From patchwork Sun Jul 14 08:27:45 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: 13732625 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 2E0935EE97; Sun, 14 Jul 2024 08:29:58 +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=1720945799; cv=none; b=WBypIajbkTVUvtODBwdz8bvSlcS07YzxNtdUjSOxFZXgT/P4iV5e9RR4xmAAM1BiViFyTky0ItF0jGIcCy/ngqjc9it+8sQSxLew+EPECtRRxjh5BnZ+q1bbrFDedMyLW/55t5ZpgJ+aBj9u17tu7b0Qfn9p8Xu8ymnFm1kbjKI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720945799; c=relaxed/simple; bh=IskF71GDKHjgxuqQkVkMv1lu202Is52qU3cvSr5TzWg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HDGD/ZVumKTrOU94k0zyF8sxEm8vg7KINKUJO177pH3rB7fpk/Zs2SLaEPkS6yOzHnBmRn4dsRioGBFB4l+eMMUYFZ7TDQxdASpNRFPAKfsMkh4h9RJmkc5sMLflorlASBRlF5YnG1KlDONqVM/KrJOLBBXuw0mgHLmtqYM0keA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ez2dMaHK; 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="ez2dMaHK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 003A3C116B1; Sun, 14 Jul 2024 08:29:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1720945798; bh=IskF71GDKHjgxuqQkVkMv1lu202Is52qU3cvSr5TzWg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ez2dMaHKVcxvJb5HVREOY3vyA8FdKoFQ2VCsgb9kbKy+Se7X83ieG3zMzk7beBRVs hz/u5AWz7B8yPyYWMGCBXauJ8IwLW7fynI9ORXtAzRqGgJG+Qbi0Wz6jxIvBbPa8Jm rZ5IpQyP2vGpnc1DEvVFoNJwgMFgphkrpcgQQHBuinoHiRgxKBiGnY+87gh7IiiAvr Owog/3UBfZ6KE/OgKxjYghrMC74PjcLcLk3AUGX/RawP7axcr+ilvlK88/eYq1CewD vxSJB07wQq+dc3Uq11gwPPwZQQYsepHTiSxelPOH19JEtCJtPNOxx3Ruteqi53j4GK +MQYRzJq5rESw== From: Naveen N Rao To: , , , linux-kbuild@vger.kernel.org, Cc: Michael Ellerman , Nicholas Piggin , Christophe Leroy , Steven Rostedt , Masami Hiramatsu , Mark Rutland , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Masahiro Yamada , Hari Bathini , Mahesh Salgaonkar , Vishal Chourasia Subject: [RFC PATCH v4 09/17] powerpc64/bpf: Fold bpf_jit_emit_func_call_hlp() into bpf_jit_emit_func_call_rel() Date: Sun, 14 Jul 2024 13:57:45 +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 Commit 61688a82e047 ("powerpc/bpf: enable kfunc call") enhanced bpf_jit_emit_func_call_hlp() to handle calls out to module region, where bpf progs are generated. The only difference now between bpf_jit_emit_func_call_hlp() and bpf_jit_emit_func_call_rel() is in handling of the initial pass where target function address is not known. Fold that logic into bpf_jit_emit_func_call_hlp() and rename it to bpf_jit_emit_func_call_rel() to simplify bpf function call JIT code. We don't actually need to load/restore TOC across a call out to a different kernel helper or to a different bpf program since they all work with the kernel TOC. We only need to do it if we have to call out to a module function. So, guard TOC load/restore with appropriate conditions. Signed-off-by: Naveen N Rao --- arch/powerpc/net/bpf_jit_comp64.c | 61 +++++++++---------------------- 1 file changed, 17 insertions(+), 44 deletions(-) diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 2cbcdf93cc19..f3be024fc685 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -202,14 +202,22 @@ void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx) EMIT(PPC_RAW_BLR()); } -static int -bpf_jit_emit_func_call_hlp(u32 *image, u32 *fimage, struct codegen_context *ctx, u64 func) +int bpf_jit_emit_func_call_rel(u32 *image, u32 *fimage, struct codegen_context *ctx, u64 func) { unsigned long func_addr = func ? ppc_function_entry((void *)func) : 0; long reladdr; - if (WARN_ON_ONCE(!kernel_text_address(func_addr))) - return -EINVAL; + /* bpf to bpf call, func is not known in the initial pass. Emit 5 nops as a placeholder */ + if (!func) { + for (int i = 0; i < 5; i++) + EMIT(PPC_RAW_NOP()); + /* elfv1 needs an additional instruction to load addr from descriptor */ + if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V1)) + EMIT(PPC_RAW_NOP()); + EMIT(PPC_RAW_MTCTR(_R12)); + EMIT(PPC_RAW_BCTRL()); + return 0; + } #ifdef CONFIG_PPC_KERNEL_PCREL reladdr = func_addr - local_paca->kernelbase; @@ -266,7 +274,8 @@ bpf_jit_emit_func_call_hlp(u32 *image, u32 *fimage, struct codegen_context *ctx, * We can clobber r2 since we get called through a * function pointer (so caller will save/restore r2). */ - EMIT(PPC_RAW_LD(_R2, bpf_to_ppc(TMP_REG_2), 8)); + if (is_module_text_address(func_addr)) + EMIT(PPC_RAW_LD(_R2, bpf_to_ppc(TMP_REG_2), 8)); } else { PPC_LI64(_R12, func); EMIT(PPC_RAW_MTCTR(_R12)); @@ -276,46 +285,14 @@ bpf_jit_emit_func_call_hlp(u32 *image, u32 *fimage, struct codegen_context *ctx, * Load r2 with kernel TOC as kernel TOC is used if function address falls * within core kernel text. */ - EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc))); + if (is_module_text_address(func_addr)) + EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc))); } #endif return 0; } -int bpf_jit_emit_func_call_rel(u32 *image, u32 *fimage, struct codegen_context *ctx, u64 func) -{ - unsigned int i, ctx_idx = ctx->idx; - - if (WARN_ON_ONCE(func && is_module_text_address(func))) - return -EINVAL; - - /* skip past descriptor if elf v1 */ - func += FUNCTION_DESCR_SIZE; - - /* Load function address into r12 */ - PPC_LI64(_R12, func); - - /* For bpf-to-bpf function calls, the callee's address is unknown - * until the last extra pass. As seen above, we use PPC_LI64() to - * load the callee's address, but this may optimize the number of - * instructions required based on the nature of the address. - * - * Since we don't want the number of instructions emitted to increase, - * we pad the optimized PPC_LI64() call with NOPs to guarantee that - * we always have a five-instruction sequence, which is the maximum - * that PPC_LI64() can emit. - */ - if (!image) - for (i = ctx->idx - ctx_idx; i < 5; i++) - EMIT(PPC_RAW_NOP()); - - EMIT(PPC_RAW_MTCTR(_R12)); - EMIT(PPC_RAW_BCTRL()); - - return 0; -} - static int bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 out) { /* @@ -1102,11 +1079,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code if (ret < 0) return ret; - if (func_addr_fixed) - ret = bpf_jit_emit_func_call_hlp(image, fimage, ctx, func_addr); - else - ret = bpf_jit_emit_func_call_rel(image, fimage, ctx, func_addr); - + ret = bpf_jit_emit_func_call_rel(image, fimage, ctx, func_addr); if (ret) return ret;