From: Palmer Dabbelt <palmerdabbelt@google.com>
To: Björn Töpel <bjorn.topel@gmail.com>
Cc: daniel@iogearbox.net, netdev@vger.kernel.org, ast@kernel.org,
Björn Töpel <bjorn.topel@gmail.com>,
linux-riscv@lists.infradead.org, bpf@vger.kernel.org
Subject: Re: [PATCH bpf-next v2 1/9] riscv, bpf: fix broken BPF tail calls
Date: Thu, 19 Dec 2019 14:02:11 -0800 (PST) [thread overview]
Message-ID: <mhng-a8b020f4-3baf-41be-908b-1a843d659b1c@palmerdabbelt-glaptop> (raw)
In-Reply-To: <20191216091343.23260-2-bjorn.topel@gmail.com>
On Mon, 16 Dec 2019 01:13:35 PST (-0800), Björn Töpel wrote:
> 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;
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>
next prev parent reply other threads:[~2019-12-19 22:04 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-16 9:13 [PATCH bpf-next v2 0/9] riscv: BPF JIT fix, optimizations and far jumps support Björn Töpel
2019-12-16 9:13 ` [PATCH bpf-next v2 1/9] riscv, bpf: fix broken BPF tail calls Björn Töpel
2019-12-16 9:13 ` [PATCH bpf-next v2 2/9] riscv, bpf: add support for far branching Björn Töpel
2019-12-16 9:13 ` [PATCH bpf-next v2 3/9] riscv, bpf: add support for far branching when emitting tail call Björn Töpel
2019-12-16 9:13 ` [PATCH bpf-next v2 4/9] riscv, bpf: add support for far jumps and exits Björn Töpel
2019-12-16 9:13 ` [PATCH bpf-next v2 5/9] riscv, bpf: optimize BPF tail calls Björn Töpel
2019-12-16 9:13 ` [PATCH bpf-next v2 6/9] riscv, bpf: provide RISC-V specific JIT image alloc/free Björn Töpel
2019-12-16 15:09 ` Daniel Borkmann
2019-12-18 6:23 ` Björn Töpel
2020-01-04 1:32 ` Paul Walmsley
2020-01-07 10:24 ` Björn Töpel
2020-01-07 10:47 ` Paul Walmsley
2020-02-02 13:37 ` Alex Ghiti
2020-02-03 12:28 ` Björn Töpel
2020-02-03 20:57 ` Alex Ghiti
2019-12-16 9:13 ` [PATCH bpf-next v2 7/9] riscv, bpf: optimize calls Björn Töpel
2019-12-16 9:13 ` [PATCH bpf-next v2 8/9] riscv, bpf: add missing uapi header for BPF_PROG_TYPE_PERF_EVENT programs Björn Töpel
2019-12-16 9:13 ` [PATCH bpf-next v2 9/9] riscv, perf: add arch specific perf_arch_bpf_user_pt_regs Björn Töpel
2019-12-19 15:07 ` [PATCH bpf-next v2 0/9] riscv: BPF JIT fix, optimizations and far jumps support Daniel Borkmann
2019-12-19 22:02 ` Palmer Dabbelt [this message]
2019-12-23 18:03 ` [PATCH bpf-next v2 2/9] riscv, bpf: add support for far branching Palmer Dabbelt
2020-01-07 8:13 ` Björn Töpel
2020-01-23 2:08 ` Palmer Dabbelt
2019-12-23 18:18 ` [PATCH bpf-next v2 3/9] riscv, bpf: add support for far branching when emitting tail call Palmer Dabbelt
2019-12-23 18:18 ` [PATCH bpf-next v2 4/9] riscv, bpf: add support for far jumps and exits Palmer Dabbelt
2019-12-23 18:29 ` [PATCH bpf-next v2 5/9] riscv, bpf: optimize BPF tail calls Palmer Dabbelt
2019-12-23 18:30 ` [PATCH bpf-next v2 6/9] riscv, bpf: provide RISC-V specific JIT image alloc/free Palmer Dabbelt
2019-12-23 18:58 ` [PATCH bpf-next v2 7/9] riscv, bpf: optimize calls Palmer Dabbelt
2020-01-07 10:14 ` Björn Töpel
2020-01-28 2:15 ` Palmer Dabbelt
2020-02-03 12:11 ` Björn Töpel
2019-12-23 18:58 ` [PATCH bpf-next v2 8/9] riscv, bpf: add missing uapi header for BPF_PROG_TYPE_PERF_EVENT programs Palmer Dabbelt
2019-12-23 18:58 ` [PATCH bpf-next v2 9/9] riscv, perf: add arch specific perf_arch_bpf_user_pt_regs Palmer Dabbelt
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