIPS_R_ZERO ? (reg) : \ + (reg) == MIPS_R_SP ? (reg) : \ + (reg) == MIPS_R_S8 ? (reg) : \ + (reg) + 1) +# define OFFHI(mem) (mem) +# define OFFLO(mem) ((mem) + sizeof(long)) +# else /* __LITTLE_ENDIAN */ +# define HI(reg) ((reg) == MIPS_R_ZERO ? (reg) : \ + (reg) == MIPS_R_SP ? MIPS_R_ZERO : \ + (reg) == MIPS_R_S8 ? MIPS_R_ZERO : \ + (reg) + 1) +# define LO(reg) (reg) +# define OFFHI(mem) ((mem) + sizeof(long)) +# define OFFLO(mem) (mem) +# endif +#endif + +#ifdef CONFIG_64BIT +# define M(expr32, expr64) (expr64) +#else +# define M(expr32, expr64) (expr32) +#endif +const struct { + /* Register or pair base */ + int reg; + /* Register flags */ + u32 flags; + /* Usage table: (MIPS32) (MIPS64) */ +} bpf2mips[] = { + /* Return value from in-kernel function, and exit value from eBPF. */ + [BPF_REG_0] = {M(MIPS_R_V0, MIPS_R_V0)}, + /* Arguments from eBPF program to in-kernel/BPF functions. */ + [BPF_REG_1] = {M(MIPS_R_A0, MIPS_R_A0)}, + [BPF_REG_2] = {M(MIPS_R_A2, MIPS_R_A1)}, + [BPF_REG_3] = {M(MIPS_R_T0, MIPS_R_A2)}, + [BPF_REG_4] = {M(MIPS_R_T2, MIPS_R_A3)}, + [BPF_REG_5] = {M(MIPS_R_T4, MIPS_R_A4)}, + /* Callee-saved registers preserved by in-kernel/BPF functions. */ + [BPF_REG_6] = {M(MIPS_R_S0, MIPS_R_S0), + M(EBPF_SAVE_S0|EBPF_SAVE_S1, EBPF_SAVE_S0)}, + [BPF_REG_7] = {M(MIPS_R_S2, MIPS_R_S1), + M(EBPF_SAVE_S2|EBPF_SAVE_S3, EBPF_SAVE_S1)}, + [BPF_REG_8] = {M(MIPS_R_S4, MIPS_R_S2), + M(EBPF_SAVE_S4|EBPF_SAVE_S5, EBPF_SAVE_S2)}, + [BPF_REG_9] = {M(MIPS_R_S6, MIPS_R_S3), + M(EBPF_SAVE_S6|EBPF_SAVE_S7, EBPF_SAVE_S3)}, + [BPF_REG_10] = {M(MIPS_R_S8, MIPS_R_S8), + M(EBPF_SAVE_S8|EBPF_SEEN_FP, EBPF_SAVE_S8|EBPF_SEEN_FP)}, + /* Internal register for rewriting insns during JIT blinding. */ + [BPF_REG_AX] = {M(MIPS_R_T6, MIPS_R_T4)}, + /* + * Internal registers for TCC runtime holding and saving during + * calls. A zero save register indicates using scratch space on + * the stack for storage during calls. A zero hold register means + * no dedicated register holds TCC during runtime (but a temp reg + * still passes TCC to tailcall or bpf2bpf call). + */ + [JIT_RUN_TCC] = {M(0, MIPS_R_V1)}, + [JIT_SAV_TCC] = {M(0, MIPS_R_S4), + M(0, EBPF_SAVE_S4)} +}; +#undef M + +static inline bool is64bit(void) +{ + return IS_ENABLED(CONFIG_64BIT); +} + +static inline bool isbigend(void) +{ + return IS_ENABLED(CONFIG_CPU_BIG_ENDIAN); +} + +/* Stack region alignment under N64 and O32 ABIs */ +#define STACK_ALIGN (2 * sizeof(long)) /* * For the mips64 ISA, we need to track the value range or type for @@ -100,6 +220,7 @@ enum reg_val_type { struct jit_ctx { const struct bpf_prog *skf; int stack_size; + int bpf_stack_off; u32 idx; u32 flags; u32 *offsets; @@ -177,6 +298,34 @@ static u32 b_imm(unsigned int tgt, struct jit_ctx *ctx) (ctx->idx * 4) - 4; } +/* Sign-extend dst register or HI 32-bit reg of pair. */ +static inline void gen_sext_insn(int dst, struct jit_ctx *ctx) +{ + if (is64bit()) + emit_instr(ctx, sll, dst, dst, 0); + else + emit_instr(ctx, sra, HI(dst), LO(dst), 31); +} + +/* + * Zero-extend dst register or HI 32-bit reg of pair, if either forced + * or the BPF verifier does not insert its own zext insns. + */ +static inline void gen_zext_insn(int dst, bool force, struct jit_ctx *ctx) +{ + if (!ctx->skf->aux->verifier_zext || force) { + if (is64bit()) + emit_instr(ctx, dinsu, dst, MIPS_R_ZERO, 32, 32); + else + emit_instr(ctx, and, HI(dst), MIPS_R_ZERO, MIPS_R_ZERO); + } +} + +static inline bool tail_call_present(struct jit_ctx *ctx) +{ + return ctx->flags & EBPF_SEEN_TC || ctx->skf->aux->tail_call_reachable; +} + enum reg_usage { REG_SRC_FP_OK, REG_SRC_NO_FP, @@ -186,9 +335,8 @@ enum reg_usage { /* * For eBPF, the