diff options
Diffstat (limited to 'arch/x86/net/bpf_jit_comp.c')
-rw-r--r-- | arch/x86/net/bpf_jit_comp.c | 278 |
1 files changed, 200 insertions, 78 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 9ba08e9abc09..42b6709e6dc7 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -158,6 +158,19 @@ static bool is_ereg(u32 reg) BIT(BPF_REG_AX)); } +/* + * is_ereg_8l() == true if BPF register 'reg' is mapped to access x86-64 + * lower 8-bit registers dil,sil,bpl,spl,r8b..r15b, which need extra byte + * of encoding. al,cl,dl,bl have simpler encoding. + */ +static bool is_ereg_8l(u32 reg) +{ + return is_ereg(reg) || + (1 << reg) & (BIT(BPF_REG_1) | + BIT(BPF_REG_2) | + BIT(BPF_REG_FP)); +} + static bool is_axreg(u32 reg) { return reg == BPF_REG_0; @@ -598,9 +611,8 @@ static void emit_stx(u8 **pprog, u32 size, u32 dst_reg, u32 src_reg, int off) switch (size) { case BPF_B: /* Emit 'mov byte ptr [rax + off], al' */ - if (is_ereg(dst_reg) || is_ereg(src_reg) || - /* We have to add extra byte for x86 SIL, DIL regs */ - src_reg == BPF_REG_1 || src_reg == BPF_REG_2) + if (is_ereg(dst_reg) || is_ereg_8l(src_reg)) + /* Add extra byte for eregs or SIL,DIL,BPL in src_reg */ EMIT2(add_2mod(0x40, dst_reg, src_reg), 0x88); else EMIT1(0x88); @@ -1361,37 +1373,140 @@ static void restore_regs(const struct btf_func_model *m, u8 **prog, int nr_args, -(stack_size - i * 8)); } +static int invoke_bpf_prog(const struct btf_func_model *m, u8 **pprog, + struct bpf_prog *p, int stack_size, bool mod_ret) +{ + u8 *prog = *pprog; + int cnt = 0; + + if (emit_call(&prog, __bpf_prog_enter, prog)) + return -EINVAL; + /* remember prog start time returned by __bpf_prog_enter */ + emit_mov_reg(&prog, true, BPF_REG_6, BPF_REG_0); + + /* arg1: lea rdi, [rbp - stack_size] */ + EMIT4(0x48, 0x8D, 0x7D, -stack_size); + /* arg2: progs[i]->insnsi for interpreter */ + if (!p->jited) + emit_mov_imm64(&prog, BPF_REG_2, + (long) p->insnsi >> 32, + (u32) (long) p->insnsi); + /* call JITed bpf program or interpreter */ + if (emit_call(&prog, p->bpf_func, prog)) + return -EINVAL; + + /* BPF_TRAMP_MODIFY_RETURN trampolines can modify the return + * of the previous call which is then passed on the stack to + * the next BPF program. + */ + if (mod_ret) + emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8); + + /* arg1: mov rdi, progs[i] */ + emit_mov_imm64(&prog, BPF_REG_1, (long) p >> 32, + (u32) (long) p); + /* arg2: mov rsi, rbx <- start time in nsec */ + emit_mov_reg(&prog, true, BPF_REG_2, BPF_REG_6); + if (emit_call(&prog, __bpf_prog_exit, prog)) + return -EINVAL; + + *pprog = prog; + return 0; +} + +static void emit_nops(u8 **pprog, unsigned int len) +{ + unsigned int i, noplen; + u8 *prog = *pprog; + int cnt = 0; + + while (len > 0) { + noplen = len; + + if (noplen > ASM_NOP_MAX) + noplen = ASM_NOP_MAX; + + for (i = 0; i < noplen; i++) + EMIT1(ideal_nops[noplen][i]); + len -= noplen; + } + + *pprog = prog; +} + +static void emit_align(u8 **pprog, u32 align) +{ + u8 *target, *prog = *pprog; + + target = PTR_ALIGN(prog, align); + if (target != prog) + emit_nops(&prog, target - prog); + + *pprog = prog; +} + +static int emit_cond_near_jump(u8 **pprog, void *func, void *ip, u8 jmp_cond) +{ + u8 *prog = *pprog; + int cnt = 0; + s64 offset; + + offset = func - (ip + 2 + 4); + if (!is_simm32(offset)) { + pr_err("Target %p is out of range\n", func); + return -EINVAL; + } + EMIT2_off32(0x0F, jmp_cond + 0x10, offset); + *pprog = prog; + return 