From patchwork Thu Jun 20 19:09:11 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Naveen N Rao X-Patchwork-Id: 13706275 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A74C224B26; Thu, 20 Jun 2024 19:09:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718910587; cv=none; b=WlyDzMc8+ZbjfXe5/0O9Zg2ucCIELpErxvpukEJsxPGYbh7+80gtxe4oP7ziqKRFlpITgddnw74Gs6ME+np87iVsHWgJpb2xOqnlBfEHCnG75NKJz4pSwzJtwYNMRa//X5N++uuQ9hEcbxtoAUcoBEVuuCwka3IJhLqCf7mPz94= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718910587; c=relaxed/simple; bh=13GFPwydLSEBN9vpa04BPNvFnpkcKl9YVFtQB7AEGV0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=tAWpoOSSaLoVu25Kvz4z0w8GDzg7ee2NcmGjMM7LIrzjEhRcXS7Oklqn0643ApMl86wNoEh9dEB9dDXMEYiX5RqLIdRlFcfdNS/qFm3iuduYgv+D8g8iEhvP/RrEF89gb55OhUuEZT01ADYWvKP6erWYxK+OXdn7+AOsTYS9Qs0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=RPyzbi7y; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="RPyzbi7y" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2FC93C2BD10; Thu, 20 Jun 2024 19:09:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1718910587; bh=13GFPwydLSEBN9vpa04BPNvFnpkcKl9YVFtQB7AEGV0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RPyzbi7y0H6LuTdgSwPog7paSQniTTmPV1DrH0CxdNC7lsERmAI+TE2eLuLy3wEYi /eA22pHJvLr8DlWPVMwQweCecjhkEyCY9BeSkZJP/jTy1OU1Tc56xP5B0CXjpL31FS e5AL0wxYzkLY7Lme7sJQlbnkdI+YLPzo2jfRcfSO4tCCSlHqQmu9odrnodbafq535A 2S8tLKwrIuzZjtXdFcp0FJlR/JQSSkE0yK1LVXT6SUadXJ63LINiR4ZLScgEuWO8iR 0Wyi4xk+a1LfzvIZibKE4m0KOl3HLfBybSE9iNNpTVFjjd/nNYe8jhdm/WDW9n9Mzb 1ZQDm7hQfPT8w== From: Naveen N Rao To: , , Cc: Michael Ellerman , Steven Rostedt , Masami Hiramatsu , Nicholas Piggin , Christophe Leroy , Masahiro Yamada , Mark Rutland , Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Song Liu , Jiri Olsa Subject: [RFC PATCH v3 11/11] powerpc64/bpf: Add support for bpf trampolines Date: Fri, 21 Jun 2024 00:39:11 +0530 Message-ID: X-Mailer: git-send-email 2.45.2 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Add support for bpf_arch_text_poke() and arch_prepare_bpf_trampoline() for 64-bit powerpc. BPF prog JIT is extended to mimic 64-bit powerpc approach for ftrace having a single nop at function entry, followed by the function profiling sequence out-of-line and a separate long branch stub for calls to trampolines that are out of range. A dummy_tramp is provided to simplify synchronization similar to arm64. BPF Trampolines adhere to the existing ftrace ABI utilizing a two-instruction profiling sequence, as well as the newer ABI utilizing a three-instruction profiling sequence enabling return with a 'blr'. The trampoline code itself closely follows x86 implementation. While the code is generic, BPF trampolines are only enabled on 64-bit powerpc. 32-bit powerpc will need testing and some updates. Signed-off-by: Naveen N Rao --- arch/powerpc/include/asm/ppc-opcode.h | 14 + arch/powerpc/net/bpf_jit.h | 11 + arch/powerpc/net/bpf_jit_comp.c | 702 +++++++++++++++++++++++++- arch/powerpc/net/bpf_jit_comp32.c | 7 +- arch/powerpc/net/bpf_jit_comp64.c | 7 +- 5 files changed, 738 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h index 076ae60b4a55..9eaa2c5d9b73 100644 --- a/arch/powerpc/include/asm/ppc-opcode.h +++ b/arch/powerpc/include/asm/ppc-opcode.h @@ -585,12 +585,26 @@ #define PPC_RAW_MTSPR(spr, d) (0x7c0003a6 | ___PPC_RS(d) | __PPC_SPR(spr)) #define PPC_RAW_EIEIO() (0x7c0006ac) +/* bcl 20,31,$+4 */ +#define PPC_RAW_BCL() (0x429f0005) #define PPC_RAW_BRANCH(offset) (0x48000000 | PPC_LI(offset)) #define PPC_RAW_BL(offset) (0x48000001 | PPC_LI(offset)) #define PPC_RAW_TW(t0, a, b) (0x7c000008 | ___PPC_RS(t0) | ___PPC_RA(a) | ___PPC_RB(b)) #define PPC_RAW_TRAP() PPC_RAW_TW(31, 0, 0) #define PPC_RAW_SETB(t, bfa) (0x7c000100 | ___PPC_RT(t) | ___PPC_RA((bfa) << 2)) +#ifdef CONFIG_PPC32 +#define PPC_RAW_STL PPC_RAW_STW +#define PPC_RAW_STLU PPC_RAW_STWU +#define PPC_RAW_LL PPC_RAW_LWZ +#define PPC_RAW_CMPLI PPC_RAW_CMPWI +#else +#define PPC_RAW_STL PPC_RAW_STD +#define PPC_RAW_STLU PPC_RAW_STDU +#define PPC_RAW_LL PPC_RAW_LD +#define PPC_RAW_CMPLI PPC_RAW_CMPDI +#endif + /* Deal with instructions that older assemblers aren't aware of */ #define PPC_BCCTR_FLUSH stringify_in_c(.long PPC_INST_BCCTR_FLUSH) #define PPC_CP_ABORT stringify_in_c(.long PPC_RAW_CP_ABORT) diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h index cdea5dccaefe..58cdfbfbef94 100644 --- a/arch/powerpc/net/bpf_jit.h +++ b/arch/powerpc/net/bpf_jit.h @@ -21,6 +21,9 @@ #define CTX_NIA(ctx) ((unsigned long)ctx->idx * 4) +#define SZL sizeof(unsigned long) +#define BPF_INSN_SAFETY 64 + #define PLANT_INSTR(d, idx, instr) \ do { if (d) { (d)[idx] = instr; } idx++; } while (0) #define EMIT(instr) PLANT_INSTR(image, ctx->idx, instr) @@ -81,6 +84,13 @@ EMIT(PPC_RAW_ORI(d, d, (uintptr_t)(i) & \ 0xffff)); \ } } while (0) +#define PPC_LI_ADDR PPC_LI64 +#define PPC64_LOAD_PACA() \ + EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc))) +#else +#define PPC_LI64 BUILD_BUG +#define PPC_LI_ADDR PPC_LI32 +#define PPC64_LOAD_PACA() BUILD_BUG() #endif /* @@ -165,6 +175,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code u32 *addrs, int pass, bool extra_pass); void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx); void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx); +void bpf_jit_build_fentry_stubs(u32 *image, struct codegen_context *ctx); void bpf_jit_realloc_regs(struct codegen_context *ctx); int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, long exit_addr); diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c index 984655419da5..54df51ce54c8 100644 --- a/arch/powerpc/net/bpf_jit_comp.c +++ b/arch/powerpc/net/bpf_jit_comp.c @@ -22,11 +22,81 @@ #include "bpf_jit.h" +/* These offsets are from bpf prog end and stay the same across progs */ +static int bpf_jit_ool_stub, bpf_jit_long_branch_stub; + static void bpf_jit_fill_ill_insns(void *area, unsigned int size) { memset32(area, BREAKPOINT_INSTRUCTION, size / 4); } +void dummy_tramp(void); + +asm ( +" .pushsection .text, \"ax\", @progbits ;" +" .global dummy_tramp ;" +" .type dummy_tramp, @function ;" +"dummy_tramp: ;" +#ifdef CONFIG_FTRACE_PFE_OUT_OF_LINE +" blr ;" +#else +" mflr 11 ;" +" mtctr 11 ;" +" mtlr 0 ;" +" bctr ;" +#endif +" .size dummy_tramp, .-dummy_tramp ;" +" .popsection ;" +); + +void bpf_jit_build_fentry_stubs(u32 *image, struct codegen_context *ctx) +{ + int ool_stub_idx, long_branch_stub_idx; + + /* + * Out-of-line stub: + * mflr r0 + * [b|bl] tramp + * mtlr r0 // only with CONFIG_FTRACE_PFE_OUT_OF_LINE + * b bpf_func + 4 + */ + ool_stub_idx = ctx->idx; + EMIT(PPC_RAW_MFLR(_R0)); + EMIT(PPC_RAW_NOP()); + if (IS_ENABLED(CONFIG_FTRACE_PFE_OUT_OF_LINE)) + EMIT(PPC_RAW_MTLR(_R0)); + WARN_ON_ONCE(!is_offset_in_branch_range(4 - (long)ctx->idx * 4)); /* TODO */ + EMIT(PPC_RAW_BRANCH(4 - (long)ctx->idx * 4)); + + /* + * Long branch stub: + * .long + * mflr r11 + * bcl 20,31,$+4 + * mflr r12 + * ld r12, -8-SZL(r12) + * mtctr r12 + * mtlr r11 // needed to retain ftrace ABI + * bctr + */ + if (image) + *((unsigned long *)&image[ctx->idx]) = (unsigned long)dummy_tramp; + ctx->idx += SZL / 4; + long_branch_stub_idx = ctx->idx; + EMIT(PPC_RAW_MFLR(_R11)); + EMIT(PPC_RAW_BCL()); + EMIT(PPC_RAW_MFLR(_R12)); + EMIT(PPC_RAW_LL(_R12, _R12, -8-SZL)); + EMIT(PPC_RAW_MTCTR(_R12)); + EMIT(PPC_RAW_MTLR(_R11)); + EMIT(PPC_RAW_BCTR()); + + if (!bpf_jit_ool_stub) { + bpf_jit_ool_stub = (ctx->idx - ool_stub_idx) * 4; + bpf_jit_long_branch_stub = (ctx->idx - long_branch_stub_idx) * 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))) { @@ -222,7 +292,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) fp->bpf_func = (void *)fimage; fp->jited = 1; - fp->jited_len = proglen + FUNCTION_DESCR_SIZE; + fp->jited_len = cgctx.idx * 4 + FUNCTION_DESCR_SIZE; if (!fp->is_func || extra_pass) { if (bpf_jit_binary_pack_finalize(fp, fhdr, hdr)) { @@ -369,3 +439,633 @@ bool bpf_jit_supports_far_kfunc_call(void) { return IS_ENABLED(CONFIG_PPC64); } + +void *arch_alloc_bpf_trampoline(unsigned int size) +{ + return bpf_prog_pack_alloc(size, bpf_jit_fill_ill_insns); +} + +void arch_free_bpf_trampoline(void *image, unsigned int size) +{ + bpf_prog_pack_free(image, size); +} + +int arch_protect_bpf_trampoline(void *image, unsigned int size) +{ + return 0; +} + +static int invoke_bpf_prog(u32 *image, u32 *ro_image, struct codegen_context *ctx, struct bpf_tramp_link *l, + int regs_off, int retval_off, int run_ctx_off, bool save_ret) +{ + struct bpf_prog *p = l->link.prog; + ppc_inst_t branch_insn; + u32 jmp_idx; + int ret = 0; + + /* Save cookie */ + if (IS_ENABLED(CONFIG_PPC64)) { + PPC_LI64(_R3, l->cookie); + EMIT(PPC_RAW_STD(_R3, _R1, run_ctx_off + offsetof(struct bpf_tramp_run_ctx, bpf_cookie))); + } else { + PPC_LI32(_R3, l->cookie >> 32); + PPC_LI32(_R4, l->cookie); + EMIT(PPC_RAW_STW(_R3, _R1, run_ctx_off + offsetof(struct bpf_tramp_run_ctx, bpf_cookie))); + EMIT(PPC_RAW_STW(_R4, _R1, run_ctx_off + offsetof(struct bpf_tramp_run_ctx, bpf_cookie) + 4)); + } + + /* __bpf_prog_enter(p, &bpf_tramp_run_ctx) */ + PPC_LI_ADDR(_R3, p); + EMIT(PPC_RAW_MR(_R25, _R3)); + EMIT(PPC_RAW_ADDI(_R4, _R1, run_ctx_off)); + ret = bpf_jit_emit_func_call_rel(image, ro_image, ctx, (unsigned long)bpf_trampoline_enter(p)); + if (ret) + return ret; + + /* Remember prog start time returned by __bpf_prog_enter */ + EMIT(PPC_RAW_MR(_R26, _R3)); + + /* + * if (__bpf_prog_enter(p) == 0) + * goto skip_exec_of_prog; + * + * Emit a nop to be later patched with conditional branch, once offset is known + */ + EMIT(PPC_RAW_CMPLI(_R3, 0)); + jmp_idx = ctx->idx; + EMIT(PPC_RAW_NOP()); + + /* p->bpf_func(ctx) */ + EMIT(PPC_RAW_ADDI(_R3, _R1, regs_off)); + if (!p->jited) + PPC_LI_ADDR(_R4, (unsigned long)p->insnsi); + if (!create_branch(&branch_insn, (u32 *)&ro_image[ctx->idx], (unsigned long)p->bpf_func, BRANCH_SET_LINK)) { + if (image) + image[ctx->idx] = ppc_inst_val(branch_insn); + ctx->idx++; + } else { + EMIT(PPC_RAW_LL(_R12, _R25, offsetof(struct bpf_prog, bpf_func))); + EMIT(PPC_RAW_MTCTR(_R12)); + EMIT(PPC_RAW_BCTRL()); + } + + if (save_ret) + EMIT(PPC_RAW_STL(_R3, _R1, retval_off)); + + /* Fix up branch */ + if (image) { + if (create_cond_branch(&branch_insn, &image[jmp_idx], + (unsigned long)&image[ctx->idx], COND_EQ << 16)) + return -EINVAL; + image[jmp_idx] = ppc_inst_val(branch_insn); + } + + /* __bpf_prog_exit(p, start_time, &bpf_tramp_run_ctx) */ + EMIT(PPC_RAW_MR(_R3, _R25)); + EMIT(PPC_RAW_MR(_R4, _R26)); + EMIT(PPC_RAW_ADDI(_R5, _R1, run_ctx_off)); + ret = bpf_jit_emit_func_call_rel(image, ro_image, ctx, (unsigned long)bpf_trampoline_exit(p)); + + return ret; +} + +static int invoke_bpf_mod_ret(u32 *image, u32 *ro_image, struct codegen_context *ctx, struct bpf_tramp_links *tl, + int regs_off, int retval_off, int run_ctx_off, u32 *branches) +{ + int i; + + /* + * The first fmod_ret program will receive