register mapping naturally falls out of the - * requirements of eBPF and the MIPS n64 ABI. We don't maintain a - * separate frame pointer, so BPF_REG_10 relative accesses are - * adjusted to be $sp relative. + * requirements of eBPF and the MIPS N64/O32 ABIs. We also maintain + * a separate frame pointer, setting BPF_REG_10 relative to $sp. */ static int ebpf_to_mips_reg(struct jit_ctx *ctx, const struct bpf_insn *insn, @@ -199,110 +347,139 @@ static int ebpf_to_mips_reg(struct jit_ctx *ctx, switch (ebpf_reg) { case BPF_REG_0: - return MIPS_R_V0; case BPF_REG_1: - return MIPS_R_A0; case BPF_REG_2: - return MIPS_R_A1; case BPF_REG_3: - return MIPS_R_A2; case BPF_REG_4: - return MIPS_R_A3; case BPF_REG_5: - return MIPS_R_A4; case BPF_REG_6: - ctx->flags |= EBPF_SAVE_S0; - return MIPS_R_S0; case BPF_REG_7: - ctx->flags |= EBPF_SAVE_S1; - return MIPS_R_S1; case BPF_REG_8: - ctx->flags |= EBPF_SAVE_S2; - return MIPS_R_S2; case BPF_REG_9: - ctx->flags |= EBPF_SAVE_S3; - return MIPS_R_S3; + case BPF_REG_AX: + ctx->flags |= bpf2mips[ebpf_reg].flags; + return bpf2mips[ebpf_reg].reg; case BPF_REG_10: if (u == REG_DST_NO_FP || u == REG_SRC_NO_FP) goto bad_reg; - ctx->flags |= EBPF_SEEN_FP; - /* - * Needs special handling, return something that - * cannot be clobbered just in case. - */ - return MIPS_R_ZERO; - case BPF_REG_AX: - return MIPS_R_T4; + ctx->flags |= bpf2mips[ebpf_reg].flags; + return bpf2mips[ebpf_reg].reg; default: bad_reg: WARN(1, "Illegal bpf reg: %d\n", ebpf_reg); return -EINVAL; } } + /* * eBPF stack frame will be something like: * * Entry $sp ------> +--------------------------------+ * | $ra (optional) | * +--------------------------------+ - * | $s0 (optional) | + * | $s8 (optional) | * +--------------------------------+ - * | $s1 (optional) | + * | $s7 (optional) | * +--------------------------------+ - * | $s2 (optional) | + * | $s6 (optional) | * +--------------------------------+ - * | $s3 (optional) | + * | $s5 (optional) | * +--------------------------------+ * | $s4 (optional) | * +--------------------------------+ - * | tmp-storage (if $ra saved) | - * $sp + tmp_offset --> +--------------------------------+ <--BPF_REG_10 + * | $s3 (optional) | + * +--------------------------------+ + * | $s2 (optional) | + * +--------------------------------+ + * | $s1 (optional) | + * +--------------------------------+ + * | $s0 (optional) | + * +--------------------------------+ + * | tmp-storage (optional) | + * $sp + bpf_stack_off->+--------------------------------+ <--BPF_REG_10 * | BPF_REG_10 relative storage | * | MAX_BPF_STACK (optional) | * | . | * | . | * | . | - * $sp --------> +--------------------------------+ + * $sp ------> +--------------------------------+ * * If BPF_REG_10 is never referenced, then the MAX_BPF_STACK sized * area is not allocated. */ -static int gen_int_prologue(struct jit_ctx *ctx) +static int build_int_prologue(struct jit_ctx *ctx) { + int tcc_run = bpf2mips[JIT_RUN_TCC].reg ? + bpf2mips[JIT_RUN_TCC].reg : + TEMP_PASS_TCC; + int tcc_sav = bpf2mips[JIT_SAV_TCC].reg; + const struct bpf_prog *prog = ctx->skf; + int r10 = bpf2mips[BPF_REG_10].reg; + int r1 = bpf2mips[BPF_REG_1].reg; int stack_adjust = 0; int store_offset; int locals_size; if (ctx->flags & EBPF_SAVE_RA) - /* - * If RA we are doing a function call and may need - * extra 8-byte tmp area. - */ - stack_adjust += 2 * sizeof(long); - if (ctx->flags & EBPF_SAVE_S0) stack_adjust += sizeof(long); - if (ctx->flags & EBPF_SAVE_S1) + if (ctx->flags & EBPF_SAVE_S8) stack_adjust += sizeof(long); - if (ctx->flags & EBPF_SAVE_S2) + if (ctx->flags & EBPF_SAVE_S7) stack_adjust += sizeof(long); - if (ctx->flags & EBPF_SAVE_S3) + if (ctx->flags & EBPF_SAVE_S6) + stack_adjust += sizeof(long); + if (ctx->flags & EBPF_SAVE_S5) stack_adjust += sizeof(long); if (ctx->flags & EBPF_SAVE_S4) stack_adjust += sizeof(long); + if (ctx->flags & EBPF_SAVE_S3) + stack_adjust += sizeof(long); + if (ctx->flags & EBPF_SAVE_S2) + stack_adjust += sizeof(long); + if (ctx->flags & EBPF_SAVE_S1) + stack_adjust += sizeof(long); + if (ctx->flags & EBPF_SAVE_S0) + stack_adjust += sizeof(long); + if (tail_call_present(ctx) && + !