0; +} + static int invoke_bpf(const struct btf_func_model *m, u8 **pprog, - struct bpf_prog **progs, int prog_cnt, int stack_size) + struct bpf_tramp_progs *tp, int stack_size) { + int i; u8 *prog = *pprog; - int cnt = 0, i; - for (i = 0; i < prog_cnt; i++) { - if (emit_call(&prog, __bpf_prog_enter, prog)) - return -EINVAL; - /* remember prog start time returned by __bpf_prog_enter */ - emit_mov_reg(&prog, true, BPF_REG_6, BPF_REG_0); - - /* arg1: lea rdi, [rbp - stack_size] */ - EMIT4(0x48, 0x8D, 0x7D, -stack_size); - /* arg2: progs[i]->insnsi for interpreter */ - if (!progs[i]->jited) - emit_mov_imm64(&prog, BPF_REG_2, - (long) progs[i]->insnsi >> 32, - (u32) (long) progs[i]->insnsi); - /* call JITed bpf program or interpreter */ - if (emit_call(&prog, progs[i]->bpf_func, prog)) + for (i = 0; i < tp->nr_progs; i++) { + if (invoke_bpf_prog(m, &prog, tp->progs[i], stack_size, false)) return -EINVAL; + } + *pprog = prog; + return 0; +} + +static int invoke_bpf_mod_ret(const struct btf_func_model *m, u8 **pprog, + struct bpf_tramp_progs *tp, int stack_size, + u8 **branches) +{ + u8 *prog = *pprog; + int i, cnt = 0; - /* arg1: mov rdi, progs[i] */ - emit_mov_imm64(&prog, BPF_REG_1, (long) progs[i] >> 32, - (u32) (long) progs[i]); - /* arg2: mov rsi, rbx <- start time in nsec */ - emit_mov_reg(&prog, true, BPF_REG_2, BPF_REG_6); - if (emit_call(&prog, __bpf_prog_exit, prog)) + /* The first fmod_ret program will receive a garbage return value. + * Set this to 0 to avoid confusing the program. + */ + emit_mov_imm32(&prog, false, BPF_REG_0, 0); + emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8); + for (i = 0; i < tp->nr_progs; i++) { + if (invoke_bpf_prog(m, &prog, tp->progs[i], stack_size, true)) return -EINVAL; + + /* mod_ret prog stored return value into [rbp - 8]. Emit: + * if (*(u64 *)(rbp - 8) != 0) + * goto do_fexit; + */ + /* cmp QWORD PTR [rbp - 0x8], 0x0 */ + EMIT4(0x48, 0x83, 0x7d, 0xf8); EMIT1(0x00); + + /* Save the location of the branch and Generate 6 nops + * (4 bytes for an offset and 2 bytes for the jump) These nops + * are replaced with a conditional jump once do_fexit (i.e. the + * start of the fexit invocation) is finalized. + */ + branches[i] = prog; + emit_nops(&prog, 4 + 2); } + *pprog = prog; return 0; } @@ -1458,12 +1573,15 @@ static int invoke_bpf(const struct btf_func_model *m, u8 **pprog, */ int arch_prepare_bpf_trampoline(void *image, void *image_end, const struct btf_func_model *m, u32 flags, - struct bpf_prog **fentry_progs, int fentry_cnt, - struct bpf_prog **fexit_progs, int fexit_cnt, + struct bpf_tramp_progs *tprogs, void *orig_call) { - int cnt = 0, nr_args = m->nr_args; + int ret, i, cnt = 0, nr_args = m->nr_args; int stack_size = nr_args * 8; + struct bpf_tramp_progs *fentry = &tprogs[BPF_TRAMP_FENTRY]; + struct bpf_tramp_progs *fexit = &tprogs[BPF_TRAMP_FEXIT]; + struct bpf_tramp_progs *fmod_ret = &tprogs[BPF_TRAMP_MODIFY_RETURN]; + u8 **branches = NULL; u8 *prog; /* x86-64 supports up to 6 arguments. 