diff options
Diffstat (limited to 'arch/powerpc/net/bpf_jit_comp.c')
-rw-r--r-- | arch/powerpc/net/bpf_jit_comp.c | 276 |
1 files changed, 276 insertions, 0 deletions
diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c new file mode 100644 index 0000000000..37043dfc1a --- /dev/null +++ b/arch/powerpc/net/bpf_jit_comp.c @@ -0,0 +1,276 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * eBPF JIT compiler + * + * Copyright 2016 Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> + * IBM Corporation + * + * Based on the powerpc classic BPF JIT compiler by Matt Evans + */ +#include <linux/moduleloader.h> +#include <asm/cacheflush.h> +#include <asm/asm-compat.h> +#include <linux/netdevice.h> +#include <linux/filter.h> +#include <linux/if_vlan.h> +#include <asm/kprobes.h> +#include <linux/bpf.h> + +#include "bpf_jit.h" + +static void bpf_jit_fill_ill_insns(void *area, unsigned int size) +{ + memset32(area, BREAKPOINT_INSTRUCTION, size / 4); +} + +int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, long exit_addr) +{ + if (!exit_addr || is_offset_in_branch_range(exit_addr - (ctx->idx * 4))) { + PPC_JMP(exit_addr); + } else if (ctx->alt_exit_addr) { + if (WARN_ON(!is_offset_in_branch_range((long)ctx->alt_exit_addr - (ctx->idx * 4)))) + return -1; + PPC_JMP(ctx->alt_exit_addr); + } else { + ctx->alt_exit_addr = ctx->idx * 4; + bpf_jit_build_epilogue(image, ctx); + } + + return 0; +} + +struct powerpc64_jit_data { + struct bpf_binary_header *header; + u32 *addrs; + u8 *image; + u32 proglen; + struct codegen_context ctx; +}; + +bool bpf_jit_needs_zext(void) +{ + return true; +} + +struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) +{ + u32 proglen; + u32 alloclen; + u8 *image = NULL; + u32 *code_base; + u32 *addrs; + struct powerpc64_jit_data *jit_data; + struct codegen_context cgctx; + int pass; + int flen; + struct bpf_binary_header *bpf_hdr; + struct bpf_prog *org_fp = fp; + struct bpf_prog *tmp_fp; + bool bpf_blinded = false; + bool extra_pass = false; + u32 extable_len; + u32 fixup_len; + + if (!fp->jit_requested) + return org_fp; + + tmp_fp = bpf_jit_blind_constants(org_fp); + if (IS_ERR(tmp_fp)) + return org_fp; + + if (tmp_fp != org_fp) { + bpf_blinded = true; + fp = tmp_fp; + } + + jit_data = fp->aux->jit_data; + if (!jit_data) { + jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL); + if (!jit_data) { + fp = org_fp; + goto out; + } + fp->aux->jit_data = jit_data; + } + + flen = fp->len; + addrs = jit_data->addrs; + if (addrs) { + cgctx = jit_data->ctx; + image = jit_data->image; + bpf_hdr = jit_data->header; + proglen = jit_data->proglen; + extra_pass = true; + /* During extra pass, ensure index is reset before repopulating extable entries */ + cgctx.exentry_idx = 0; + goto skip_init_ctx; + } + + addrs = kcalloc(flen + 1, sizeof(*addrs), GFP_KERNEL); + if (addrs == NULL) { + fp = org_fp; + goto out_addrs; + } + + memset(&cgctx, 0, sizeof(struct codegen_context)); + bpf_jit_init_reg_mapping(&cgctx); + + /* Make sure that the stack is quadword aligned. */ + cgctx.stack_size = round_up(fp->aux->stack_depth, 16); + + /* Scouting faux-generate pass 0 */ + if (bpf_jit_build_body(fp, 0, &cgctx, addrs, 0, false)) { + /* We hit something illegal or unsupported. */ + fp = org_fp; + goto out_addrs; + } + + /* + * If we have seen a tail call, we need a second pass. + * This is because bpf_jit_emit_common_epilogue() is called + * from bpf_jit_emit_tail_call() with a not yet stable ctx->seen. + * We also need a second pass if we ended up with too large + * a program so as to ensure BPF_EXIT branches are in range. + */ + if (cgctx.seen & SEEN_TAILCALL || !is_offset_in_branch_range((long)cgctx.idx * 4)) { + cgctx.idx = 0; + if (bpf_jit_build_body(fp, 0, &cgctx, addrs, 0, false)) { + fp = org_fp; + goto