(ctx->flags & EBPF_TCC_IN_RUN) && !tcc_sav) + /* Allocate scratch space for holding TCC if needed. */ + stack_adjust += sizeof(long); - BUILD_BUG_ON(MAX_BPF_STACK & 7); - locals_size = (ctx->flags & EBPF_SEEN_FP) ? MAX_BPF_STACK : 0; + stack_adjust = ALIGN(stack_adjust, STACK_ALIGN); + + locals_size = (ctx->flags & EBPF_SEEN_FP) ? prog->aux->stack_depth : 0; + locals_size = ALIGN(locals_size, STACK_ALIGN); stack_adjust += locals_size; ctx->stack_size = stack_adjust; + ctx->bpf_stack_off = locals_size; + + /* + * First instruction initializes the tail call count (TCC) if + * called from kernel or via BPF tail call. A BPF tail-caller + * will skip this instruction and pass the TCC via register. + * As a BPF2BPF subprog, we are called directly and must avoid + * resetting the TCC. + */ + if (!ctx->skf->is_func) + emit_instr(ctx, addiu, tcc_run, MIPS_R_ZERO, MAX_TAIL_CALL_CNT); /* - * First instruction initializes the tail call count (TCC). - * On tail call we skip this instruction, and the TCC is - * passed in $v1 from the caller. + * If called from kernel under O32 ABI we must set up BPF R1 context, + * since BPF R1 is an endian-order regster pair ($a0:$a1 or $a1:$a0) + * but context is always passed in $a0 as 32-bit pointer. Entry from + * a tail-call looks just like a kernel call, which means the caller + * must set up R1 context according to the kernel call ABI. If we are + * a BPF2BPF call then all registers are already correctly set up. */ - emit_instr(ctx, addiu, MIPS_R_V1, MIPS_R_ZERO, MAX_TAIL_CALL_CNT); + if (!is64bit() && !ctx->skf->is_func) { + if (isbigend()) + emit_instr(ctx, move, LO(r1), MIPS_R_A0); + /* Sanitize upper 32-bit reg */ + gen_zext_insn(r1, true, ctx); + } + if (stack_adjust) emit_instr_long(ctx, daddiu, addiu, MIPS_R_SP, MIPS_R_SP, -stack_adjust); @@ -316,24 +493,24 @@ static int gen_int_prologue(struct jit_ctx *ctx) MIPS_R_RA, store_offset, MIPS_R_SP); store_offset -= sizeof(long); } - if (ctx->flags & EBPF_SAVE_S0) { + if (ctx->flags & EBPF_SAVE_S8) { emit_instr_long(ctx, sd, sw, - MIPS_R_S0, store_offset, MIPS_R_SP); + MIPS_R_S8, store_offset, MIPS_R_SP); store_offset -= sizeof(long); } - if (ctx->flags & EBPF_SAVE_S1) { + if (ctx->flags & EBPF_SAVE_S7) { emit_instr_long(ctx, sd, sw, - MIPS_R_S1, store_offset, MIPS_R_SP); + MIPS_R_S7, store_offset, MIPS_R_SP); store_offset -= sizeof(long); } - if (ctx->flags & EBPF_SAVE_S2) { + if (ctx->flags & EBPF_SAVE_S6) { emit_instr_long(ctx, sd, sw, - MIPS_R_S2, store_offset, MIPS_R_SP); + MIPS_R_S6, store_offset, MIPS_R_SP); store_offset -= sizeof(long); } - if (ctx->flags & EBPF_SAVE_S3) { + if (ctx->flags & EBPF_SAVE_S5) { emit_instr_long(ctx, sd, sw, - MIPS_R_S3, store_offset, MIPS_R_SP); + MIPS_R_S5, store_offset, MIPS_R_SP); store_offset -= sizeof(long); } if (ctx->flags & EBPF_SAVE_S4) { @@ -341,10 +518,40 @@ static int gen_int_prologue(struct jit_ctx *ctx) MIPS_R_S4, store_offset, MIPS_R_SP); store_offset -= sizeof(long); } + if (ctx->flags & EBPF_SAVE_S3) { + emit_instr_long(ctx, sd, sw, + MIPS_R_S3, store_offset, MIPS_R_SP); + store_offset -= sizeof(long); + } + if (ctx->flags & EBPF_SAVE_S2) { + emit_instr_long(ctx, sd, sw, + MIPS_R_S2, store_offset, MIPS_R_SP); + store_offset -= sizeof(long); + } + if (ctx->flags & EBPF_SAVE_S1) { + emit_instr_long(ctx, sd, sw, + MIPS_R_S1, store_offset, MIPS_R_SP); + store_offset -= sizeof(long); + } + if (ctx->flags & EBPF_SAVE_S0) { + emit_instr_long(ctx, sd, sw, + MIPS_R_S0, store_offset, MIPS_R_SP); + store_offset -= sizeof(long); + } + + /* Store TCC in backup register or stack scratch space if indicated. */ + if (tail_call_present(ctx) && !