a garbage return value. + * Set this to 0 to avoid confusing the program. + */ + EMIT(PPC_RAW_LI(_R3, 0)); + EMIT(PPC_RAW_STL(_R3, _R1, retval_off)); + for (i = 0; i < tl->nr_links; i++) { + if (invoke_bpf_prog(image, ro_image, ctx, tl->links[i], regs_off, retval_off, run_ctx_off, true)) + return -EINVAL; + + /* + * mod_ret prog stored return value after prog ctx. Emit: + * if (*(u64 *)(ret_val) != 0) + * goto do_fexit; + */ + EMIT(PPC_RAW_LL(_R3, _R1, retval_off)); + EMIT(PPC_RAW_CMPLI(_R3, 0)); + + /* + * Save the location of the branch and generate a nop, which is + * replaced with a conditional jump once do_fexit (i.e. the + * start of the fexit invocation) is finalized. + */ + branches[i] = ctx->idx; + EMIT(PPC_RAW_NOP()); + } + + return 0; +} + +static void bpf_trampoline_save_args(u32 *image, struct codegen_context *ctx, int nr_regs, int regs_off) +{ + for (int i = 0; i < nr_regs; i++) + EMIT(PPC_RAW_STL(_R3 + i, _R1, regs_off + i * SZL)); +} + +static void bpf_trampoline_restore_args(u32 *image, struct codegen_context *ctx, int nr_regs, int regs_off) +{ + for (int i = 0; i < nr_regs; i++) + EMIT(PPC_RAW_LL(_R3 + i, _R1, regs_off + i * SZL)); +} + +static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_image, + void *rw_image_end, void *ro_image, + const struct btf_func_model *m, u32 flags, + struct bpf_tramp_links *tlinks, + void *func_addr) +{ + int regs_off, nregs_off, ip_off, run_ctx_off, retval_off, nvr_off, alt_lr_off; + struct bpf_tramp_links *fentry = &tlinks[BPF_TRAMP_FENTRY]; + struct bpf_tramp_links *fexit = &tlinks[BPF_TRAMP_FEXIT]; + struct bpf_tramp_links *fmod_ret = &tlinks[BPF_TRAMP_MODIFY_RETURN]; + int i, ret, nr_regs = m->nr_args, stack_size = 0; + struct codegen_context codegen_ctx, *ctx; + u32 *image = (u32 *)rw_image; + ppc_inst_t branch_insn; + u32 *branches = NULL; + bool save_ret; + + /* TODO: 32-bit enablement */ + if (IS_ENABLED(CONFIG_PPC32)) + return -ENOTSUPP; + + /* Extra registers for struct arguments */ + for (i = 0; i < m->nr_args; i++) + if (m->arg_size[i] > sizeof(unsigned long)) + nr_regs += round_up(m->arg_size[i], sizeof(unsigned long)) / sizeof(unsigned long) - 1; + + /* TODO: We only support functions with in-register arguments - up to 8 per powerpc ABI */ + if (nr_regs > 8) + return -ENOTSUPP; + + ctx = &codegen_ctx; + memset(ctx, 0, sizeof(*ctx)); + + /* + * Generated stack layout: + * + * func prev back chain [ back chain ] + * [ ] -- + * LR save area [ r0 save (64-bit) ] | header + * [ r0 save (32-bit) ] | + * dummy frame for unwind [ back chain 1 ] -- + * [ padding ] align stack frame + * alt_lr_off [ real lr (pfe ool) ] optional - actual lr + * [ r26? ] + * nvr_off [ r25? ] nvr save area + * retval_off [ return value ] + * [ reg argN ] + * [ ... ] + * regs_off [ reg_arg1 ] prog ctx context + * nregs_off [ args count ] + * ip_off [ traced function ] + * [ ... ] + * run_ctx_off [ bpf_tramp_run_ctx ] + * [ TOC save (64-bit) ] -- + * [ LR save (64-bit) ] | header + * [ LR save (32-bit) ] | + * bpf trampoline frame [ back chain 2 ] -- + * + * TODO: tail call cnt? + */ + + /* Minimum stack frame header */ + stack_size = STACK_FRAME_MIN_SIZE; + + /* Room for struct bpf_tramp_run_ctx */ + run_ctx_off = stack_size; + stack_size += round_up(sizeof(struct bpf_tramp_run_ctx), SZL); + + /* Room for IP address argument */ + ip_off = stack_size; + if (flags & BPF_TRAMP_F_IP_ARG) + stack_size += SZL; + + /* Room for args count */ + nregs_off = stack_size; + stack_size += SZL; + + /* Room for args */ + regs_off = stack_size; + stack_size += nr_regs * SZL; + + /* Room for return value of func_addr or