linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
	kafai@fb.com, songliubraving@fb.com, yhs@fb.com,
	john.fastabend@gmail.com, kpsingh@chromium.org,
	naveen.n.rao@linux.ibm.com, sandipan@linux.ibm.com
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: [PATCH 2/3] powerpc/ebpf32: Rework 64 bits shifts to avoid tests and branches
Date: Mon, 12 Apr 2021 11:44:17 +0000 (UTC)	[thread overview]
Message-ID: <03167350b05b2fe8b741e53363ee37709d0f878d.1618227846.git.christophe.leroy@csgroup.eu> (raw)
In-Reply-To: <34d12a4f75cb8b53a925fada5e7ddddd3b145203.1618227846.git.christophe.leroy@csgroup.eu>

Re-implement BPF_ALU64 | BPF_{LSH/RSH/ARSH} | BPF_X with branchless
implementation copied from misc_32.S.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/net/bpf_jit_comp32.c | 39 +++++++++++++++----------------
 1 file changed, 19 insertions(+), 20 deletions(-)

diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c
index ca6fe1583460..ef21b09df76e 100644
--- a/arch/powerpc/net/bpf_jit_comp32.c
+++ b/arch/powerpc/net/bpf_jit_comp32.c
@@ -548,16 +548,15 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
 			EMIT(PPC_RAW_SLW(dst_reg, dst_reg, src_reg));
 			break;
 		case BPF_ALU64 | BPF_LSH | BPF_X: /* dst <<= src; */
-			EMIT(PPC_RAW_ADDIC_DOT(__REG_R0, src_reg, -32));
-			PPC_BCC_SHORT(COND_LT, (ctx->idx + 4) * 4);
-			EMIT(PPC_RAW_SLW(dst_reg_h, dst_reg, __REG_R0));
-			EMIT(PPC_RAW_LI(dst_reg, 0));
-			PPC_JMP((ctx->idx + 6) * 4);
+			bpf_set_seen_register(ctx, tmp_reg);
 			EMIT(PPC_RAW_SUBFIC(__REG_R0, src_reg, 32));
 			EMIT(PPC_RAW_SLW(dst_reg_h, dst_reg_h, src_reg));
+			EMIT(PPC_RAW_ADDI(tmp_reg, src_reg, 32));
 			EMIT(PPC_RAW_SRW(__REG_R0, dst_reg, __REG_R0));
-			EMIT(PPC_RAW_SLW(dst_reg, dst_reg, src_reg));
+			EMIT(PPC_RAW_SLW(tmp_reg, dst_reg, tmp_reg));
 			EMIT(PPC_RAW_OR(dst_reg_h, dst_reg_h, __REG_R0));
+			EMIT(PPC_RAW_SLW(dst_reg, dst_reg, src_reg));
+			EMIT(PPC_RAW_OR(dst_reg_h, dst_reg_h, tmp_reg));
 			break;
 		case BPF_ALU | BPF_LSH | BPF_K: /* (u32) dst <<= (u32) imm */
 			if (!imm)
@@ -585,16 +584,15 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
 			EMIT(PPC_RAW_SRW(dst_reg, dst_reg, src_reg));
 			break;
 		case BPF_ALU64 | BPF_RSH | BPF_X: /* dst >>= src */
-			EMIT(PPC_RAW_ADDIC_DOT(__REG_R0, src_reg, -32));
-			PPC_BCC_SHORT(COND_LT, (ctx->idx + 4) * 4);
-			EMIT(PPC_RAW_SRW(dst_reg, dst_reg_h, __REG_R0));
-			EMIT(PPC_RAW_LI(dst_reg_h, 0));
-			PPC_JMP((ctx->idx + 6) * 4);
-			EMIT(PPC_RAW_SUBFIC(0, src_reg, 32));
+			bpf_set_seen_register(ctx, tmp_reg);
+			EMIT(PPC_RAW_SUBFIC(__REG_R0, src_reg, 32));
 			EMIT(PPC_RAW_SRW(dst_reg, dst_reg, src_reg));
+			EMIT(PPC_RAW_ADDI(tmp_reg, src_reg, 32));
 			EMIT(PPC_RAW_SLW(__REG_R0, dst_reg_h, __REG_R0));
-			EMIT(PPC_RAW_SRW(dst_reg_h, dst_reg_h, src_reg));
+			EMIT(PPC_RAW_SRW(tmp_reg, dst_reg_h, tmp_reg));
 			EMIT(PPC_RAW_OR(dst_reg, dst_reg, __REG_R0));
+			EMIT(PPC_RAW_SRW(dst_reg_h, dst_reg_h, src_reg));
+			EMIT(PPC_RAW_OR(dst_reg, dst_reg, tmp_reg));
 			break;
 		case BPF_ALU | BPF_RSH | BPF_K: /* (u32) dst >>= (u32) imm */
 			if (!imm)
@@ -622,16 +620,17 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
 			EMIT(PPC_RAW_SRAW(dst_reg_h, dst_reg, src_reg));
 			break;
 		case BPF_ALU64 | BPF_ARSH | BPF_X: /* (s64) dst >>= src */
-			EMIT(PPC_RAW_ADDIC_DOT(__REG_R0, src_reg, -32));
-			PPC_BCC_SHORT(COND_LT, (ctx->idx + 4) * 4);
-			EMIT(PPC_RAW_SRAW(dst_reg, dst_reg_h, __REG_R0));
-			EMIT(PPC_RAW_SRAWI(dst_reg_h, dst_reg_h, 31));
-			PPC_JMP((ctx->idx + 6) * 4);
-			EMIT(PPC_RAW_SUBFIC(0, src_reg, 32));
+			bpf_set_seen_register(ctx, tmp_reg);
+			EMIT(PPC_RAW_SUBFIC(__REG_R0, src_reg, 32));
 			EMIT(PPC_RAW_SRW(dst_reg, dst_reg, src_reg));
 			EMIT(PPC_RAW_SLW(__REG_R0, dst_reg_h, __REG_R0));
-			EMIT(PPC_RAW_SRAW(dst_reg_h, dst_reg_h, src_reg));
+			EMIT(PPC_RAW_ADDI(tmp_reg, src_reg, 32));
 			EMIT(PPC_RAW_OR(dst_reg, dst_reg, __REG_R0));
+			EMIT(PPC_RAW_RLWINM(__REG_R0, tmp_reg, 0, 26, 26));
+			EMIT(PPC_RAW_SRAW(tmp_reg, dst_reg_h, tmp_reg));
+			EMIT(PPC_RAW_SRAW(dst_reg_h, dst_reg_h, src_reg));
+			EMIT(PPC_RAW_SLW(tmp_reg, tmp_reg, __REG_R0));
+			EMIT(PPC_RAW_OR(dst_reg, dst_reg, tmp_reg));
 			break;
 		case BPF_ALU | BPF_ARSH | BPF_K: /* (s32) dst >>= imm */
 			if (!imm)
-- 
2.25.0


