From fe121ee531d1362810bfd30f38a1b88b1d3d376c Mon Sep 17 00:00:00 2001 From: Björn Töpel Date: Tue, 21 May 2019 15:46:22 +0200 Subject: bpf, riscv: clear target register high 32-bits for and/or/xor on ALU32 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When using 32-bit subregisters (ALU32), the RISC-V JIT would not clear the high 32-bits of the target register and therefore generate incorrect code. E.g., in the following code: $ cat test.c unsigned int f(unsigned long long a, unsigned int b) { return (unsigned int)a & b; } $ clang-9 -target bpf -O2 -emit-llvm -S test.c -o - | \ llc-9 -mattr=+alu32 -mcpu=v3 .text .file "test.c" .globl f .p2align 3 .type f,@function f: r0 = r1 w0 &= w2 exit .Lfunc_end0: .size f, .Lfunc_end0-f The JIT would not clear the high 32-bits of r0 after the and-operation, which in this case might give an incorrect return value. After this patch, that is not the case, and the upper 32-bits are cleared. Reported-by: Jiong Wang Fixes: 2353ecc6f91f ("bpf, riscv: add BPF JIT for RV64G") Signed-off-by: Björn Töpel Signed-off-by: Daniel Borkmann --- arch/riscv/net/bpf_jit_comp.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'arch') diff --git a/arch/riscv/net/bpf_jit_comp.c b/arch/riscv/net/bpf_jit_comp.c index 80b12aa5e10d..e5c8d675bd6e 100644 --- a/arch/riscv/net/bpf_jit_comp.c +++ b/arch/riscv/net/bpf_jit_comp.c @@ -759,14 +759,20 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, case BPF_ALU | BPF_AND | BPF_X: case BPF_ALU64 | BPF_AND | BPF_X: emit(rv_and(rd, rd, rs), ctx); + if (!is64) + emit_zext_32(rd, ctx); break; case BPF_ALU | BPF_OR | BPF_X: case BPF_ALU64 | BPF_OR | BPF_X: emit(rv_or(rd, rd, rs), ctx); + if (!is64) + emit_zext_32(rd, ctx); break; case BPF_ALU | BPF_XOR | BPF_X: case BPF_ALU64 | BPF_XOR | BPF_X: emit(rv_xor(rd, rd, rs), ctx); + if (!is64) + emit_zext_32(rd, ctx); break; case BPF_ALU | BPF_MUL | BPF_X: case BPF_ALU64 | BPF_MUL | BPF_X: -- cgit v1.2.3 From 1e692f09e091bf5c8b38384f297d6dae5dbf0f12 Mon Sep 17 00:00:00 2001 From: Luke Nelson Date: Thu, 30 May 2019 15:29:22 -0700 Subject: bpf, riscv: clear high 32 bits for ALU32 add/sub/neg/lsh/rsh/arsh MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In BPF, 32-bit ALU operations should zero-extend their results into the 64-bit registers. The current BPF JIT on RISC-V emits incorrect instructions that perform sign extension only (e.g., addw, subw) on 32-bit add, sub, lsh, rsh, arsh, and neg. This behavior diverges from the interpreter and JITs for other architectures. This patch fixes the bugs by performing zero extension on the destination register of 32-bit ALU operations. Fixes: 2353ecc6f91f ("bpf, riscv: add BPF JIT for RV64G") Cc: Xi Wang Signed-off-by: Luke Nelson Acked-by: Song Liu Acked-by: Björn Töpel Reviewed-by: Palmer Dabbelt Signed-off-by: Alexei Starovoitov --- arch/riscv/net/bpf_jit_comp.