From patchwork Tue Oct 29 22:17:07 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yonghong Song X-Patchwork-Id: 13855586 X-Patchwork-Delegate: bpf@iogearbox.net Received: from 66-220-155-179.mail-mxout.facebook.com (66-220-155-179.mail-mxout.facebook.com [66.220.155.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 557C4206E61 for ; Tue, 29 Oct 2024 22:20:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=66.220.155.179 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730240427; cv=none; b=dgvW3kt6sTpgj6maQx6OSUeUjiUTAEBgh5KJN+2PLXq2aA5McapH4l2WG41gZ0ZMGE/2h5pBG546YH3Kgq5cE3nPqzsZkaXo+CNLudf4d7jy6MzU+O9rcwam7Rr/ZGdUIRusbB+sLrAapfDpkbon+IlQbwbrPgRC2bm6hTqhVl4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730240427; c=relaxed/simple; bh=yGemHCqZpB+JfjrCz1yYHHmGhW+9Mr3xLUKBtAzyyR0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=e7o1amcbmQ11WGk6HS9NoWC/lnwUCwnOs5qoTXKBpQ1hoEJ//AzDo66ZPsv+njmv0yRxDjrUtpx18k+59x0ryJ9Vpj+8zvUM08fSyR9LCDkEOO5K8yP4AifK/UD/hbBgQi8jVXCyt0Oyi1P6W6FFAl3S4rZ6NBgB3Fm8rr0j23Q= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.dev; spf=fail smtp.mailfrom=linux.dev; arc=none smtp.client-ip=66.220.155.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=linux.dev Received: by devbig309.ftw3.facebook.com (Postfix, from userid 128203) id 2D35DA91CFBF; Tue, 29 Oct 2024 15:17:07 -0700 (PDT) From: Yonghong Song To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , kernel-team@fb.com, Martin KaFai Lau , Tejun Heo Subject: [PATCH bpf-next v7 6/9] bpf, x86: Support private stack in jit Date: Tue, 29 Oct 2024 15:17:07 -0700 Message-ID: <20241029221707.266393-1-yonghong.song@linux.dev> X-Mailer: git-send-email 2.43.5 In-Reply-To: <20241029221637.264348-1-yonghong.song@linux.dev> References: <20241029221637.264348-1-yonghong.song@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net Support private stack in jit. The x86 register 9 (X86_REG_R9) is used to replace bpf frame register (BPF_REG_10). The private stack is used per subprog if it is enabled by verifier. The X86_REG_R9 is saved and restored around every func call (not including tailcall) to maintain correctness of X86_REG_R9. Signed-off-by: Yonghong Song --- arch/x86/net/bpf_jit_comp.c | 61 +++++++++++++++++++++++++++++++++++++ 1 file changed, 61 insertions(+) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 181d9f04418f..4ee69071c26d 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -325,6 +325,22 @@ struct jit_context { /* Number of bytes that will be skipped on tailcall */ #define X86_TAIL_CALL_OFFSET (12 + ENDBR_INSN_SIZE) +static void push_r9(u8 **pprog) +{ + u8 *prog = *pprog; + + EMIT2(0x41, 0x51); /* push r9 */ + *pprog = prog; +} + +static void pop_r9(u8 **pprog) +{ + u8 *prog = *pprog; + + EMIT2(0x41, 0x59); /* pop r9 */ + *pprog = prog; +} + static void push_r12(u8 **pprog) { u8 *prog = *pprog; @@ -1404,6 +1420,24 @@ static void emit_shiftx(u8 **pprog, u32 dst_reg, u8 src_reg, bool is64, u8 op) *pprog = prog; } +static void emit_priv_frame_ptr(u8 **pprog, void __percpu *priv_frame_ptr) +{ + u8 *prog = *pprog; + + /* movabs r9, priv_frame_ptr */ + emit_mov_imm64(&prog, X86_REG_R9, (__force long) priv_frame_ptr >> 32, + (u32) (__force long) priv_frame_ptr); + +#ifdef CONFIG_SMP + /* add , gs:[] */ + EMIT2(0x65, 0x4c); + EMIT3(0x03, 0x0c, 0x25); + EMIT((u32)(unsigned long)&this_cpu_off, 4); +#endif + + *pprog = prog; +} + #define INSN_SZ_DIFF (((addrs[i] - addrs[i - 1]) - (prog - temp))) #define __LOAD_TCC_PTR(off) \ @@ -1421,6 +1455,7 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, u8 *rw_image int insn_cnt = bpf_prog->len; bool seen_exit = false; u8 temp[BPF_MAX_INSN_SIZE + BPF_INSN_SAFETY]; + void __percpu *priv_frame_ptr = NULL; u64 arena_vm_start, user_vm_start; int i, excnt = 0; int ilen, proglen = 0; @@ -1429,6 +1464,10 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, u8 *rw_image int err; stack_depth = bpf_prog->aux->stack_depth; + if (bpf_prog->aux->priv_stack_ptr) { + priv_frame_ptr = bpf_prog->aux->priv_stack_ptr + round_up(stack_depth, 8); + stack_depth = 0; + } arena_vm_start = bpf_arena_get_kern_vm_start(bpf_prog->aux->arena); user_vm_start = bpf_arena_get_user_vm_start(bpf_prog->aux->arena); @@ -1457,6 +1496,9 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, u8 *rw_image emit_mov_imm64(&prog, X86_REG_R12, arena_vm_start >> 32, (u32) arena_vm_start); + if (priv_frame_ptr) + emit_priv_frame_ptr(&prog, priv_frame_ptr); + ilen = prog - temp; if (rw_image) memcpy(rw_image + proglen, temp, ilen); @@ -1476,6 +1518,14 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, u8 *rw_image u8 *func; int nops; + if (priv_frame_ptr) { + if (src_reg == BPF_REG_FP) + src_reg = X86_REG_R9; + + if (dst_reg == BPF_REG_FP) + dst_reg = X86_REG_R9; + } + switch (insn->code) { /* ALU */ case BPF_ALU | BPF_ADD | BPF_X: @@ -2136,9 +2186,15 @@ st: if (is_imm8(insn->off)) } if (!imm32) return -EINVAL; + if (priv_frame_ptr) { + push_r9(&prog); + ip += 2; + } ip += x86_call_depth_emit_accounting(&prog, func, ip); if (emit_call(&prog, func, ip)) return -EINVAL; + if (priv_frame_ptr) + pop_r9(&prog); break; } @@ -3563,6 +3619,11 @@ bool bpf_jit_supports_exceptions(void) return IS_ENABLED(CONFIG_UNWINDER_ORC); } +bool bpf_jit_supports_private_stack(void) +{ + return true; +} + void arch_bpf_stack_walk(bool (*consume_fn)(void *cookie, u64 ip, u64 sp, u64 bp), void *cookie) { #if defined(CONFIG_UNWINDER_ORC)