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From: Daniel Borkmann <daniel@iogearbox.net>
To: "Björn Töpel" <bjorn.topel@gmail.com>
Cc: netdev@vger.kernel.org, linux-riscv@lists.infradead.org,
	bpf@vger.kernel.org, ast@kernel.org
Subject: Re: [PATCH bpf-next v2 0/9] riscv: BPF JIT fix, optimizations and far jumps support
Date: Thu, 19 Dec 2019 16:07:26 +0100	[thread overview]
Message-ID: <20191219150726.GA23959@pc-9.home> (raw)
In-Reply-To: <20191216091343.23260-1-bjorn.topel@gmail.com>

On Mon, Dec 16, 2019 at 10:13:34AM +0100, Björn Töpel wrote:
> 
> This series contain one non-critical fix, support for far jumps. and
> some optimizations for the BPF JIT.
> 
> Previously, the JIT only supported 12b branch targets for conditional
> branches, and 21b for unconditional branches. Starting with this
> series, 32b branching is supported.
> 
> As part of supporting far jumps, branch relaxation was introduced. The
> idea is to start with a pessimistic jump (e.g. auipc/jalr) and for
> each pass the JIT will have an opportunity to pick a better
> instruction (e.g. jal) and shrink the image. Instead of two passes,
> the JIT requires more passes. It typically converges after 3 passes.
> 
> The optimizations mentioned in the subject are for calls and tail
> calls. In the tail call generation we can save one instruction by
> using the offset in jalr. Calls are optimized by doing (auipc)/jal(r)
> relative jumps instead of loading the entire absolute address and
> doing jalr. This required that the JIT image allocator was made RISC-V
> specific, so we can ensure that the JIT image and the kernel text are
> in range (32b).
> 
> The last two patches of the series is not critical to the series, but
> are two UAPI build issues for BPF events. A closer look from the
> RV-folks would be much appreciated.
> 
> The test_bpf.ko module, selftests/bpf/test_verifier and
> selftests/seccomp/seccomp_bpf pass all tests.
> 
> RISC-V is still missing proper kprobe and tracepoint support, so a lot
> of BPF selftests cannot be run.

Applied, thanks!


  parent reply	other threads:[~2019-12-19 15:07 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 ` Daniel Borkmann [this message]
2019-12-19 22:02 ` [PATCH bpf-next v2 1/9] riscv, bpf: fix broken BPF tail calls Palmer Dabbelt
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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