fentry prog */ + retval_off = stack_size; + save_ret = flags & (BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_RET_FENTRY_RET); + if (save_ret) + stack_size += SZL; + + /* Room for nvr save area */ + nvr_off = stack_size; + stack_size += 2 * SZL; + + /* Optional save area for actual LR in case of ool ftrace */ + if (IS_ENABLED(CONFIG_FTRACE_PFE_OUT_OF_LINE)) { + alt_lr_off = stack_size; + stack_size += SZL; + } + + /* Padding to align stack frame, if any */ + stack_size = round_up(stack_size, SZL * 2); + + + /* Create dummy frame for unwind, store original return value */ + EMIT(PPC_RAW_STL(_R0, _R1, PPC_LR_STKOFF)); + EMIT(PPC_RAW_STLU(_R1, _R1, -STACK_FRAME_MIN_SIZE)); + + /* Create our stack frame */ + EMIT(PPC_RAW_STLU(_R1, _R1, -stack_size)); + + /* 64-bit: Save TOC and load kernel TOC */ + if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2) && !IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) { + EMIT(PPC_RAW_STD(_R2, _R1, 24)); + PPC64_LOAD_PACA(); + } + + bpf_trampoline_save_args(image, ctx, nr_regs, regs_off); + + /* Save our return address */ + EMIT(PPC_RAW_MFLR(_R3)); + if (IS_ENABLED(CONFIG_FTRACE_PFE_OUT_OF_LINE)) + EMIT(PPC_RAW_STL(_R3, _R1, alt_lr_off)); + else + EMIT(PPC_RAW_STL(_R3, _R1, stack_size + PPC_LR_STKOFF)); + + /* + * Save ip address of the traced function. + * We could recover this from LR, but we will need to address for OOL trampoline, + * and optional GEP area. + */ + if (IS_ENABLED(CONFIG_FTRACE_PFE_OUT_OF_LINE) || flags & BPF_TRAMP_F_IP_ARG) { + EMIT(PPC_RAW_LWZ(_R4, _R3, 4)); + EMIT(PPC_RAW_SLWI(_R4, _R4, 6)); + EMIT(PPC_RAW_SRAWI(_R4, _R4, 6)); + EMIT(PPC_RAW_ADD(_R3, _R3, _R4)); + EMIT(PPC_RAW_ADDI(_R3, _R3, 4)); + } + + if (flags & BPF_TRAMP_F_IP_ARG) + EMIT(PPC_RAW_STL(_R3, _R1, ip_off)); + + if (IS_ENABLED(CONFIG_FTRACE_PFE_OUT_OF_LINE)) + /* Fake our LR for unwind */ + EMIT(PPC_RAW_STL(_R3, _R1, stack_size + PPC_LR_STKOFF)); + + /* Save function arg count -- see bpf_get_func_arg_cnt() */ + /* TODO: should this be nr_args? */ + EMIT(PPC_RAW_LI(_R3, nr_regs)); + EMIT(PPC_RAW_STL(_R3, _R1, nregs_off)); + + /* Save nv regs */ + EMIT(PPC_RAW_STL(_R25, _R1, nvr_off)); + EMIT(PPC_RAW_STL(_R26, _R1, nvr_off + SZL)); + + if (flags & BPF_TRAMP_F_CALL_ORIG) { + PPC_LI_ADDR(_R3, (unsigned long)im); + ret = bpf_jit_emit_func_call_rel(image, ro_image, ctx, (unsigned long)__bpf_tramp_enter); + if (ret) + return ret; + } + + for (i = 0; i < fentry->nr_links; i++) + if (invoke_bpf_prog(image, ro_image, ctx, fentry->links[i], regs_off, retval_off, run_ctx_off, + flags & BPF_TRAMP_F_RET_FENTRY_RET)) + return -EINVAL; + + if (fmod_ret->nr_links) { + branches = kcalloc(fmod_ret->nr_links, sizeof(u32), GFP_KERNEL); + if (!branches) + return -ENOMEM; + + if (invoke_bpf_mod_ret(image, ro_image, ctx, fmod_ret, regs_off, retval_off, run_ctx_off, branches)) { + ret = -EINVAL; + goto cleanup; + } + } + + /* Call the traced function */ + if (flags & BPF_TRAMP_F_CALL_ORIG) { + /* + * The address in LR save area points to the correct point in the original function + * with both FTRACE_PFE_OUT_OF_LINE as well as with traditional ftrace instruction + * sequence + */ + EMIT(PPC_RAW_LL(_R3, _R1, stack_size + PPC_LR_STKOFF)); + EMIT(PPC_RAW_MTCTR(_R3)); + + /* Restore args */ + bpf_trampoline_restore_args(image, ctx, nr_regs, regs_off); + + /* Restore TOC for 64-bit */ + if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2) && !IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) + EMIT(PPC_RAW_LD(_R2, _R1, 24)); + EMIT(PPC_RAW_BCTRL()); + if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2) && !IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) + PPC64_LOAD_PACA(); + + /* Store