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'arch') diff --git a/arch/riscv/net/bpf_jit_comp.c b/arch/riscv/net/bpf_jit_comp.c index e5c8d675bd6e..426d5c33ea90 100644 --- a/arch/riscv/net/bpf_jit_comp.c +++ b/arch/riscv/net/bpf_jit_comp.c @@ -751,10 +751,14 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, case BPF_ALU | BPF_ADD | BPF_X: case BPF_ALU64 | BPF_ADD | BPF_X: emit(is64 ? rv_add(rd, rd, rs) : rv_addw(rd, rd, rs), ctx); + if (!is64) + emit_zext_32(rd, ctx); break; case BPF_ALU | BPF_SUB | BPF_X: case BPF_ALU64 | BPF_SUB | BPF_X: emit(is64 ? rv_sub(rd, rd, rs) : rv_subw(rd, rd, rs), ctx); + if (!is64) + emit_zext_32(rd, ctx); break; case BPF_ALU | BPF_AND | BPF_X: case BPF_ALU64 | BPF_AND | BPF_X: @@ -795,14 +799,20 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, case BPF_ALU | BPF_LSH | BPF_X: case BPF_ALU64 | BPF_LSH | BPF_X: emit(is64 ? rv_sll(rd, rd, rs) : rv_sllw(rd, rd, rs), ctx); + if (!is64) + emit_zext_32(rd, ctx); break; case BPF_ALU | BPF_RSH | BPF_X: case BPF_ALU64 | BPF_RSH | BPF_X: emit(is64 ? rv_srl(rd, rd, rs) : rv_srlw(rd, rd, rs), ctx); + if (!is64) + emit_zext_32(rd, ctx); break; case BPF_ALU | BPF_ARSH | BPF_X: case BPF_ALU64 | BPF_ARSH | BPF_X: emit(is64 ? rv_sra(rd, rd, rs) : rv_sraw(rd, rd, rs), ctx); + if (!is64) + emit_zext_32(rd, ctx); break; /* dst = -dst */ @@ -810,6 +820,8 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, case BPF_ALU64 | BPF_NEG: emit(is64 ? rv_sub(rd, RV_REG_ZERO, rd) : rv_subw(rd, RV_REG_ZERO, rd), ctx); + if (!is64) + emit_zext_32(rd, ctx); break; /* dst = BSWAP##imm(dst) */ @@ -964,14 +976,20 @@ out_be: case BPF_ALU | BPF_LSH | BPF_K: case BPF_ALU64 | BPF_LSH | BPF_K: emit(is64 ? rv_slli(rd, rd, imm) : rv_slliw(rd, rd, imm), ctx); + if (!is64) + emit_zext_32(rd, ctx); break; case BPF_ALU | BPF_RSH | BPF_K: case BPF_ALU64 | BPF_RSH | BPF_K: emit(is64 ? rv_srli(rd, rd, imm) : rv_srliw(rd, rd, imm), ctx); + if (!is64) + emit_zext_32(rd, ctx); break; case BPF_ALU | BPF_ARSH | BPF_K: case BPF_ALU64 | BPF_ARSH | BPF_K: emit(is64 ? rv_srai(rd, rd, imm) : rv_sraiw(rd, rd, imm), ctx); + if (!is64) + emit_zext_32(rd, ctx); break; /* JUMP off */ -- cgit v1.2.3 From 758f2046ea040773ae8ea7f72dd3bbd8fa984501 Mon Sep 17 00:00:00 2001 From: "Naveen N. Rao" Date: Thu, 13 Jun 2019 00:21:40 +0530 Subject: powerpc/bpf: use unsigned division instruction for 64-bit operations BPF_ALU64 div/mod operations are currently using signed division, unlike BPF_ALU32 operations. Fix the same. DIV64 and MOD64 overflow tests pass with this fix. Fixes: 156d0e290e969c ("powerpc/ebpf/jit: Implement JIT compiler for extended BPF") Cc: stable@vger.kernel.org # v4.8+ Signed-off-by: Naveen N. Rao Signed-off-by: Daniel Borkmann --- arch/powerpc/include/asm/ppc-opcode.h | 1 + arch/powerpc/net/bpf_jit.h | 2 +- arch/powerpc/net/bpf_jit_comp64.c | 8 ++++---- 3 files changed, 6 insertions(+), 5 deletions(-) (limited to 'arch') diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h index 493c5c943acd..2291daf39cd1 100644 --- a/arch/powerpc/include/asm/ppc-opcode.h +++ b/arch/powerpc/include/asm/ppc-opcode.h @@ -338,6 +338,7 @@ #define PPC_INST_MADDLD 0x10000033 #define PPC_INST_DIVWU 0x7c000396 #define PPC_INST_DIVD 0x7c0003d2 +#define PPC_INST_DIVDU 