(ctx->flags & EBPF_TCC_IN_RUN)) { + if (tcc_sav) + emit_instr(ctx, move, tcc_sav, tcc_run); + else + emit_instr_long(ctx, sd, sw, + tcc_run, ctx->bpf_stack_off, MIPS_R_SP); + } - if ((ctx->flags & EBPF_SEEN_TC) && !(ctx->flags & EBPF_TCC_IN_V1)) - emit_instr_long(ctx, daddu, addu, - MIPS_R_S4, MIPS_R_V1, MIPS_R_ZERO); + /* Prepare BPF FP as single-reg ptr, emulate upper 32-bits as needed.*/ + if (ctx->flags & EBPF_SEEN_FP) + emit_instr_long(ctx, daddiu, addiu, r10, + MIPS_R_SP, ctx->bpf_stack_off); return 0; } @@ -354,14 +561,38 @@ static int build_int_epilogue(struct jit_ctx *ctx, int dest_reg) const struct bpf_prog *prog = ctx->skf; int stack_adjust = ctx->stack_size; int store_offset = stack_adjust - sizeof(long); + int r1 = bpf2mips[BPF_REG_1].reg; + int r0 = bpf2mips[BPF_REG_0].reg; enum reg_val_type td; - int r0 = MIPS_R_V0; - if (dest_reg == MIPS_R_RA) { - /* Don't let zero extended value escape. */ - td = get_reg_val_type(ctx, prog->len, BPF_REG_0); - if (td == REG_64BIT) - emit_instr(ctx, sll, r0, r0, 0); + /* + * Returns from BPF2BPF calls consistently use the BPF 64-bit ABI + * i.e. register usage and mapping between JIT and OS is unchanged. + * Returning to the kernel must follow the N64 or O32 ABI, and for + * the latter requires fixup of BPF R0 to MIPS V0 register mapping. + * + * Tails calls must ensure the passed R1 context is consistent with + * the kernel ABI, and requires fixup on MIPS32 bigendian systems. + */ + if (dest_reg == MIPS_R_RA && !ctx->skf->is_func) { /* kernel return */ + if (is64bit()) { + /* Don't let zero extended value escape. */ + td = get_reg_val_type(ctx, prog->len, BPF_REG_0); + if (td == REG_64BIT) + gen_sext_insn(r0, ctx); + } else if (isbigend()) { /* and 32-bit */ + /* + * O32 ABI specifies 32-bit return value always + * placed in MIPS_R_V0 regardless of the native + * endianness. This would be in the wrong position + * in a BPF R0 reg pair on big-endian systems, so + * we must relocate. + */ + emit_instr(ctx, move, MIPS_R_V0, LO(r0)); + } + } else if (dest_reg == MIPS_R_T9) { /* tail call */ + if (!is64bit() && isbigend()) + emit_instr(ctx, move, MIPS_R_A0, LO(r1)); } if (ctx->flags & EBPF_SAVE_RA) { @@ -369,24 +600,24 @@ static int build_int_epilogue(struct jit_ctx *ctx, int dest_reg) MIPS_R_RA, store_offset, MIPS_R_SP); store_offset -= sizeof(long); } - if (ctx->flags & EBPF_SAVE_S0) { + if (ctx->flags & EBPF_SAVE_S8) { emit_instr_long(ctx, ld, lw, - MIPS_R_S0, store_offset, MIPS_R_SP); + MIPS_R_S8, store_offset, MIPS_R_SP); store_offset -= sizeof(long); } - if (ctx->flags & EBPF_SAVE_S1) { + if (ctx->flags & EBPF_SAVE_S7) { emit_instr_long(ctx, ld, lw, - MIPS_R_S1, store_offset, MIPS_R_SP); + MIPS_R_S7, store_offset, MIPS_R_SP); store_offset -= sizeof(long); } - if (ctx->flags & EBPF_SAVE_S2) { + if (ctx->flags & EBPF_SAVE_S6) { emit_instr_long(ctx, ld, lw, - MIPS_R_S2, store_offset, MIPS_R_SP); + MIPS_R_S6, store_offset, MIPS_R_SP); store_offset -= sizeof(long); } - if (ctx->flags & EBPF_SAVE_S3) { + if (ctx->flags & EBPF_SAVE_S5) { emit_instr_long(ctx, ld, lw, - MIPS_R_S3, store_offset, MIPS_R_SP); + MIPS_R_S5, store_offset, MIPS_R_SP); store_offset -= sizeof(long); } if (ctx->flags & EBPF_SAVE_S4) { @@ -394,8 +625,29 @@ static int build_int_epilogue(struct jit_ctx *ctx, int dest_reg) MIPS_R_S4, store_offset, MIPS_R_SP); store_offset -= sizeof(long); } + if (ctx->flags & EBPF_SAVE_S3) { + emit_instr_long(ctx, ld, lw, + MIPS_R_S3, store_offset, MIPS_R_SP); + store_offset -= sizeof(long); + } + if (ctx->flags & EBPF_SAVE_S2) { + emit_instr_long(ctx, ld, lw, + MIPS_R_S2, store_offset, MIPS_R_SP); + store_offset -= sizeof(long); + } + if (ctx->flags & EBPF_SAVE_S1) { + emit_instr_long(ctx, ld, lw, + MIPS_R_S1, store_offset, MIPS_R_SP); + store_offset -= sizeof(long); + } + if (ctx->flags & EBPF_SAVE_S0) { + emit_instr_long(ctx, ld, lw, + MIPS_R_S0, store_offset, MIPS_R_SP); + store_offset -= sizeof(long); + } emit_instr(ctx, jr, dest_reg); + /* Delay slot */ if (stack_adjust) emit_instr_long(ctx, daddiu, addiu, MIPS_R_SP, MIPS_R_SP, stack_adjust); @@ -415,7 +667,9 @@ static void gen_imm_to_reg(const struct bpf_insn *insn, int reg, int upper = insn->imm - lower; emit_instr(ctx, lui, reg, upper >> 16); - emit_instr(ctx, addiu, reg, reg, lower); + /* lui already clears lower halfword */ + if (lower) + emit_instr(ctx, addiu, reg, reg, lower); } } @@ -564,12 +818,12 @@ static int gen_imm_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, return 0; } -static void emit_const_to_reg(struct jit_ctx *ctx, int dst, u64 value) +static void emit_const_to_reg(struct jit_ctx *ctx, int dst, unsigned long value) { - if (value >= 0xffffffffffff8000ull || value < 0x8000ull) { - emit_instr(ctx, daddiu, dst, MIPS_R_ZERO, (int)value); - } else if (value >= 0xffffffff80000000ull || - (value < 0x80000000 && value > 0xffff)) { + if (value >= S16_MIN || value <= S16_MAX) { + emit_instr_long(ctx, daddiu, addiu, dst, MIPS_R_ZERO, (int)value); + } else if (value >= S32_MIN || + (value <= S32_MAX && value > U16_MAX)) { emit_instr(ctx, lui, dst, (s32)(s16)(value >> 16)); emit_instr(ctx, ori, dst, dst, (unsigned int)(value & 0xffff)); } else { @@ -601,54 +855,145 @@ static void emit_const_to_reg(struct jit_ctx *ctx, int dst, u64 value) } } +/* + * Push BPF regs R3-R5 to the stack, skipping BPF regs R1-R2 which are + * passed via MIPS register pairs in $a0-$a3. Register order within pairs + * and the memory storage order are identical i.e. endian native. + */ +static void emit_push_args(struct jit_ctx *ctx) +{ + int store_offset = 2 * sizeof(u64); /* Skip R1-R2 in $a0-$a3 */ + int bpf, reg; + + for (bpf = BPF_REG_3; bpf <= BPF_REG_5; bpf++) { + reg = bpf2mips[bpf].reg; + + emit_instr(ctx, sw, LO(reg), OFFLO(store_offset), MIPS_R_SP); + emit_instr(ctx, sw, HI(reg), OFFHI(store_offset), MIPS_R_SP); + store_offset += sizeof(u64); + } +} + +/* + * Common helper for BPF_CALL insn, handling TCC and ABI variations. + * Kernel calls under O32 ABI require arguments passed on the stack, + * while BPF2BPF calls need the TCC passed via register as expected + * by the subprog's prologue. + * + * Under MIPS32 O32 ABI calling convention, u64 BPF regs R1-R2 are passed + * via reg pairs in $a0-$a3, while BPF regs R3-R5 are passed via the stack. + * Stack space is still reserved for $a0-$a3, and the whole area aligned. + */ +#define ARGS_SIZE (5 * sizeof(u64)) + +void emit_bpf_call(struct jit_ctx *ctx, const struct bpf_insn *insn) +{ + int stack_adjust = ALIGN(ARGS_SIZE, STACK_ALIGN); + int tcc_run = bpf2mips[JIT_RUN_TCC].reg ? + bpf2mips[JIT_RUN_TCC].reg : + TEMP_PASS_TCC; + int tcc_sav = bpf2mips[JIT_SAV_TCC].reg; + long func_addr; + + ctx->flags |= EBPF_SAVE_RA; + + /* Ensure TCC passed into BPF subprog */ + if ((insn->src_reg == BPF_PSEUDO_CALL) && + tail_call_present(ctx) && !