return value for bpf prog to access */ + EMIT(PPC_RAW_STL(_R3, _R1, retval_off)); + + /* Reserve space to patch branch instruction to skip fexit progs */ + im->ip_after_call = &((u32 *)ro_image)[ctx->idx]; + EMIT(PPC_RAW_NOP()); + } + + /* Update branches saved in invoke_bpf_mod_ret with address of do_fexit */ + for (i = 0; i < fmod_ret->nr_links && image; i++) { + if (create_cond_branch(&branch_insn, &image[branches[i]], + (unsigned long)&image[ctx->idx], COND_NE << 16)) { + ret = -EINVAL; + goto cleanup; + } + + image[branches[i]] = ppc_inst_val(branch_insn); + } + + for (i = 0; i < fexit->nr_links; i++) + if (invoke_bpf_prog(image, ro_image, ctx, fexit->links[i], regs_off, retval_off, run_ctx_off, false)) { + ret = -EINVAL; + goto cleanup; + } + + if (flags & BPF_TRAMP_F_CALL_ORIG) { + im->ip_epilogue = &((u32 *)ro_image)[ctx->idx]; + PPC_LI_ADDR(_R3, im); + ret = bpf_jit_emit_func_call_rel(image, ro_image, ctx, (unsigned long)__bpf_tramp_exit); + if (ret) + goto cleanup; + } + + if (flags & BPF_TRAMP_F_RESTORE_REGS) + bpf_trampoline_restore_args(image, ctx, nr_regs, regs_off); + + /* Restore return value of func_addr or fentry prog */ + if (save_ret) + EMIT(PPC_RAW_LL(_R3, _R1, retval_off)); + + /* Restore nv regs */ + EMIT(PPC_RAW_LL(_R26, _R1, nvr_off + SZL)); + EMIT(PPC_RAW_LL(_R25, _R1, nvr_off)); + + /* Epilogue */ + if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2) && !IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) + EMIT(PPC_RAW_LD(_R2, _R1, 24)); + if (flags & BPF_TRAMP_F_SKIP_FRAME) { + /* Skip the traced function and return to parent */ + EMIT(PPC_RAW_ADDI(_R1, _R1, stack_size + STACK_FRAME_MIN_SIZE)); + EMIT(PPC_RAW_LL(_R0, _R1, PPC_LR_STKOFF)); + EMIT(PPC_RAW_MTLR(_R0)); + EMIT(PPC_RAW_BLR()); + } else { + if (IS_ENABLED(CONFIG_FTRACE_PFE_OUT_OF_LINE)) { + EMIT(PPC_RAW_LL(_R0, _R1, alt_lr_off)); + EMIT(PPC_RAW_MTLR(_R0)); + EMIT(PPC_RAW_ADDI(_R1, _R1, stack_size + STACK_FRAME_MIN_SIZE)); + EMIT(PPC_RAW_LL(_R0, _R1, PPC_LR_STKOFF)); + EMIT(PPC_RAW_BLR()); + } else { + EMIT(PPC_RAW_LL(_R0, _R1, stack_size + PPC_LR_STKOFF)); + EMIT(PPC_RAW_MTCTR(_R0)); + EMIT(PPC_RAW_ADDI(_R1, _R1, stack_size + STACK_FRAME_MIN_SIZE)); + EMIT(PPC_RAW_LL(_R0, _R1, PPC_LR_STKOFF)); + EMIT(PPC_RAW_MTLR(_R0)); + EMIT(PPC_RAW_BCTR()); + } + } + + /* Make sure the trampoline generation logic doesn't overflow */ + if (image && WARN_ON_ONCE(&image[ctx->idx] > (u32 *)rw_image_end - BPF_INSN_SAFETY)) { + ret = -EFAULT; + goto cleanup; + } + ret = ctx->idx * 4 + BPF_INSN_SAFETY * 4; + +cleanup: + kfree(branches); + return ret; +} + +int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags, + struct bpf_tramp_links *tlinks, void *func_addr) +{ + struct bpf_tramp_image im; + void *image; + int ret; + + /* + * Allocate a temporary buffer for __arch_prepare_bpf_trampoline(). + * This will NOT cause fragmentation in direct map, as we do not + * call set_memory_*() on this buffer. + * + * We cannot use kvmalloc here, because we need image to be in + * module memory range. + */ + image = bpf_jit_alloc_exec(PAGE_SIZE); + if (!image) + return -ENOMEM; + + ret = __arch_prepare_bpf_trampoline(&im, image, image + PAGE_SIZE, image, + m, flags, tlinks, func_addr); + bpf_jit_free_exec(image); + + return ret; +} + +int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end, + const struct btf_func_model *m, u32 flags, + struct bpf_tramp_links *tlinks, + void *func_addr) +{ + u32 size = image_end - image; + void *rw_image, *tmp; + int ret; + + /* + * rw_image doesn't need to be in