0x7c000392 #define PPC_INST_RLWINM 0x54000000 #define PPC_INST_RLWINM_DOT 0x54000001 #define PPC_INST_RLWIMI 0x50000000 diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h index dcac37745b05..1e932898d430 100644 --- a/arch/powerpc/net/bpf_jit.h +++ b/arch/powerpc/net/bpf_jit.h @@ -116,7 +116,7 @@ ___PPC_RA(a) | IMM_L(i)) #define PPC_DIVWU(d, a, b) EMIT(PPC_INST_DIVWU | ___PPC_RT(d) | \ ___PPC_RA(a) | ___PPC_RB(b)) -#define PPC_DIVD(d, a, b) EMIT(PPC_INST_DIVD | ___PPC_RT(d) | \ +#define PPC_DIVDU(d, a, b) EMIT(PPC_INST_DIVDU | ___PPC_RT(d) | \ ___PPC_RA(a) | ___PPC_RB(b)) #define PPC_AND(d, a, b) EMIT(PPC_INST_AND | ___PPC_RA(d) | \ ___PPC_RS(a) | ___PPC_RB(b)) diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 21a1dcd4b156..e3fedeffe40f 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -399,12 +399,12 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, case BPF_ALU64 | BPF_DIV | BPF_X: /* dst /= src */ case BPF_ALU64 | BPF_MOD | BPF_X: /* dst %= src */ if (BPF_OP(code) == BPF_MOD) { - PPC_DIVD(b2p[TMP_REG_1], dst_reg, src_reg); + PPC_DIVDU(b2p[TMP_REG_1], dst_reg, src_reg); PPC_MULD(b2p[TMP_REG_1], src_reg, b2p[TMP_REG_1]); PPC_SUB(dst_reg, dst_reg, b2p[TMP_REG_1]); } else - PPC_DIVD(dst_reg, dst_reg, src_reg); + PPC_DIVDU(dst_reg, dst_reg, src_reg); break; case BPF_ALU | BPF_MOD | BPF_K: /* (u32) dst %= (u32) imm */ case BPF_ALU | BPF_DIV | BPF_K: /* (u32) dst /= (u32) imm */ @@ -432,7 +432,7 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, break; case BPF_ALU64: if (BPF_OP(code) == BPF_MOD) { - PPC_DIVD(b2p[TMP_REG_2], dst_reg, + PPC_DIVDU(b2p[TMP_REG_2], dst_reg, b2p[TMP_REG_1]); PPC_MULD(b2p[TMP_REG_1], b2p[TMP_REG_1], @@ -440,7 +440,7 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, PPC_SUB(dst_reg, dst_reg, b2p[TMP_REG_1]); } else - PPC_DIVD(dst_reg, dst_reg, + PPC_DIVDU(dst_reg, dst_reg, b2p[TMP_REG_1]); break; } -- cgit v1.2.3 From fe8d9571dc50232b569242fac7ea6332a654f186 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Fri, 14 Jun 2019 15:43:28 -0700 Subject: bpf, x64: fix stack layout of JITed bpf code Since commit 177366bf7ceb the %rbp stopped pointing to %rbp of the previous stack frame. That broke frame pointer based stack unwinding. This commit is a partial revert of it. Note that the location of tail_call_cnt is fixed, since the verifier enforces MAX_BPF_STACK stack size for programs with tail calls. Fixes: 177366bf7ceb ("bpf: change x86 JITed program stack layout") Signed-off-by: Alexei Starovoitov --- arch/x86/net/bpf_jit_comp.c | 74 +++++++++++++-------------------------------- 1 file changed, 21 insertions(+), 53 deletions(-) (limited to 'arch') diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index afabf597c855..d88bc0935886 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -190,9 +190,7 @@ struct jit_context { #define BPF_MAX_INSN_SIZE 128 #define BPF_INSN_SAFETY 64 -#define AUX_STACK_SPACE 40 /* Space for RBX, R13, R14, R15, tailcnt */ - -#define PROLOGUE_SIZE 37 +#define PROLOGUE_SIZE 20 /* * Emit x86-64 prologue code for BPF