  reply	other threads:[~2021-04-12 11:50 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-12 11:44 [PATCH 1/3] powerpc/ebpf32: Fix comment on BPF_ALU{64} | BPF_LSH | BPF_K Christophe Leroy
2021-04-12 11:44 ` Christophe Leroy [this message]
2021-04-12 11:44 ` [PATCH 3/3] powerpc/ebpf32: Use standard function call for functions within 32M distance Christophe Leroy
2021-04-21 13:08 ` [PATCH 1/3] powerpc/ebpf32: Fix comment on BPF_ALU{64} | BPF_LSH | BPF_K Michael Ellerman

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=03167350b05b2fe8b741e53363ee37709d0f878d.1618227846.git.christophe.leroy@csgroup.eu \
    --to=christophe.leroy@csgroup.eu \
    --cc=andrii@kernel.org \
    --cc=ast@kernel.org \
    --cc=benh@kernel.crashing.org \
    --cc=bpf@vger.kernel.org \
    --cc=daniel@iogearbox.net \
    --cc=john.fastabend@gmail.com \
    --cc=kafai@fb.com \
    --cc=kpsingh@chromium.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=mpe@ellerman.id.au \
    --cc=naveen.n.rao@linux.ibm.com \
    --cc=netdev@vger.kernel.org \
    --cc=paulus@samba.org \
    --cc=sandipan@linux.ibm.com \
    --cc=songliubraving@fb.com \
    --cc=yhs@fb.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).