(ctx->flags & EBPF_TCC_IN_RUN)) { + /* Set TCC from reg or stack */ + if (tcc_sav) + emit_instr(ctx, move, tcc_run, tcc_sav); + else + emit_instr_long(ctx, ld, lw, tcc_run, + ctx->bpf_stack_off, MIPS_R_SP); + } + + /* Push O32 stack args for kernel call */ + if (!is64bit() && (insn->src_reg != BPF_PSEUDO_CALL)) { + emit_instr(ctx, addiu, MIPS_R_SP, MIPS_R_SP, -stack_adjust); + emit_push_args(ctx); + } + + func_addr = (long)__bpf_call_base + insn->imm; + emit_const_to_reg(ctx, MIPS_R_T9, func_addr); + emit_instr(ctx, jalr, MIPS_R_RA, MIPS_R_T9); + /* Delay slot */ + emit_instr(ctx, nop); + + /* Restore stack */ + if (!is64bit() && (insn->src_reg != BPF_PSEUDO_CALL)) + emit_instr(ctx, addiu, MIPS_R_SP, MIPS_R_SP, stack_adjust); +} + +/* + * Tail call helper arguments passed via BPF ABI as u64 parameters. On + * MIPS64 N64 ABI systems these are native regs, while on MIPS32 O32 ABI + * systems these are reg pairs: + * + * R1 -> &ctx + * R2 -> &array + * R3 -> index + */ static int emit_bpf_tail_call(struct jit_ctx *ctx, int this_idx) { + int tcc_run = bpf2mips[JIT_RUN_TCC].reg ? + bpf2mips[JIT_RUN_TCC].reg : + TEMP_PASS_TCC; + int tcc_sav = bpf2mips[JIT_SAV_TCC].reg; + int r2 = bpf2mips[BPF_REG_2].reg; + int r3 = bpf2mips[BPF_REG_3].reg; int off, b_off; - int tcc_reg; + int tcc; ctx->flags |= EBPF_SEEN_TC; /* * if (index >= array->map.max_entries) * goto out; */ - /* Mask index as 32-bit */ - emit_instr(ctx, dinsu, MIPS_R_A2, MIPS_R_ZERO, 32, 32); + if (is64bit()) + /* Mask index as 32-bit */ + gen_zext_insn(r3, true, ctx); off = offsetof(struct bpf_array, map.max_entries); - emit_instr(ctx, lwu, MIPS_R_T5, off, MIPS_R_A1); - emit_instr(ctx, sltu, MIPS_R_AT, MIPS_R_T5, MIPS_R_A2); + emit_instr_long(ctx, lwu, lw, MIPS_R_AT, off, LO(r2)); + emit_instr(ctx, sltu, MIPS_R_AT, MIPS_R_AT, LO(r3)); b_off = b_imm(this_idx + 1, ctx); - emit_instr(ctx, bne, MIPS_R_AT, MIPS_R_ZERO, b_off); + emit_instr(ctx, bnez, MIPS_R_AT, b_off); /* * if (TCC-- < 0) * goto out; */ /* Delay slot */ - tcc_reg = (ctx->flags & EBPF_TCC_IN_V1) ? MIPS_R_V1 : MIPS_R_S4; - emit_instr(ctx, daddiu, MIPS_R_T5, tcc_reg, -1); + tcc = (ctx->flags & EBPF_TCC_IN_RUN) ? tcc_run : tcc_sav; + /* Get TCC from reg or stack */ + if (tcc) + emit_instr(ctx, move, MIPS_R_T8, tcc); + else + emit_instr_long(ctx, ld, lw, MIPS_R_T8, + ctx->bpf_stack_off, MIPS_R_SP); b_off = b_imm(this_idx + 1, ctx); - emit_instr(ctx, bltz, tcc_reg, b_off); + emit_instr(ctx, bltz, MIPS_R_T8, b_off); /* * prog = array->ptrs[index]; * if (prog == NULL) * goto out; */ /* Delay slot */ - emit_instr(ctx, dsll, MIPS_R_T8, MIPS_R_A2, 3); - emit_instr(ctx, daddu, MIPS_R_T8, MIPS_R_T8, MIPS_R_A1); + emit_instr_long(ctx, dsll, sll, MIPS_R_AT, LO(r3), ilog2(sizeof(long))); + emit_instr_long(ctx, daddu, addu, MIPS_R_AT, MIPS_R_AT, LO(r2)); off = offsetof(struct bpf_array, ptrs); - emit_instr(ctx, ld, MIPS_R_AT, off, MIPS_R_T8); + emit_instr_long(ctx, ld, lw, MIPS_R_AT, off, MIPS_R_AT); b_off = b_imm(this_idx + 1, ctx); - emit_instr(ctx, beq, MIPS_R_AT, MIPS_R_ZERO, b_off); + emit_instr(ctx, beqz, MIPS_R_AT, b_off); /* Delay slot */ emit_instr(ctx, nop); /* goto *(prog->bpf_func + 4); */ off = offsetof(struct bpf_prog, bpf_func); - emit_instr(ctx, ld, MIPS_R_T9, off, MIPS_R_AT); - /* All systems are go... propagate TCC */ - emit_instr(ctx, daddu, MIPS_R_V1, MIPS_R_T5, MIPS_R_ZERO); + emit_instr_long(ctx, ld, lw, MIPS_R_T9, off, MIPS_R_AT); + /* All systems are go... decrement and propagate TCC */ + emit_instr_long(ctx, daddiu, addiu, tcc_run, MIPS_R_T8, -1); /* Skip first instruction (TCC initialization) */ - emit_instr(ctx, daddiu, MIPS_R_T9, MIPS_R_T9, 4); + emit_instr_long(ctx, daddiu, addiu, MIPS_R_T9, MIPS_R_T9, 