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From: Breno Leitao <leitao@debian.org>
To: Puranjay Mohan <puranjay@kernel.org>
Cc: bpf@vger.kernel.org, "Alexei Starovoitov" <ast@kernel.org>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	"Andrii Nakryiko" <andrii@kernel.org>,
	"Martin KaFai Lau" <martin.lau@linux.dev>,
	"Eduard Zingerman" <eddyz87@gmail.com>,
	"Kumar Kartikeya Dwivedi" <memxor@gmail.com>,
	"Song Liu" <song@kernel.org>,
	"Yonghong Song" <yonghong.song@linux.dev>,
	"Jiri Olsa" <jolsa@kernel.org>,
	"Xu Kuohai" <xukuohai@huaweicloud.com>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	"Will Deacon" <will@kernel.org>,
	"Luke Nelson" <luke.r.nels@gmail.com>,
	"Xi Wang" <xi.wang@gmail.com>, "Björn Töpel" <bjorn@kernel.org>,
	"Pu Lehui" <pulehui@huawei.com>, "Paul Walmsley" <pjw@kernel.org>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	"Alexandre Ghiti" <alex@ghiti.fr>,
	linux-arm-kernel@lists.infradead.org,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH bpf-next v2 1/2] bpf, arm64: Remove redundant bpf_flush_icache() after pack allocator finalize
Date: Wed, 15 Apr 2026 05:38:01 -0700	[thread overview]
Message-ID: <ad-GmdGbXrZAi7WA@gmail.com> (raw)
In-Reply-To: <20260413191111.3426023-2-puranjay@kernel.org>

On Mon, Apr 13, 2026 at 12:11:08PM -0700, Puranjay Mohan wrote:
> bpf_flush_icache() calls flush_icache_range() to clean the data cache
> and invalidate the instruction cache for the JITed code region. However,
> since commit 1dad391daef1 ("bpf, arm64: use bpf_prog_pack for memory
> management"), this flush is redundant.
> 
> bpf_jit_binary_pack_finalize() copies the JITed instructions to the ROX
> region via bpf_arch_text_copy() -> aarch64_insn_copy() -> __text_poke(),
> and __text_poke() already calls flush_icache_range() on the written
> range. The subsequent bpf_flush_icache() repeats the same cache
> maintenance on an overlapping range, including an unnecessary second
> synchronous IPI to all CPUs via kick_all_cpus_sync().
> 
> Remove the redundant bpf_flush_icache() call and its now-unused
> definition.
> 
> Fixes: 1dad391daef1 ("bpf, arm64: use bpf_prog_pack for memory management")
> Acked-by: Song Liu <song@kernel.org>
> Signed-off-by: Puranjay Mohan <puranjay@kernel.org>

Acked-by: Breno Leitao <leitao@debian.org>

WARNING: multiple messages have this Message-ID (diff)
From: Breno Leitao <leitao@debian.org>
To: Puranjay Mohan <puranjay@kernel.org>
Cc: bpf@vger.kernel.org, "Alexei Starovoitov" <ast@kernel.org>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	"Andrii Nakryiko" <andrii@kernel.org>,
	"Martin KaFai Lau" <martin.lau@linux.dev>,
	"Eduard Zingerman" <eddyz87@gmail.com>,
	"Kumar Kartikeya Dwivedi" <memxor@gmail.com>,
	"Song Liu" <song@kernel.org>,
	"Yonghong Song" <yonghong.song@linux.dev>,
	"Jiri Olsa" <jolsa@kernel.org>,
	"Xu Kuohai" <xukuohai@huaweicloud.com>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	"Will Deacon" <will@kernel.org>,
	"Luke Nelson" <luke.r.nels@gmail.com>,
	"Xi Wang" <xi.wang@gmail.com>, "Björn Töpel" <bjorn@kernel.org>,
	"Pu Lehui" <pulehui@huawei.com>, "Paul Walmsley" <pjw@kernel.org>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	"Albert Ou" <aou@eecs.berkeley.edu>,
	"Alexandre Ghiti" <alex@ghiti.fr>,
	linux-arm-kernel@lists.infradead.org,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH bpf-next v2 1/2] bpf, arm64: Remove redundant bpf_flush_icache() after pack allocator finalize
Date: Wed, 15 Apr 2026 05:38:01 -0700	[thread overview]
Message-ID: <ad-GmdGbXrZAi7WA@gmail.com> (raw)
In-Reply-To: <20260413191111.3426023-2-puranjay@kernel.org>

On Mon, Apr 13, 2026 at 12:11:08PM -0700, Puranjay Mohan wrote:
> bpf_flush_icache() calls flush_icache_range() to clean the data cache
> and invalidate the instruction cache for the JITed code region. However,
> since commit 1dad391daef1 ("bpf, arm64: use bpf_prog_pack for memory
> management"), this flush is redundant.
> 
> bpf_jit_binary_pack_finalize() copies the JITed instructions to the ROX
> region via bpf_arch_text_copy() -> aarch64_insn_copy() -> __text_poke(),
> and __text_poke() already calls flush_icache_range() on the written
> range. The subsequent bpf_flush_icache() repeats the same cache
> maintenance on an overlapping range, including an unnecessary second
> synchronous IPI to all CPUs via kick_all_cpus_sync().
> 
> Remove the redundant bpf_flush_icache() call and its now-unused
> definition.
> 
> Fixes: 1dad391daef1 ("bpf, arm64: use bpf_prog_pack for memory management")
> Acked-by: Song Liu <song@kernel.org>
> Signed-off-by: Puranjay Mohan <puranjay@kernel.org>

Acked-by: Breno Leitao <leitao@debian.org>

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  parent reply	other threads:[~2026-04-15 12:38 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-04-13 19:11 [PATCH bpf-next v2 0/2] bpf, arm64/riscv: Remove redundant icache flush after pack allocator finalize Puranjay Mohan
2026-04-13 19:11 ` Puranjay Mohan
2026-04-13 19:11 ` [PATCH bpf-next v2 1/2] bpf, arm64: Remove redundant bpf_flush_icache() " Puranjay Mohan
2026-04-13 19:11   ` Puranjay Mohan
2026-04-14  1:55   ` Xu Kuohai
2026-04-14  1:55     ` Xu Kuohai
2026-04-14  9:38     ` Puranjay Mohan
2026-04-14  9:38       ` Puranjay Mohan
2026-04-14 11:16       ` Xu Kuohai
2026-04-14 11:16         ` Xu Kuohai
2026-04-15 12:38   ` Breno Leitao [this message]
2026-04-15 12:38     ` Breno Leitao
2026-04-13 19:11 ` [PATCH bpf-next v2 2/2] bpf, riscv: " Puranjay Mohan
2026-04-13 19:11   ` Puranjay Mohan
2026-04-14  1:13   ` Pu Lehui
2026-04-14  1:13     ` Pu Lehui
2026-04-14 14:48   ` Paul Chaignon
2026-04-14 14:48     ` Paul Chaignon
2026-04-15 19:20 ` [PATCH bpf-next v2 0/2] bpf, arm64/riscv: Remove redundant icache flush " patchwork-bot+netdevbpf
2026-04-15 19:20   ` patchwork-bot+netdevbpf
2026-04-30  3:25 ` patchwork-bot+linux-riscv
2026-04-30  3:25   ` patchwork-bot+linux-riscv

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