program and check its size. @@ -203,44 +201,19 @@ static void emit_prologue(u8 **pprog, u32 stack_depth, bool ebpf_from_cbpf) u8 *prog = *pprog; int cnt = 0; - /* push rbp */ - EMIT1(0x55); - - /* mov rbp,rsp */ - EMIT3(0x48, 0x89, 0xE5); - - /* sub rsp, rounded_stack_depth + AUX_STACK_SPACE */ - EMIT3_off32(0x48, 0x81, 0xEC, - round_up(stack_depth, 8) + AUX_STACK_SPACE); - - /* sub rbp, AUX_STACK_SPACE */ - EMIT4(0x48, 0x83, 0xED, AUX_STACK_SPACE); - - /* mov qword ptr [rbp+0],rbx */ - EMIT4(0x48, 0x89, 0x5D, 0); - /* mov qword ptr [rbp+8],r13 */ - EMIT4(0x4C, 0x89, 0x6D, 8); - /* mov qword ptr [rbp+16],r14 */ - EMIT4(0x4C, 0x89, 0x75, 16); - /* mov qword ptr [rbp+24],r15 */ - EMIT4(0x4C, 0x89, 0x7D, 24); - + EMIT1(0x55); /* push rbp */ + EMIT3(0x48, 0x89, 0xE5); /* mov rbp, rsp */ + /* sub rsp, rounded_stack_depth */ + EMIT3_off32(0x48, 0x81, 0xEC, round_up(stack_depth, 8)); + EMIT1(0x53); /* push rbx */ + EMIT2(0x41, 0x55); /* push r13 */ + EMIT2(0x41, 0x56); /* push r14 */ + EMIT2(0x41, 0x57); /* push r15 */ if (!ebpf_from_cbpf) { - /* - * Clear the tail call counter (tail_call_cnt): for eBPF tail - * calls we need to reset the counter to 0. It's done in two - * instructions, resetting RAX register to 0, and moving it - * to the counter location. - */ - - /* xor eax, eax */ - EMIT2(0x31, 0xc0); - /* mov qword ptr [rbp+32], rax */ - EMIT4(0x48, 0x89, 0x45, 32); - + /* zero init tail_call_cnt */ + EMIT2(0x6a, 0x00); BUILD_BUG_ON(cnt != PROLOGUE_SIZE); } - *pprog = prog; } @@ -285,13 +258,13 @@ static void emit_bpf_tail_call(u8 **pprog) * if (tail_call_cnt > MAX_TAIL_CALL_CNT) * goto out; */ - EMIT2_off32(0x8B, 0x85, 36); /* mov eax, dword ptr [rbp + 36] */ + EMIT2_off32(0x8B, 0x85, -36 - MAX_BPF_STACK); /* mov eax, dword ptr [rbp - 548] */ EMIT3(0x83, 0xF8, MAX_TAIL_CALL_CNT); /* cmp eax, MAX_TAIL_CALL_CNT */ #define OFFSET2 (30 + RETPOLINE_RAX_BPF_JIT_SIZE) EMIT2(X86_JA, OFFSET2); /* ja out */ label2 = cnt; EMIT3(0x83, 0xC0, 0x01); /* add eax, 1 */ - EMIT2_off32(0x89, 0x85, 36); /* mov dword ptr [rbp + 36], eax */ + EMIT2_off32(0x89, 0x85, -36 - MAX_BPF_STACK); /* mov dword ptr [rbp -548], eax */ /* prog = array->ptrs[index]; */ EMIT4_off32(0x48, 0x8B, 0x84, 0xD6, /* mov rax, [rsi + rdx * 8 + offsetof(...)] */ @@ -1040,19 +1013,14 @@ emit_jmp: seen_exit = true; /* Update cleanup_addr */ ctx->cleanup_addr = proglen; - /* mov rbx, qword ptr [rbp+0] */ - EMIT4(0x48, 0x8B, 0x5D, 0); - /* mov r13, qword ptr [rbp+8] */ - EMIT4(0x4C, 0x8B, 0x6D, 8); - /* mov r14, qword ptr [rbp+16] */ - EMIT4(0x4C, 0x8B, 0x75, 16); - /* mov r15, qword ptr [rbp+24] */ - EMIT4(0x4C, 0x8B, 0x7D, 24); - - /* add rbp, AUX_STACK_SPACE */ - EMIT4(0x48, 0x83, 0xC5, AUX_STACK_SPACE); - EMIT1(0xC9); /* leave */ - EMIT1(0xC3); /* ret */ + if (!bpf_prog_was_classic(bpf_prog)) + EMIT1(0x5B); /* get rid of tail_call_cnt */ + EMIT2(0x41, 0x5F); /* pop r15 */ + EMIT2(0x41, 0x5E); /* pop r14 */ + EMIT2(0x41, 0x5D); /* pop r13 */ + EMIT1(0x5B); /* pop rbx */ + EMIT1(0xC9); /* leave */ + EMIT1(0xC3); /* ret */ break; default: -- cgit v1.2.3