4); return build_int_epilogue(ctx, MIPS_R_T9); } @@ -828,15 +1173,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, if (get_reg_val_type(ctx, this_idx, insn->dst_reg) == REG_32BIT) emit_instr(ctx, dinsu, dst, MIPS_R_ZERO, 32, 32); did_move = false; - if (insn->src_reg == BPF_REG_10) { - if (bpf_op == BPF_MOV) { - emit_instr(ctx, daddiu, dst, MIPS_R_SP, MAX_BPF_STACK); - did_move = true; - } else { - emit_instr(ctx, daddiu, MIPS_R_AT, MIPS_R_SP, MAX_BPF_STACK); - src = MIPS_R_AT; - } - } else if (get_reg_val_type(ctx, this_idx, insn->src_reg) == REG_32BIT) { + if (get_reg_val_type(ctx, this_idx, insn->src_reg) == REG_32BIT) { int tmp_reg = MIPS_R_AT; if (bpf_op == BPF_MOV) { @@ -917,7 +1254,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, case BPF_ALU | BPF_LSH | BPF_X: /* ALU_REG */ case BPF_ALU | BPF_RSH | BPF_X: /* ALU_REG */ case BPF_ALU | BPF_ARSH | BPF_X: /* ALU_REG */ - src = ebpf_to_mips_reg(ctx, insn, REG_SRC_NO_FP); + src = ebpf_to_mips_reg(ctx, insn, REG_SRC_FP_OK); dst = ebpf_to_mips_reg(ctx, insn, REG_DST_NO_FP); if (src < 0 || dst < 0) return -EINVAL; @@ -1029,8 +1366,8 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, case BPF_JMP | BPF_JGT | BPF_X: case BPF_JMP | BPF_JGE | BPF_X: case BPF_JMP | BPF_JSET | BPF_X: - src = ebpf_to_mips_reg(ctx, insn, REG_SRC_NO_FP); - dst = ebpf_to_mips_reg(ctx, insn, REG_DST_NO_FP); + src = ebpf_to_mips_reg(ctx, insn, REG_SRC_FP_OK); + dst = ebpf_to_mips_reg(ctx, insn, REG_DST_FP_OK); if (src < 0 || dst < 0) return -EINVAL; td = get_reg_val_type(ctx, this_idx, insn->dst_reg); @@ -1311,12 +1648,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, return 2; /* Double slot insn */ case BPF_JMP | BPF_CALL: - ctx->flags |= EBPF_SAVE_RA; - t64s = (s64)insn->imm + (long)__bpf_call_base; - emit_const_to_reg(ctx, MIPS_R_T9, (u64)t64s); - emit_instr(ctx, jalr, MIPS_R_RA, MIPS_R_T9); - /* delay slot */ - emit_instr(ctx, nop); + emit_bpf_call(ctx, insn); break; case BPF_JMP | BPF_TAIL_CALL: @@ -1364,16 +1696,10 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, case BPF_ST | BPF_H | BPF_MEM: case BPF_ST | BPF_W | BPF_MEM: case BPF_ST | BPF_DW | BPF_MEM: - if (insn->dst_reg == BPF_REG_10) { - ctx->flags |= EBPF_SEEN_FP; - dst = MIPS_R_SP; - mem_off = insn->off + MAX_BPF_STACK; - } else { - dst = ebpf_to_mips_reg(ctx, insn, REG_DST_NO_FP); - if (dst < 0) - return dst; - mem_off = insn->off; - } + dst = ebpf_to_mips_reg(ctx, insn, REG_DST_FP_OK); + if (dst < 0) + return dst; + mem_off = insn->off; gen_imm_to_reg(insn, MIPS_R_AT, ctx); switch (BPF_SIZE(insn->code)) { case BPF_B: @@ -1395,19 +1721,11 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, case BPF_LDX | BPF_H | BPF_MEM: case BPF_LDX | BPF_W | BPF_MEM: case BPF_LDX | BPF_DW | BPF_MEM: - if (insn->src_reg == BPF_REG_10) { - ctx->flags |= EBPF_SEEN_FP; - src = MIPS_R_SP; - mem_off = insn->off + MAX_BPF_STACK; - } else { - src = ebpf_to_mips_reg(ctx, insn, REG_SRC_NO_FP); - if (src < 0) - return src; - mem_off = insn->off; - } dst = ebpf_to_mips_reg(ctx, insn, REG_DST_NO_FP); - if (dst < 0) - return dst; + src = ebpf_to_mips_reg(ctx, insn, REG_SRC_FP_OK); + if (dst < 0 || src < 0) + return -EINVAL; + mem_off = insn->off; switch (BPF_SIZE(insn->code)) { case BPF_B: emit_instr(ctx, lbu, dst, mem_off, src); @@ -1430,25 +1748,16 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, case BPF_STX | BPF_DW | BPF_MEM: case BPF_STX | BPF_W | BPF_ATOMIC: case BPF_STX | BPF_DW | BPF_ATOMIC: - if (insn->dst_reg == BPF_REG_10) { - ctx->flags |= EBPF_SEEN_FP; - dst = MIPS_R_SP; - mem_off = insn->off + MAX_BPF_STACK; - } else { - dst = ebpf_to_mips_reg(ctx, insn, REG_DST_NO_FP); - if (dst < 0) - return