7+ can be added in the future */ @@ -1492,28 +1610,64 @@ int arch_prepare_bpf_trampoline(void *image, void *image_end, save_regs(m, &prog, nr_args, stack_size); - if (fentry_cnt) - if (invoke_bpf(m, &prog, fentry_progs, fentry_cnt, stack_size)) + if (fentry->nr_progs) + if (invoke_bpf(m, &prog, fentry, stack_size)) return -EINVAL; + if (fmod_ret->nr_progs) { + branches = kcalloc(fmod_ret->nr_progs, sizeof(u8 *), + GFP_KERNEL); + if (!branches) + return -ENOMEM; + + if (invoke_bpf_mod_ret(m, &prog, fmod_ret, stack_size, + branches)) { + ret = -EINVAL; + goto cleanup; + } + } + if (flags & BPF_TRAMP_F_CALL_ORIG) { - if (fentry_cnt) + if (fentry->nr_progs || fmod_ret->nr_progs) restore_regs(m, &prog, nr_args, stack_size); /* call original function */ - if (emit_call(&prog, orig_call, prog)) - return -EINVAL; + if (emit_call(&prog, orig_call, prog)) { + ret = -EINVAL; + goto cleanup; + } /* remember return value in a stack for bpf prog to access */ emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8); } - if (fexit_cnt) - if (invoke_bpf(m, &prog, fexit_progs, fexit_cnt, stack_size)) - return -EINVAL; + if (fmod_ret->nr_progs) { + /* From Intel 64 and IA-32 Architectures Optimization + * Reference Manual, 3.4.1.4 Code Alignment, Assembly/Compiler + * Coding Rule 11: All branch targets should be 16-byte + * aligned. + */ + emit_align(&prog, 16); + /* Update the branches saved in invoke_bpf_mod_ret with the + * aligned address of do_fexit. + */ + for (i = 0; i < fmod_ret->nr_progs; i++) + emit_cond_near_jump(&branches[i], prog, branches[i], + X86_JNE); + } + + if (fexit->nr_progs) + if (invoke_bpf(m, &prog, fexit, stack_size)) { + ret = -EINVAL; + goto cleanup; + } if (flags & BPF_TRAMP_F_RESTORE_REGS) restore_regs(m, &prog, nr_args, stack_size); + /* This needs to be done regardless. If there were fmod_ret programs, + * the return value is only updated on the stack and still needs to be + * restored to R0. + */ if (flags & BPF_TRAMP_F_CALL_ORIG) /* restore original return value back into RAX */ emit_ldx(&prog, BPF_DW, BPF_REG_0, BPF_REG_FP, -8); @@ -1525,45 +1679,15 @@ int arch_prepare_bpf_trampoline(void *image, void *image_end, EMIT4(0x48, 0x83, 0xC4, 8); /* add rsp, 8 */ EMIT1(0xC3); /* ret */ /* Make sure the trampoline generation logic doesn't overflow */ - if (WARN_ON_ONCE(prog > (u8 *)image_end - BPF_INSN_SAFETY)) - return -EFAULT; - return prog - (u8 *)image; -} - -static int emit_cond_near_jump(u8 **pprog, void *func, void *ip, u8 jmp_cond) -{ - u8 *prog = *pprog; - int cnt = 0; - s64 offset; - - offset = func - (ip + 2 + 4); - if (!is_simm32(offset)) { - pr_err("Target %p is out of range\n", func); - return -EINVAL; + if (WARN_ON_ONCE(prog > (u8 *)image_end - BPF_INSN_SAFETY)) { + ret = -EFAULT; + goto cleanup; } - EMIT2_off32(0x0F, jmp_cond + 0x10, offset); - *pprog = prog; - return 0; -} + ret = prog - (u8 *)image; -static void emit_nops(u8 **pprog, unsigned int len) -{ - unsigned int i, noplen; - u8 *prog = *pprog; - int cnt = 0; - - while (len > 0) { - noplen = len; - - if (noplen > ASM_NOP_MAX) - noplen = ASM_NOP_MAX; - - for (i = 0; i < noplen; i++) - EMIT1(ideal_nops[noplen][i]); - len -= noplen; - } - - *pprog = prog; +cleanup: + kfree(branches); + return ret; } static int emit_fallback_jump(u8 **pprog) @@ -1588,7 +1712,7 @@ static int emit_fallback_jump(u8 **pprog) static int emit_bpf_dispatcher(u8 **pprog, int a, int b, s64 *progs) { - u8 *jg_reloc, *jg_target, *prog = *pprog; + u8 *jg_reloc, *prog = *pprog; int pivot, err, jg_bytes = 1, cnt = 0; s64 jg_offset; @@ -1643,9 +1767,7 @@ static int emit_bpf_dispatcher(u8 **pprog, int a, int b, s64 *progs) * Coding Rule 11: All branch targets should be 16-byte * aligned. */ - jg_target = PTR_ALIGN(prog, 16); - if (jg_target != prog) - emit_nops(&prog, jg_target - prog); + emit_align(&prog, 16); jg_offset = prog - jg_reloc; emit_code(jg_reloc - jg_bytes, jg_offset, jg_bytes); |