out_addrs; + } + } + + bpf_jit_realloc_regs(&cgctx); + /* + * Pretend to build prologue, given the features we've seen. This will + * update ctgtx.idx as it pretends to output instructions, then we can + * calculate total size from idx. + */ + bpf_jit_build_prologue(0, &cgctx); + addrs[fp->len] = cgctx.idx * 4; + bpf_jit_build_epilogue(0, &cgctx); + + fixup_len = fp->aux->num_exentries * BPF_FIXUP_LEN * 4; + extable_len = fp->aux->num_exentries * sizeof(struct exception_table_entry); + + proglen = cgctx.idx * 4; + alloclen = proglen + FUNCTION_DESCR_SIZE + fixup_len + extable_len; + + bpf_hdr = bpf_jit_binary_alloc(alloclen, &image, 4, bpf_jit_fill_ill_insns); + if (!bpf_hdr) { + fp = org_fp; + goto out_addrs; + } + + if (extable_len) + fp->aux->extable = (void *)image + FUNCTION_DESCR_SIZE + proglen + fixup_len; + +skip_init_ctx: + code_base = (u32 *)(image + FUNCTION_DESCR_SIZE); + + /* Code generation passes 1-2 */ + for (pass = 1; pass < 3; pass++) { + /* Now build the prologue, body code & epilogue for real. */ + cgctx.idx = 0; + cgctx.alt_exit_addr = 0; + bpf_jit_build_prologue(code_base, &cgctx); + if (bpf_jit_build_body(fp, code_base, &cgctx, addrs, pass, extra_pass)) { + bpf_jit_binary_free(bpf_hdr); + fp = org_fp; + goto out_addrs; + } + bpf_jit_build_epilogue(code_base, &cgctx); + + if (bpf_jit_enable > 1) + pr_info("Pass %d: shrink = %d, seen = 0x%x\n", pass, + proglen - (cgctx.idx * 4), cgctx.seen); + } + + if (bpf_jit_enable > 1) + /* + * Note that we output the base address of the code_base + * rather than image, since opcodes are in code_base. + */ + bpf_jit_dump(flen, proglen, pass, code_base); + +#ifdef CONFIG_PPC64_ELF_ABI_V1 + /* Function descriptor nastiness: Address + TOC */ + ((u64 *)image)[0] = (u64)code_base; + ((u64 *)image)[1] = local_paca->kernel_toc; +#endif + + fp->bpf_func = (void *)image; + fp->jited = 1; + fp->jited_len = proglen + FUNCTION_DESCR_SIZE; + + bpf_flush_icache(bpf_hdr, (u8 *)bpf_hdr + bpf_hdr->size); + if (!fp->is_func || extra_pass) { + bpf_jit_binary_lock_ro(bpf_hdr); + bpf_prog_fill_jited_linfo(fp, addrs); +out_addrs: + kfree(addrs); + kfree(jit_data); + fp->aux->jit_data = NULL; + } else { + jit_data->addrs = addrs; + jit_data->ctx = cgctx; + jit_data->proglen = proglen; + jit_data->image = image; + jit_data->header = bpf_hdr; + } + +out: + if (bpf_blinded) + bpf_jit_prog_release_other(fp, fp == org_fp ? tmp_fp : org_fp); + + return fp; +} + +/* + * The caller should check for (BPF_MODE(code) == BPF_PROBE_MEM) before calling + * this function, as this only applies to BPF_PROBE_MEM, for now. + */ +int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, int pass, struct codegen_context *ctx, + int insn_idx, int jmp_off, int dst_reg) +{ + off_t offset; + unsigned long pc; + struct exception_table_entry *ex; + u32 *fixup; + + /* Populate extable entries only in the last pass */ + if (pass != 2) + return 0; + + if (!fp->aux->extable || + WARN_ON_ONCE(ctx->exentry_idx >= fp->aux->num_exentries)) + return -EINVAL; + + pc = (unsigned long)&image[insn_idx]; + + fixup = (void *)fp->aux->extable - + (fp->aux->num_exentries * BPF_FIXUP_LEN * 4) + + (ctx->exentry_idx * BPF_FIXUP_LEN * 4); + + fixup[0] = PPC_RAW_LI(dst_reg, 0); + if (IS_ENABLED(CONFIG_PPC32)) + fixup[1] = PPC_RAW_LI(dst_reg - 1, 0); /* clear higher 32-bit register too */ + + fixup[BPF_FIXUP_LEN - 1] = + PPC_RAW_BRANCH((long)(pc + jmp_off) - (long)&fixup[BPF_FIXUP_LEN - 1]); + + ex = &fp->aux->extable[ctx->exentry_idx]; + + offset = pc - (long)&ex->insn; + if (WARN_ON_ONCE(offset >= 0 || offset < INT_MIN)) + return -ERANGE; + ex->insn = offset; + + offset = (long)fixup - (long)&ex->fixup; + if (WARN_ON_ONCE(offset >= 0 || offset < INT_MIN)) + return -ERANGE; + ex->fixup = offset; + + ctx->exentry_idx++; + return 0; +} |