dst; - mem_off = insn->off; - } - src = ebpf_to_mips_reg(ctx, insn, REG_SRC_NO_FP); - if (src < 0) - return src; + dst = ebpf_to_mips_reg(ctx, insn, REG_DST_FP_OK); + src = ebpf_to_mips_reg(ctx, insn, REG_SRC_FP_OK); + if (src < 0 || dst < 0) + return -EINVAL; + mem_off = insn->off; if (BPF_MODE(insn->code) == BPF_ATOMIC) { if (insn->imm != BPF_ADD) { pr_err("ATOMIC OP %02x NOT HANDLED\n", insn->imm); return -EINVAL; } - /* * If mem_off does not fit within the 9 bit ll/sc * instruction immediate field, use a temp reg. @@ -1829,6 +2138,73 @@ static void jit_fill_hole(void *area, unsigned int size) uasm_i_break(&p, BRK_BUG); /* Increments p */ } +/* + * Save and restore the BPF VM state across a direct kernel call. This + * includes the caller-saved registers used for BPF_REG_0 .. BPF_REG_5 + * and BPF_REG_AX used by the verifier for blinding and other dark arts. + * Restore avoids clobbering bpf_ret, which holds the call return value. + * BPF_REG_6 .. BPF_REG_10 and TCC are already callee-saved or on stack. + */ +static const int bpf_caller_save[] = { + BPF_REG_0, + BPF_REG_1, + BPF_REG_2, + BPF_REG_3, + BPF_REG_4, + BPF_REG_5, + BPF_REG_AX, +}; + +#define CALLER_ENV_SIZE (ARRAY_SIZE(bpf_caller_save) * sizeof(u64)) + +void emit_caller_save(struct jit_ctx *ctx) +{ + int stack_adj = ALIGN(CALLER_ENV_SIZE, STACK_ALIGN); + int i, bpf, reg, store_offset; + + emit_instr_long(ctx, daddiu, addiu, MIPS_R_SP, MIPS_R_SP, -stack_adj); + + for (i = 0; i < ARRAY_SIZE(bpf_caller_save); i++) { + bpf = bpf_caller_save[i]; + reg = bpf2mips[bpf].reg; + store_offset = i * sizeof(u64); + + if (is64bit()) { + emit_instr(ctx, sd, reg, store_offset, MIPS_R_SP); + } else { + emit_instr(ctx, sw, LO(reg), + OFFLO(store_offset), MIPS_R_SP); + emit_instr(ctx, sw, HI(reg), + OFFHI(store_offset), MIPS_R_SP); + } + } +} + +void emit_caller_restore(struct jit_ctx *ctx, int bpf_ret) +{ + int stack_adj = ALIGN(CALLER_ENV_SIZE, STACK_ALIGN); + int i, bpf, reg, store_offset; + + for (i = 0; i < ARRAY_SIZE(bpf_caller_save); i++) { + bpf = bpf_caller_save[i]; + reg = bpf2mips[bpf].reg; + store_offset = i * sizeof(u64); + if (bpf == bpf_ret) + continue; + + if (is64bit()) { + emit_instr(ctx, ld, reg, store_offset, MIPS_R_SP); + } else { + emit_instr(ctx, lw, LO(reg), + OFFLO(store_offset), MIPS_R_SP); + emit_instr(ctx, lw, HI(reg), + OFFHI(store_offset), MIPS_R_SP); + } + } + + emit_instr_long(ctx, daddiu, addiu, MIPS_R_SP, MIPS_R_SP, stack_adj); +} + struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) { struct bpf_prog *orig_prog = prog; @@ -1889,14 +2265,14 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) goto out_err; /* - * If no calls are made (EBPF_SAVE_RA), then tail call count - * in $v1, else we must save in n$s4. + * If no calls are made (EBPF_SAVE_RA), then tailcall count located + * in runtime reg if defined, else we backup to save reg or stack. */ - if (ctx.flags & EBPF_SEEN_TC) { + if (tail_call_present(&ctx)) { if (ctx.flags & EBPF_SAVE_RA) - ctx.flags |= EBPF_SAVE_S4; - else - ctx.flags |= EBPF_TCC_IN_V1; + ctx.flags |= bpf2mips[JIT_SAV_TCC].flags; + else if (bpf2mips[JIT_RUN_TCC].reg) + ctx.flags |= EBPF_TCC_IN_RUN; } /* @@ -1910,7 +2286,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) ctx.idx = 0; ctx.gen_b_offsets = 1; ctx.long_b_conversion = 0; - if (gen_int_prologue(&ctx)) + if (build_int_prologue(&ctx)) goto out_err; if (build_int_body(&ctx)) goto out_err; @@ -1929,7 +2305,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) /* Third pass generates the code */ ctx.idx = 0; - if (gen_int_prologue(&ctx)) + if (build_int_prologue(&ctx)) goto out_err; if (build_int_body(&ctx)) goto out_err;