[bpf-next,v2,1/9] riscv, bpf: fix broken BPF tail calls

Message ID	20191216091343.23260-2-bjorn.topel@gmail.com
State	Accepted
Delegated to:	BPF Maintainers
Headers	show Return-Path: <bpf-owner@vger.kernel.org> From: =?utf-8?b?QmrDtnJuIFTDtnBlbA==?= <bjorn.topel@gmail.com> To: daniel@iogearbox.net, ast@kernel.org, netdev@vger.kernel.org Cc: =?utf-8?b?QmrDtnJuIFTDtnBlbA==?= <bjorn.topel@gmail.com>, linux-riscv@lists.infradead.org, bpf@vger.kernel.org Subject: [PATCH bpf-next v2 1/9] riscv, bpf: fix broken BPF tail calls Date: Mon, 16 Dec 2019 10:13:35 +0100 Message-Id: <20191216091343.23260-2-bjorn.topel@gmail.com> In-Reply-To: <20191216091343.23260-1-bjorn.topel@gmail.com> References: <20191216091343.23260-1-bjorn.topel@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: bpf-owner@vger.kernel.org Precedence: bulk
Series	riscv: BPF JIT fix, optimizations and far jumps support \| expand [bpf-next,v2,0/9] riscv: BPF JIT fix, optimizations and far jumps support [bpf-next,v2,1/9] riscv, bpf: fix broken BPF tail calls [bpf-next,v2,2/9] riscv, bpf: add support for far branching [bpf-next,v2,3/9] riscv, bpf: add support for far branching when emitting tail call [bpf-next,v2,4/9] riscv, bpf: add support for far jumps and exits [bpf-next,v2,5/9] riscv, bpf: optimize BPF tail calls [bpf-next,v2,6/9] riscv, bpf: provide RISC-V specific JIT image alloc/free [bpf-next,v2,7/9] riscv, bpf: optimize calls [bpf-next,v2,8/9] riscv, bpf: add missing uapi header for BPF_PROG_TYPE_PERF_EVENT programs [bpf-next,v2,9/9] riscv, perf: add arch specific perf_arch_bpf_user_pt_regs

Message ID

20191216091343.23260-2-bjorn.topel@gmail.com

State

Accepted

Delegated to:

BPF Maintainers

Headers

From: =?utf-8?b?QmrDtnJuIFTDtnBlbA==?= <bjorn.topel@gmail.com>
To: daniel@iogearbox.net, ast@kernel.org, netdev@vger.kernel.org
Cc: =?utf-8?b?QmrDtnJuIFTDtnBlbA==?= <bjorn.topel@gmail.com>,
	linux-riscv@lists.infradead.org, bpf@vger.kernel.org
Subject: [PATCH bpf-next v2 1/9] riscv, bpf: fix broken BPF tail calls
Date: Mon, 16 Dec 2019 10:13:35 +0100
Message-Id: <20191216091343.23260-2-bjorn.topel@gmail.com>
In-Reply-To: <20191216091343.23260-1-bjorn.topel@gmail.com>
References: <20191216091343.23260-1-bjorn.topel@gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Sender: bpf-owner@vger.kernel.org
Precedence: bulk

Series

riscv: BPF JIT fix, optimizations and far jumps support | expand

Commit Message

Björn Töpel Dec. 16, 2019, 9:13 a.m. UTC

The BPF JIT incorrectly clobbered the a0 register, and did not flag
usage of s5 register when BPF stack was being used.

Fixes: 2353ecc6f91f ("bpf, riscv: add BPF JIT for RV64G")
Signed-off-by: Björn Töpel <bjorn.topel@gmail.com>
---
 arch/riscv/net/bpf_jit_comp.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/net/bpf_jit_comp.c b/arch/riscv/net/bpf_jit_comp.c
index 5451ef3845f2..1606ebd49666 100644
--- a/arch/riscv/net/bpf_jit_comp.c
+++ b/arch/riscv/net/bpf_jit_comp.c
@@ -120,6 +120,11 @@  static bool seen_reg(int reg, struct rv_jit_context *ctx)
 	return false;
 }
 
+static void mark_fp(struct rv_jit_context *ctx)
+{
+	__set_bit(RV_CTX_F_SEEN_S5, &ctx->flags);
+}
+
 static void mark_call(struct rv_jit_context *ctx)
 {
 	__set_bit(RV_CTX_F_SEEN_CALL, &ctx->flags);
@@ -596,7 +601,8 @@  static void __build_epilogue(u8 reg, struct rv_jit_context *ctx)
 
 	emit(rv_addi(RV_REG_SP, RV_REG_SP, stack_adjust), ctx);
 	/* Set return value. */
-	emit(rv_addi(RV_REG_A0, RV_REG_A5, 0), ctx);
+	if (reg == RV_REG_RA)
+		emit(rv_addi(RV_REG_A0, RV_REG_A5, 0), ctx);
 	emit(rv_jalr(RV_REG_ZERO, reg, 0), ctx);
 }
 
@@ -1426,6 +1432,10 @@  static void build_prologue(struct rv_jit_context *ctx)
 {
 	int stack_adjust = 0, store_offset, bpf_stack_adjust;
 
+	bpf_stack_adjust = round_up(ctx->prog->aux->stack_depth, 16);
+	if (bpf_stack_adjust)
+		mark_fp(ctx);
+
 	if (seen_reg(RV_REG_RA, ctx))
 		stack_adjust += 8;
 	stack_adjust += 8; /* RV_REG_FP */
@@ -1443,7 +1453,6 @@  static void build_prologue(struct rv_jit_context *ctx)
 		stack_adjust += 8;
 
 	stack_adjust = round_up(stack_adjust, 16);
-	bpf_stack_adjust = round_up(ctx->prog->aux->stack_depth, 16);
 	stack_adjust += bpf_stack_adjust;
 
 	store_offset = stack_adjust - 8;

[bpf-next,v2,1/9] riscv, bpf: fix broken BPF tail calls

Commit Message

Patch