module memory range, so we can + * use kvmalloc. + */ + rw_image = kvmalloc(size, GFP_KERNEL); + if (!rw_image) + return -ENOMEM; + + ret = __arch_prepare_bpf_trampoline(im, rw_image, rw_image + size, image, m, + flags, tlinks, func_addr); + if (ret < 0) + goto out; + + if (bpf_jit_enable > 1) + bpf_jit_dump(1, ret - BPF_INSN_SAFETY * 4, 1, rw_image); + + tmp = bpf_arch_text_copy(image, rw_image, size); + if (IS_ERR(tmp)) + ret = PTR_ERR(tmp); + +out: + kvfree(rw_image); + return ret; +} + +static int bpf_modify_inst(void *ip, ppc_inst_t old_inst, ppc_inst_t new_inst) +{ + ppc_inst_t org_inst; + + if (copy_inst_from_kernel_nofault(&org_inst, ip)) { + pr_err("0x%lx: fetching instruction failed\n", (unsigned long)ip); + return -EFAULT; + } + + if (!ppc_inst_equal(org_inst, old_inst)) { + pr_err("0x%lx: expected (%08lx) != found (%08lx)\n", + (unsigned long)ip, ppc_inst_as_ulong(old_inst), ppc_inst_as_ulong(org_inst)); + return -EINVAL; + } + + if (ppc_inst_equal(old_inst, new_inst)) + return 0; + + return patch_instruction(ip, new_inst); +} + +/* + * A 3-step process for bpf prog entry: + * 1. At bpf prog entry, a single nop/b: + * bpf_func: + * [nop|b] ool_stub + * 2. Out-of-line stub: + * ool_stub: + * mflr r0 + * [b|bl] / + * mtlr r0 // CONFIG_FTRACE_PFE_OUT_OF_LINE only + * b bpf_func + 4 + * 3. Long branch stub: + * long_branch_stub: + * .long / + * mflr r11 + * bcl 20,31,$+4 + * mflr r12 + * ld r12, -16(r12) + * mtctr r12 + * mtlr r11 // needed to retain ftrace ABI + * bctr + * + * dummy_tramp is used to reduce synchronization requirements. Old trampoline is only freed + * through bpf_tramp_image_put() which uses rcu_tasks, so we don't need to do the same here. + */ +int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type poke_type, + void *old_addr, void *new_addr) +{ + unsigned long bpf_func, bpf_func_end, size, offset; + ppc_inst_t old_inst, new_inst; + int ret = 0, branch_flags; + char name[KSYM_NAME_LEN]; + + /* TODO: 32-bit enablement */ + if (IS_ENABLED(CONFIG_PPC32)) + return -ENOTSUPP; + + bpf_func = (unsigned long)ip; + branch_flags = poke_type == BPF_MOD_CALL ? BRANCH_SET_LINK : 0; + + /* We currently only support poking bpf programs */ + if (!__bpf_address_lookup(bpf_func, &size, &offset, name)) { + pr_err("%s (0x%lx): kernel/modules are not supported\n", __func__, bpf_func); + return -ENOTSUPP; + } + + /* + * If we are not poking at bpf prog entry, then we are simply patching in/out + * an unconditional branch instruction at im->ip_after_call + */ + if (offset) { + if (poke_type != BPF_MOD_JUMP) { + pr_err("%s (0x%lx): calls are not supported in bpf prog body\n", __func__, + bpf_func); + return -ENOTSUPP; + } + old_inst = ppc_inst(PPC_RAW_NOP()); + if (old_addr) + if (create_branch(&old_inst, ip, (unsigned long)old_addr, 0)) + return -ERANGE; + new_inst = ppc_inst(PPC_RAW_NOP()); + if (new_addr) + if (create_branch(&new_inst, ip, (unsigned long)new_addr, 0)) + return -ERANGE; + mutex_lock(&text_mutex); + ret = bpf_modify_inst(ip, old_inst, new_inst); + mutex_unlock(&text_mutex); + return ret; + } + + bpf_func_end = bpf_func + size; + + /* Address of the jmp/call instruction in the out-of-line stub */ + ip = (void *)(bpf_func_end - bpf_jit_ool_stub + 4); + + if (!is_offset_in_branch_range((long)ip - 4 - bpf_func)) { + pr_err("%s (0x%lx): bpf prog too large, ool stub out of branch range\n", __func__, + bpf_func); + return -ERANGE; + } + + old_inst = ppc_inst(PPC_RAW_NOP()); + if (old_addr) { + if (is_offset_in_branch_range(ip - old_addr)) + create_branch(&old_inst, ip, (unsigned long)old_addr, branch_flags); + else + create_branch(&old_inst, ip, bpf_func_end - bpf_jit_long_branch_stub, + branch_flags); + } + new_inst = ppc_inst(PPC_RAW_NOP()); + if (new_addr) { + if (is_offset_in_branch_range(ip - new_addr)) + create_branch(&new_inst, ip, (unsigned long)new_addr, branch_flags); + else + create_branch(&new_inst, ip, bpf_func_end - bpf_jit_long_branch_stub, + branch_flags); + } + + mutex_lock(&text_mutex); + + /* + * 1. Update the address in the long branch stub: + * If new_addr is out of range, we will have to use the long branch stub, so patch new_addr + * here. Otherwise, revert to dummy_tramp, but only if we had patched old_addr here. + */ + if ((new_addr && !is_offset_in_branch_range(new_addr - ip)) || + (old_addr && !is_offset_in_branch_range(old_addr - ip))) + ret = patch_ulong((void *)(bpf_func_end - bpf_jit_long_branch_stub - SZL), + (new_addr && !is_offset_in_branch_range(new_addr - ip)) ? + (unsigned long)new_addr : (unsigned long)dummy_tramp); + if (ret) + goto out; + + /* 2. Update the branch/call in the out-of-line stub */ + ret = bpf_modify_inst(ip, old_inst, new_inst); + if (ret) + goto out; + + /* 3. Update instruction at bpf prog entry */ + ip = (void *)bpf_func; + if (!old_addr || !new_addr) { + if (!old_addr) { + old_inst = ppc_inst(PPC_RAW_NOP()); + create_branch(&new_inst, ip, bpf_func_end - bpf_jit_ool_stub, 0); + } else { + new_inst = ppc_inst(PPC_RAW_NOP()); + create_branch(&old_inst, ip, bpf_func_end - bpf_jit_ool_stub, 0); + } + ret = bpf_modify_inst(ip, old_inst, new_inst); + } + +out: + mutex_unlock(&text_mutex); + return ret; +} diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c index a0c4f1bde83e..c4db278dae36 100644 --- a/arch/powerpc/net/bpf_jit_comp32.c +++ b/arch/powerpc/net/bpf_jit_comp32.c @@ -127,13 +127,16 @@ void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx) { int i; + /* Instruction for trampoline attach */ + EMIT(PPC_RAW_NOP()); + /* Initialize tail_call_cnt, to be skipped if we do tail calls. */ if (ctx->seen & SEEN_TAILCALL) EMIT(PPC_RAW_LI(_R4, 0)); else EMIT(PPC_RAW_NOP()); -#define BPF_TAILCALL_PROLOGUE_SIZE 4 +#define BPF_TAILCALL_PROLOGUE_SIZE 8 if (bpf_has_stack_frame(ctx)) EMIT(PPC_RAW_STWU(_R1, _R1, -BPF_PPC_STACKFRAME(ctx))); @@ -198,6 +201,8 @@ void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx) bpf_jit_emit_common_epilogue(image, ctx); EMIT(PPC_RAW_BLR()); + + bpf_jit_build_fentry_stubs(image, ctx); } /* Relative offset needs to be calculated based on final image location */ diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 288ff32d676f..b58d1be63ea4 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -126,6 +126,9 @@ void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx) { int i; + /* Instruction for trampoline attach */ + EMIT(PPC_RAW_NOP()); + #ifndef CONFIG_PPC_KERNEL_PCREL if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2)) EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc))); @@ -200,6 +203,8 @@ void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx) EMIT(PPC_RAW_MR(_R3, bpf_to_ppc(BPF_REG_0))); EMIT(PPC_RAW_BLR()); + + bpf_jit_build_fentry_stubs(image, ctx); } int bpf_jit_emit_func_call_rel(u32 *image, u32 *fimage, struct codegen_context *ctx, u64 func) @@ -303,7 +308,7 @@ static int bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 o */ int b2p_bpf_array = bpf_to_ppc(BPF_REG_2); int b2p_index = bpf_to_ppc(BPF_REG_3); - int bpf_tailcall_prologue_size = 8; + int bpf_tailcall_prologue_size = 12; if (!IS_ENABLED(CONFIG_PPC_KERNEL_PCREL) && IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2)) bpf_tailcall_prologue_size += 4; /* skip past the toc load */